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October 2014
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Weekend Wx Outlook

Posted: October 1st, 2014

 

Strong ridge forcing storms to our north (via NWS EAFD)

Strong ridge forcing storms to our north (via NWS EAFD)

 

A strong ridge of high pressure is expected to keep storminess away from us for as far as the models can see. The weak edges of a few frontal systems may brush by and produce light, scattered showers on Friday and again next week, but otherwise we’ll remain warmer and drier than normal, just as recent long-range outlooks have been suggesting. Blame “The Blob.”

 

The latest NWS precipitation forecast gives us 0.05″ on Friday, 0.06″ on Sunday, and 0.07″ on Monday; the UW WRF-GFS has no rainfall at all through Sunday; and the ECMWF has no rainfall through Monday, followed by more substantial but highly uncertain rainfall both next Wednesday and Saturday.

 

Excerpts from the 9:00 AM NWS Area Forecast Discussion (emphasis added):

 

HIGH PRESSURE ALOFT BUILDS LATE THURSDAY INTO FRIDAY. LOW LEVEL NLY FLOW WILL HELP CLEAR OUT MUCH OF THE RESIDUAL MOISTURE BUT RADIATIVE COOLING WILL LEAD TO MORE FOG. SOME AREAS AROUND THE S SOUND/SW INTERIOR COULD HAVE FOG LINGER INTO THE EARLY AFTERNOON. FOG WILL MIX OUT AND SOME MID/HIGH CLOUDS WILL DRIFT ACROSS THE AREA AS A WARM FRONTAL SYSTEM PUSHES INTO BRITISH COLUMBIA. MODELS ARE STILL HAVING TROUBLE RESOLVING THE FRIDAY NIGHT AND BEYOND PERIOD. THE 00Z GFS/ECMWF BOTH BRING SOME LIGHT QPF TO NRN PORTIONS OF THE FORECAST AREA FRIDAY NIGHT. WILL NEED TO WAIT FOR ALL THE 12Z MODELS TO ARRIVE BEFORE ANY ADJUSTMENTS ARE MADE TO THE EXTENDED.

THE UPPER RIDGE WILL WEAKEN AND PROBABLY SHIFT EASTWARD FRIDAY NIGHT AND SATURDAY…ALLOWING THE FRONTAL SYSTEM IMMEDIATELY UPSTREAM OF THE RIDGE AXIS TO SAG INTO WESTERN WASHINGTON. DURING THE LAST COUPLE OF RUN CYCLES…THE MODELS HAVE TRENDED TOWARD DRIER SOLUTIONS FOR SATURDAY NIGHT THROUGH AT LEAST MONDAY. IN GENERAL THEY ARE KEEPING THE UPPER RIDGE OVER THE PACIFIC NORTHWEST. THERE IS STILL SOME UNCERTAINTY WITH REGARD TO THE THREAT OF RAIN BUT THIS SHOULD BE A PERIOD OF MILD WEATHER OVERALL — ANY PRECIPITATION THAT DOES OCCUR SHOULD BE LIGHT AND HIGHS WILL BE IN THE MID 60S TO LOWER 70S.

 

References:
NWS Area Forecast Discussion
NWS Forecast Table Interface