MOS Tendencies and Forecasting Tips
for WeatherWorks Zones
Zone 1
MOS Tendencies
ORH: this is not very representative of Central or South Central MA. It's too cold as it's elevation is 900+ ft.
Worcester is only 500 feet (where most of our clients are). Only use for the hills.
BED: More representative for Central MA and Middlesex/Inland Essex along with LWM
BVY: Good proxy for the Essex coast
BOS: Typically too warm in the winter and too cool in the summer for Boston metro as it sits right on the
water. Doesn't cool enough at night either. Don't use it for Boston burbs! Use it to modify OWD for burbs.
OWD: pretty good for Norfolk, however don't use it for Eastern Norfolk - too much ocean influence.
MQE: doesn't help much with Norfolk as it's on a hill
MHT/ASH: typically a good blend for Inland Southern NH
PSM: pretty solid for coastal NH
DAW: not bad for Inland SE NH, but I feel it may be slightly too cold at times (it is located pretty far north)
Zone Forecast Tips
Zone 1 Overview: Definitely be aware of a north wind! This will lock cold air into Central MA/Inland NH/Inland
Essex Middlesex, even Boston Burbs. In a freezing rain situation, this will hold sub 32 degree air into the region
well beyond what bufkit indicates (3 hours past bufkit warming is not unusual).
- A north wind shift on the Essex coast (if snowing and cold north) will quickly drop temps in a winter storm!
- Coastal fronts tend to set up at I-95, right near our Boston Metro to Boston burbs line. One side will be
raining, with heavy snow just west.
- Beware of inland cutter with a weak low developing near the benchmark or Cape! Even though bufkit will
indicate a good warming wind from the E or SE, it's usually pretty calm and warming doesn't happen.
- Watch back-building of snow bands in a coastal low situation. It always happens...it just does. You may want
to account for this in end times.
- Beware of a cold easterly wind ahead of a warm front pushing in from the south. The shield will progress
north, but then ocean effect snow can develop into Plymouth or Essex Co. You may want to have an earlier
start time because of this on the coasts. In some instances, this ocean effect can even become a "firehose" of
snow, esp with a little convergence at the surface and very cold air with deep unidirectional easterly flow.
- Radar has a tough time "seeing" MHT into Dover, it may look light, but it's really heavy (I know, I've gotten
calls). Keep an eye on infrared satellite to help, especially in snow shower situations. Watch cameras.
- Snow showers on a NW-W flow typically have a hard time making to Boston, unless aided by a strong vort
Zone 2
MOS Tendencies:
HFD and BDL are generally representative of Hartford Metro, carefully with BDL mos, it is typically colder than
HFD at night and warmer during the day in winter. Use BDL as "outlier" lows at night (think Avon/Bloomfield).
MMK is pretty good for Central CT, I use it for Waterbury too, but it's usually too warm for the Western CT
zone. I would blend it with DXR for Western CT
HVN/BDR careful with wind direction, on a SE - E wind it can be too warm, W wind they can be too cold for
highs
GON usually pretty solid for Eastern CT coast. Watch your wind directions again. Not representative of SE CT
Hills, you have to go cooler in the winter.
IJD is a good start for NE CT, but go colder than it in the winter. It is not representative of the hills of Tolland
and Windham
PVD/TAN not bad for SE MA, but don't use PVD for Inland RI, not representative. Side more on SFZ
A blend of UUU/WST is typically good for Southern RI
A blend of PYM and EWB is typically good for SE MA Coast.
FMH/CQX/PVC blend is pretty good for the Cape, however they can run too cold in the winter at night if the
wind is up
Forecast Zone Tips
- First off Hartford likes to warm on a downsloping westerly or SW wind...in winter watch a north wind as this
will lock cold air into the valley. This is particularly true with a frz rain event...when a secondary is taking over
on the coast. Snow showers have a hard time making it to Hartford, and watch the "Hartford hole" as precip
has a hard time getting in there in the winter...dry air/virga
- CT Coast - Need to watch winds carefully and sound temps... a S or SE wind can kill high temps in the
summer... a W or WSW wind can warm nicely… In winter, watch the area just inland from the coast (West CT
to Central and SE Hills) for a heavy snow band. It just happens.
- Tolland always gets crushed in winter...snow showers tend to end up here too.
- RI always has a tough time seeing tons of snow, but NW RI does well. PVD is not a good MOS to use for Inland
RI, use SZF instead.
- TAN warms and cools well on nice days and nights...rain/snow mix lines usually set up NW here in coastals
but watch a wind shifting north as that can quickly change to snow, especially if snowing and cold to north.
- Cape Cod watch ocean effect on a N or NE wind with very cold temps at 850mb (need similar conditions to
lake effect snow) and also ahead of winter storms on a E wind.
Zone 3
MOS Tendencies:
SWF's MOS max/min temperatures can be misleading (sometimes by a good 5 degrees). This goes back to the
fact that SWF doesn't report highs & lows...so it does the best it can with just hourly numbers. Also
contributing to the problem is that the airport itself does not radiate (or sometimes warm) as well as the rest
of the region (or maybe there is an issue with the thermometer/siting too). Thus, MOS minimums can be too
high, and MOS maximums can be too low compared to the surrounding area.
OXC is on a hill (726'), and is often cooler under typical conditions than the surrounding area (especially
Waterbury, 300'). Sometimes they will be warmer in an inversion!
HPN's MOS is ok. However, it's really right on the border between the Northern & Southern Westchester
zones, and is not really representative of either. In the daytime, it's generally OK for both zones (add a few
degrees for the South except in cases of onshore flow). At night it's a often a blend of the 2 zones for lows...so
just lean low north, lean high south.
FOK can radiate very, very, very well. Its readings can be as much as 10 degrees colder than any other number
we can find nearby. So for Eastern LI forecasts in radiating situations...generally use it as a "lower bound"
number. Also be aware that considering they're far out on LI, their winds calm out much easier than you would
think and sometimes MOS doesn't pick up on it. I've seen FOK's MOS be 12-14 degrees to warm at night, and a
general 4-7 warmer than the region's representative temperature.
Forecast Zone Tips
Zone 3 (NY & W CT) experiences just about everything from areas that never warm in Orange County to
extreme coastal influences in Eastern Long Island. Thankfully, the zones pretty much work in gradient fashion
from northwest to southeast...but here are some general things to keep in mind.
Orange & Dutchess Counties:
Obviously the least influenced by the coast, and usually have similar weather conditions. However, there are
some important notes:
1. Orange is almost always colder than Dutchess by a few degrees in most situations. (With wintertime WAA
patterns, Dutchess always warms a bit more quickly as warm air gets up the valley faster). While both zones
have mountains of 800'+, most of our clients are not impacted by them. The only slight exception is the
Monroe area in Orange County where it gets close to 700'. (This area can also get up slope enhancement and
get slightly higher snowfall totals)
2. More often than not, Orange gets more snow (and usually precip too) than Dutchess. There are two reasons
for this: The Dutchess County zone is a little further north and as a result further removed from coastal lows.
Additionally, systems moving in from the west have a tendency to weaken as they move further east.
3. In WAA patterns that involve P-Type changes to plain rain...when there isn't a lot of surface wind (which
seems to happen a lot), and when MOS/Bufkits show warming well above freezing...this warming can take a
longer time than modeled. This long delay can result in temps holding near freezing and a long duration threat
of freezing rain, or freezing drizzle if the atmosphere is saturated. In fact, sometimes it takes the
Cold/Occluded front moving in from the west to mix out the atmosphere. As a result, the warmest
temperatures in these events often occur BEHIND the cold front in a CAA pattern...even at night!
4. Radar can be very deceiving. These regions are pretty far away from OKX, ENX, DIX & BGM. It often misses
light precipitation or makes what can be heavy precip look rather light. Unfortunately, there aren't too many
cams to compare it to. Sometimes JFK Tower radar can help, but it doesn't go nearly far enough northward. Do
the best you can with METARs, and intuition. You will likely get more than one call from a client telling you that
it's snowing heavily, and you would suspect ~2-4 mile light snow.
Putnam/N. West & Western CT:
These regions can behave like coastal one at times...but usually trend towards their inland counterparts.
Obviously, given their location they are subject to tight north to south gradients in terms of temperatures and
snowfall.
