High Wind in Washington, January 30, 2009

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
300 PM PST FRI JAN 30 2009

.SYNOPSIS...A WEAK COLD FRONT WILL DISSIPATE AS IT MOVE THROUGH
WESTERN WASHINGTON EARLY THIS EVENING. COOLER TEMPERATURES ARE
EXPECTED BEHIND THE FRONT LATER TONIGHT INTO SATURDAY WITH A CHANCE
OF SHOWERS ALONG WITH MOUNTAIN SNOW SHOWERS. A WEAK WARM FRONT WILL
BRUSH NORTHERN PARTS OF WESTERN WASHINGTON SUNDAY AFTERNOON THROUGH
MONDAY. MOSTLY DRY AND MILD WEATHER WILL FOLLOW ON TUESDAY AND
WEDNESDAY UNDER AN UPPER LEVEL RIDGE.

&&

.SHORT TERM...IR SATELLITE IMAGERY SHOWS THE APPROACHING WEAK
FRONTAL BAND CURRENTLY OVER VANCOUVER ISLAND SLIDING SE TOWARD WA.
LIGHT RAIN IS DEVELOPING ALONG THE N WA COAST AND WILL PUSH INTO THE
REST OF WRN WA EARLY THIS EVENING. QPF LOOKS QUITE LIGHT WITH SOME
SPOTS POSSIBLY NOT EVEN MEASURING AS THE FRONT RAPIDLY DISSIPATES AS
IT MOVES ACROSS. THIS TREND IS ALREADY NOTICEABLE WITH CLOUD TOP
WARMING APPARENT ON THE IR IMAGE.

THE POST FRONTAL AIR MASS WILL BE COLDER AND UNSTABLE WITH A BETTER
CHANCE OF PRECIP IN THE FORM OF SHOWERS ACROSS THE AREA. ALSO...THE
SURFACE PATTERN FAVORS A PSCZ WHICH SHOULD FORM OVER SNOHOMISH
COUNTY. MODELS SHOW THE 850 MB FLOW TURNING MORE NWLY BY 06Z...SO
THE CONVERGENCE BAND COULD SAG SWD INTO N KING COUNTY AND POSSIBLY
INTO THE SEATTLE AREA.  MODELS STILL SHOW 850 MB TEMPS TO FALL OFF
TO -5 OR -6 C OVERNIGHT SO IT IS POSSIBLE SOME WET SNOW COULD MIX IN
BUT ACCUMULATION IS NOT EXPECTED. A GLANCE AT THE 4KM MM5 ALSO SHOWS
NO SNOW ACCUMULATION.  HOWEVER...SNOW WILL ACCUMULATE IN THE
MOUNTAINS WITH STRONG FLOW PRODUCING GOOD OROGRAPHICS. MODEL QPF
AROUND A QUARTER TO A THIRD OF AN INCH OVERNIGHT SHOULD TRANSLATE TO
AT LEAST A FEW INCHES OF SNOW AT THE PASSES. WILL INDICATE SNOW
AMOUNTS OF 3 TO 5 INCHES OVERNIGHT...JUST UNDER ADVISORY CRITERIA.
WILL NEED TO WATCH THE CONVERGENCE ZONE WHICH COULD DUMP SOME
LOCALLY HIGHER AMOUNTS IN STEVENS PASS...AND POSSIBLY SNOQUALMIE
PASS LATER ON TONIGHT AND EARLY SATURDAY.

SHOWERS CONTINUE INTO SATURDAY WITH A SURFACE RIDGE OFFSHORE STILL
CONDUCIVE FOR A PSCZ MOST THE DAY. THE MM5 REDEVELOPS A CONVERGENCE
BAND OVER WRN SKAGIT/SNOHOMISH COUNTY. HOWEVER...THIS SEEMS A BIT
FAR NORTH GIVEN THE MID/UPPER FLOW OUT OF THE NW WHICH SHOULD TEND
TO PUSH THE BAND FURTHER SOUTH MORE TOWARD THE KING/SNOHOMISH LINE.
REGARDLESS...THERE WILL BE A CHANCE OF SHOWERS JUST ABOUT ANYWHERE
THROUGH THE DAY.

MODELS STILL SHOW A DRY PERIOD SATURDAY NIGHT. DECIDED TO ADD SOME
PATCHY FOG FOR LATE SAT NIGHT/SUN MORNING GIVEN THE LIGHT SURFACE
GRADIENTS. SUNDAY SHOULD BE A RATHER CLOUDY DAY WITH A WARM FRONT
SPREADING RAIN ALONG THE COAST BY MIDDAY. THE NEW 12Z ECMWF CAME IN
A LITTLE FURTHER SOUTH WITH THE PRECIP AND MORE IN LINE WITH THE GFS
SO POPS HAVE BEEN INCREASED OVER THE INTERIOR FOR SUNDAY AFTERNOON.

HIGH PRESSURE BUILDS SLIGHTLY STRONGER ON MONDAY WITH THE BULK OF
THE FLOW INTO SRN BRITISH COLUMBIA. HOWEVER...MODELS STILL BRUSH THE
NORTH COAST AND N INTERIOR WITH LIGHT QPF. KEPT SOME PRECIP CONFINED
TO NORTH AND WEST OF EVERETT AND DRIED OUT THE SEATTLE AREA.

