The Oregon Radar Gap

The Oregon Coast has the WORST coastal radar coverage anywhere in the lower 48 states and it’s time to change that.  In fact there is no radar located along our coastline.  Local forecasters (private/public/media) have known about it for years.  I’ve blogged about it numerous times and Professor Cliff Mass up at the UW in Seattle has been pushing it for years too.

Important points:

  1. The central and southern Oregon coastline has no radar coverage below 10,000′;  almost all cool-season weather happens below that elevation.
  2. How is it possible Oregon’s 2nd largest city (Eugene) has no coverage below 10,000′???
  3. A tornado or squall line can roar ashore in Lincoln City, Newport, Florence, or Coos Bay with no warning.
  4. A tornado or squall line with damaging winds could move through the Eugene or Roseburg areas with very little indication on radar.
  5. NOAA’s Pacific Fleet is based in a location (Newport) with no good radar coverage…that’s a huge surprise.

#3 happened in the mid 1990s at Lincoln City, and #4 just happened January 16th this year in Lane County (near Eugene).

What Is The Problem?

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 Oregon coastal zone is poorly served compared to the California, Gulf of Mexico, and Atlantic coastal regions. Click for a better view:

wsr-88dconuscoverage2011

Note there IS a radar on the Washington Coast.  That was just put in 4 years ago after a years-long lobbying effort by a group up there.  A closer view shows the situation here in Oregon:

markradar_neworegoncoast3

The “partial coverage” refers to some blocking by mountains in the Coast Range.  The lowest beam from the Portland radar (located on Dixie Mtn. southwest of Scappoose) is intercepted in a few spots by the Coast Range.  We were extremely lucky that Manzanita was not behind one of those “blockages”.  But in general coverage is sketchy on the north coastline south of about Cannon Beach.

What about farther south?  It gets worse.   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!  

capture2

You can see the issue here from the image above created by folks up at the UW before the Washington coastal radar was installed.  Very little useful information comes from that Medford radar in the cool season.  Dr. Mass has suggested moving the Medford radar down to the coastline around Coos Bay or Brookings.  However that would leave the largest southwest Oregon population (the Rogue Valley) with very little severe thunderstorm coverage in the summertime.  That’s not going to happen.

Where Would A New Radar Go?

The ideal location would be somewhere between Coos Bay and Newport.  Seems like Florence is a good location, up at a high enough elevation to get a clear path to watch Eugene, but not too high.  Coverage would look about like this:

markradar_neworegoncoast2

Much better don’t you think?  How much would it cost?  Maybe $5 million dollars to install and then regular maintenance and operational costs of course.  Is it worth it?  Yes, even one big event could erase some of that cost.  Consider the South Valley Surprise windstorm of February 7, 2002.

trees

A much deeper than expected low pressure center moved onshore just south of Florence, then raced northeast into the Columbia Basin.  The strongest wind gusts in that area since the Columbus Day Storm of 1962 peaked between 70-80 mph.  There was NO WARNING until the wind had already arrived.

markradar_neworegoncoast

Since there was no warning, local utility crews were caught completely off guard.  Nowadays utilities prepare for these storms days ahead of time by positioning their crews/supplies and having extra workers ready to go.  With some warning (even just a few hours) they may have been able to restore power more quickly thus saving a million or two worth of damage?  Just a guess, but you get the point.  That storm cost $10-$12 million dollars damage.  By the way, there was no strong wind in the Portland metro area or Salem because the low pressure passed by to the south.  We just had a breezy westerly wind.  This is just one example of what we’re missing.  A squall line moved into the southern Willamette Valley just this past January 16th, barely detectable (if at all) on Portland’s radar.  Check out the storm report, click for a better view.

capture

Where Do We Go From Here?

First, don’t bother calling the Portland or Medford National Weather Service offices and complaining.  Those folks do all sorts of good work forecasting and keeping on top of our wild winter weather…but they don’t control the money!  It’s a political solution, which means the U.S. Congress has to appropriate the money.

A coordinated effort has begun in our area; that’s why the story has now appeared on two TV stations (and hopefully soon on the other two!).  A group started by the Oregon AMS (American Meteorological Society) will have its first meeting in a couple of weeks.  It involves members of the local media, former television meteorologists, former NWS employees, educators, and many others.

I’ll keep you in the loop as we go through what will likely be a very long, but hopefully productive, journey.   I know there are lots of you on the Oregon Coast and down south in the Valley that want to help out.  The effort to get a Washington coastal radar included support from all sorts of community groups.

The Other Oregon Radar Gap

Of course there is one more huge hole in Oregon radar coverage.  There is no cool season coverage in Central Oregon either.  By that I mean we can’t see anything below 12,000′ or so in the area from Warm Springs to Redmond to Bend to La Pine.  Just before Thanksgiving 2015 a foot of snow fell in one evening in Bend and the Pendleton radar showed nothing.  At least the very tall thunderstorms in summer are detectable by surrounding radars, but at some point that area (where 200,000 people live!) needs a radar too.  There are many other gaps in the interior west, so that one might be a tougher sell.

Chief Meteorologist Mark Nelsen

Thanks to Dr. Cliff Mass and his NW Radar Problem page for some descriptions used above.

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