The Pacific Northwest has the Worst Coastal Weather Radar Coverage in the Lower 48 States:  Documentation of the Problem and Call for Action


The coastal radar acquisition is receiving strong support from local cities and counties, environmental groups, local businesses and fishermen, the timber and wood-products industry, and newpaper editorial writers from throughout the region

Improve1 radar

Latest News (11/25/09)

President Obama's 2010 budget request includes full funding for the coastal weather radar.  If this passes Congress this year, the radar will become a reality.  So let your Senator's and Congressmen know you support it.

The site survey process has begun and several excellent potential sites have been found, some on private and some on public lands.  A report on the potential sites should be released by the National Weather Service during the next few months, followed by public hearings.

Senator Maria Cantwell has secured 2 million dollars for the radar in the 2009 Omnibus bill signed by President Obama.  This is roughly 1/3 the total cost of the coastal radar.  This is a major advance for the effort.

Hoquiam Daily World Article (3/21/09)
Seattle Times Article (3/22/09)

Senator Maria Cantwell's staff  organized a well-attended meeting to discuss the need for the coastal radar on March 6, 2008 in Aberdeen at Grays Harbor Community College. Also there were representatives of Congressmen Dicks, Inslee, and Baird. An article on the gathering in the Aberdeen Daily World is found here. And an article from the Seattle Times is here.

Cliff Mass' presentation to the meeting is found here.

  Your help is needed to fix this problem!

A National Weather Service WSR-88D Doppler Radar

  • There is little useful weather radar coverage over Northwest coastal waters or along the immediate coast.
  • Northwest meteorologists lack radar information about crucial weather features along the NW coast, such as heavy precipitation and strong winds.
  • In contrast to the rest of the country, Northwest weather forecasters cannot view the details of weather systems approaching the coast. 
  • The lack of a coastal weather radar degrades warnings and forecasts for the entire region from what would be possible with proper coverage.
  • Major storms can hit our coastal regions with little warning and short-term forecasts are degraded.
  • Research on Northwest coastal meteorology is greatly hindered by the absence of an operational coastal radar.
  •     This report describes the situation and what needs to be done to correct it.


         The National Weather Service completed a major modernization in the 1990s, a central component being the installation of powerful Doppler weather radars across the country.   Such units, known as WSR-88Ds or NEXRADs, describe precipitation and winds in their environs and have revolutionized forecasting and meteorological research.
        The range of useful radar coverage is controlled by a number of factors.  Terrain blockage is important in mountainous regions like the Northwest.  Furthermore,  the height of the radar beam increases with distance from the radar--resulting in an inability to see important low-level features at distances from the radar.  Under perfect conditions, the maximum range of the WSR-88D for wind information is 230 km (138 miles) and for precipitation sensing roughly twice as far.
        An official National Weather Service map of national weather radar coverage (for precipitation) is shown below.  A second image with a blow-up of the Northwest section is also provided.  These radar coverage maps are valid at 10,000 ft ABOVE THE RADAR SITES (many of which are already thousands of feet above the surface!), not at the surface.  Radar coverage near the surface is far poorer, particularly over the western U.S. where blockage by terrain is significant.  Even for the optimistic 10,000 ft coverage, the Northwest coastal zone is poorly served compared to the California, Gulf of Mexico, and Atlantic coastal regions.  But as shown below, the NWS radar coverage maps do not provide the real story.

        The National Weather Service installed three radars to provide coverage over western Washington and western Oregon:  Camano Island (WA), Portland (OR) and Medford (OR).  The figures shown below indicate their locations and provide more exact coverage maps using high-resolution terrain data.

        The left diagram shows the location of the National Weather Service radars (tower symbols) and some other sites of interest.  The right diagram indicates the effective coverage of the Weather Service radars (at 3-km, approximately 10,000 ft above mean sea level), with hatching indicating substantial blockage. Coverage at lower levels is far worse.  Notice that low-level coastal coverage is virtually absent.

        The Camano Island and Portland radars are blocked to the west by the Olympic and coastal mountains and provide little information about  weather over the coast and the near-offshore waters.  Even without the mountains, these radars are positioned too far inland to provide useful information about weather systems approaching the Washington and Oregon coasts.  This is particularly true for the Doppler winds, which are only available within 138 miles of the radar.  The Medford radar is even more problematic:  it is located at a very high (7500 ft) elevation to minimize blockage, causing it to miss most coastal and valley precipitation.  The Medford radar is also too far inland to provide useful information over the coast.  One has to go as far south as California (the Eureka radar) to get proper coastal radar coverage.

