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January 2015
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More Warm and Dry

Posted: January 20th, 2015

 

z500_nh_30d_anim

Looking down on both the north pole and regional snowpack

 

This winter’s dominant weather pattern will persist this week and beyond, keeping us mostly dry and relatively warm. Said pattern is defined by upper level high pressure in the vicinity of the Gulf of Alaska (see the animated red blob above indicating higher than normal pressure).

 

As we saw this weekend, in some cases dramatically, and as we’ll see again later this week, the regime is not totally blocking all systems from approaching, but overall the story will remain the same.

 


 

Regarding this past weekend, you may have noticed it was wet. Rainfall started in earnest during Saturday afternoon and was followed by stronger than expected winds overnight. Most locations across the City recorded under an inch in 12 hours, which was slightly less than forecast. But as is common following windstorms, post-frontal showers grew quite intense.

 

Between 9AM and noon about three particularly strong cells passed through Central Seattle just as many folks were gathering to watch the foot ball. The most intense amount recorded by an SPU rain gauge was 0.47″ in 30-minutes at UW, which is good for a ten-year recurrence. Radar analysis suggests that slightly stronger returns occurred right over downtown and up Madison, as well as over a sliver of Bryant. Further evidence of added atmospheric vigor came from Gig Harbor where a confirmed tornado briefly touched down.

 


 

After yet another photogenically foggy morning tomorrow, clouds and spotty light rain will move in by Thursday. Just under an inch of rain is currently forecast to fall across Seattle Thursday through Saturday. In the Cascades, the latest NWS numbers call for around 2 inches of rainfall during the same period. Snow levels will frustratingly climb from 5000 feet to over 10,000 feet by Sunday.

 

Also of note this week is the next round of King Tides. Between Wednesday and Monday predicted tides will be high, and the highest predicted tide of the year will occur on Saturday morning. A full blog with details and perspective will be published tomorrow.

 

NWS Area Forecast Discussion
NWS Forecast Table Interface—Seattle
NWS Forecast Table Interface—Tolt Reservoir
NWS Forecast Table Interface—Chester Morse Lake
SPU Water Supply Outlook

 

JRH