FXUS66 KSEW 150529
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
930 PM PST TUE FEB 14 2012

.SYNOPSIS...HIGH PRESSURE WILL BUILD OVER THE REGION THROUGH 
WEDNESDAY. A WEAK WEATHER SYSTEM WILL REACH THE REGION THURSDAY.
A STRONGER FRONTAL SYSTEM WILL REACH THE AREA FRIDAY AFTERNOON AND 
NIGHT. A COLD UPPER TROUGH WILL BE OVER THE REGION SATURDAY.

&&

.SHORT TERM...MOSTLY CLEAR TONIGHT AS AN UPPER RIDGE AND SURFACE 
HIGH PRES BUILD INTO THE AREA. THE UPPER LOW CENTER IS OVER EASTERN 
OREGON AND THAT WILL DROP SOUTH THROUGH CALIF WED. THE UPPER RIDGE 
AND SFC HIGH PRES PEAK OVER WRN WA WED EVENING...THE CENTER OF THE 
SFC HIGH IS ABOUT 1030MB BY THAT TIME OVER SE BRITISH COLUMBIA AND A 
WEAK FRONTAL SYS IS ALONG 130W. THAT FRONT BREAKS UP OVER THE B.C. 
COAST AND WRN WA THU MORNING. HIGH PRES REBUILDS SOMEWHAT THU 
NITE...AND THEN HEIGHTS FALL OFF FRIDAY AND FRIDAY NIGHT AS A MORE 
VIGOROUS WEATHER SYSTEM  MOVES INTO THE PACNW. 19

.LONG TERM...COOL UPPER TROUGH WITH SHOWERS ON TAP FOR THE WEEKEND 
WITH FLAT RIDGE BUILDING INTO THE REGION SUN AND MONDAY. AFTER COLD 
AIR ALOFT SATURDAY TEMPS WILL MODERATE AND THE AIR MASS WILL 
STABILIZE SUN AND MON...BUT THE RIDGE MAY BE TOO FLAT TO OFFER MUCH 
PROTECTION FROM THE WESTERLIES AND WARM ADVECTION...THE EARLY PART 
OF NEXT WEEK COULD BE DAMP. 19

&&

.HYDROLOGY...FLOODING IS UNLIKELY DURING THE NEXT 7 DAYS. 

&&

.AVIATION...UPPER LEVEL LOW OVER CENTRAL OREGON WILL CONTINUE TO 
MOVE SOUTH TONIGHT. WEAK UPPER LEVEL RIDGE BUILDING OVER THE AREA ON 
WEDNESDAY. NORTHERLY FLOW ALOFT BECOMING NORTHWESTERLY WEDNESDAY 
AFTERNOON. 

SHOWER ACTIVITY HAS COME TO AN END OVER THE AREA WITH NO 
PRECIPITATION ECHOES ON THE WSR-88D`S. SURFACE GRADIENTS FLAT AND 
WILL REMAIN FLAT THROUGH WEDNESDAY. FLOW ALOFT FROM 850 MB TO THE 
SURFACE ALSO REMAINING LIGHT. WITH THE LIGHT FLOW AT THE LOWER 
LEVELS SC DECK WILL BE SLOW TO SCOUR OUT TONIGHT FROM KPAE SOUTHWARD 
WITH THE SC HANGING AROUND INTO WEDNESDAY MORNING. SCATTERED CLOUDS 
LATER WEDNESDAY MORNING WITH INCREASING HIGH CLOUDS IN THE 
AFTERNOON. FOR LOCATIONS NORTH OF KPAE MOSTLY CLEAR SKIES WITH 
PATCHY FOG FORMING REDUCING VISIBILITIES BELOW 1 SM 09 UTC TO 15 
UTC. 

KSEA...SCATTERED TO BROKEN CLOUDS BETWEEN 3500 AND 5000 FEET INTO 
THE MORNING HOURS. JUST SCATTERED CLOUDS BY 15 UTC WEDNESDAY. LIGHT 
WIND THROUGH WEDNESDAY AFTERNOON. FELTON

&&

.MARINE...WEAK HIGH PRESSURE BUILDING OVER THE WATERS WITH LIGHT 
SURFACE GRADIENTS THROUGH WEDNESDAY. A FRONTAL SYSTEM EMANATING OUT 
OF THE GULF OF ALASKA WILL APPROACH THE COASTAL WATERS WED NIGHT 
BEFORE MOVING ACROSS THE AREA ON THU.

SMALL CRAFT ADVISORIES IN EFFECT FOR THE COASTAL WATERS AND WEST 
ENTRANCE TO THE STRAIT FOR HAZARDOUS SEAS WITH SWELLS RUNNING IN THE 
10 TO 13 FOOT RANGE. A LARGER SWELL TRAIN WILL IMPACT THE COASTAL 
WATERS THIS WEEKEND. WESTERLY SWELLS OF 20 TO 23 FEET ARE EXPECTED 
TO ARRIVE ON SATURDAY...RESULTING IN HAZARDOUS SEAS AND HIGH SURF ON 
THE BEACHES. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES FOR HAZARDOUS SEAS ARE IN EFFECT UNTIL
     6 PM PST WEDNESDAY FOR THE COASTAL WATERS AND WEST ENTRANCE
     TO THE STRAIT OF JUAN DE FUCA.

     SMALL CRAFT ADVISORY FOR ROUGH BAR UNTIL MIDNIGHT PST WEDNESDAY 
     NIGHT FOR THE GRAYS HARBOR BAR.

&&

$$

YOU CAN SEE AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION AT 
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML.

WWW.WEATHER.GOV/SEATTLE