Wednesday, February 23, 2011

NOWCAST 4:45 PM: SHOWTIME

Folks...the big threat for central Puget Sound...the one suggested by the model's last night is coming up now.

So far things have gone pretty much on track.... we started with rainshadowing over Seattle and the southern Sound. The as the flow turned more southwesterly the rainshadow shifted northward and the southern Sound had increased snow showers. As the northerly wind picked up a convergence line developed over NW Washington the brought snow to the San Juans to Skagit County...and then the northern Olympic Peninsula (here is a shot from Port Townsend to illustrate.


But now things are shifting to the Puget Sound basin. The northerlies are starting to push southward into the southerlies over Puget Sound (see map):


The radar is showing the impact---moderate echos are now moving toward Everett and down the Sound. (see radar). If the line continues to push southward, the battleground between the two air masses could be fierce and significant snow the result. Temperatures are relatively mild from a day's worth of heating, but melting of precipitation and the ingestion of cool, dry air from the north should help it turn to snow. I think Seattle commuters will be fine....the roads are warm and salted (sound likes a good meal!)...but tonight could get very interesting very fast if this boundary locks over someone. Watch the radar now...if will be very entertaining!

Here is the link to the NWS site:

http://radar.weather.gov/radar.php?rid=ATX&product=N0R&overlay=11101111&loop=yes


5:20 PM---the line has just hit the UW....ice pellets are starting to hit my windows....

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