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November 2014

Wettest Week of the Year?

Posted: November 17th, 2014


Not normal.

Not normal.


The somewhat “ridiculous” ridge that has kept us persistently sunny and cold is forecast to break down this week. Our old climatological friend, the Aluetian Low—the one that was obliterated by ex-Typhoon Nuri—received upper level reinforcement via Siberia over the weekend, and the jet stream is starting to respond.


The warm-up will be gradual, but gone are freezing temperatures, and by later Wednesday, gone will be these clear blue skies. The extent to which rainfall returns thus becomes our focus—as it should: this week is supposed to represent the peak of our rainy season. With an average of 0.222″, the 19th of November is Seattle’s wettest day of the year.


We’ll be lucky to get a few drops on Wednesday, but if models verify, this weekend will at least be close to normal. Which is good because we’ve only received 18% of average November precipitation so far. October was of course soggy, so SPU’s reservoirs are in relatively good shape. But since there’s very little snow in the mountains, some normalcy, however beautiful recent sunrises and sunsets have been, is welcome.



Latest UW WRF-GFS forecast worth watching.

Latest UW WRF-GFS forecast worth watching.


The latest National Weather Service forecast for Seattle has no rainfall until 0.05″ late Wednesday, followed by 0.20″ Thursday, 0.40″ Friday, 0.61″ Saturday, and 0.38″ Sunday. Those numbers seem to split the difference between the generally dry ECMWF and the latest UW WRF-GFS, which gets interesting Friday into Saturday indicating perhaps 1.50″ in 24-hours city-wide.


Over SPU’s mountain reservoirs, the NWS forecast shows up to 2″ in the 48-hour period ending about midday Saturday. Winds are expected to be southerly and relatively light, which should minimize enhancement, but post-frontal showers at the moment look to keep the mountains quite wet through the weekend. Snow levels will rise to over 9000′ (!) tomorrow, and then likely drop to below 5000′ by Saturday.


NWS Area Forecast Discussion
NWS Forecast Table Interface—Seattle
NWS Forecast Table Interface—Tolt Reservoir
NWS Forecast Table Interface—Chester Morse Lake