ILLINOIS WATER AND CLIMATE SUMMARY
December 2009
Illinois State Water Survey
2204 Griffith Drive, Champaign, IL 61820 • Tel (217) 333-2210 • Fax (217) 333-6540
December 2009 Overview (Bob Scott)
Temperatures in Illinois during December were below average,
while precipitation was above average. Soil moisture within the top
40 inches of soil was above the long-term statewide average. Mean
streamflows were well above median values. Shallow groundwater
levels were above long-term average depths.
Temperatures across Illinois (Figure 1) for December were
below average (a -1.0-degree departure). Crop Reporting District
(CRD) temperatures ranged from 1.4 degrees below average
(southwest CRD) to 0.5 degrees below average (east CRD).
Precipitation amounts for Illinois in December were above
average (Figure 1). The statewide average of 4.11 inches represented
a 1.42-inch surplus or 153 percent of average for the month. The east
CRD received the least amount of rainfall, 3.34 inches (130 percent
of average), while the southwest CRD recorded the greatest rainfall
total with 4.95 inches (144 percent of average).
Soil moisture conditions in the 0- to 40-inch (0- to
100-centimeter) layer in Illinois at the end of December were
generally above normal (Figure 1). Statewide, moisture in the soil
averaged nearly 1 inch above normal.
Mean provisional streamflow statewide was well above the
median flow in December, 500 percent of median (Figure 1). Rivers
throughout Illinois recorded monthly mean discharges from above
normal to much above normal for December. River stages reached or
exceeded local flood stages on the Mississippi River at Grafton and
Chester, on the Ohio River at Cairo, and at most Illinois River gage
locations in December.
Water surface levels at the end of December were below the
full pool/target operating level at three of 28 reporting reservoirs.
Rend Lake was 5.4 feet above spillway level, Lake Shelbyville was
21.5 feet above winter target level, and Carlyle Lake was 8.7 feet
above winter target level. Lake Michigan’s mean level remains
below the long-term average.
Statewide, shallow groundwater levels were above normal
with an average departure of +3.9 feet. Combined with the change
in normal monthly groundwater levels from the end of November
to the end of December, a 0.3-foot decrease in departures from last
month was observed (Figure 1). Levels averaged 0.5 feet higher than
November levels and were approximately 1.6 feet above December
levels of last year.
&,(/#/,,#510&
Figure 1.
Statewide departures from normal
Note: The WARM Network maps and extended network descriptions appear in the January and July issues.
Water and Atmospheric Resources Monitoring Program | www.isws.illinois.edu/warm
Illinois State Water Survey | Institute of Natural Resource Sustainability | University of Illinois at Urbana-Champaign
Contact Bob Scott: (217) 333-4966, email: [email protected]
Weather/Climate Information (Jim Angel and Bob Scott)
Temperatures across Illinois for December were below average (Figure 2 and Table 1). The warmest
temperature reported in Illinois for the month was 59° F in Alton, Bentley, Mt. Carroll, Prairie City, and Smithland
on December 2. The coldest temperature for the month was -5° F in both Elizabeth and Mt. Carroll on December 11.
Precipitation for December was above average statewide (Figure 2 and Table 1). Du Quoin reported the highest
one-day precipitation of 2.23 inches on December 24. Centralia had the highest monthly total of 6.45 inches.
Based on preliminary, objectively-analyzed data, this was the 13th wettest December, the second wettest
October–December (three months), the third wettest July–December (six months), and the second wettest January–
December (12 months) since 1895.
Snowfall for December was widespread across Illinois (Figure 2). No measureable snow was reported in far
southern Illinois. One to 12 inches were reported across central Illinois and 8 to 21 inches were reported across
northern Illinois. Belvidere reported the largest monthly snowfall total in the state, 22.3 inches.
Severe weather was not reported in Illinois during December.
