Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 091643
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
845 AM PST TUE FEB 9 2016

.SYNOPSIS...A STRONG UPPER LEVEL RIDGE AND LOW LEVEL OFFSHORE FLOW
WILL MAKE TUESDAY ONE MORE SUNNY AND MILD DAY...AFTER MORNING FOG
DISSIPATES. SOUTHWEST FLOW ALOFT WILL DEVELOP LATER TODAY AS THE
RIDGE MOVES EAST...ALLOWING EMBEDDED SYSTEMS TO BRING CLOUDS AND
SOME RAIN AT TIMES FROM TUESDAY NIGHT THROUGH EARLY NEXT WEEK.

&&

.SHORT TERM...PATCHY OR SOMEWHAT MORE THAN PATCHY FOG DEVELOPED
AROUND PUGET SOUND LATE LAST NIGHT AND EARLY THIS MORNING. THIS
SHOULD BE DISSIPATED BY NOON OR SO...REVEALING MOSTLY SUNNY SKIES.
HIGH TEMPERATURES MAY FINISH A DEGREE OR TWO BELOW YESTERDAY...BUT
WILL STILL MAINLY BE IN THE 55-60 RANGE...WITH HIGHS AROUND 60 ON
THE COAST.

AN UPPER LEVEL RIDGE NOW CENTERED OVER EASTERN WASHINGTON WILL
WEAKEN TONIGHT. A WEAK SYSTEM EMBEDDED IN SOUTHWESTERLY FLOW ALOFT
WILL BRUSH THE COAST 12Z-15Z WEDNESDAY AND PERHAPS SPREAD SOME LIGHT
RAIN INLAND DURING THE DAY WEDNESDAY. CURRENTLY LOW NONZERO POPS
HANDLE THIS POSSIBILITY. WILL EXAMINE 12Z MODEL RUNS FOR THE
AFTERNOON FORECASTS TO SEE IF ANY CONSENSUS IS REACHED. WITH LOTS OF
CLOUD COVER THE HIGHS ON WEDNESDAY WILL BE MAINLY IN THE 50S.

A STRONGER SYSTEM WILL ARRIVE FROM THE SOUTHWEST ON THURSDAY. RAIN
IS LIKELY ON THE COAST IN THE MORNING AND WILL BECOME LIKELY INLAND
IN THE AFTERNOON. HIGHS WILL AGAIN BE IN THE 50S. BURKE

.LONG TERM...PREVIOUS DISCUSSION...GOOD CONSISTENCY IN THE SHORT TERM
SOLUTIONS EXTEND INTO THE LONG TERM ON THE 00Z RUN. SYSTEM THURSDAY
STALLS OVER THE AREA THURSDAY NIGHT WITH ANOTHER WAVE MOVING UP THE
BOUNDARY ON FRIDAY KEEP RAIN IN THE FORECAST FOR BOTH DAYS. SYSTEM
KICKING EAST FRIDAY NIGHT WITH AN UPPER LEVEL TROUGH MOVING THROUGH
ON SATURDAY FOR A CHANCE OF SHOWERS. LONG FETCH OF MOISTURE MOVING
ACROSS THE EASTERN PACIFIC SUNDAY INTO MONDAY. MODELS HAVE BEEN
WAFFLING A BIT ON WHERE THE JET WILL SET UP. PREVIOUS RUNS HAVE HAD
IT TO THE NORTH OF THE AREA. THE CURRENT SOLUTION POINTS THE JET
RIGHT AT WESTERN WASHINGTON WITH THE MOISTURE TAP ALL THE WAY BACK
TO NEAR 30N/155W. THE ECMWF IS MORE CONSOLIDATED WITH WITH THE
MOISTURE FETCH VERSUS THE GFS BUT BOTH MODELS ARE WET FOR WESTERN
WASHINGTON. HAVE INCREASED THE POPS INTO THE LIKELY CATEGORY FOR
BOTH DAYS. FELTON

