The Need for a Weather Radar along the Washington Coast
Cliff Mass
Department of Atmospheric Sciences
University of Washington

Weather radar is one of the key technologies of modern weather forecasting
Modern Doppler Radars can tell us:
– where is is precipitating
– how hard it is precipitating
– the velocity of air towards and away from the radar
– some radars (polarized ones) can also define the type of precipitation

Weather Radars
Although weather radars have proven value for viewing strong thunderstorms they are also invaluable for other uses:
– To locate and describe weather fronts
– To define the circulations around storms
– To determine the extent of heavy precipitation, including precipitation on mountain barriers.
– To define local weather phenomena, like the Puget
Sound convergence zone and rain shadows.

During the
1980s, the NWS installed a network of powerful
Doppler
Weather
Radars, aka
NEXRAD
WSR88D

NWS Radar Sites

But there was a major problem in the Pacific Northwest...
The two NW radars (Camano Island, WA and Portland, OR) were placed east of the
Olympics and Coastal Mountains and thus the radar beams are generally blocked before they reached the coast.

Radar coverage for the lowest beam (.5 degree elevation angle) for the current network. Red areas indicate no coverage below 8000 m
(25,000 ft). Radar coverage calculations by
Ken Westrick

The right diagram indicates the effective coverage of the
Weather Service radars for all elevation angles at 10,000 ft above mean sea level, with hatching indicating substantial blockage.

Northwest Coastal Radar Problem
• The Pacific Northwest has the worst coastal radar coverage of any region of the lower 48states.
• There is virtually no radar coverage for the lower atmosphere over the coastal zone and the near-shore waters.
• It is particularly disturbing that such poor coverage exists for a region of often intense storms AND a great deal of military, shipping, fishing and other marine traffic.

The Irony
• The coastal NW has the worst radar coverage in the nation
• The NW has the stormiest coastal weather and the heaviest annual precipitation in the nation.

The Northwest Has the Stormiest Coastal
Waters in the Nation
Storminess Index

Billion Dollar Storms are Regular
Visitors
The latest: December 2-4, 2007:Chehalis
Flooding and Devastating Coastal Winds

Coastal Weather Radars Can
Provide Critical Information When
Major Storms Approach

When Hurricane Katrina
Approached the Gulf Coast
Radar Clearly Showed the Threat

Or Cape Hatteras….

The Northwest has it own
Hurricanes
The Northwest experiences the most intense non-tropical storms in the U.S.
Some greatly exceed hurricane strength

1921 Olympic Blow Down Storm

In some areas over 40% of the trees were blown down
As a result, this event has become known as the
“The Olympic Blowdown Storm ”

An Extraordinary Event
• Hurricane-Force Winds Struck the Entire
Washington Coast
– At North Head sustained (5 minute average) winds reached 126 mph, with a maximum oneminute wind of 150 mph before the sensor failed.
– At Tatoosh Island, 150 miles to the north, winds reached 110 mph.
– At Astoria, on the south side of the Columbia, there were unofficial reports of gusts to 130 mph.

The most extreme non-tropical windstorm in the last 150 years: The Columbus Day windstorm of 12 October 1962

The Big One
• The Columbus Day Storm was the most damaging windstorm to strike the Pacific Northwest in at least
150 years.
• An extensive area, stretching from northern
California to southern British Columbia experienced hurricane-force winds, massive treefalls, and power outages, with some winds exceeding 150 mph.
• In Oregon and Washington, 46 died and 317 required hospitalization as a result of the storm.

Columbus Day 1962: At Cape Blanco there were
150 mph with gusts to 179! Strongest winds on bluffs and windward slopes of coastal orography

The December 7, 2008 Coastal Storm

Some of these major storms are poorly forecast or not forecast at all
…and there is no coastal radar to tell forecasters and others that the computer models are going wrong.

