Case Study: The Great Coastal
Gale… and a lot more!
The winter storms of 1-5 December 2007
Brad Colman, Sc.D.
NOAA/National Weather Service
Seattle, Washington
Outline
• Overview of the event and impacts
• Forecast process as an event timeline
• Webinar (Friday, 11 AM)
• What worked and what didn’t
• Changes since the event
• NOAA’s Weather Ready Nation
Overview
• December 1-5, 2007, three successive powerful storms
pounded the Pacific Northwest (mostly over a weekend)
• A mix of winter weather inland and mountains
• Hurricane force winds occurred over the coastal waters of
Oregon and southern Washington
• Extremely heavy rainfall (19.33 inch max on Rock Creek)
resulted in many new record flood crests
• 11 fatalities occurred with the most fatalities (5) due to
avalanches
• Thousands of landslides and mudslides
• Tremendous economic impact – in excess of $1 Billion
Interior lowland snow
West Seattle, courtesy
Shawn McClung
Avalanches
SR 2, Tumwater Canyon
Snow – Impacts
• Mountain Snow
– 1-3 feet (Sat Dec 1 – Mon Dec 3)
• Avalanche
– 5 fatalities (on Sun Dec 2)
• 2 near Alpental (Snoqualmie Pass)
• 3 near Crystal Mountain (NE of Mt Rainier)
– 1 injury (on Sun Dec 2 near Alpental)
• Lowland Snow
– Hood Canal/Kitsap Peninsula
• 5 to 9 inches (PM Sat Dec 1 – Midday Sun Dec
2)
– Rest of Lowlands
• Trace to 5 inches (PM Sat Dec 1 – Midday Sun
Dec 2)
Incredible wind damage coast
Aberdeen Wind damage
Weyerhaeuser forest near
Aberdeen
Peak Gusts 2-3 Dec 2007
• Fastest winds focused on the
coastal strip from CA to BC
• Most of coast without power (~55
thousand customers)
• “Ground Zero” in coastal:
• Tillamook County, OR
• Clatsop County, OR
• Pacific County, WA
• Grays Harbor County, WA
• Numerous locations with gusts
exceeding 57 mph
• Peak wind Category II hurricane
above 120 mph
• Perhaps 10-15,000 mi2 afflicted by
high-wind criteria gusts.
StormTotal
Total Precipitation
Storm
Precipitation
(24-h amounts approximately a 500-800 year event)
14.7”
15.3”
10.5”
5.6”
14.1”
19+”
16”
12.5”
Precipitation estimates
from the Seattle Radar
~30% of observed
Hydrologic Impacts
River Flooding
Areal Flooding
Landslides
Record Flooding in Vernonia, Oregon
Nehalem Basin
ASTORIA
USGS GAGE
14299800
USGS GAGE
14301000
Saddle Mountain
River Stage
Rate of Rise
~0.6 ft/hr
Precip Rate
.43”/hr
Precipitation
Precip Rate
.17”/hr
Snowmelt Component
Saddle Mountain SNOTEL, Elev. 3110’
Snow-Water
Equivalent
9 inches of water
Released between
14Z and 22Z
(8 hours)
Temperature
River Flooding
Record
Major
Areal Flood and Landslides
• Several hundred rescues
– Helicopter, SAR boats, vehicles, personal water craft
– Rooftops, cars, through holes cut into roof
• Many injuries and near escapes
• Areal flooding
– Much of the area impacted and much of the damage
– Moderate intensity for extended period
– 2 fatalities
• Landslides
–
–
–
–
Dozens in Seattle
Many more across Region
Homes, apartments evacuated
1 fatality
Known Landslides
>1000 in south west alone
SR6 – Outside Pe Ell
Courtesy WSDOT
Forecasts
and Actions
1100 AM PST: GoTo web briefing with Emergency Managers
428 PM PST: Flood Warning
Wed
12/5
Thu
12/6
1215 PM PST: Chehalis River drops below Flood Stage
Tue
12/4
1200 AM PST: Chehalis River at Porter – Record Stage
(26.05 ft)
