Cold in the Extended?

Monday, October 15, 2012
10:42 A.M.

Folks, let me just start out by saying that the Seahawks game yesterday was incredible. Especially since I would have lost all my hair had the Hawks come up short to the Patriots via a bet with a New Englander. Now, normally, I wouldn’t care about losing my hair (free haircut, right?), but after looking at the models, I’m pretty glad the Hawks won. It is about to get COLD here in October, and I don’t know if my body has quite adapted to the change yet, so I need all the extra hair on my head that I can get. Nevertheless, I am still extremely excited, because if the long-range models turn out to be correct, we will get an early start to our skiing season, and it’s been far too long since I’ve been on the slopes.

For now, though, we’ve got some weather to go through.

This picture above was taken from the Seattle National Weather Service’s graphical forecast discussion, and it shows the storm we will be dealing with today currently off our coast. This storm will move quickly through the area and give us a brief shot of heavy rain and a good deal of wind to boot. In fact, we currently have a low-end wind advisory over our area for 5 P.M. tonight to 5 A.M. Tuesday morning. Below is the exact wording of the advisory.

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE SEATTLE WA
958 AM PDT MON OCT 15 2012

...VERY WINDY CONDITIONS THIS AFTERNOON AND TONIGHT...

.A RAPIDLY MOVING FRONTAL SYSTEM WILL MOVE THROUGH WESTERN
WASHINGTON TONIGHT. SOUTHERLY WINDS AHEAD OF THE FRONT WILL
INCREASE OVER THE COAST AND NORTHWEST INTERIOR TO 20 TO 30 MPH
WITH GUSTS TO 50 MPH BEGINNING THIS AFTERNOON. THE WINDS WILL
CONTINUE INTO THE EVENING HOURS. OVER THE REST OF THE INTERIOR
WINDS WILL INCREASE AFTER THE FRONT PASSES THIS EVENING AND LAST
THROUGH THE NIGHT. WINDS WILL BE IN THE 20 TO 30 MPH RANGE WITH
GUSTS TO 45 MPH.

WAZ504-505-507>509-511-512-514-515-152330-
/O.EXB.KSEW.WI.Y.0027.121016T0000Z-121016T1200Z/
SOUTHWEST INTERIOR-EAST PUGET SOUND LOWLANDS-EVERETT AND VICINITY-
SEATTLE/BREMERTON AREA-TACOMA AREA-HOOD CANAL AREA-
LOWER CHEHALIS VALLEY AREA-EASTERN STRAIT OF JUAN DE FUCA-
WESTERN STRAIT OF JUAN DE FUCA-
958 AM PDT MON OCT 15 2012

...WIND ADVISORY IN EFFECT FROM 5 PM THIS AFTERNOON TO 5 AM PDT
TUESDAY...

THE NATIONAL WEATHER SERVICE IN SEATTLE HAS ISSUED A WIND
ADVISORY...WHICH IS IN EFFECT FROM 5 PM THIS AFTERNOON TO 5 AM
PDT TUESDAY.

* SOME AFFECTED LOCATIONS...SEATTLE...EVERETT...BREMERTON...
OLYMPIA...TACOMA...CHEHALIS...PORT ANGELES.

* TIMING...THIS AFTERNOON THROUGH THIS EVENING.

* WIND...SOUTHWEST WINDS WILL INCREASE TO 20 TO 30 MPH WITH GUSTS
TO 45 MPH LATE THIS AFTERNOON. WINDS WILL CONTINUE INTO THE LATE
NIGHT HOURS.

* IMPACTS...STRONG SOUTHERLY WINDS WILL PRUNE DEAD BRANCHES FROM
TREES. FALLING BRANCHES MAY RESULT IN LOCAL POWER OUTAGES AT
TIMES. SOME WEAKENED TREES COULD FALL IN THE WIND. MOST TREES
STILL HAVE SOME OR ALL OF THEIR LEAVES...WHICH WILL HEIGHTEN THE
IMPACT OF THE WIND ON THE TREES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WIND ADVISORY IS ISSUED WHEN SUSTAINED WINDS OF 30 TO 39 MPH OR
GUSTS OF 45 TO 57 MPH ARE LIKELY.

&&

$$

As you can see, we are on the very low end of the wind advisory, with gusts to 45 mph and sustained winds of 20 to 30. I have a feeling that if this storm occurred in December, a wind advisory would not be issued. The reason why it is being issued here is because many of the trees still have their leaves on them, and they also have a bunch of dead branches that haven’t been blown off by previous storms because, well, there haven’t been any. A closer look at the UW’s high resolution 4km WRF-GFS shows us that the winds won’t be anything to really worry about. Of course, relative to this past summer, it will probably feel like a hurricane out there.

Valid 05:00 pm PDT Mon, 15 Oct 2012 – 12hr Fcst – UW 4km 12z WRF-GFS 10 meter wind, SLP
The above picture shows the wind as predicted at 5 P.M. Pretty decent winds on the coast and San Juans, but nothing here.
Valid 11:00 pm PDT Mon, 15 Oct 2012 – 18hr Fcst – UW 4km 12z WRF-GFS 10 meter wind, SLP
Later in the night, we will get a surge of wind down the Strait, but again, we won’t see much wind in the Seattle metropolitan area. If I was the National Weather Service, I would not be issuing a wind advisory based on these models. Of course, I’m not the National Weather Service, so for now, a wind advisory remains in effect.
Precipitation-wise, this storm will be lighter than the one we just saw because it will move through our area at a higher velocity (to use a term from the intro physics class I am taking this quarter). I’d expect 24-hour totals of a quarter to a half inch of rain in the Western Washington lowlands, but the Olympics and Cascades could see two to three inches. Not enough to cause flooding, but enough to make the Skokomish River come close.
Valid 05:00 am PDT Tue, 16 Oct 2012 – 24hr Fcst – UW 4km 12z WRF-GFS 24 hour precip
After this guy rolls on through, we will be dry for a couple days, and then we’ll have another storm come through our area on Friday. This one could deliver a bit more wind and a bit more rain. It seems as though autumn is making up for lost time.

Valid 05:00 am PDT Fri, 19 Oct 2012 – 96hr Fcst – UW 12km 12z WRF-GFS 24 hour precip

But it is into next week that things start to get rather interesting.
Forecast retrieved from Brian Schmit’s “16-Day GFS Extraction” Program
Of course, you have to take these direct extraction things with a grain of salt. Earlier runs had Seattle in the low 30s for four straight days. This is because the resolution on these global models is very low, and it doesn’t account for the local moderating effects of the Pacific Ocean, and also because the forecast is in the extremely far extended. It is very useful for picking up patterns in the models though. They have been consistent with this pattern, and at this point, I’m definitely forecasting snow in Snoqualmie Pass next week. 
Have a nice day!
Charlie
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