        These figures, and the experience of Northwest meteorologists, demonstrate that the coastal regions of Washington and Oregon have extremely poor or non-existent radar coverage--demonstrably the worst radar coverage of any coastal region of the continental U.S.  Such poor coverage is particularly disturbing considering the powerful weather systems that make landfall over the area, the continual threat of heavy precipitation and flooding over the Olympics and coastal terrain, and the intense use of the near-shore waters for fishing, shipping, recreation, and military exercises.  Some important considerations:
  •   The western entrance to the Strait of Juan de Fuca and the dangerous Columbia River bars do not have useful low-level weather radar coverage.
  •  Offshore military exercises run out of Whidbey Island Naval Air Station, McChord Air Force Base, the Everett Home Port, and the Bangor Submarine base are without the comprehensive meteorological oversight that coastal radars could provide.
  •  Weather Service forecasters cannot garner critical information on weather systems approaching the Northwest coast, clearly degrading short-term forecasts.  Some examples are given below.
  •  Incidents such as the grounding of the New Carisa and the loss of Coast Guard personnel during a rescue attempt in 1997 demonstrate the need for timely weather information over the Pacific coast for emergency situations.  For the New Carisa, poor weather guidance resulted in the initial salvage attempt failing.
  • Doppler winds from the Weather Service radar are only available within 230 km (138 miles) of the radar.  Considering that the nearest coastline is 160 and 100 km away from the Camano Island and Portland radars, respectively, offshore wind coverage would be very limited even without the mountains .
  • Radar beams ascend higher the farther they get from the radar.  By the time they get to the coast (approximately 150 km out), the radar beams are already at approximately 1500 m (approximately 5000 ft).  Thus, current radars cannot determine low-level coastal and offshore precipitation and wind features of great interest to mariners and people living on the coast, even if the coastal terrain wasn't there.

  • When the New Carisa grounded Near Coos Bay, Oregon, there
    was no radar coverage to help manage salvage operations.

    What Would We See With Radars on the Northwest Coast?

        To illustrate the kind of radar coverage two coastal radars could provide, the potential coverage of the lowest radar beam for the current and proposed radar networks is shown below.  The current network (left figure below) provides little radar coverage along most of the Oregon and Washington coasts, and what coverage does exists is for higher altitudes. In contrast, northern California enjoys excellent coastal coverage due to the Eureka radar site. Wth the addition of two radars along the central Washington coast (perhaps Westport, WA) and the central Oregon Coast (perhaps Newport), the Pacific Northwest gains excellent coastal radar coverage, allowing a clear view of storms approaching from the Pacific.

    Radar coverage maps for the lowest beam (.5 degree elevation angle) for the current
    network (left) and the proposed network (right) with radars at Westport (WA) and
    along the central Oregon coast.  Red areas indicate no coverage below 8000 m (25,000 ft).
    Note that someof the coastal terrain without coverage would be included at a higher scanning angle.

    Examples of Failed Forecasts that a Coastal Weather Radar Would Have Helped

        It is easy to provide many examples of forecasts that would have been greatly improved if a coastal radar would have been available.  A few examples:

    February 7, 2002

        On the morning of 7 February 2002 an intense low center, with 70-100 mph winds, struck the the southern Oregon coast and the southern half of the Willamette Valley.   Massive treefalls and property damage resulted.  There was absolutely no warning by the National Weather Service.  The computer models did not have the storm and it was not clearly evident in the weather satellite pictures.  And, of course there was no useful coastal radar.  If there had been radar coverage forecasters could have seen the approaching storm and at least provided several hours warning. 

    Massive Treefalls

    15 May 2001

        On 15 May 2001 the National Weather Service had to deal with a difficult situation, as a small low pressure system approached the Washington Coast.  Satellite imagery was inconclusive, and without a good observational fix on the system, the NWS forecaster was forced to follow the computer models which indicated the potential for strong winds over Puget Sound.  Unfortunately, the low went farther north than the computer models predicted and the high winds never materialized.  A coastal radar would have provided the exact location for the low center hours before landfall and a far more accurate forecast could have been made.