1. From a snow standpoint, (in coastal storms) these zones can often end up with the most. Even though they
might not be as cold as areas to the north, they usually have more moisture, and can have "lollipops". In case
of all snow events...heavy bands often form in this area (esp. the southern half of the zone). In mixing events,
sometimes the region looks like they will mix, but don't, or will sit just north of the mix line for a while where
there are often the heaviest snowfall rates.
2. In the WAA scenarios discussed above, these areas usually at least warm into the mid 30s, and don't have
the same duration threat for icing. Sometimes there can be additional warming behind the cold/occluded
front.
3. The Danbury-Waterbury area is often a good spot for streamers to sneak in from Upstate NY on a NW flow,
especially in the presence of a vort max. In the winter of 2014-15, some hi-res models picked this out.
S. West & Western CT Coast:
Depending on the situation, these can be the trickiest regions of the entire zone. While it's easy to consider
them coastal, sometimes the warming just doesn't quite get there in the winter...so they may stay snow longer
than you think. Some of my worst busts have been in these areas because the NE or N wind (10+ kt) can hold
off a change to the E or SE.
Also...these regions are particularly subject to sharp North to South differences. Unlike in the zones just to the
north, we have clients all over these regions, so there's a good chance our clients will be experiencing very
different conditions at the same time within the region.
NYC:
Another hard area to forecast. Despite there being 2 zones, which work pretty well for Manhattan, Brooklyn &
Queens, it's not perfect. Oftentimes, Staten Island (away from the coast) is more like an inland SW suburb
(think Central NJ). Sometimes the Bronx is just another world, and is really more like Southern Westchester
and can get up to 8" while Central Park may barely get 4”.
Other notes:
1. Obviously highly urban, it doesn't radiate well. It also takes Mod/Heavy Snow or really cold temps with light
snow to stick on pavements in the urban areas during the daylight hours. Be careful though, parts of each
Borough (even northern Manhattan) have suburban/park-like areas where these rules to do not apply.
2. Southern Queens & Brooklyn usually warm-up as fast or faster than the models suggest. Watch JFK's wind,
it's usually the first sign of things.
3. Make sure to make use of METARs & boards. With 8 million people and 2 first-order airports (3 if you
include EWR) and, you usually have a very good idea as to what's actually going on. Note that KNYC will not
report mixed precip, as the observer does NOT augment ASOS obs. In that respect, KNYC is no better than
KCDW or other similar stations.
4. In cases of NE Winds, use your Western Coastal CT Forecast to help. If it will snow there...that helps it to
snow in NYC (especially Bronx). Meanwhile if you are expecting mixed precip up there, it becomes very hard to
snow in NYC.
LI/Eastern LI:
In a lot of respects, everything from NYC applies to Long Island (not quite as urban...especially in Suffolk
County). Other specific notes:
1. Airports (obs/MOS) are "Central/South" and not representative of the beaches or the north shore...boards &
cams are your friends here. Expect some variation.
2. The North Shore from Northport to Port Jefferson (north of the Northern State Pkwy/347) is a well-known
sweet spot for snow. Some theories to explain this: enhancement from LI Sound & hills (150-200') just north of
LIE slow down mixing
3. To repeat point 4 from above...because it's most important here. If Eastern CT/RI/SE MA are seeing mixed
precip or rain, and there's any hint of a NE wind...it's quite hard for LI to snow. The main exception would be if
LI has higher precip intensity...even then it's very difficult.
Zone 4
MOS Tendencies
Scranton/WB AVP 948 FT – Representative of the valley cities in NEPA (Scranton to WB). This is where the
clients cover most. Do understand NE PA zone goes down to 550 ft, and above 1500 ft.
Mount Pocono MPO 1893 FT – Generally the highest and coldest spot. Generally only representative of
Hazleton, and even at that MPO will be a bit cold most times. Can be looked at for reference for some of the
hills above 1000 ft in NW NJ, but understand it is only to be used as a reference and not actually what will take
place.
Sussex FWN 420 FT – Typically good for Sussex and the Gap, but need to be careful with elevations and on
radiational cooling nights. FWN is one of the best radiating MOSs
Andover K12N 581 FT - A good representation of Warren and Sussex and somewhat Morris Co. Despite the
higher elevation, it often warmer than FWN because of geography and being further south.
Morristown MMU 187 FT & Caldwell CDW 174 FT – No real glaring notes here. I think MMU often times
won’t have lows or temps at all. Mainly use CDW and not so much MMU.
Teterboro TEB 10 FT – Also generally representative of where it is. Can typically be a guide for the lower end
temps in Northeast NJ, but not quite the lowest possible. Northern parts of Bergen Co are often a few degrees
cooler than TEB.
EWR 30 FT – Typically the highest you can go with temperatures for Northeast NJ. Just a few miles west with
some minor elevation is generally a few degrees cooler.
SMQ 105 FT – Probably the most inconsistent site in all of NNJ. Radiational cooling nights it can be way, way
too low. And even on a number of just calm nights it can be too cold. In terms of high temps, it is pretty good
for Somerset Co, but often too warm for Hunterdon Co, especially as you go north. ABE can be helpful there.
Forecast Zones Tips - Winter
Sussex – Most times my starting point. Most populated areas are between 450-800ft elevation, however the
most important thing to remember is most clients cover at least some area which go to 1000-1400, so when
applicable, you must include notes as to higher snow totals or colder temperatures in elevations and if it will
impact their work or ice watches.
Typical Mos: FWN / 12N, though need to figure out what is going on above 1000’.
Gap – Can most times be very similar if not the same as Sussex. The biggest difference will be the snow totals,
if there is any difference at all. Perhaps a degree or two difference on the temps in the warmer direction.
Elevation does still play a factor here for snow totals, but not quite to the extreme of Sussex. Generally, areas
are around 300-600’ and up to 1000-1100’ in some locations.
Typical Mos: FWN/12N blend, with some consideration of ABE / AVP.
Morris – the real snow capitol of NJ. Despite Sussex getting more snow in the elevations, most of Morris is
over 900’ and up to 1300’ making the entire region an elevation. Often times temps will be similar to Sussex,
however with any elevation dependent storms (and even storms that you think aren’t elevation dependent),
Morris should be the same if not higher than Sussex in terms of snow (all things being equal). It seems
counterintuitive, but it happens quite a bit. Typical Mos: Situational, although typically similar to Sussex… Need
to figure out what is going on above 1000’.
Warren – Home to the Hackettstown hole. 12N / ABE are good guides for temps, however Snow totals are
always a tough forecast. A Majority of the client base is in Hackettstown, so totals can be on the lower end of
your thinking in some instances, but we do have to take into consideration the surrounding elevations as
well. Comparatively speaking, Sussex is generally a 50/50 split elevation/valley; Morris is 90/10
elevation/valley and warren, while there are many elevated places, we generally look at as mainly valley with
consideration to some higher hills.
Typical Mos: 12N / ABE
NOTE: For these NW 4 zones above, on radiational cooling nights valleys can be MUCH colder than
elevations. Additionally, these zones are most prone to accumulating snow showers from the NW.
Northcentral – This is one of the toughest zones. Most times this is a battle ground for the mixing line, this is
where tight snowfall gradients often set up, and typically have the largest temperatures spreads across the
area. “north of I-78” and “in the northern part of the county” are usually in a lot of forecasts to try and portray
higher impacts.
Typical Mos: ABE/SMQ blend, with some situational intuition
West Rockberg – Depending on the situation, West Rockberg will act like Sussex or Warren or Morris for most
storms, so one of these (again depending on the situation) can typically be a starting point (IE: elevation
dependent storm? Warren. SW to NE mixing line? Morris. Cold air daming? Sussex. (not for every case, but
just some potential ideas. You need to figure out which it might act most like). There are elevations to the
West (Passaic Co) and it drops off to the East (Bergen Co), though goes north as well (Rockland Co). Most areas
are 400-500’, up to 800’, so it’s not typically as imperative to mention higher hills; But do keep this in mind
when picking a snowfall forecast.
Typical Mos: 12N / CDW… But overall usually acts similar to Sussex/Warren
East Rockberg – Often times with temperature and snowfall when compared to West Rockberg, you should be
thinking higher on the temps and lower on the snow, primarily due to elevation and urbanization.
