Sunday, June 25, 2017

Cool Air is Starting to Move In

Today broke several daily temperature records,  with temperature climbing into the mid nineties around Seattle and upper 90s to the east.  The interior of SW WA and the Portland area jumped to 100F and more, as did the Tri-Cities.

Here in Seattle, temperature were quite pleasant on Puget Sound, but jumped into the mid-90s over NE Seattle.   Even hotter over Bellevue and Redmond.


But as forecast, everything is changing now.  The trough of low pressure (the thermal trough) has jumped over the Cascades and an onshore pressure gradient has developed (see pressure difference table below). The Hoquiam minus Seattle pressure difference jumped to 3.5 hPa...guaranteeing the inland movement of cool air.

The winds  and temperatures above Seattle Tacoma Airport show the incipient changes,  with hot SE winds replaced by cooling southwesterlies aloft.  And temperatures aloft are falling.
Coastal clouds have moving northward and thickening during the day (see satellite image from an hour ago) and those clouds will move in overnight.


I look forward to hearing the tinkling of my wind chimes around midnight, a sign of the influx of welcome marine air.  Our regional AC has been turned on....now it is only a matter of time.

2 comments:

Paul said...

Yesterday beat a record high set in 2006. According to KOMO, the record high for today - June 26 - was set in 1896. What is the distribution by year in which the current daily record highs were set? I can't imagine there are many 19th century records still standing, and I would think years from 2000-2015 would have a disproportionate share of daily heat records. Is this something you've covered before?

Paul said...

I ended up compiling some data myself and creating a distribution of years in which daily records were set. I wrote up the trend here: https://medium.com/@paulkriloff/the-historical-context-of-daily-high-temperatures-in-seattle-9d0a9fa7a6ca