Major Marine Push Occurring Right Now

A huge pressure difference has developed between the Washington coast and the western interior, resulting in a rapid increase in onshore winds.  In some locations, such as the Strait of Juan de Fuca, the winds are blowing as high as 50-60 mph right now!

This table shows differences in pressure (HR is in UTC, 23 is 4 PM).  The Hoquiam minus Seattle pressure difference was up to 5.2 hPa (higher a Hoquiam).    That is HUGE (to quote our President) and always provides a good blow. That will push winds in from the west.

Here are some of the maximum gusts as of 5 PM.  59 mph at Race Rocks at the SE tip of Vancouver Island.  Lots of winds between 30 and 50 mph in the Strait.  40 mph in Shelton.  And it is getting gusty even here in Seattle right now.

The winds at buoy 46088 and Smith Island in the eastern portion of the Strait show accelerating winds to roughly 45 knots (52 mph)...and they aren't done revving up yet!  Fun day to take the Clipper to Victoria.

This situation is a good example of a Northwesterly Onshore Push, a rapid inland surge of marine air initiated by the passage of an upper level trough (see an upper level forecast map for 5 PM below to see the trough).

We had warm air and low pressure over region before the trough, and behind the trough there is cooler air and higher pressure.  The result is a large pressure change (or gradient) and the replacement of the warm air by cool, marine flow.  Known as an onshore or marine push in the weather business and very typical this time of the year.

Tomorrow will be much cooler day, with temperatures falling back into the mid-60s.  But don't get rid of your sunscreen and shorts yet...the ridge of high pressure will rebuild later this week and temperatures will quickly surge into the 70s and low 80s by this weekend.



from Cliff Mass Weather Blog http://ift.tt/2qeyvVi