Typical Mos: CDW / TEB… and usually just a bit warmer than the W Rock forecast
Morsex – One of the more straightforward zones, all things considered. There are hills here (300-500 ft) so it is
certainly cooler that NE NJ, but certainly warmer than Morris Co for the most part. A lot of clients have Morsex
in addition to other regions.
Typical Mos: CDW with MMU consideration
Northeast – This can also be a battle ground for temps and mixing. General mentality is to think of your
forecast as the outskirts of Newark with mention to colder suburbs, meaning generally leaning lower on snow
totals with mention to higher totals in surrounding areas. An E / SE wind will easily warm this area. Margin
temps scenarios may struggle to accumulate on pavements here during the daytime, especially early / late in
the season.
Typical Mos: EWR as the high end/ Moresex/East Rockberg low end blend.
Northeast PA – Clients fall in the valley cities (Scranton to Wilkes-barre) with one or two going down to
Hazleton. Hazleton is a different world compared to SWB, but not so much that you change your forecast to
reflect it. You do need to mention “continued icing for elevations over 1000’” or “Higher totals towards
Hazleton” or just “higher in the elevations” if that’s the case. Typical Mos: AVP, with consideration of MPO
Forecast Zones Tips - Summer
As you would expect, NE NJ is typically much warmer than NW NJ, especially at night. There are certain days
where the high temps are the same across the board, but it is tough to say when that exactly happens. I
believe it is on fairly warm aloft days, with a light-moderate S-SW wind but not entirely sure.
It is tough for Containers to get radiational fog. The main fog nights are either evening / night rain followed by
calm winds, or advective fog in the spring from SE winds
Often times W  E squall lines dissipate as they enter NJ. In general, Sussex / Warren have the best chance to
see severe weather in this scenario (but being located in HKT, it is infrequent).
NE NJ seems to have a slightly enhanced tornado potential during the AM hours with a warm front in the area.
In general, if a tornado warning is issued in this zone, because of how densely populated our client base is with
DPWs and Schools there is often a panic of calls and even if we don’t agree with the warning, we must touch
base with our clients in the warning.
It is not uncommon to get orographic pop-up showers / storms in the zone, which may be a surprise at times.
Zone 5 / SE PA
MOS Tendencies
KSMQ - Generally not representative of C NJ (mainly NC NJ) as it is WAY too cold at night from radiational
cooling
KTTN - most representative of CNJ, though understand it is far away from New Bruns / Edison, so can be
different up there at times.
KBLM - careful as this is not truly representative of the shore (5 mi inland), or Monmouth Co Zone (too close to
shore). Wind direction plays a big role on how much weight to give it to each zone (i.e. West wind and
it should be representative of Monmouth Co, strong E wind it will be representative of N. Shore.)
S flow days or sea breezes it is often too warm for N. Shore, but too cold for Monmouth.
KACY - not the shore (11 mi inland), but can offer clues. Better to use for SE NJ zone and is a good radiator (as
are most of the pine barrens down there).
KMIV - solid for Extreme South and often SE NJ too. This is another good radiator.
KVAY - I've noticed some oddities sometimes with this...like temps too high. For South NJ, a blend of KPHL and
KPNE is best, with some accounting of VAY and MIV
Most SE PA mos is representative, however be aware of KDYL and KPTW, which are much more Upper
Bucks/Mont and less representative of the population centers and client cores lower in the
county(s). For that, KLOM is best.
KPHL - good for Philly Metro, though Delaware Co (i.e. Union) can be a little cooler sometimes at night
Forecast Zones Tips - Winter
Central NJ
- There are times when Mercer and Middlesex Co. differ and that needs to be pointed out in the forecast. The
client base though is so huge that you can't really pick out different clients, you just have to send one forecast
talking about both counties (unless you really know the region). Also, don't forget that S. Somerset county is
part of this region, so that needs mentioning as well (usually I would loop them in with either Mercer or
Middlesex)
- Warm fronts can get hung up in this area and it is often a border area, where north more often stays cold and
south more often warms up
Monmouth/Mid-South
- The last five years, this area has been the jackpot for snowfall. Often, it gets the highest amounts somehow
or someway. Models may indicate this (though not all the time), but it has just happened a lot lately.
North Shore/Mid-Shore
- Also a jackpot area, if they don't switch to rain. There are no good METARs here and because of the vast
differences given proximity to the ocean, it is imperative that the meteorologist is looking at webcams and
mesonets
- There is a bufkit site (ATLH) that is very helpful, though this is in a spot where no clients are (Sandy Hook), it
gives a good indication of atmospheric conditions in the lower levels that may differ from inland
- Because of friction, SW winds often turn to a more southerly direction
- For winds out of the NE, that doesn't always mean rain because it is off the ocean. Colder air can be advected
in in this case and make it snow. A big sign is if LI is snowing and winds are NE. That means it is quite likely
that the north shores snow
South NJ
Nothing too insightful to add
SE NJ and Extreme South
- Majority of the time, they will have no problem warming up and going to rain if a warm front is approaching
or winds turning to the south or se
- Pine Barrens, so they radiate quite well at night. While in theory, you would think they have more of a FZRA
threat in early AM then others because of this, it just does not happen. Most times the arrival of clouds or just
a breath of wind will shoot them up from 28 to 38 and there really never ends up being fzra
South Shore
- Similar to north shore's stuff....careful with ACY, as it is inland. Though it often mirrors the shore, temps may
differ. Imperative to use webcams/mesonets
- Stafford goes more inland than one would think
Cape May
- Very hard to know what is going on in this area. Need webcams/mesonets
- WWD is frusterating as it is off/on and A01. It also doesn't report trace's, just when there is 0.01" or more
- Don't forget that Dover's radar is very helpful down here...this also can be said for Extreme South/SE NJ
Delaware
- KILG and KGED are solid metars, but KDOV is suspect. The dewpoint there is never right and p-types are
occasionally funky and need to be called into question at times
- There is an excellent video cam network via DelDot. Use this!
- Clients refer to the C&D Canal. Learn where this is (it is the Chesapeake & Delaware Canal)
- In N. DE, the Wilmington-Newark can differ from S. New Castle Co, I-95 is an excellent road to use for splitting
up a forecast if needed
- In far N. DE, it is hilly. Places like Talleyville can be a bit different and have an easier time sticking snow to
pavements than further south
Philly
- This region is not just Center City! Delaware County can be different, especially in the Media area.
- KPHL is very representative of the city
- Obviously a notable heat island in Philly County, also easily warm during most storms
Bucks-Mont
- Big region that sometimes needs to be distinguished. The correct verbage is Upper (NW part) and Lower (SE
Part)
- More rural than one thinks and they can radiate at times.
- This is an area quite prone to snow showers/squalls. On climo NW flow days and when meso models have
something, believe it
- Hard to get good obs here, boards are quite helpful
Chester
- Often colder than the rest of SE PA
- Most clients lie in the middle, along the Route 30 corridor
- Like Bucks/Mont, this is an area quite prone to snow showers/squalls. On climo NW flow days and when
meso models have something, believe it
- Though no clients (currently) go up north, the hills in this area are high (800-900 ft). Snow amounts almost
always higher up here and they last with fzra for awhile
Forecast Zones Tips - Summer
In general, the shores don’t rain (particularly S Shore and Cape May). Of course that isn’t always true, but on
S-SW flow days, often times a sea breeze keeps them stable. Or on a typical W  E moving complex of storms
they will dissipate before reaching the shores. This mainly applies to S Shore and Cape May (N. Shore generally
is more active and close to Monmouth Co).
Overall, N NJ is more active than S NJ and pops through this zone are often higher NW and lower SE. This also
applies to W  E severe lines, as they often dissipate / become non-severe towards NJ / PA border.
A rare, but interesting type of severe day is wet microbursts. These are sneaky and hard to predict, but with
little to no flow and high CAPE and P-Wats, a sea breeze or lee side trough can be a trigger for a few pop-up
storms, that produce isolated strong winds, but more importantly heavy, slow moving downpours. Again, this
only happens a handful times a summer, and if it does, most likely is in Monmouth or Ocean Co.