Illinois Climate Network (ICN) Data. Average daily wind speeds across Illinois for December (Figure 3)
ranged from 5.2 mph at Dixon Springs to 12.3 mph at Bondville. Bondville and Stelle reported the highest wind
gusts for the month, 52 and 51 mph, respectively, on December 9. The prevailing wind direction for the month was
southwesterly to west-southwesterly across the state. Wind speeds in excess of 8 mph during the month varied
from 169 hours at Dixon Springs to 539 hours at Bondville and Monmouth. (December has 744 hours.) Average air
temperatures in December ranged from 23° F at Freeport to 35° F at Carbondale and Dixon Springs.
Solar radiation totals in December decreased to near seasonal minimums, ranging from 122 Mega-Joules per
meter squared (MJ/m 2) at Freeport to near 183 MJ/m2at Carbondale, Rend Lake, and Dixon Springs. Similarly,
potential evapotranspiration observations decreased and varied from 0.5 inches at Freeport to 1.3 inches at
Carbondale. Soil temperatures in Illinois decreased during December and ranged from 34° F at Springfield and
Monmouth to 39° F at Dixon Springs and Belleville (4-inch level) and from 35° F at Monmouth and Kilbourne to
nearly 45° F at Rend Lake (8-inch level).
5PQYHCNN
Figure 2. Illinois temperature and precipitation during December 2009
23
Table 1. Illinois Precipitation (inches) and Temperature (ºF) by Crop Reporting District
Crop Reporting
District
Last Month
Dec 09
%
Temp
Amount
Avg
Dev
Last 3 Months
Oct 09%
Temp
Dec 09
Avg
Dev
Last 6 Months
Jul 09%
Temp
Dec 09
Avg
Dev
Last 12 Months
Jan 09%
Temp
Dec 09
Avg
Dev
Northwest
3.73
183
-0.9
12.31
165
-0.1
27.98
149
-1.6
52.20
Northeast
3.38
146
-0.9
11.93
150
-0.1
21.96
114
-1.5
46.87
West
3.40
151
-1.0
14.98
185
-0.4
28.26
146
-1.9
54.96
Central
3.98
159
-0.8
15.71
188
-0.1
27.73
146
-1.6
53.60
East
3.34
130
-0.5
14.56
171
0.2
24.76
128
-1.1
48.55
West-southwest
4.37
160
-1.1
19.66
220
-0.4
31.32
167
-1.8
53.40
East-southeast
4.94
160
-1.0
16.67
168
-0.4
26.80
131
-1.4
53.32
Southwest
4.95
144
-1.4
17.97
167
-0.5
31.46
150
-1.4
57.67
Southeast
4.91
136
-1.0
15.99
146
-0.1
30.57
146
-1.0
56.89
State Average
4.11
153
-1.0
15.54
174
-0.2
27.79
142
-1.5
52.85
________________
Note: Data are provisional. Complete, quality-controlled data are available about six months after a given month.
144
128
147
144
129
142
130
135
128
136
-1.4
-1.4
-1.2
-1.2
-0.7
-0.9
-0.6
-0.3
-0.1
-0.9
Extended climate outlooks issued by the U.S. Department of Commerce, National Oceanic and Atmospheric
Administration, Climate Prediction Center for January call for a slight chance of below normal temperatures in
southern Illinois, and a slight chance of below precipitation in eastern and southern Illinois. Outlooks for January–
March call for a slight chance of above normal temperatures in northwestern Illinois and a slight chance of below
normal precipitation in eastern and southern Illinois.
Soil Moisture Information (Bob Scott)
Precipitation during December was above average across Illinois. Regardless, frozen top soils kept nearsurface soil moisture near normal levels (Figure 4). In the 0- to 6-inch layer, values ranged from 89 percent of
normal at Carbondale to 111 percent at Bondville. Conditions in the 6- to 20-inch layer were more variable and
ranged from 83 percent at East Peoria to 161 percent at Olney. Soils in deeper layers were generally wet in eastern
and northwestern Illinois and drier in central and southwestern Illinois. Values ranged from 62 percent (East
Peoria) to 186 percent (Olney) in the 20- to 40-inch layer and from 68 percent (Freeport) to 181 percent (Dixon
Springs) in the 40- to 72-inch layer. Overall, soil moisture in Illinois at the end of December continued to be above
normal (Figure 1).