Forecast Failure of a Major Storm:
February 7, 2002
• On the morning of 7
February 2002 an intense low center moved into the central
Oregon coast, with absolutely no warnings by the National
Weather Service.
• Produced strong winds with gusts exceeding
70 mph

A surprise storm in southern Oregon on
February 7, 2002 caused massive tree falls and damage
NO WARNINGS!!

Other Implications of Poor Coastal
Radar Coverage
Northwest forecasters often have a poor idea of the structure of weather systems approaching the area.
– The ability to provide short-term forecasts over western Oregon and Washington is greatly lessened.

The Implications of Poor Coastal Radar Coverage
• With no low level Doppler wind and reflectivity from radar, critical warnings and weather guidance over the coastal zone are degraded. No assistance for emergency situations, pollutant spills, and the like.
When the New Carrisa grounded Near Coos
Bay, Oregon, there was no radar coverage to help manage salvage operations.

The Implications of Poor Coastal Radar
Coverage
• There is no radar coverage of the heavy orographic precipitation on the western and southern sides of the Olympics and coastal mountains….thus, degrading flood and river forecasting.

Input from Larry Schick,
Lead Forecaster, U.S.
Army Corps of Engineers
• “An additional one or two radar sites on the NW coast is imperative for managing risk and for confident flood control operations”
• “No doubt coastal radar would have helped in detecting precipitation and real time management of the floods in
December.”
• “Coastal radar would help greatly in all our flood operations , not just the coastal areas, as we often need to know the timing of the end of the rain or increase in the Cascade projects as well.
Coastal radar coverage would help us with that too and understanding near offshore precipitation conditions.”

The Implications of Poor Coastal Radar
Coverage
• There is a distinct lack of high resolution weather data offshore for initializing weather prediction models. A coastal radar could provide such data. Without such radars, future short-term forecast skill of weather features approaching our coast will be limited.
• Weather radar information is invaluable for research, allowing the understanding of important local weather features.

The Solution: Acquisition of
Additional Coastal Radars

Coverage for Lowest Elevation Angle (.5 degrees)
Now With Two New Radars

Acquisition of Additional Coastal Radars
• Ideally two radars would be acquired with one positioned on the central WA coast (e.g., Westport to Pacific Beach) and the other on the central
Oregon coast (e.g.,Florence)
• If we could secure only one, a central WA coast radar should be the priority…since it provides coverage of entrances to the Columbia River and the Strait entrances, Gray’s Harbor, precipitation on the wet side of the Olympics, and is upstream of the densely populated Puget Sound region.

We have an idea of the advantages of such a radar, because one was in place for a research experiment…IMPROVE I, in
January-February 2001.

Westport S-Pol Radar (January-February 2001)

Reflectivity from S-Pol radar at Westport
0031 UTC 2 Feb 2001 at 0.5 degree elevation dBZ

National Weather Service
Forecasters Found the Coastal
Radar Highly Useful During Those
Two Months in 2001

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
325 PM PST THU JAN 4 2001
SATELLITE IMAGERY SHOWS COLD FRONT OFFSHORE NOW NEAR 133W...STILL
WEST OF BUOY 5. WARM ADVECTION PRECIPITATION BEGAN ALONG THE COAST
AROUND 18Z AND OVER THE INTERIOR AROUND 21Z. S-POL RADAR AT WESTPORT
HAS SW WIND AT 40 KT BEGINNING AROUND 1500FEET. THIS COMBINED WITH JUICY AMS
ASSOCIATED WITH THE FRONT WILL MAKE FOR HEAVY RAINFALL OVER THE OLYMPICS
TONIGHT. THE WESTPORT RADAR IS ALREADY SHOWING MODERATE ECHOES JUST
OFFSHORE. WILL CONTINUE FLOOD WATCH FOR THE SKOKOMISH RIVER. MODELS
PRETTY CONSISTENT WITH THE
NATIONAL WEATHER SERVICE SEATTLE WA
223 PM PST TUE JAN 23 2001
UPR LVL LOW IS SETTLING IN W OF THE OREGON CST NR 45N/133W AND PER
12Z PROGS...WL HANG AROUND THRU WED NIGHT...BEFORE BEING ABSORBED ON
THU BY A 2ND UPR LVL LOW THAT DIGS SE TWD CA. AVN IS MDL OF CHOICE.
WK FNTL BAND DRAPED NW-SE ACRS NW OREGON WL MOV SLOWLY NWD INTO W WA
TNGT WITH AREAS LGT RAIN BUT LOW ACCUMULATION . CONFIDENCE IN A LITTLE
LGT RAIN TNGT IS GOOD GIVEN S-POL RESEARCH RADAR AT KHQM SHOWG LGT ECHOES
EXTENDING NNW ALG FNT TO ABT 35NM W QUILLAYUTE.

