During the past 24 hours, the Northwest has experienced an unusual April blow--both in wind strength and longevity.
Consider the maximum gusts during the 24h ending 7 PM Monday (see below). Several locations topped 60 mph along the coast and over NW Washington. Even the eastern side of the region was very windy, with winds over 50 mph common.
Want to be more impressed? Here is a close-up over the southern Cascades and eastern Washington. Some locations hit 80-100 mph!
With such strong winds in eastern Washington in spring, you can bet there will be dust blowing, and this event did not disappoint (see WSDOT image at Davenport, WA).
Why such strong winds?
I have already talked about the strong jet stream that reached our shores from off the Pacific. And this jet stream was associated with strong north-south pressure differences, which were enhanced by a 978 hPa low-pressure center that moved into British Columbia.
Take a look at the sea level pressure forecast for 8 AM this morning. The solid lines are isobars--lines of constant sea level pressure.
Mama mia!...there are a lot of isobars and thus a strong pressure gradient to drive powerful winds from the south. Strong winds aloft were from the west...and the sustained winds at 25,000 to 35,000 ft were around 120 knots (around 140 mph)
But what really stood out today was how long the strong winds lasted---over 24 hr at some locations. Such duration of strong wind is unusual around here.
But that is not all. A cold front moved through this morning, with cold, showery conditions behind. As a result, temperatures were about 10F below normal today in the west.
And are you ready for a flash heatwave? On Thursday, as high pressure builds east of us, strong easterly flow will drive the temperature to near 70F in western Washington!
Wow! That 102MPH reading looks to be downslope flow from Rainier, correct?
ReplyDeleteOur barometers here in NE Seattle bottomed out at 988 mbs, in my decades of experience an unusually low reading for April. Also intriguing were the rates of descent and the climb back toward normal, both associated with very strong winds.
ReplyDeleteMy old cheapo altimeter had run out of batteries so I put new ones in, and it showed our sea level condo at 550 feet altitude. I assumed it was totally out of order, then a 'wait a sec' moment, we are having a gale. This morning it was showing 40-100 feet below sea level. So it is not totally wrong, I use it on road trips. Unfortunately WA ST DOT does not list altitudes at the top of the various state roads crossing the coastal range. This is unfortunate. It would remind people that those are indeed passes, albeit not all that high, and that life threatening weather for the unprepared is often present well into the spring.
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