Compared to conditions at the end of November, soil moisture in Illinois at the end of December changed only
slightly at all sites (Table 2). Soil moisture in the 0- to 6-inch layer increased by 26 percent at Ina (Rend Lake),
but only by 5 percent or less elsewhere. Changes in the 6- to 20-inch layer included an increase of 13 percent at
Freeport, but by 5 percent or less elsewhere in the state. Freeport’s soil moisture increased by 42 percent in the 20to 40-inch layer; however, changes elsewhere were less than 4 percent.
3
45
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Figure 3. December monthly averages and totals as collected by the Illinois Climate Network
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Figure 4. January 1 observed percent-of-normal soil moisture based on 1985-1995 mean
5
Table 2. Soil Moisture in Various Layers on January 1, 2009
Location
Freeport (NW)
DeKalb (NE)
Monmouth (W)
East Peoria (C)
Stelle (E)
Champaign (E)
Bondville (E)
Perry (WSW)
Springfield (WSW)
Brownstown (ESE)
Olney (ESE)
Belleville (SW)
Carbondale (SW)
Ina (SE)
Fairfield (SE)
Dixon Springs (SE)
Jan 1
0-6
(inches)
Change
from
Dec 1 (%)
Jan 1
6 - 20
(inches)
Change
from
Dec 1 (%)
Jan 1
20 - 40
(inches)
Change
from
Dec 1 (%)
2.3
2.3
2.2
2.3
2.2
2.3
2.2
2.4
2.3
2.3
2.3
2.3
2.3
2.3
2.3
2.3
2
3
-2
0
-3
3
0
0
1
4
5
4
4
26
2
2
5.2
5.5
5.0
5.1
5.4
5.1
5.4
5.6
5.1
5.3
5.4
5.3
5.4
5.4
5.3
5.4
13
2
-2
0
0
-1
0
4
-1
1
3
0
5
4
1
1
7.6
7.7
7.5
7.4
7.8
7.1
7.9
8.0
7.5
7.3
7.9
8.1
7.9
7.4
7.8
7.9
42
0
-1
0
-1
-1
0
4
-1
-1
1
-2
2
2
-1
1
Surface Water Information (Bill Saylor and Vern Knapp)
River and stream discharge and stage data are obtained from gaging stations operated by the U.S.
Geological Survey (USGS) or the U.S. Army Corps of Engineers (USACE). The USGS gaging station network is
supported, in part, by the Illinois Department of Natural Resources Office of Water Resources, the Illinois State
Water Survey (ISWS), and the USACE. Provisional discharge data are obtained from the USGS.
Table 3 lists the provisional peak stage for the current month compared to flood stage at selected streamgaging
stations located on the Illinois, Mississippi, and Ohio Rivers. The peak stage is determined from the daily morning
readings posted by the National Weather Service and/or the USACE.
The Illinois River crested above local flood stages at most gaging stations downstream of the Fox River
(Ottawa) in December. The Mississippi River reached local flood stages at Grafton and at Chester. The Ohio River
exceeded local flood stage at Cairo at the end of the month.
Provisional monthly mean flows for 26 streamgaging stations located throughout Illinois are shown in
Table 4. Mean values posted by the USGS are listed if available; otherwise, daily mean discharge data posted by
the USGS are used to estimate the mean flow for the month. Long-term mean flows for each month are published
by the USGS. The month’s median flow for each station listed in Table 4 was determined by ranking the December
mean flow for each year of record, and selecting the middle value, 50 percent exceedence probability.
The statewide percent of historical mean flow and percent of historical median flow are calculated by dividing
the sum of the average flows this month at stations in Table 4 by the sum of the historical mean and median
flows calculated for the month, respectively, at the same stations. This method is intended to weight individual
observations proportionately in the aggregate comparison. (The Illinois River and Rock River stations are excluded
from the statewide calculation because other rivers listed in Table 4 contribute to their flow.)
