Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 031649
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
900 AM PST TUE MAR 3 2015

.SYNOPSIS...HIGH PRESSURE AND OFFSHORE FLOW WILL GIVE FAIR WEATHER
THROUGH WEDNESDAY. A WEAK FRONT WILL BRUSH THE NORTH PART OF WESTERN
WASHINGTON THURSDAY. HIGH PRESSURE WILL REBUILD FOR THE WEEKEND.

&&

.SHORT TERM...THERE IS AN UPPER RIDGE OFFSHORE WITH NORTHERLY FLOW
ALOFT OVER THE PACIFIC NORTHWEST. IT LOOKS LIKE CIRRUS WILL INCREASE
BUT OTHERWISE THE WEATHER WILL BE FAIR AND DRY TODAY AND WEDNESDAY.
LOW TEMPS TONIGHT WILL BE FROSTY AGAIN. THERE IS SURFACE HIGH
PRESSURE INLAND WITH LOWER PRESSURE OVER CALIF WHICH EXTENDS
SOMEWHAT NORTH ALONG THE OREGON AND WA COASTAL WATERS...THIS IS
GIVING LIGHT OFFSHORE FLOW. THE AIR IS STABLE AND MAINLY DRY.

THE RIDGE WILL WEAKEN ON WEDNESDAY AS THE OFFSHORE RIDGE FLATTENS
AND SHIFTS EAST OVER THE AREA. A WEAK UPPER LEVEL SHORT WAVE TROUGH
AND ASSOCIATED FRONTAL SYSTEM WILL MOVE INTO BRITISH COLUMBIA
THURSDAY. OVER WESTERN WA CLOUDS WILL INCREASE THU AND THERE IS A
CHANCE OF RAIN IN THE FORECAST FOR THE NORTHERNMOST PORTION OF WRN
WA. THE 12Z GFS IS DRY OVER WA BUT DOES HAVE SOME RAIN ABOUT HALFWAY
DOWN VANCOUVER ISLAND THU AFTERNOON.

.LONG TERM...ANOTHER UPPER LEVEL RIDGE WILL BUILD INTO THE WEEKEND.
SURFACE HIGH PRESSURE WITH A MILD AIR MASS AND SOME SUNSHINE SHOULD
GIVE HIGHS HIGHS IN THE MID 50S TO LOWER 60S AND LOWS AROUND 40. IT
LOOKS DRY NEXT WEEKEND THROUGH EARLY NEXT WEEK.

&&

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

&&

.AVIATION...AN UPPER RIDGE WILL REMAIN CENTERED OFFSHORE. CONTD NLY
FLOW ALOFT. THE LOW LEVEL FLOW WILL BE WEAK OFFSHORE.

MEANWHILE...THERE WAS PATCHY SHALLOW FOG REDUCING VSBYS IN THE
4-6SM RANGE THIS MORNING. THE FOG WILL LIKELY DISSIPATE BY 1800
UTC. FOG WILL PROBABLY BE A LITTLE MORE WIDESPREAD WED MORNING
COMPARED TO THIS MORNING DUE TO A WEAKER SFC PRES GRADIENT.

KSEA...VFR CONDITIONS WILL PREVAIL. WINDS WILL BE LIGHT AND
VARIABLE.

&&

.MARINE...
HIGH PRES E OF THE CASCADES WITH LOWER PRES ALONG OR JUST OFF THE
WASHINGTON COAST WILL RESULT IN WEAK EASTERLY OR OFFSHORE FLOW
THROUGH TONIGHT. THE FLOW WILL BECOME LIGHT ONSHORE ON WED DUE TO
HIGHER PRES BUILDING OVER THE COASTAL WATERS. WEAK ONSHORE FLOW
WILL PERSIST ON THU.

&&

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

&&

$$

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