Understanding the shore’s geography is crucial in making summer time forecasts. The sea breeze is strongest
in S Shore and Cape May (I think because of a combo of SW / NE orientation of land vs N / S and they are
barrier islands), so they will often be colder than N Shore on S / SW flow days. Also, understand the shores can
be much breezier than just a few miles inland and no MOS / BUFKIT shows that very well. As far as forecasting
temps along the shore, BLM / ACY are not very good and even WWD can be too warm. Need to look at 2m
temp maps, and understand winds and geography. Lastly, understand that the immediate coast can be
different from ¼ inland, which can be different than 3 miles inland. These zones can include all of the above, so
sometime you need to mention “warmer just inland”, or “60s along the coast”, etc.
Zone 7 / C PA
Random Notes:
Not many know Carroll County actually has a MOS station available (KDMW) since it is not listed in our custom
MOS but I typically use a blend of this and KTHV for Carroll County.
Even though I - 95 on a map runs northeast to southwest, clients in Maryland reference spots on either side of
the interstate by saying west and east. Clients in northeast MD are especially picky if a meteorologist says
"spots north of I - 95." Maybe make a note to say "west of I - 95" instead of north and "east of I - 95" instead of
south just so new employees are not confused if a client questions them about it.
MOS Tendencies:
- For northeast MD, we typically use a blend of KILG and KMTN but realize that interior sections of
Harford/Cecil county (i.e west of I - 95) typically favor more KILG and KTHV
- For the northern Baltimore Suburbs (Cockeysville, Reisterstown, Owings Mills), we use a blend of KBWI and
KTHV but lean a bit more towards KBWI. For the coastal areas of the Baltimore suburbs (Middle River, Essex)
we use a blend of KMTN and KBWI
- In Central MD, we look at KIAD and KBWI but typically lean more towards KIAD.
- If the Frederick MOS is out in left field, we use a blend of KHGR and KJYO unless it is a night of good radiation
cooling in which case KTHV is reasonable
- For the D.C southeast area, KDCA is really only good for the area of DC near the Potomac River as it runs too
warm for the other areas in the zone. For northern/western DC and PG County, we used a blend of KADW and
KBWI.
Forecast Zones Tips – Winter
- Under a north wind, Westminster, Frederick, Hagerstown, northern Montgomery County (Gaithersburg
north) and Leesburg tend to get stuck so during any icing situations, they will continue to ice much later than
BUFKIT will show with Carroll County typically the last to warm above freezing. As a guide, when NAM MOS
has Westminster or KTHV rising to the mid - upper 30s, that's usually my end time for icing. Also, Frederick is
in a valley so it can radiate well below MOS predictions under clear skies/calm winds.
- For an east wind during the early winter (November, December), Baltimore. northeast MD and D.C will stay
warm (33 - 36) unless precip intensity is strong enough to lead to dynamic cooling.
- During March, pavements will have trouble accumulating in Maryland during the daytime unless wintry
precip is falling very heavily.
- For most of the winter, it is tough for a storm to produce all snow in Maryland and northern VA if the 850mb
low passes along or north of I - 95. 9 out of 10 times, they will see initial snow change to mix and then go to
rain with some snow mixing back behind the front. In addition, the snow ratios tend to be poor in these
situations. The main exceptions to this is if they experienced a prolonged cold period before an incoming
storm or if intensity at the onset can cool temperatures.
- This is really a problem across the board but I thought I would make note that even in Maryland, models tend
to under predict the intensity of snow bands, especially in central MD and northern VA, with storms that have
strong warm air advection. I think the terrain in this region provides addition lift that the models don't
properly consider. A good example of this occurred during the Feb 21 2015 event.
- There tends to be big differences in snowfall totals across our central MD and Baltimore suburbs zone. The
area from Gaithersburg northward tends to have higher totals than those just north of I - 95. Those just north
of I - 95 behave similarly to D.C while those from Gaithersburg north act more like our northwest VA zone. In
Baltimore suburbs, those north and west of the beltway (i.e Owings Mills, Reisterstown) are 500 - 700 feet in
elevation while those south and east (White Marsh, Middle Rive) are less than 100 feet so there typically are
sharp differences. I sometimes give two separate snowfall ranges in the total snowfall box to show the
difference with those south and east of the beltway behaving more like Baltimore City and those north and
west similar to Carroll County.
Forecast Zones Tips - Summer
- On a day that thunderstorms are expected in Maryland, once cumulus clouds start developing along the
mountains of Virginia and western MD, showers and storms typically start moving/developing in MD within
2 - 4 hours.
- Pressure troughs over the elevations of VA and MD can act as enough of a lifting mechanism to produce
storms in western Maryland (including Goddard). In these instance, storms typically loss intensity as they
progress eastward so Baltimore usually only sees remnant showers.
- Winds sometimes shift southeast off the Chesapeake Bay while other areas are southerly or southwesterly
which can sometimes act as a convergence zone.
- Maryland doesn't have too many rivers/streams that are especially prone to flooding so during flash flooding
events from thunderstorms, mainly concerned with roadway/poor drainage flooding
Zone 8
Forecast Zone Tips – Winter
General Notes – The Midwest is very flat so don’t worry about elevation changes.
Northeast Illinois can get lake-effect snow on N to NE winds
Central Indiana can get lake-effect snow on NNW winds
Low-level cloudiness tends to persist over NE IL due to lingering lake moisture
West Chicago – A good starting point since it’s in the middle of the zone. There are three MOS stations in this
zone: PWK towards the north, ORD right in the middle, and MDW towards the south. As you would expect
PWK is the coldest while MDW is the warmest. There are a reasonable number of clients in this region that go
close to the lake shore and none of these MOS stations are entirely representative of the shore (use mesonets
to get a better idea what is going on there – it is typically warmer due to the moderating influence of the lake).
For N-S variations in snowfall, I typically use I-88 or I-90 as geographical delimiters.
Chicago Metro – No MOS station in this region. It is highly urbanized so I mainly use MDW and bump up a
couple degrees to account for any heat island effect. I-90 is useful to depict E-W variations in snowfall or areas
expected to see lake-effect snow showers.
South Chicago – The only MOS station in this region is LOT and is on the very western edge of the region.
Temperature wise it is fine, but beware of lake-effect snow bands that make it into the eastern part of the
region on a NNE flow. I-80 can be a useful geographic delimiter to depict N-S variations in snowfall.
Far West Chicago – The only MOS station is DPA, right in the middle of the region. ARR is located just outside
the southwestern edge and is a bit on the colder side for this region, but still representative of locations that
radiate well. Strong, concentrated lake-effect bands usually do not make it this far inland but the region does
get broader lake-effect snow showers. Similar to West Chicago, for N-S variations in snowfall, I-88 or I-90 are
good geographical delimiters.
North Chicago – There are two MOS stations that can be used here: KUGN in the middle of the zone and KENW
towards the very northern edge. As with North Chicago, a good number of clients are close to the lake shore
and both aforementioned MOS stations are 3-6 miles inland, so be careful. I-94 is useful to depict E-W
variations in snowfall or areas expected to see lake-effect snow showers.
Rockford – A different animal than the NE IL regions. They rarely get lake-effect snow but are more prone to
snow showers with weak clipper systems passing through. The one MOS station in the region, RFD, is
representative of the area.
Indianapolis – This is a very large region, about 45 miles N-S and almost 50 miles E-W. There are a number of
MOS stations in the region but the most useful ones are IND and EYE (both just west of downtown
Indianapolis), and TYQ (in the northwestern part of the region). Since the region is large there tends to be
relatively frequent variations in the forecast. The most common is a N-S gradient in snowfall (or the location of
the rain/snow line in more complex scenarios). In those cases I tend to use the city of Indianapolis or I-70 as a
geographical delimiter. Although rare, lake-effect snow showers can make it into this area on NNW flow.
Forecast Zone Tips – Summer
West Chicago – As of Summer 2015, the clients in this region are at least 10 miles away from the lake shore so
ORD, PWK, MDW (and even DPA) are good for this zone. Lake-breezes can develop and move westward
through this region.
North Chicago – As of Summer 2015, the one client in this region is in the southern part of the region, between
PWK and UGN. They go right up to the lake shore but also 20 miles inland. The MOS stations are right in the
middle but locations closer to the lake are typically cooler while locations more inland are a bit warmer. Like
West Chicago, lake-breezes can develop and move westward through this region.
