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November 2014

Atmospheric Vigor

Posted: November 6th, 2014


Above: post-frontal sun; post-frontal squall. Note Harborview’s flag.


A strong front passed through the region this morning. It was tied to a compact low pressure system that spun into Vancouver Island around midday. The front was quite striking on the radar, not to mention on the ground—two neighborhoods, Crown Hill and Magnuson Park, recorded notably intense 10-minute rainfall totals of 0.17 inches. The line also generated a single RainWatch 1-hour forecast alert at 7:40 AM, and a single 1-hour accumulation alert at 7:59 AM. With respect to impacts, the event prompted 31 customers to report street ponding and 1 to call to report flooding. Fortunately emergency response was not required, though SPU crews remain busy clearing more and more leaves from drains.


Satellite image
RainWatch 7:40 AM radar image
RainWatch 7:40 AM forecast alert image
RainWatch 7:59 AM accumulation alert image
SPU customer call image
Cliff Mass Discussion



2014-09-02 nws warn

NWS Wind Advisory still in effect


The now departing, vigorous low is weakening and advisory-level winds are starting to subside. As they weaken further a Puget Sound Convergence Zone is likely to form, though models suggest it will be fleeting. The local atmosphere will continue calm down tomorrow, and if the forecast holds, it’ll remain relatively quiet for up to a week. Patchy, seasonal fog is likely tomorrow and Saturday, followed by a chance of showers on Sunday when a dissipating front will brush by.


NWS Area Forecast Discussion
NWS Watches and Warnings



2014-09-02 usgs

In the red


Seattle still remains very much on the wet side of the USGS landslide threshold, though we should drop below pretty soon.


USGS Landslide Information
City of Seattle Landslide Preparedness Information



More sun ahead

More sun ahead


Beyond today, the only day out of the next four in which rain is expected is Sunday when 0.23″ is predicted citywide by the NWS. The latest UW WRF-GFS and ECMWF model runs generally concur. (For what it’s worth the ECMWF keeps us rain-free all the way until next Saturday the 16th.) Some breezy conditions are possible on Sunday morning; otherwise winds will remain light. Temperatures are also expected to brazenly remain slightly warmer than normal.


Over SPU’s mountain reservoirs, the story is much the same. Closer to 0.50″ on Sunday; otherwise very little to any rainfall throughout the forecast period. And after a foray down to around 3000′ tomorrow morning, snow levels will return to mostly above 6000 feet through next week.


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