    December 14, 2006

        On the day prior to the big windstorm, an intense line of extraordinarily heavy precipitation moved into Puget Sound.  Associated with a frontal zone, the heavy rainfall caused record flooding and contributed to the death of a woman in the Madison Valley area of Seattle.  The computer models did not predict this feature and without a coastal radar there was no warning before this intense rainfall line entered Puget Sound. 

    What would be the benefits of additional coastal radars?
  • Meteorologists would be able to see the details of incoming weather systems during the 6-18 hr period before they arrived.  Forecasts and warnings for the entire Northwest would improve.
  • Coastal search and rescue, as well as offshore military operations, would gain critical weather radar information on winds and precipitation.
  • The data from coastal radars could help provide a real-time detailed description of the weather in the coastal zone.  Not only could this information be provided to the public and interested users, but it could be used in numerical weather prediction models to improve downstream predictions.  Such data is particularly critical in the Northwest where we lack detailed observations upstream over the eastern Pacific.
  • For the first time, the distribution and intensity of coastal precipitation could be diagnosed, aiding more accurate streamflow and flood forecasting.
  • Researchers would gain a continuous view of the interaction of Pacific weather systems with Northwest coastal terrain, thus improving our understanding of these features, which should lead to better forecasts.
  • The radar would provide crucial data for homeland security needs.  For example, the data from the radars would enhance local weather prediction, thus providing better forecasts of toxic plume dispersion.  It would also help protect the population from major storms.

  • The rest of the nation would not accept a lack coastal radar coverage...why should we?

        The other coastal areas of the continental U.S. have good offshore radar coverage.  When a major storm approaches their shores, forecast or not, residents can be given several hours warning based on the weather radar.  The figure below shows the radar coverage of Hurricane Katrina, with the eye of the storm clearly evident in the NWS radar picture.  The Northwest can get strong storms, some with hurricane force gusts. In fact, the strongest non-tropical storm to ever strike the U.S. hit here during the 1962 Columbus Day Storm. 

    Katrina radar

    National Weather Radar image of Katrina near landfall on the Louisiana coast in 2005

        In contrast, below is a radar image from the NWS radar at Camano Island.  The large wedge-shaped void on the Washington coast is due to blocking by the Olympics--it is raining along the coast and offshore but we can't see it.  There is some radar returns west of the Strait of Juan de Fuca, but by the time the radar beam gets there it is already about 5000 ft above the surface!

    What needs to be done?

        To address at least one and more optimally two additional Weather Service radar need to be place on the Pacific Northwest coast.  With two radars, one radar could be place on the central Washington Coast--Westport would be a good placement--with the other radar along the central Oregon Coast, perhaps near Newport.   If only one radar could be acquired, the central Washington coast would probably be the best location, since it would provide surveillance for the entrances to both the Strait of Juan de Fuca and the Columbia River, would provide crucial precipitation information over the flood prone southern flanks of the Olympics, and would give upstream weather information for the highly populous region stretching from the northern Willamette Valley to Puget Sound.

        The acquisition costs for an additional radar would be substantial (roughly 4 million), with additional  costs for land, utilities and maintenance each year .  But such costs are small compared to the substantial benefits such coastal radars would provide.  A single improved forecast could save millions of dollars and several lives.  It is of interest that several local TV stations have been able to afford weather radars (although far less capable than the NWS units).  Other regions of the country (e.g., Indiana) have requested and secured additional radars to fill in holes in coverage.  The Pacific Northwest has a strong claim to similar treatment.

      How do we proceed from here?  Perhaps the best approach would be to contact our representatives in the Senate and the House of Representatives, asking them to supply additional funds to the National Weather Service to add one or two Northwest coastal radars.  (Click here for Senatorial contact information).  Additional funds are crucial because the NWS does not have support for extensions to the current radar network.  It would also be useful to directly contact higher officials in the National Weather Service and NOAA, letting them know about our concerns regarding this major deficiency in the national observing network.

    For more information:  Cliff Mass, Professor of Atmospheric Sciences, University of Washington (206-685-0910),


        Ken Westrick of  3-Tier, Inc. provided several of figures shown above and provided several useful comments.

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