MOS Tendencies and Forecasting Tips
for WeatherWorks Zones
Zone 1
MOS Tendencies
ORH: this is not very representative of Central or South Central MA. It's too cold as it's elevation is 900+ ft.
Worcester is only 500 feet (where most of our clients are). Only use for the hills.
BED: More representative for Central MA and Middlesex/Inland Essex along with LWM
BVY: Good proxy for the Essex coast
BOS: Typically too warm in the winter and too cool in the summer for Boston metro as it sits right on the
water. Doesn't cool enough at night either. Don't use it for Boston burbs! Use it to modify OWD for burbs.
OWD: pretty good for Norfolk, however don't use it for Eastern Norfolk - too much ocean influence.
MQE: doesn't help much with Norfolk as it's on a hill
MHT/ASH: typically a good blend for Inland Southern NH
PSM: pretty solid for coastal NH
DAW: not bad for Inland SE NH, but I feel it may be slightly too cold at times (it is located pretty far north)
Zone Forecast Tips
Zone 1 Overview: Definitely be aware of a north wind! This will lock cold air into Central MA/Inland NH/Inland
Essex Middlesex, even Boston Burbs. In a freezing rain situation, this will hold sub 32 degree air into the region
well beyond what bufkit indicates (3 hours past bufkit warming is not unusual).
- A north wind shift on the Essex coast (if snowing and cold north) will quickly drop temps in a winter storm!
- Coastal fronts tend to set up at I-95, right near our Boston Metro to Boston burbs line. One side will be
raining, with heavy snow just west.
- Beware of inland cutter with a weak low developing near the benchmark or Cape! Even though bufkit will
indicate a good warming wind from the E or SE, it's usually pretty calm and warming doesn't happen.
- Watch back-building of snow bands in a coastal low situation. It always happens...it just does. You may want
to account for this in end times.
- Beware of a cold easterly wind ahead of a warm front pushing in from the south. The shield will progress
north, but then ocean effect snow can develop into Plymouth or Essex Co. You may want to have an earlier
start time because of this on the coasts. In some instances, this ocean effect can even become a "firehose" of
snow, esp with a little convergence at the surface and very cold air with deep unidirectional easterly flow.
- Radar has a tough time "seeing" MHT into Dover, it may look light, but it's really heavy (I know, I've gotten
calls). Keep an eye on infrared satellite to help, especially in snow shower situations. Watch cameras.
- Snow showers on a NW-W flow typically have a hard time making to Boston, unless aided by a strong vort
Zone 2
MOS Tendencies:
HFD and BDL are generally representative of Hartford Metro, carefully with BDL mos, it is typically colder than
HFD at night and warmer during the day in winter. Use BDL as "outlier" lows at night (think Avon/Bloomfield).
MMK is pretty good for Central CT, I use it for Waterbury too, but it's usually too warm for the Western CT
zone. I would blend it with DXR for Western CT
HVN/BDR careful with wind direction, on a SE - E wind it can be too warm, W wind they can be too cold for
highs
GON usually pretty solid for Eastern CT coast. Watch your wind directions again. Not representative of SE CT
Hills, you have to go cooler in the winter.
IJD is a good start for NE CT, but go colder than it in the winter. It is not representative of the hills of Tolland
and Windham
PVD/TAN not bad for SE MA, but don't use PVD for Inland RI, not representative. Side more on SFZ
A blend of UUU/WST is typically good for Southern RI
A blend of PYM and EWB is typically good for SE MA Coast.
FMH/CQX/PVC blend is pretty good for the Cape, however they can run too cold in the winter at night if the
wind is up
Forecast Zone Tips
- First off Hartford likes to warm on a downsloping westerly or SW wind...in winter watch a north wind as this
will lock cold air into the valley. This is particularly true with a frz rain event...when a secondary is taking over
on the coast. Snow showers have a hard time making it to Hartford, and watch the "Hartford hole" as precip
has a hard time getting in there in the winter...dry air/virga
- CT Coast - Need to watch winds carefully and sound temps... a S or SE wind can kill high temps in the
summer... a W or WSW wind can warm nicely… In winter, watch the area just inland from the coast (West CT
to Central and SE Hills) for a heavy snow band. It just happens.
- Tolland always gets crushed in winter...snow showers tend to end up here too.
- RI always has a tough time seeing tons of snow, but NW RI does well. PVD is not a good MOS to use for Inland
RI, use SZF instead.
- TAN warms and cools well on nice days and nights...rain/snow mix lines usually set up NW here in coastals
but watch a wind shifting north as that can quickly change to snow, especially if snowing and cold to north.
- Cape Cod watch ocean effect on a N or NE wind with very cold temps at 850mb (need similar conditions to
lake effect snow) and also ahead of winter storms on a E wind.
Zone 3
MOS Tendencies:
SWF's MOS max/min temperatures can be misleading (sometimes by a good 5 degrees). This goes back to the
fact that SWF doesn't report highs & lows...so it does the best it can with just hourly numbers. Also
contributing to the problem is that the airport itself does not radiate (or sometimes warm) as well as the rest
of the region (or maybe there is an issue with the thermometer/siting too). Thus, MOS minimums can be too
high, and MOS maximums can be too low compared to the surrounding area.
OXC is on a hill (726'), and is often cooler under typical conditions than the surrounding area (especially
Waterbury, 300'). Sometimes they will be warmer in an inversion!
HPN's MOS is ok. However, it's really right on the border between the Northern & Southern Westchester
zones, and is not really representative of either. In the daytime, it's generally OK for both zones (add a few
degrees for the South except in cases of onshore flow). At night it's a often a blend of the 2 zones for lows...so
just lean low north, lean high south.
FOK can radiate very, very, very well. Its readings can be as much as 10 degrees colder than any other number
we can find nearby. So for Eastern LI forecasts in radiating situations...generally use it as a "lower bound"
number. Also be aware that considering they're far out on LI, their winds calm out much easier than you would
think and sometimes MOS doesn't pick up on it. I've seen FOK's MOS be 12-14 degrees to warm at night, and a
general 4-7 warmer than the region's representative temperature.
Forecast Zone Tips
Zone 3 (NY & W CT) experiences just about everything from areas that never warm in Orange County to
extreme coastal influences in Eastern Long Island. Thankfully, the zones pretty much work in gradient fashion
from northwest to southeast...but here are some general things to keep in mind.
Orange & Dutchess Counties:
Obviously the least influenced by the coast, and usually have similar weather conditions. However, there are
some important notes:
1. Orange is almost always colder than Dutchess by a few degrees in most situations. (With wintertime WAA
patterns, Dutchess always warms a bit more quickly as warm air gets up the valley faster). While both zones
have mountains of 800'+, most of our clients are not impacted by them. The only slight exception is the
Monroe area in Orange County where it gets close to 700'. (This area can also get up slope enhancement and
get slightly higher snowfall totals)
2. More often than not, Orange gets more snow (and usually precip too) than Dutchess. There are two reasons
for this: The Dutchess County zone is a little further north and as a result further removed from coastal lows.
Additionally, systems moving in from the west have a tendency to weaken as they move further east.
3. In WAA patterns that involve P-Type changes to plain rain...when there isn't a lot of surface wind (which
seems to happen a lot), and when MOS/Bufkits show warming well above freezing...this warming can take a
longer time than modeled. This long delay can result in temps holding near freezing and a long duration threat
of freezing rain, or freezing drizzle if the atmosphere is saturated. In fact, sometimes it takes the
Cold/Occluded front moving in from the west to mix out the atmosphere. As a result, the warmest
temperatures in these events often occur BEHIND the cold front in a CAA pattern...even at night!
4. Radar can be very deceiving. These regions are pretty far away from OKX, ENX, DIX & BGM. It often misses
light precipitation or makes what can be heavy precip look rather light. Unfortunately, there aren't too many
cams to compare it to. Sometimes JFK Tower radar can help, but it doesn't go nearly far enough northward. Do
the best you can with METARs, and intuition. You will likely get more than one call from a client telling you that
it's snowing heavily, and you would suspect ~2-4 mile light snow.
Putnam/N. West & Western CT:
These regions can behave like coastal one at times...but usually trend towards their inland counterparts.
Obviously, given their location they are subject to tight north to south gradients in terms of temperatures and
snowfall.
