Friday, November 18, Weather Advisory...

posted Nov 18, 2011, 9:23 AM by smike@guemesfire.org

427 AM PST FRI NOV 18 2011

...A MIX OF RAIN AND SNOW SHOWERS POSSIBLE ACROSS THE LOWLANDS OF WESTERN WASHINGTON THROUGH SATURDAY MORNING...

...A COLD UPPER TROUGH WILL SETTLE OVER WESTERN WASHINGTON THROUGH SATURDAY MORNING BRINGING SHOWERS TO THE AREA. TEMPERATURES WILL BE MARGINALLY COLD ENOUGH SO THAT SOME SHOWERS MAY MIX WITH SNOW AT TIMES DOWN TO SEA LEVEL. MOST LOCATIONS WILL SEE LITTLE OR NO SNOW ACCUMULATION. HOWEVER...HIGHER HILL TOPS AND AREAS WITH PERSISTENT OR HEAVY SHOWERS COULD SEE LIGHT ACCUMULATIONS OF SNOW UNDER ONE INCH.

...MODEL GUIDANCE CONTINUES TO INDICATE THE POSSIBILITY OF A CONVERGENCE ZONE DEVELOPING SOMEWHERE NORTH OF SEATTLE THIS MORNING. IF THIS DEVELOPS AND PERSISTS LONG ENOUGH THEN ACCUMULATIONS OF ONE TO TWO INCHES COULD BE POSSIBLE IN THIS BAND.

...A WEAK SURFACE LOW WILL TRACK ACROSS FAR SOUTHERN WASHINGTON TONIGHT. THIS FEATURE MAY GENERATE AN ENHANCED AREA OF SHOWER ACTIVITY FROM THE SOUTH WASHINGTON COAST TO THE SOUTHWEST INTERIOR. THE AIR MASS WILL BE SLIGHTLY COLDER BY THIS TIME WHICH COULD ALLOW FOR MORE PRECIPITATION TO FALL AS SNOW THAN RAIN. LOCALIZED ACCUMULATIONS ACROSS THE SOUTHWEST INTERIOR COULD REACH ONE INCH AND UP TO 2 INCHES ON HILLTOPS OVERNIGHT. MANY AREAS WILL SEE LITTLE OR NO ACCUMULATION.

...COLDER TEMPERATURES ARE EXPECTED ACROSS WESTERN WASHINGTON THROUGH THE WEEKEND WITH WIDESPREAD LOW TEMPERATURES FALLING INTO THE LOW 30S THIS MORNING AND INTO THE MID 20S TO AROUND 30 DEGREES SATURDAY MORNING. AS A RESULT WET ROADWAYS MAY ICE UP DURING THE NIGHT AND MORNING HOURS...PRODUCING POTENTIALLY HAZARDOUS DRIVING CONDITIONS. COLD MORNING TEMPERATURES WILL OCCUR AGAIN ON SUNDAY MORNING WITH MODERATING TEMPERATURES DURING THE AFTERNOON.


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