Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 052234
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
235 PM PST THU MAR 5 2015

.SYNOPSIS...AN UPPER RIDGE AND HIGH PRESSURE WILL GIVE FAIR DRY
WEATHER THROUGH THE WEEKEND. WEATHER SYSTEMS SHOULD REACH WESTERN
WASHINGTON TUESDAY OR WEDNESDAY OF NEXT WEEK.

&&

.SHORT TERM...THERE IS A 1030 MB SURFACE HIGH CENTERED OVER SRN
VANCOUVER ISLAND WITH LIGHT PRESSURE GRADIENTS OVER THE REGION. A
FRONT IS MOVING INTO B.C. THIS AFTERNOON WITH SOME HIGH CLOUDS OVER
WRN WA. THE UPPER RIDGE WILL BUILD A BIT AGAIN FRIDAY AND THEN SHIFT
JUST OFFSHORE OVER THE WEEKEND. THERE WILL BE HIGH CLOUDS AT TIMES
BUT OTHERWISE FAIR DRY MILD WEATHER FOR WRN WA WILL PERSIST. WE MAY
SEE SOME PATCHY MORNING FOG...THE BEST CHANCE OF FOG IS PROBABLY
SATURDAY MORNING...THE UW WRFGFS LOWEST LEVEL CLOUD PRODUCT SHOWS
LOW CLOUDS SATURDAY MORNING...MAINLY OVER THE COAST AND INLAND
MARINE AREAS SO SAT MORNING PROBABLY HAS THE BEST CHANCE OF FOG. FOR
NOW PATCHY FOG IS IN THE FORECAST EACH MORNING FOR PORTIONS OF SW WA
AND THE COAST...THE AIR IS STABLE AND DEW POINTS SHOULD CREEP UP
INTO THE WEEKEND.

.LONG TERM...THE UPPER RIDGE SHOULD CONTINUE TO PROTECT WRN WA FROM
WEATHER SYSTEMS INTO EARLY NEXT WEEK. THE RIDGE WILL BREAK DOWN OR
SHIFT AWAY FROM THE AREA AND THE WESTERLIES SHOULD START TO AFFECT
THE AREA AGAIN TUE AND WED. THE 12Z GFS HAD THE TAIL END OF A FRONT
REACHING WRN WA AROUND DAYBREAK TUESDAY FOLLOWED BY A WARM FRONT
LATER TUE THAT EXTENDED OUT TO THE SRN STREAM TROUGH THAT KICKS OUT
THROUGH THE AREA MIDWEEK. THE 18Z GFS IS SIMPLER AND KEEPS WRN WA
DRY TIL WEDNESDAY AS THE SRN STREAM SYSTEM MOVES ASHORE...AND THE
12Z EURO NOW LOOKS A BIT MORE LIKE THE OLD GFS SOLUTIONS WITH SOME
PRECIP FOR THE NRN STREAM WESTERLIES SAGGING INTO THE AREA TUE AND
TUE NIGHT...FOLLOWED BY THE SRN LOW FINALLY KICKING INLAND...BUT IT
IS ACTUALLY MUCH FURTHER SOUTH WITH THAT AND HAS THE HEAVIER RAIN
MOVING INTO CALIF AND NOT UNTIL THU.

&&

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

&&

.AVIATION...WESTERLY FLOW ALOFT WILL CONTINUE TONIGHT...THEN TURN
MORE NORTHWESTERLY FRIDAY AS AN UPPER RIDGE OF HIGH PRESSURE BUILDS
OFF THE COAST. A WEAK SYSTEM MOVING ACROSS SOUTHERN BRITISH COLUMBIA
WILL BRING HIGH CLOUDS INTO WESTERN WASHINGTON AT TIMES. AIR MASS IS
STABLE AND DRY IN THE LOWER AND MID LEVELS. AT THE SURFACE WINDS ARE
LIGHT.

KSEA...LIGHT NORTHERLY WINDS TONIGHT AND FRIDAY. HIGH CLOUDS AT
TIMES WITH VFR CONDITIONS. CHB

&&

.MARINE...SURFACE HIGH PRESSURE OVER THE PACIFIC NORTHWEST WILL
RESULT IN WEAK PRESSURE GRADIENTS AND LIGHT WINDS THROUGH THE
WEEKEND. ON MONDAY MODERATE ONSHORE FLOW MAY DEVELOP. A FRONT IS
FORECAST TO REACH THE COASTAL WATERS TUESDAY AND IT MAY BRING SMALL
CRAFT ADVISORY WINDS TO THE COAST. CHB

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...NONE.

&&

$$

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