1. From a snow standpoint, (in coastal storms) these zones can often end up with the most. Even though they
might not be as cold as areas to the north, they usually have more moisture, and can have "lollipops". In case
of all snow events...heavy bands often form in this area (esp. the southern half of the zone). In mixing events,
sometimes the region looks like they will mix, but don't, or will sit just north of the mix line for a while where
there are often the heaviest snowfall rates.
2. In the WAA scenarios discussed above, these areas usually at least warm into the mid 30s, and don't have
the same duration threat for icing. Sometimes there can be additional warming behind the cold/occluded
front.
3. The Danbury-Waterbury area is often a good spot for streamers to sneak in from Upstate NY on a NW flow,
especially in the presence of a vort max. In the winter of 2014-15, some hi-res models picked this out.
S. West & Western CT Coast:
Depending on the situation, these can be the trickiest regions of the entire zone. While it's easy to consider
them coastal, sometimes the warming just doesn't quite get there in the winter...so they may stay snow longer
than you think. Some of my worst busts have been in these areas because the NE or N wind (10+ kt) can hold
off a change to the E or SE.
Also...these regions are particularly subject to sharp North to South differences. Unlike in the zones just to the
north, we have clients all over these regions, so there's a good chance our clients will be experiencing very
different conditions at the same time within the region.
NYC:
Another hard area to forecast. Despite there being 2 zones, which work pretty well for Manhattan, Brooklyn &
Queens, it's not perfect. Oftentimes, Staten Island (away from the coast) is more like an inland SW suburb
(think Central NJ). Sometimes the Bronx is just another world, and is really more like Southern Westchester
and can get up to 8" while Central Park may barely get 4”.
Other notes:
1. Obviously highly urban, it doesn't radiate well. It also takes Mod/Heavy Snow or really cold temps with light
snow to stick on pavements in the urban areas during the daylight hours. Be careful though, parts of each
Borough (even northern Manhattan) have suburban/park-like areas where these rules to do not apply.
2. Southern Queens & Brooklyn usually warm-up as fast or faster than the models suggest. Watch JFK's wind,
it's usually the first sign of things.
3. Make sure to make use of METARs & boards. With 8 million people and 2 first-order airports (3 if you
include EWR) and, you usually have a very good idea as to what's actually going on. Note that KNYC will not
report mixed precip, as the observer does NOT augment ASOS obs. In that respect, KNYC is no better than
KCDW or other similar stations.
4. In cases of NE Winds, use your Western Coastal CT Forecast to help. If it will snow there...that helps it to
snow in NYC (especially Bronx). Meanwhile if you are expecting mixed precip up there, it becomes very hard to
snow in NYC.
LI/Eastern LI:
In a lot of respects, everything from NYC applies to Long Island (not quite as urban...especially in Suffolk
County). Other specific notes:
1. Airports (obs/MOS) are "Central/South" and not representative of the beaches or the north shore...boards &
cams are your friends here. Expect some variation.
2. The North Shore from Northport to Port Jefferson (north of the Northern State Pkwy/347) is a well-known
sweet spot for snow. Some theories to explain this: enhancement from LI Sound & hills (150-200') just north of
LIE slow down mixing
3. To repeat point 4 from above...because it's most important here. If Eastern CT/RI/SE MA are seeing mixed
precip or rain, and there's any hint of a NE wind...it's quite hard for LI to snow. The main exception would be if
LI has higher precip intensity...even then it's very difficult.
Zone 4
MOS Tendencies
Scranton/WB AVP 948 FT – Representative of the valley cities in NEPA (Scranton to WB). This is where the
clients cover most. Do understand NE PA zone goes down to 550 ft, and above 1500 ft.
Mount Pocono MPO 1893 FT – Generally the highest and coldest spot. Generally only representative of
Hazleton, and even at that MPO will be a bit cold most times. Can be looked at for reference for some of the
hills above 1000 ft in NW NJ, but understand it is only to be used as a reference and not actually what will take
place.
Sussex FWN 420 FT – Typically good for Sussex and the Gap, but need to be careful with elevations and on
radiational cooling nights. FWN is one of the best radiating MOSs
Andover K12N 581 FT - A good representation of Warren and Sussex and somewhat Morris Co. Despite the
higher elevation, it often warmer than FWN because of geography and being further south.
Morristown MMU 187 FT & Caldwell CDW 174 FT – No real glaring notes here. I think MMU often times
won’t have lows or temps at all. Mainly use CDW and not so much MMU.
Teterboro TEB 10 FT – Also generally representative of where it is. Can typically be a guide for the lower end
temps in Northeast NJ, but not quite the lowest possible. Northern parts of Bergen Co are often a few degrees
cooler than TEB.
EWR 30 FT – Typically the highest you can go with temperatures for Northeast NJ. Just a few miles west with
some minor elevation is generally a few degrees cooler.
SMQ 105 FT – Probably the most inconsistent site in all of NNJ. Radiational cooling nights it can be way, way
too low. And even on a number of just calm nights it can be too cold. In terms of high temps, it is pretty good
for Somerset Co, but often too warm for Hunterdon Co, especially as you go north. ABE can be helpful there.
Forecast Zones Tips - Winter
Sussex – Most times my starting point. Most populated areas are between 450-800ft elevation, however the
most important thing to remember is most clients cover at least some area which go to 1000-1400, so when
applicable, you must include notes as to higher snow totals or colder temperatures in elevations and if it will
impact their work or ice watches.
Typical Mos: FWN / 12N, though need to figure out what is going on above 1000’.
Gap – Can most times be very similar if not the same as Sussex. The biggest difference will be the snow totals,
if there is any difference at all. Perhaps a degree or two difference on the temps in the warmer direction.
Elevation does still play a factor here for snow totals, but not quite to the extreme of Sussex. Generally, areas
are around 300-600’ and up to 1000-1100’ in some locations.
Typical Mos: FWN/12N blend, with some consideration of ABE / AVP.
Morris – the real snow capitol of NJ. Despite Sussex getting more snow in the elevations, most of Morris is
over 900’ and up to 1300’ making the entire region an elevation. Often times temps will be similar to Sussex,
however with any elevation dependent storms (and even storms that you think aren’t elevation dependent),
Morris should be the same if not higher than Sussex in terms of snow (all things being equal). It seems
counterintuitive, but it happens quite a bit. Typical Mos: Situational, although typically similar to Sussex… Need
to figure out what is going on above 1000’.
Warren – Home to the Hackettstown hole. 12N / ABE are good guides for temps, however Snow totals are
always a tough forecast. A Majority of the client base is in Hackettstown, so totals can be on the lower end of
your thinking in some instances, but we do have to take into consideration the surrounding elevations as
well. Comparatively speaking, Sussex is generally a 50/50 split elevation/valley; Morris is 90/10
elevation/valley and warren, while there are many elevated places, we generally look at as mainly valley with
consideration to some higher hills.
Typical Mos: 12N / ABE
NOTE: For these NW 4 zones above, on radiational cooling nights valleys can be MUCH colder than
elevations. Additionally, these zones are most prone to accumulating snow showers from the NW.
Northcentral – This is one of the toughest zones. Most times this is a battle ground for the mixing line, this is
where tight snowfall gradients often set up, and typically have the largest temperatures spreads across the
area. “north of I-78” and “in the northern part of the county” are usually in a lot of forecasts to try and portray
higher impacts.
Typical Mos: ABE/SMQ blend, with some situational intuition
West Rockberg – Depending on the situation, West Rockberg will act like Sussex or Warren or Morris for most
storms, so one of these (again depending on the situation) can typically be a starting point (IE: elevation
dependent storm? Warren. SW to NE mixing line? Morris. Cold air daming? Sussex. (not for every case, but
just some potential ideas. You need to figure out which it might act most like). There are elevations to the
West (Passaic Co) and it drops off to the East (Bergen Co), though goes north as well (Rockland Co). Most areas
are 400-500’, up to 800’, so it’s not typically as imperative to mention higher hills; But do keep this in mind
when picking a snowfall forecast.
Typical Mos: 12N / CDW… But overall usually acts similar to Sussex/Warren
East Rockberg – Often times with temperature and snowfall when compared to West Rockberg, you should be
thinking higher on the temps and lower on the snow, primarily due to elevation and urbanization.