Mean provisional flow statewide was well above the median value for December (500 percent of the median)
and above the long-term mean for the month (approximately 300 percent of the mean). Monthly mean streamflow
conditions throughout Illinois, as represented by Table 4 stations, ranged from above normal to much above normal
for December. (Note that the percent exceedence calculation in Table 4 does not take into account December 2008
monthly mean streamflows, which remain provisional; monthly mean streamflow values at some northern Illinois
streamgages in December 2008 exceeded those shown in Table 4 in December 2009.)
Some river flows and gage operations in northern Illinois were affected by ice during parts of the month.
Streamflow records may be significantly revised in the future by USGS during data review.
67
Table 3. Peak Stages for Major Rivers during December 2009
River
Illinois
Mississippi
Ohio
Station
River
mile*
Flood stage
(feet)*
Peak stage
(feet)**
Date
Morris
La Salle
Peoria
Havana
Beardstown
Hardin
263.1
224.7
164.6
119.6
88.6
21.5
16
20
18
14
14
25
14.0
24.3
19.5
19.0
20.9
27.0
26
27
31
31
31
29
Dubuque
Keokuk
Quincy
Grafton
St. Louis
Chester
Thebes
579.9
364.2
327.9
218.0
180.0
109.9
43.7
17
16
17
18
30
27
33
8.9
10.7
14.6
18.2
23.9
27.0
30.6
26
27
27
28
28
29
29
Cairo
2.0
40
40.4
31
________________
Notes:
* River mile and flood stage from River Stages in Illinois: Flood and Damage Data, Illinois Department of Natural Resources,
Office of Water Resources, August 2004 (and Addendum, February 2007).
** Peak stage based on daily a.m. readings, not instantaneous peak. Stage data obtained from U.S. Army Corps of Engineers.
Note: The USGS monthly long-term mean streamflow values for the Kankakee River at the Momence
streamgage were misreported in Table 4 of the October 2009 and November 2009 issues of the Illinois Water and
Climate Summary. The correct long-term monthly mean streamflow values published for the Kankakee River at
Momence for the months of October and November, during the period of record through Water Year 2008, are
1208 cfs and 1564 cfs, respectively. (Source: USGS Water Data Report - Illinois, Water Year 2008.)
Water-Supply Lakes and Major Reservoirs. Table 5 lists reservoirs in Illinois, their normal pool or target
water surface elevation, and other data related to observed variations in water surface elevations. Reservoir levels
are obtained from a network of cooperating reservoir operators who are contacted each month by ISWS staff for
the current water levels. Reservoir levels are reported in terms of their difference from normal pool (or target
level). The average of the month-end readings for the period of record is reported in terms of the difference from
normal pool or target level (column 6 of Table 5), and the number of years of record for each reservoir also is given
(column 7). Most reservoirs serve as public water supplies, with the exceptions noted in the last column.
Compared to end-of-November water levels at 27 reservoirs, reported end-of-December water levels were
lower at nine reservoirs, higher at seven reservoirs, and the same as at the end of last month at 11 reservoirs. For
the 28 reservoirs with observations reported at the end of November, water levels at three reservoirs were below
normal pool, nine reservoirs were at normal pool or spillway level, and 16 reservoirs were above normal pool or
spillway level. Note that some observers do not measure or report lake levels higher than “full pool” (spillway
level) during overflow conditions.
Major Reservoirs. Compared to water levels at the end of November, at the end of December Lake Shelbyville
was 2.2 feet higher, Carlyle Lake was 1.0 foot higher, and Rend Lake was 2.5 feet higher. At the end of December,
Lake Shelbyville was 21.5 feet above January 1 target level, Carlyle Lake was 8.7 feet above winter target level, and
Rend Lake was 5.4 feet above spillway level. (Lake Shelbyville target level decreased 5.7 feet from December to
January.)
Great Lakes. Current month mean and end-of-month values are provisional and are relative to International
Great Lakes Datum 1985. The December mean level for Lake Michigan was 578.1 feet, compared to a mean level
of 577.3 feet in December 2008. The long-term average lake level for December is 578.5 feet, based on 1918–2008
data. Historically, the lowest mean level for Lake Michigan in December occurred in 1964 at 576.2 feet, and the
highest level occurred in 1986 at 581.6 feet. The month-end level of Lake Michigan was 578.1 feet.
