What is in Oregon's Radar Gap?

As I have noted on several occasions, Oregon has some of the worst weather radar coverage in the nation, with a huge radar gap off its central and southern coast and another in eastern Oregon

Important weather features approaching the coast can be missed, reducing the skill of short-term forecasts from western Oregon into western Washington.   Perhaps including the missed Portland snowstorm of February 22.

Below is a National Weather Service radar coverage map,  with yellow indicating the regions of low-level coverage (coverage below 3000 ft above ground level).  The coverage would be much worse near sea level.  Western Washington and the Washington coast have good coverage thanks to the Langley Hill radar (Hoquiam), the Camano Island radar north of Seattle, and the Portland radar.  

But most of the Oregon Coast has no coverage.  The Portland radar is blocked by the coastal mountains at low levels and the Medford radar is poorly placed, positioned so high (7500 ft) that the radar beam reaches the coast at 13000 ft and is even higher offshore.

Eastern Oregon is a radar disaster, with no coverage for vast areas.

So what are we missing with such poor radar coverage?  What would we see if a radar was there?

I think I can tell you, using our regional high-resolution forecasting system.   

Believe it or not, we can simulate what a radar image would be like using the 3-D precipitation produced by forecast models.

Consider yesterday evening at 6 PM.  A short-term (2-h) forecast predicted heavy precipitation along and offshore of the central and southern Oregon coast.  Western Oregon is experiencing showers, and some precipitation has crossed the Cascades into eastern Oregon.

Not compare that predicted precipitation to what echos indicated by combination of all local radars at the same time.  

A big difference.  

Nothing along the central and southern coast.   Nothing immediately downstream of the Cascades in eastern Washington.  Huge gaps in radar coverag.

Want another example?  Consider March 2 at 10 AM.  The model predicted a potent front extending from off the Pacific into northwest Washington.  Meteorologists need to know the details of such an important feature.

The weather radars pick up the extension over land but NOTHING offshore.  Very bad.

We can not assume that our models are always going to be correct.  During some periods, such as the recent Portland snow event, our best numerical models are wrong, even in the short term, and thus we need to be able to monitor what is coming in offshore.  Only then can we provide the public with reliable forecasts and warnings.

Modern forecasting technology allows information from the radars to be ingested into short-term forecasting models, such as the NOAA High-Resolution Rapid Refresh (HRRR) modeling system.  Thus, forecasts over western Washingon are improved because we have a coastal radar (Langley Hill)

Oregon has no such coastal radar and thus western Oregon's forecasts are degraded.  

Hopefully, some of Oregon's U.S. representatives and senators will take up this issue.