218 PM PST: Flooding and debris flow reported Brinnon, WA.
1000 AM PST: Chehalis River near Grand Mound – Record Stage
(20.23 ft)
Mon
12/3
453 AM PST: Winter Storm Warning
330 AM PST: Chehalis River at Centralia – Record Stage (74.78 ft)
330 PM PST: Elwha River at McDonald Bridge – Record Stage (24.65 ft)
230 PM PST: Skokomish River near Potlatch – Record Stage (18.12 ft)
1100 AM PST: Aberdeen, WA county official reports fatality caused by
a falling tree
900 AM PST: Spotter report sustained winds 30-40 MPH, gust 93 MPH
Clallam Bay, WA
913 AM PST: SPS for landslide potential
800 AM PST: Forks, WA 2 injuries (utility workers)
Sun
12/2
643 AM PST: Bogachiel River rises above flood stage
612 AM PST: Urban flooding reported Bothell, WA
400 AM PST: Fatality, single man buried in his home by landslide,
just North of Hoodsport, WA
409 AM PST: Coastal Flood Warning
600 AM PST: Spotter reported wind gust of 44 MPH at Bellingham, WA
230 AM PST: wind gust 72 MPH Aberdeen, WA
250 AM PST: Buoy 41 max wave height 11.9 meters
128 AM PST: Hurricane Force Wind Warning
900 PM PST: Montesano, WA 1 fatality due to power failure - elderly
man died after his oxygen power supply was cut off.
1149 PM PST (KHQM) ASOS reports gust of 58 knots from SSE
430 PM PST: Areal Flood Warning
Sat
12/1
300 PM PST: 2 avalanches reported with 5 fatalties/1 injury
Snoqualmie Pass, WA and Crystal Mt, WA.
1252 PM PST: HIGH WIND WARNING/Wind Advisory
406 AM PST: COASTAL FLOOD WATCH
306 AM PST: Storm Warning
1035 PM PST: HIGH SURF WARNING
934 PM PST: HIGH WIND WATCH
348 PM PST: Flood Watch
Fri
11/30
143 PM PST: Heavy Snow Warning – Hood Canal
453 AM PST: Snow Advisory for much of W. WA
903 AM PST: Gale Warning
353 PM PST: Hydrologic Outlook
306 PM PST: Winter Storm Warning for the Cascades and Olympics
Thur
11/29
402 AM PST: SPS for High Wind
830 AM PST: Avalanche Watch (NWAC)
440 PM PST: Marine Weather Statement
510 AM PST: SPS for lowland snow
Event Timeline (PST)
Fri
12/7
GoToMeeting
•
Purpose
– Raise Awareness and Preparedness Sat-Mon
– Suite of Weather Events to Unfold
•
•
Fri Nov 30 – 11 AM
Who Attended
–
–
–
–
–
•
State, County, City Emergency Management Officials
Power Utilities
State, County, City DOTs
Corp of Engineers
School Districts
Highlights
–
–
–
–
Snow to Begin on Sat
Change to Rain on Sun
Heavy Rain and Rising Wind Midday Sun Into Mon
Potential for Flooding Early Next Week
• 10-15 inches of rain possible in the Olympics
– Statements Being Issued Today
– Stay Tuned Through the Weekend !!
– Slide Show Was Posted on the Web
Lessons Learned
•
•
•
•
An historic series of storms for the PNW
Multi-hazard event, over a weekend
Intensity of heavy rain and melting snow was missed
Eye opener on communications
–
–
–
–
–
Early statements on Thursday
Hosted Webinar on Friday
Many watches, warnings, statements, etc.
Yet, many coastal residents felt unwarned
The process failed for many… Why?
Our current single greatest challenge is getting
the word out to the right people and getting them
to make the right decision!!
Changes Since the Storm
• Improved Webinars and Briefings
• Personal phone calls to EMs
• New treatment of Major/Record Floods
and Extreme Wind events
• Improved office operations plan
• E-Warn and NWSChat; Facebook
• New observing stations and backup power
at some
Coastal radar dedicated
29 September 2011
NOAA’s Response to the Challenge
Building a WeatherReady Nation
GOAL: A Society that
is Prepared for, and
Responds to, Hazardous
Weather Events
A Changing World
UPDATE
Meeting the Nation’s Needs
Building a Weather-Ready Nation
• NOAA/NWS must:
- Continue to improve forecasts
- Effectively communicate risk and forecast
confidence levels
- Develop more responsive and meaningful
products and services
- Provide more efficient delivery of products
and services in a technologically changing
world
As a community we must…
• Learn from these past events
• Work together to improve communication
• Preparedness is critical
• Outreach and education
• Community impact mitigation
• Coordinated effort, we are all in it together!