7
Table 4. Provisional Mean Flows, December 2009
Station
Drainage Years
area
of
(sq mi) record
2009
Long-term flows
mean flow Mean* Median
(cfs)
(cfs) (cfs)
Flow condition
Rock River at Rockton
6363
74
6329
3331
3078
much above normal
Rock River near Joslin
9549
66
11,000
5078
4875
much above normal
Pecatonica River at Freeport
1326
90
N/A
690
582
much above normal
Green River near Geneseo
1003
70
2107
473
368
much above normal
Edwards River near New Boston
445
71
835
180
102
much above normal
Kankakee River at Momence
2294
91
~ 2900
2037
1724
above normal
Iroquois River near Chebanse
2091
85
~ 2300
1626
991
above normal
Fox River at Dayton
2642
90
> 3600
1516
1257
much above normal
Vermilion River at Pontiac
579
65
1070
376
158
above normal
Spoon River at Seville
1636
92
3109
672
397
much above normal
LaMoine River at Ripley
1293
85
2571
501
240
much above normal
Bear Creek near Marceline
349
64
511
145
33
much above normal
Mackinaw River near Congerville
767
60
1564
419
194
much above normal
1804
67
4007
1066
533
much above normal
Salt Creek near Greenview
Sangamon River at Monticello
550
96
1118
359
184
much above normal
South Fork Sangamon near Rochester 867
59
2443
547
133
much above normal
26,743
70
47,180
18,200
14,962
much above normal
Illinois River at Valley City
Macoupin Creek near Kane
868
80
2747
456
138
much above normal
Vermilion River near Danville
1290
87
2280
927
504
above normal
Kaskaskia River at Vandalia
1940
39
5204
1949
1457
much above normal
Shoal Creek near Breese
735
65
2475
555
178
much above normal
1516
95
4238
1267
777
much above normal
Embarras River at Ste. Marie
Skillet Fork at Wayne City
464
89
1561
419
214
much above normal
Little Wabash below Clay City
1131
94
4407
1020
481
much above normal
Big Muddy at Plumfield
794
38
1685
670
294
above normal
Cache River at Forman
244
85
752
345
214
above normal
________________
Notes:
Source streamflow data are obtained from the U.S. Geological Survey.
N/A = not available.
Much below normal flow = 90-100% chance of exceedence.
Below normal flow = 70-90% chance of exceedence.
Normal flow = 30-70% chance of exceedence.
Above normal flow = 10-30% chance of exceedence.
Much above normal flow = 0-10% chance of exceedence.
*As reported in U.S. Geological Survey (USGS) Water Resources Data, Illinois, Water Year 2008.
(Note: December 2008 values not included in analysis.)
89
Percent Days of
chance of data this
exceedence month
7
4
N/A
1
4
23
28
4
11
3
2
8
5
4
10
5
4
4
17
10
4
6
5
4
18
16
31
30
N/A
31
31
31
31
28
31
31
31
31
31
31
31
31
31
31
29
31
31
31
31
31
31
31
Table 5. Reservoir Levels in Illinois, December 2009
Reservoir
County
Current level
Normal pool difference from
or target
normal or target
level (feet)
(feet)
Monthly
change
(feet)
Average
difference from
normal or target
(feet)
Years
of
record
November
reported
pumpage
(million gallons)
Altamont
Effingham
582.0
0.0
-0.1
-2.5
26
6.3
Bloomington
McLean
719.5
+0.4
+0.1
-3.7
23
No pumpage
Canton
Fulton
577.5
+0.1
0.0
-2.5
19
63.8
Carlinville
Macoupin
571.1
0.0
-0.3
-0.8
26
22.9
Carlyle(1)
Clinton
443.0
+8.7
+1.0