&&

.HYDROLOGY...RIVER FLOODING IS UNLIKELY THROUGH SATURDAY. THERE IS
SOME POTENTIAL FOR HEAVY RAINS OVER THE OLYMPICS BEGINNING SUNDAY
WHICH COULD CAUSE THE FLOOD PRONE SKOKOMISH TO REACH FLOOD STAGE
EARLY NEXT WEEK. FELTON

&&

.AVIATION...LIGHT FLOW ALOFT WILL BECOME SOUTHERLY THIS
AFTERNOON AS AN UPPER RIDGE OVER THE AREA SHIFTS EAST. HIGH PRESSURE
EAST OF THE CASCADES WITH LOWER PRESSURE OFFSHORE WILL CONTINUE TO
GIVE OFFSHORE FLOW THROUGH TONIGHT. THE AIR MASS IS DRY AND STABLE
WITH AREAS OF LOW LEVEL MOISTURE BELOW A LOW LEVEL SUBSIDENCE
INVERSION.

THERE WILL BE AREAS OF SHALLOW FOG OVER MAINLY THE SOUTHERN HALF OF
OF THE INLAND VALLEYS...EVERETT SOUTHWARD...UNTIL 20Z. PATCHY
SHALLOW FOG OVER THE NORTH INTERIOR WILL BURN OFF BY 18Z. ONCE THE
FOG BURNS OFF...EXPECT ONLY SCT-BKN CIRRUS.

UPPER LEVEL MOISTURE WILL THICKEN AND CLOUD BASES LOWER STARTING
THIS EVENING AS A WARM FRONT WELL OFFSHORE APPROACHES THE AREA FROM
THE SOUTHWEST. EXPECT THE INCREASE IN CLOUDS LATE TONIGHT TO IMPEDE
FOG FORMATION...EXCEPT IN NORMALLY FOGGY RIVER VALLEYS IN THE
INTERIOR. ALBRECHT


KSEA...PILOT REPORTS SHOWING FOG TOPS 700 TO 800 FEET THIS
MORNING...SO EXPECT FOG TO RAPIDLY THIN AND BURN OFF STARTING 18Z.
BY 20Z EXPECT JUST SCT-BKN250 WITH GOOD VIS. AT THIS TIME IT APPEARS
THAT THICKENING MID AND HIGH LEVEL MOISTURE WILL KEEP FOG FROM
FORMING AROUND THE TERMINAL WED MORNING. ALBRECHT

&&

.MARINE...HIGH PRESSURE EAST OF THE CASCADES AND LOWER PRESSURE
OFFSHORE IS GIVING OFFSHORE FLOW TODAY. SMALL CRAFT ADVISORY OUTFLOW
WILL CONTINUE TODAY AT THE WEST ENTRANCE TO THE STRAIT OF JUAN DE
FUCA AND THE ADJACENT INNER COASTAL WATERS NEAR THE STRAIT.

THE FLOW IS WEAK ENOUGH THAT AREAS OF FOG HAVE FORMED OVER PUGET
SOUND AND HOOD CANAL...SOUTHERN PORTIONS OF ADMIRALTY INLET...AND
AROUND THE STRAIT OF JUAN DE FUCA. THE FOG IS EXPECTED TO BURN OFF
BY NOON TODAY.

A WEAK WARM FRONT WILL BRUSH THE AREA ON WED. THIS FRONT WILL GIVE
AREAS OF SMALL CRAFT ADVISORY SOUTH TO SOUTHEAST WINDS TO PORTIONS
OF THE COASTAL WATERS.

ANOTHER FRONTAL SYSTEM WILL STALL JUST OFFSHORE THU AND FRI...MOVING
INLAND SAT. ALBRECHT

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 3 PM PST THIS AFTERNOON FOR COASTAL
     WATERS FROM CAPE FLATTERY TO JAMES ISLAND OUT 10 NM-WEST
     ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.

&&

$$

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