Cooler West, Windy East

During the last day, winds have surged to amazingly levels in eastern Washington with gusty easterly winds reaching  60 mph.   Strong enough that it blew down a power line and started the first significant fire of the season (now about 50 acres) near Entiat, Washington (near the Columbia River).
 Here are the max gusts for the 24h ending 7 PM Monday for a domain stretching from southern Puget Sound to Walla Qalla.   The red numbers are winds over 50 mph.

In the spring, the winds increase rapidly when cool, Pacific air floods western Washington and Oregon as it did on late Saturday night.     Cool air is denser than warm air and is associated with higher pressure.  With the Cascades blocking much of cooler air on the west side, a large pressure difference (or gradient) develops across the Cascades.  In addition, the flux of cool air is often forced by an upper trough, which results in pressure declines east of the Cascades as it passes through.

Let me illustrate the development of a large pressure gradient across the Cascades with the sea level pressure forecasts for 8 AM Sunday.   The shading shows low-level temperatures, with green temperatures being cooler and orange/red warmer.   You can see the contrast in air temperature across the Cascades.  The solid lines are isobars (lines of constant pressure).  You note a lot of lines (strong pressure gradient) across the Cascades.    Such large pressure gradients produce strong winds as air accelerates from high to low pressure, particularly within the lower areas of the central Cascades.

There is a weakness in the Cascades north of Mt. Rainier called the Stampede Gap, so some of the strongest winds are around Ellensburg.  There is a reason there are a lot of wind turbines around there.  

Modern numerical models run at high resolution can forecast the strong winds along the eastern slopes of the Cascades fairly well.   Here is the sustained wind speed prediction for 8 AM on Sunday from the UW high resolution WRF model.  You see the strong winds along the lower Cascade slopes?

And here is a blow-up from our uber-resolution (4/3 km grid spacing) WRF model forecasts for gusts at the same time.  The model had isolated locations reaching 60 knots--not bad.

This is the windy season on the eastern Cascade slopes--with cool marine air on the west side and the eastern side warming rapidly (producing low pressure).  Wind power season.
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Major news:  the proposed coal terminal near Cherry Point (near Bellingham) has been stopped by the US Army Corps of Engineers.   Their reason:  to honor the treaty rights of the Lummi tribe to use those waters.  This is a huge victory for those concerned about coal dust, traffic backups near rail crossings, and the climatic effects of sending huge amounts of coal to Asia.

Vigorous Onshore Marine Push and Good News for Mothers

Tonight, the passage of a weak front is resulting in a strong inland surge of marine air.  What we call a northerly onshore push.

The visible satellite image at 7 PM Saturday shows a narrow, but weak, front moving into western Washington.  There is virtually no precipitation with this feature.  But it is strong enough to cause cool marine air to push inland, particularly in the Strait of Juan de Fuca, where it is REALLY blowing right now.

For example, take a look at the maximum hourly gusts at Smith Island, located over the eastern side of the Strait.  WOW...gusts to 47 knots (54 mph)!

The UW WRF model has been forecasting the marine surge--here is the predicted gusts for 8 PM Saturday.   Red area is strongest winds--50 knot gusts over the eastern Strait.

And now the good news for all mothers.  Sunday really won't be bad at all.  A few sprinklers in the AM at most--particularly over central Puget Sound (where a weak convergence zone will be).  Low clouds in the morning, but plenty of breaks in the afternoon, particularly away from the central Sound.  Highs around 63-65F.    Plenty good enough to enjoy a nice walk with Mom at some park to admire the flowers.  Mom's like that kind of thing.  Plus flowers, cards, and chocolates.