+2.0
31
N/A
Coulterville
Randolph
515.9
N/A
N/A
-1.8
11
N/A
Macon
612.5
+1.3
-0.1
+0.1
26
968.6
Decatur(1,3)
Evergreen(4)
Woodford
720.0
+0.3
+0.1
-3.7
19
275.3
Glenn Shoals(2) Montgomery
590.0
N/A
N/A
-0.1
15
w/Hillsboro
Greenfield
Greene
566.2
+0.3
-1.5
-1.0
15
2.4
Highland
Madison
500.0
+0.3
0.0
-0.1
21
31.7
Montgomery
589.0
N/A
N/A
0.0
15
29.1
Hillsboro(2)
Jacksonville(2)
Morgan
644.0
N/A
N/A
-0.7
6
w/Mauvaise Terre
Kinkaid
Jackson
420.0
0.0
0.0
-0.5
21
59.6
Lake of Egypt
Williamson
500.0
+0.3
N/A
-0.4
15
N/A
Mattoon
Coles
632.0
0.0
0.0
-0.6
14
w/Paradise
Mauvaise Terre(2) Morgan
588.5
N/A
N/A
0.0
11
no meter
Mt. Olive (new) Macoupin
600.0
0.0
0.0
-0.4
8
w/Mt. Olive (old)
Mt. Olive (old) Macoupin
654.0
0.0
0.0
-0.6
13
5.7
Nashville(3)
Washington
503.8
N/A
N/A
-0.5
22
16.1
Pana
Christian
641.6
+0.1
0.0
-1.3
24
N/A
Paradise
Coles
685.0
0.0
0.0
-0.3
18
59.7
Paris (east)
Edgar
660.0
+0.1
-0.1
-0.6
24
38.6
Paris (west)
Edgar
660.1
+0.1
-0.1
+0.2
14
w/Paris (east)
Pinckneyville
Perry
445.0
N/A
N/A
-1.3
15
N/A
Pittsfield
Pike
596.0
0.0
-0.5
-0.4
19
15.1
Marion
477.0
+0.5
-0.2
N/A
N/A
100.4
Raccoon(1)
Rend
Franklin
405.0
+5.4
+2.5
+1.4
31
N/A
Salem(3)
Marion
546.5
-0.1
+0.8
-1.1
14
25.4
Shelbyville(1)
Shelby
594.0
+21.5
+2.2
+5.9
31
Not PWS
Randolph
497.5
-0.5
0.0
-0.9
11
19.5
Sparta(3)
Spring(4)
McDonough
654.0
N/A
N/A
-0.8
25
N/A
Springfield(1,3)
Sangamon
559.6
-0.1
-1.0
-1.5
26
619.0
Taylorville
Christian
590.0
+0.4
+0.2
-0.9
16
52.9
Vermilion(4)
Vermilion
581.7
0.0
0.0
-0.6
24
233.1
Virginia
Cass
575.0
+0.1
0.0
-0.2
20
Not PWS
_______________
Notes:
Normal pool and target level datum is NGVD 1929.
Current levels reported represent water surface levels at the end of the month, not the monthly average.
Average difference from normal or target level is the arithmetic average of reported month-end values for the period of record
indicated.
Years of record = total number of monthly readings included in month-end average. Total period of record may be longer.
Not PWS = not a public water supply.
N/A = not available.
(1)
Target operating level may vary. Seasonal target levels this month represent January 1 values.
(2)
Instrumentation not available to measure height of water elevation above spillway.
(3)
Natural inflow can be supplemented by other sources.
(4)
Normal pool elevations have changed during period of record reported.
9
Groundwater Information (Ken Hlinka)
Comparison to Average Levels. Shallow groundwater levels in 15 observation wells, which are remote from
pumping centers, were above average for the month. December levels were 3.9 feet above normal and ranged from
0.0 feet to 9.3 feet above normal levels (Table 6).
Comparison to Previous Month. Shallow groundwater levels were above those of last month. Levels averaged
0.5 feet above and ranged from 0.9 feet below to 2.0 feet above levels of last month.
Comparison to Same Month, Previous Year. Shallow groundwater levels in December were above levels
measured one year ago. Levels averaged 1.6 feet above and ranged from 1.2 feet to 4.1 feet higher this month than in
December 2008.