Typical Mos: CDW / TEB… and usually just a bit warmer than the W Rock forecast
Morsex – One of the more straightforward zones, all things considered. There are hills here (300-500 ft) so it is
certainly cooler that NE NJ, but certainly warmer than Morris Co for the most part. A lot of clients have Morsex
in addition to other regions.
Typical Mos: CDW with MMU consideration
Northeast – This can also be a battle ground for temps and mixing. General mentality is to think of your
forecast as the outskirts of Newark with mention to colder suburbs, meaning generally leaning lower on snow
totals with mention to higher totals in surrounding areas. An E / SE wind will easily warm this area. Margin
temps scenarios may struggle to accumulate on pavements here during the daytime, especially early / late in
the season.
Typical Mos: EWR as the high end/ Moresex/East Rockberg low end blend.
Northeast PA – Clients fall in the valley cities (Scranton to Wilkes-barre) with one or two going down to
Hazleton. Hazleton is a different world compared to SWB, but not so much that you change your forecast to
reflect it. You do need to mention “continued icing for elevations over 1000’” or “Higher totals towards
Hazleton” or just “higher in the elevations” if that’s the case. Typical Mos: AVP, with consideration of MPO
Forecast Zones Tips - Summer
As you would expect, NE NJ is typically much warmer than NW NJ, especially at night. There are certain days
where the high temps are the same across the board, but it is tough to say when that exactly happens. I
believe it is on fairly warm aloft days, with a light-moderate S-SW wind but not entirely sure.
It is tough for Containers to get radiational fog. The main fog nights are either evening / night rain followed by
calm winds, or advective fog in the spring from SE winds
Often times W  E squall lines dissipate as they enter NJ. In general, Sussex / Warren have the best chance to
see severe weather in this scenario (but being located in HKT, it is infrequent).
NE NJ seems to have a slightly enhanced tornado potential during the AM hours with a warm front in the area.
In general, if a tornado warning is issued in this zone, because of how densely populated our client base is with
DPWs and Schools there is often a panic of calls and even if we don’t agree with the warning, we must touch
base with our clients in the warning.
It is not uncommon to get orographic pop-up showers / storms in the zone, which may be a surprise at times.
Zone 5 / SE PA
MOS Tendencies
KSMQ - Generally not representative of C NJ (mainly NC NJ) as it is WAY too cold at night from radiational
cooling
KTTN - most representative of CNJ, though understand it is far away from New Bruns / Edison, so can be
different up there at times.
KBLM - careful as this is not truly representative of the shore (5 mi inland), or Monmouth Co Zone (too close to
shore). Wind direction plays a big role on how much weight to give it to each zone (i.e. West wind and
it should be representative of Monmouth Co, strong E wind it will be representative of N. Shore.)
S flow days or sea breezes it is often too warm for N. Shore, but too cold for Monmouth.
KACY - not the shore (11 mi inland), but can offer clues. Better to use for SE NJ zone and is a good radiator (as
are most of the pine barrens down there).
KMIV - solid for Extreme South and often SE NJ too. This is another good radiator.
KVAY - I've noticed some oddities sometimes with this...like temps too high. For South NJ, a blend of KPHL and
KPNE is best, with some accounting of VAY and MIV
Most SE PA mos is representative, however be aware of KDYL and KPTW, which are much more Upper
Bucks/Mont and less representative of the population centers and client cores lower in the
county(s). For that, KLOM is best.
KPHL - good for Philly Metro, though Delaware Co (i.e. Union) can be a little cooler sometimes at night
Forecast Zones Tips - Winter
Central NJ
- There are times when Mercer and Middlesex Co. differ and that needs to be pointed out in the forecast. The
client base though is so huge that you can't really pick out different clients, you just have to send one forecast
talking about both counties (unless you really know the region). Also, don't forget that S. Somerset county is
part of this region, so that needs mentioning as well (usually I would loop them in with either Mercer or
Middlesex)
- Warm fronts can get hung up in this area and it is often a border area, where north more often stays cold and
south more often warms up
Monmouth/Mid-South
- The last five years, this area has been the jackpot for snowfall. Often, it gets the highest amounts somehow
or someway. Models may indicate this (though not all the time), but it has just happened a lot lately.
North Shore/Mid-Shore
- Also a jackpot area, if they don't switch to rain. There are no good METARs here and because of the vast
differences given proximity to the ocean, it is imperative that the meteorologist is looking at webcams and
mesonets
- There is a bufkit site (ATLH) that is very helpful, though this is in a spot where no clients are (Sandy Hook), it
gives a good indication of atmospheric conditions in the lower levels that may differ from inland
- Because of friction, SW winds often turn to a more southerly direction
- For winds out of the NE, that doesn't always mean rain because it is off the ocean. Colder air can be advected
in in this case and make it snow. A big sign is if LI is snowing and winds are NE. That means it is quite likely
that the north shores snow
South NJ
Nothing too insightful to add
SE NJ and Extreme South
- Majority of the time, they will have no problem warming up and going to rain if a warm front is approaching
or winds turning to the south or se
- Pine Barrens, so they radiate quite well at night. While in theory, you would think they have more of a FZRA
threat in early AM then others because of this, it just does not happen. Most times the arrival of clouds or just
a breath of wind will shoot them up from 28 to 38 and there really never ends up being fzra
South Shore
- Similar to north shore's stuff....careful with ACY, as it is inland. Though it often mirrors the shore, temps may
differ. Imperative to use webcams/mesonets
- Stafford goes more inland than one would think
Cape May
- Very hard to know what is going on in this area. Need webcams/mesonets
- WWD is frusterating as it is off/on and A01. It also doesn't report trace's, just when there is 0.01" or more
- Don't forget that Dover's radar is very helpful down here...this also can be said for Extreme South/SE NJ
Delaware
- KILG and KGED are solid metars, but KDOV is suspect. The dewpoint there is never right and p-types are
occasionally funky and need to be called into question at times
- There is an excellent video cam network via DelDot. Use this!
- Clients refer to the C&D Canal. Learn where this is (it is the Chesapeake & Delaware Canal)
- In N. DE, the Wilmington-Newark can differ from S. New Castle Co, I-95 is an excellent road to use for splitting
up a forecast if needed
- In far N. DE, it is hilly. Places like Talleyville can be a bit different and have an easier time sticking snow to
pavements than further south
Philly
- This region is not just Center City! Delaware County can be different, especially in the Media area.
- KPHL is very representative of the city
- Obviously a notable heat island in Philly County, also easily warm during most storms
Bucks-Mont
- Big region that sometimes needs to be distinguished. The correct verbage is Upper (NW part) and Lower (SE
Part)
- More rural than one thinks and they can radiate at times.
- This is an area quite prone to snow showers/squalls. On climo NW flow days and when meso models have
something, believe it
- Hard to get good obs here, boards are quite helpful
Chester
- Often colder than the rest of SE PA
- Most clients lie in the middle, along the Route 30 corridor
- Like Bucks/Mont, this is an area quite prone to snow showers/squalls. On climo NW flow days and when
meso models have something, believe it
- Though no clients (currently) go up north, the hills in this area are high (800-900 ft). Snow amounts almost
always higher up here and they last with fzra for awhile
Forecast Zones Tips - Summer
In general, the shores don’t rain (particularly S Shore and Cape May). Of course that isn’t always true, but on
S-SW flow days, often times a sea breeze keeps them stable. Or on a typical W  E moving complex of storms
they will dissipate before reaching the shores. This mainly applies to S Shore and Cape May (N. Shore generally
is more active and close to Monmouth Co).
Overall, N NJ is more active than S NJ and pops through this zone are often higher NW and lower SE. This also
applies to W  E severe lines, as they often dissipate / become non-severe towards NJ / PA border.
A rare, but interesting type of severe day is wet microbursts. These are sneaky and hard to predict, but with
little to no flow and high CAPE and P-Wats, a sea breeze or lee side trough can be a trigger for a few pop-up
storms, that produce isolated strong winds, but more importantly heavy, slow moving downpours. Again, this
only happens a handful times a summer, and if it does, most likely is in Monmouth or Ocean Co.