The Coastal Radar Helped During a Flooding Event
NATIONAL WEATHER SERVICE SEATTLE WA
930 AM PST THU JAN 4 2001
SATELLITE IMAGERY SHOWS COLD FRONT OFFSHORE NOW NEAR 134W. SSMI
IMAGERY OLD BUT IMAGERY FROM YESTERDAY SHOWED PW VALUES OVER 2 INCHES
AND MAX RAINFALL RATES AROUND A HALF INCH AND HOUR ASSOCIATED WITH
THE FRONT. GIVEN THE CONNECTION TO THE TYPHOON IN THE WESTERN PACIFIC
THIS IS NOT UNREASONABLE. 12Z MODEL RUNS CONSISTENT IN BRING FRONT
THROUGH WESTERN WASHINGTON 12Z-18Z FRIDAY. SOUTHWESTERLY 850 MB WINDS
OF 40 KNOTS AHEAD OF THE FRONT MAKES FOR STRONG OROGRAPHICS ALONG THE
SOUTHERN SLOPES OF THE OLYMPICS TONIGHT BETWEEN 00Z-12Z. WILL KEEP
WATCH FOR THE SKOKOMISH GOING. S-POL RADAR AT WESTPORT SHOWS LEADING
EDGE OF THE PRECIPITATION OUT AHEAD OF THE FRONT JUST WEST OF KHQM AT
16Z.
CURRENT TIMING BRINGS THIS PRECIPITATION INTO THE INTERIOR MID
TO LATE AFTERNOON. MORE COOL AIR BEHIND THIS FRONT THEN THE FRONTS
THAT WENT THROUGH THE PAST WEEK FOR SCATTERED SHOWERS FRIDAY
AFTERNOON BUT MOST OF THE PRECIP WILL BE IN THE MOUNTAINS. SATURDAY
STILL LOOKS DRY WITH UPPER LEVEL RIDGE MOVING OVER THE AREA AND
OFFSHORE SURFACE PRESSURE GRADIENTS. LITTLE CHANGE TO CURRENT
PACKAGE. FELTON

Weather Radar Greatly Improves
Daily Lives
• Able to plan recreational activities or even bicycle commuting.
• Assists weather sensitive businesses from fishing and crabbing to construction, painting and forestry.
• Why should the coastal portion of
Washington be denied these advantages?

Maritime Interests
• The coastal waters of Washington heavily traveled by both civilian and military vessels.
• Important fisheries offshore and alongshore.
• Knowing weather is needed for safety.

Radar Costs
• The radar, with polarization option, would cost approximately four million dollars
(including installation).
• Costs of land, site surveys, bringing in utilities, and spare parts are additional.

Growing Support for the Coastal
Radar
• Northwest Weather Modeling Consortium
• Friends of Gray’s Harbor
• Crab Industry, Fishers, and Oystermen
• Audubon Society
• Port Blakely Tree Farms
• Cities and Counties
• Puget Sound Clean Air Agency
• Editorials in major local papers

For More Information Check the Web Site http://www.atmos.washington.edu/~cliff/coastalradar.html