Table 6. Month-End Shallow Groundwater Level Data Sites, December 2009
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Well name
County
Galena
Mt. Morris
Crystal Lake
Cambridge
Fermi Lab
Good Hope
Snicarte
Coffman
Greenfield
Janesville
St. Peter
SWS #2
Boyleston
Sparta
SE College
Dixon Springs
Bondville
JoDaviess
Ogle
McHenry
Henry
DuPage
McDonough
Mason
Pike
Greene
Cumberland
Fayette
St. Clair
Wayne
Randolph
Saline
Pope
Champaign
________________
Notes:
* Data not used in analysis
N/A - Data not available.
Deviation from
Period of
Previous
record avg.
month
(feet)
(feet)
Well depth
(feet)
This month’s
reading (depth
to water, feet)
15-year
avg. level
(feet)
25.00
55.00
18.00
42.00
17.00
30.00
40.30
28.00
20.70
11.00
15.00
80.00
23.00
27.00
10.19
8.63
21.00
18.37
11.21
3.44
N/A
2.82
N/A
34.09
2.80
3.18
4.86
1.70
9.02
2.59
3.07
2.26
1.40
3.16
+2.91
+8.70
+2.13
N/A
+4.51
N/A
+3.60
+9.61
+9.69
+0.07
+0.47
+4.48
+1.11
+4.87
+1.91
+2.68
+1.56
+3.19
+8.76
+2.02
N/A
+4.29
N/A
+3.38
+9.31
+9.17
+0.03
+0.56
+6.17
+1.92
+5.25
+1.59
+1.27
+0.83
+0.78
+1.53
-0.04
N/A
+1.97
N/A
+0.08
+0.11
+0.60
-0.14
-0.44
+1.49
-0.93
+0.55
-0.24
+1.92
-0.40
+1.73
+2.78
-0.07
N/A
+0.85
N/A
+1.23
+3.34
+4.10
-0.33
-0.46
+3.36
-0.69
+3.69
+2.89
+3.31
-1.23
Averages
+3.89
+3.85
+0.46
+1.63
Addendum (Nancy Westcott)
Previous
year
(feet)
Imperial Valley Precipitation. Precipitation for December 2009 was heavy. Monthly gage totals were greatest
in the western portion of the network, and precipitation was lightest in the northeastern portion of the network.
Individual gage amounts ranged from 4.25 inches at Site #2 to 2.05 inches at Site #6. The 1971–2000, 30-year
average precipitation amounts for November at Havana and Mason City are 2.63 and 2.41 inches, respectively. The
December 2009 network average of 3.30 inches is about 195 percent of the 17-year (1992–2008) IVWA December
network average of 1.70 inches.
Cook County Precipitation. December 2009 total precipitation amounts were heavy. The greatest
precipitation was found in the eastern part of the county, and the lightest precipitation was in the western and
southern portions of the network. Precipitation values ranged from 4.21 inches at Site #2 (Winnetka) to 2.49 inches
at Site #25 (Chicago Heights). The December 2009 network average of 3.22 inches is about 159 percent of the 20year (1989–2008) December network average of 2.02 inches.
11
10
+ORGTKCN8CNNG[9CVGT#WVJQTKV[
2TGEKRKVCVKQP
KPEJGU
a. Imperial
Valley
&GEGODGT
5ECNGQH/KNGU
b. Cook County
&GEGODGT
Figure 5. Long-term raingage network precipitation totals (inches) for December 2009
Data sources for information in this publication include the following:
CPC - Climate Predication Center, http://www.cpc.ncep.noaa.gov/index.php
ISWS - Illinois State Water Survey, http://www.isws.illinois.edu/
MRCC - Midwestern Regional Climate Center, http://mrcc.isws.illinois.edu/
NCDC - National Climate Data Center, http://www.ncdc.noaa.gov/
NWS - National Weather Service, http://www.nws.noaa.gov/
USACE - U.S. Army Corp of Engineers, http://rivergages.com, http://www.lre.usace.army.mil/greatlakes/hh/
USGS - U.S. Geological Survey, http://waterdata.usgs.gov/il/nwis
WARM - Water and Atmospheric Resources Monitoring Program, http://www.isws.illinois.edu/warm/
11