Huge Storm Offshore

A huge, deep midlatitude cyclone is parked off our coast right now, with very strong winds over the Pacific and large easterly flow in the Columbia Gorge, the Strat of Juan de Fuca, and within east-west passes in the Cascades.

The sea level pressure forecast for 1 PM is impressive and huge, with the low center spread over much of the NE Pacific, with a deep 974 hPa low center due west of the CA/OR border.

The latest visible satellite image illustrates the large scale of the storm, a very long cold front, and the cold, unstable air circling into the low center.

The moisture imagery (white showing lots of upper tropospheric water vapor) shows the vast amount of water vapor spiraling into the storm.

This large pressure gradient associated with the storm is producing strong winds over the ocean, with gust forecasts over the ocean show areas reaching 40-70 mph at 1 PM today.

 As the low slowly drift towards us, the strong winds will reach the Oregon/Washington coastline (see gust forecast for 10 AM Wednesday).

A huge, slow-moving storm has strong winds, lots of fetch, and plenty of time for the wind to work on the water.  The result are big waves, something predicted by the NOAA WaveWatch3 system: (9-11 meters high shown by orange colors below)

With a low offshore and higher pressure offshore, local winds are accelerating from east to west in our regional gaps.  For example, winds are quite strong in the Strait of Juan de Fuca (see forecast for 1 PM below).

And easterly winds are accelerating over the western side of the Columbia Gorge:

Windstorm Details

Well....my power did go out last night, as it did for roughly 300,000 power customers in western Washington.

Model forecasts were quite good, particularly in describing the substantial local variations in strong winds. As shown by max gust map below, winds got to 60 mph at Sea Tac, along the coast (e.g., Hoquiam) and in the central Strait of Juan de Fuca.

Strong enough, that even with the "pruning" of past windstorms, plenty of trees and branches were felled.  Winds were weaker over western Kitsap county, something the models predicted (see below).

One of the most interesting aspects of the event was the strong surge of westerly winds in the Strait that followed behind the trough of low pressure, something that was well forecast.  At the leading edge of the surge there was intense low-level convergence (air coming together), which forced air to rise and produce a line of intense thunderstorms.  You can see this on the radar image at 3:29 AM today (Sunday)--see below.  The red indicated pouring rain or small hail.

There was report of an amazing deluge and a hail-covered I-5 and adjacent areas (see example)

You think stormfest is over?   No way!    Look what is lurking off our coast on Wednesday at 4 AM---A HUGE DEEP LOW CENTER. 

Expect strong winds offshore and some good size waves.... NOAA's Wavewatch 3 model is predicting about 8-9 meters at that time (26+ ft).

So reset your clocks, clean up the debris, and keep tuned.