.LONG TERM...HIGH PRESSURE BUILDS STRONGER ON TUESDAY WITH DRY
WEATHER EXPECTED ACROSS ALL OF WRN WA. MODELS SHOW SOME DECENT ELY
GRADIENT BUT NOT SURE IF IT WILL BE STRONG ENOUGH TO MIX THE LOW
LEVELS. HELD OFF ON ADDING FOR NOW AND WENT WITH THE WARMER MOS
TEMPS...UPPER 40S TO NEAR 50S. WEDNESDAY COULD BE SLIGHTLY ABOVE
AVERAGE AS WELL ASSUMING WE GET SOME MIXING IN THE AFTERNOON. IF THE
LOW LEVELS DO NOT MIX...INVERSIONS AND FOG COULD STICK AROUND ALONG
WITH COLDER HIGH TEMPS. THE GFS/ECMWF BOTH BRING A SPLIT TROUGH
ACROSS WRN WA ON THURSDAY WITH A THREAT OF PRECIP FOR THE END OF THE
WEEK.

MERCER

&&

.AVIATION...A WEAK COLD FRONT AND UPPER TROUGH OVER WESTERN
WASHINGTON WILL MOVE QUICKLY EAST OF THE CASCADES TONIGHT. NORTHWEST
FLOW ALOFT WILL FOLLOW THE FRONT THROUGH SATURDAY. THE AIR MASS WILL
BECOME GENERALLY MOIST AND WEAKLY UNSTABLE AS THE FRONT MOVES
THROUGH TONIGHT.

RAIN AHEAD OF THE FRONT HAS ALREADY STARTED ALONG THE COAST AND IN
THE NORTH INTERIOR OF WESTERN WASHINGTON...AND IT WILL SPREAD INTO
THE SEATTLE AREA AROUND 6 PM. STEADY PRECIPITATION WILL BE RATHER
BRIEF AND AMOUNTS WONT BE GREAT. MOST OF THE POST-FRONTAL SHOWERS
WILL BE CONFINED TO THE PUGET SOUND CONVERGENCE ZONE AND CASCADES
TONIGHT. CEILINGS WITH AND BEHIND THE FRONT WILL BE IN THE 2000-3500
FT RANGE FOR THE MOST PART.

KSEA...SOUTH 12-18 KT AND GUSTING 25 KT...EASING TO 8-12 KT
OVERNIGHT AND SATURDAY. EXPECTING MVFR CEILINGS IN THE 2000-3000 FT
RANGE TO BE THE PREVAILING CONDITION 6 PM THIS EVENING THROUGH 4 AM
SATURDAY. PUGET SOUND CONVERGENCE ZONE WILL FORM BEHIND THE FRONT
THIS EVENING OR OVERNIGHT...WHICH WILL LIKELY REMAIN NORTH OF KSEA.
MCDONNAL

&&

.MARINE...A COLD FRONT OVER WESTERN WASHINGTON WILL MOVE EAST OF THE
CASCADES LATE THIS EVENING. THE FRONT IS PRODUCING SMALL CRAFT
ADVISORY WINDS OVER MUCH OF THE FORECAST AREA ALREADY...AND
POST-FRONTAL COLD ADVECTION WILL PRODUCE GALE WESTERLIES IN THE
STRAIT OF JUAN DE FUCA BEGINNING THIS EVENING. THERE IS EVEN A
CHANCE OF NORTHWEST GALES IN ADMIRALTY INLET...BUT I WILL STAY WITH
20-30 KT AS THE MOST LIKELY SCENARIO. A PUGET SOUND CONVERGENCE ZONE
WILL DEVELOP BEHIND THE FRONT AS WELL.

ONCE SMALL CRAFT ADVISORY WINDS EASE OVER THE COASTAL WATERS AND
WEST ENTRANCE TO THE STRAIT ON SATURDAY...A SMALL CRAFT ADVISORY FOR
HAZARDOUS SEAS WILL BE IN EFFECT DUE TO WEST SWELL 11 TO 13 FT.

HIGH PRESSURE WILL BUILD OVER THE AREA LATE SATURDAY...THEN SHIFT
INLAND BY EARLY SUNDAY AS A WARM FRONT BRUSHES WESTERN WASHINGTON ON
ITS WAY INTO BRITISH COLUMBIA. HIGH PRESSURE OVER THE ROCKIES AND A
TROUGH OF LOW PRESSURE WELL OFFSHORE WILL PRODUCE OFFSHORE FLOW
MONDAY THROUGH WEDNESDAY. MCDONNAL

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE
PZ...GALE WARNING CENTRAL STRAIT AND EAST ENTRANCE.
    .SMALL CRAFT ADVISORY CENTRAL STRAIT...EAST ENTRANCE...ADMIRALTY
     INLET...NORTHERN INLAND WATERS...PUGET SOUND AND HOOD CANAL.
    .SMALL CRAFT ADVISORY FOR ROUGH BAR CONDITIONS GRAYS HARBOR.

&&

WEATHER.GOV/SEATTLE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
521 PM PST FRI JAN 30 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0520 PM     NON-TSTM WND GST 4 ESE LOWER ELWHA       48.13N 123.48W
01/30/2009  E45 MPH          CLALLAM            WA   TRAINED SPOTTER

            SUSTAINED WINDS 25 TO 30 MPH. POWER OUT. SMALL TREE LIMBS
            ARE DOWN.

&&

GRUB