Understanding the shore’s geography is crucial in making summer time forecasts. The sea breeze is strongest
in S Shore and Cape May (I think because of a combo of SW / NE orientation of land vs N / S and they are
barrier islands), so they will often be colder than N Shore on S / SW flow days. Also, understand the shores can
be much breezier than just a few miles inland and no MOS / BUFKIT shows that very well. As far as forecasting
temps along the shore, BLM / ACY are not very good and even WWD can be too warm. Need to look at 2m
temp maps, and understand winds and geography. Lastly, understand that the immediate coast can be
different from ¼ inland, which can be different than 3 miles inland. These zones can include all of the above, so
sometime you need to mention “warmer just inland”, or “60s along the coast”, etc.
Zone 7 / C PA
Random Notes:
Not many know Carroll County actually has a MOS station available (KDMW) since it is not listed in our custom
MOS but I typically use a blend of this and KTHV for Carroll County.
Even though I - 95 on a map runs northeast to southwest, clients in Maryland reference spots on either side of
the interstate by saying west and east. Clients in northeast MD are especially picky if a meteorologist says
"spots north of I - 95." Maybe make a note to say "west of I - 95" instead of north and "east of I - 95" instead of
south just so new employees are not confused if a client questions them about it.
MOS Tendencies:
- For northeast MD, we typically use a blend of KILG and KMTN but realize that interior sections of
Harford/Cecil county (i.e west of I - 95) typically favor more KILG and KTHV
- For the northern Baltimore Suburbs (Cockeysville, Reisterstown, Owings Mills), we use a blend of KBWI and
KTHV but lean a bit more towards KBWI. For the coastal areas of the Baltimore suburbs (Middle River, Essex)
we use a blend of KMTN and KBWI
- In Central MD, we look at KIAD and KBWI but typically lean more towards KIAD.
- If the Frederick MOS is out in left field, we use a blend of KHGR and KJYO unless it is a night of good radiation
cooling in which case KTHV is reasonable
- For the D.C southeast area, KDCA is really only good for the area of DC near the Potomac River as it runs too
warm for the other areas in the zone. For northern/western DC and PG County, we used a blend of KADW and
KBWI.
Forecast Zones Tips – Winter
- Under a north wind, Westminster, Frederick, Hagerstown, northern Montgomery County (Gaithersburg
north) and Leesburg tend to get stuck so during any icing situations, they will continue to ice much later than
BUFKIT will show with Carroll County typically the last to warm above freezing. As a guide, when NAM MOS
has Westminster or KTHV rising to the mid - upper 30s, that's usually my end time for icing. Also, Frederick is
in a valley so it can radiate well below MOS predictions under clear skies/calm winds.
- For an east wind during the early winter (November, December), Baltimore. northeast MD and D.C will stay
warm (33 - 36) unless precip intensity is strong enough to lead to dynamic cooling.
- During March, pavements will have trouble accumulating in Maryland during the daytime unless wintry
precip is falling very heavily.
- For most of the winter, it is tough for a storm to produce all snow in Maryland and northern VA if the 850mb
low passes along or north of I - 95. 9 out of 10 times, they will see initial snow change to mix and then go to
rain with some snow mixing back behind the front. In addition, the snow ratios tend to be poor in these
situations. The main exceptions to this is if they experienced a prolonged cold period before an incoming
storm or if intensity at the onset can cool temperatures.
- This is really a problem across the board but I thought I would make note that even in Maryland, models tend
to under predict the intensity of snow bands, especially in central MD and northern VA, with storms that have
strong warm air advection. I think the terrain in this region provides addition lift that the models don't
properly consider. A good example of this occurred during the Feb 21 2015 event.
- There tends to be big differences in snowfall totals across our central MD and Baltimore suburbs zone. The
area from Gaithersburg northward tends to have higher totals than those just north of I - 95. Those just north
of I - 95 behave similarly to D.C while those from Gaithersburg north act more like our northwest VA zone. In
Baltimore suburbs, those north and west of the beltway (i.e Owings Mills, Reisterstown) are 500 - 700 feet in
elevation while those south and east (White Marsh, Middle Rive) are less than 100 feet so there typically are
sharp differences. I sometimes give two separate snowfall ranges in the total snowfall box to show the
difference with those south and east of the beltway behaving more like Baltimore City and those north and
west similar to Carroll County.
Forecast Zones Tips - Summer
- On a day that thunderstorms are expected in Maryland, once cumulus clouds start developing along the
mountains of Virginia and western MD, showers and storms typically start moving/developing in MD within
2 - 4 hours.
- Pressure troughs over the elevations of VA and MD can act as enough of a lifting mechanism to produce
storms in western Maryland (including Goddard). In these instance, storms typically loss intensity as they
progress eastward so Baltimore usually only sees remnant showers.
- Winds sometimes shift southeast off the Chesapeake Bay while other areas are southerly or southwesterly
which can sometimes act as a convergence zone.
- Maryland doesn't have too many rivers/streams that are especially prone to flooding so during flash flooding
events from thunderstorms, mainly concerned with roadway/poor drainage flooding
Zone 8
Forecast Zone Tips – Winter
General Notes – The Midwest is very flat so don’t worry about elevation changes.
Northeast Illinois can get lake-effect snow on N to NE winds
Central Indiana can get lake-effect snow on NNW winds
Low-level cloudiness tends to persist over NE IL due to lingering lake moisture
West Chicago – A good starting point since it’s in the middle of the zone. There are three MOS stations in this
zone: PWK towards the north, ORD right in the middle, and MDW towards the south. As you would expect
PWK is the coldest while MDW is the warmest. There are a reasonable number of clients in this region that go
close to the lake shore and none of these MOS stations are entirely representative of the shore (use mesonets
to get a better idea what is going on there – it is typically warmer due to the moderating influence of the lake).
For N-S variations in snowfall, I typically use I-88 or I-90 as geographical delimiters.
Chicago Metro – No MOS station in this region. It is highly urbanized so I mainly use MDW and bump up a
couple degrees to account for any heat island effect. I-90 is useful to depict E-W variations in snowfall or areas
expected to see lake-effect snow showers.
South Chicago – The only MOS station in this region is LOT and is on the very western edge of the region.
Temperature wise it is fine, but beware of lake-effect snow bands that make it into the eastern part of the
region on a NNE flow. I-80 can be a useful geographic delimiter to depict N-S variations in snowfall.
Far West Chicago – The only MOS station is DPA, right in the middle of the region. ARR is located just outside
the southwestern edge and is a bit on the colder side for this region, but still representative of locations that
radiate well. Strong, concentrated lake-effect bands usually do not make it this far inland but the region does
get broader lake-effect snow showers. Similar to West Chicago, for N-S variations in snowfall, I-88 or I-90 are
good geographical delimiters.
North Chicago – There are two MOS stations that can be used here: KUGN in the middle of the zone and KENW
towards the very northern edge. As with North Chicago, a good number of clients are close to the lake shore
and both aforementioned MOS stations are 3-6 miles inland, so be careful. I-94 is useful to depict E-W
variations in snowfall or areas expected to see lake-effect snow showers.
Rockford – A different animal than the NE IL regions. They rarely get lake-effect snow but are more prone to
snow showers with weak clipper systems passing through. The one MOS station in the region, RFD, is
representative of the area.
Indianapolis – This is a very large region, about 45 miles N-S and almost 50 miles E-W. There are a number of
MOS stations in the region but the most useful ones are IND and EYE (both just west of downtown
Indianapolis), and TYQ (in the northwestern part of the region). Since the region is large there tends to be
relatively frequent variations in the forecast. The most common is a N-S gradient in snowfall (or the location of
the rain/snow line in more complex scenarios). In those cases I tend to use the city of Indianapolis or I-70 as a
geographical delimiter. Although rare, lake-effect snow showers can make it into this area on NNW flow.
Forecast Zone Tips – Summer
West Chicago – As of Summer 2015, the clients in this region are at least 10 miles away from the lake shore so
ORD, PWK, MDW (and even DPA) are good for this zone. Lake-breezes can develop and move westward
through this region.
North Chicago – As of Summer 2015, the one client in this region is in the southern part of the region, between
PWK and UGN. They go right up to the lake shore but also 20 miles inland. The MOS stations are right in the
middle but locations closer to the lake are typically cooler while locations more inland are a bit warmer. Like
West Chicago, lake-breezes can develop and move westward through this region.