Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 271036 CCA
AFDSEW

AREA FORECAST DISCUSSION...CORRECTION
NATIONAL WEATHER SERVICE SEATTLE WA
330 AM PDT MON APR 27 2015

.SYNOPSIS...A WEAK WARM FRONT WILL LIFT NORTH THROUGH WESTERN
WASHINGTON THIS MORNING...WITH DRY WEATHER THIS AFTERNOON. A PAIR OF
FRONTS WILL CROSS THE REGION TUESDAY AND WEDNESDAY FOR COOLER AND
WETTER WEATHER. WEAK UPPER LEVEL DISTURBANCES WILL MAINTAIN A SLIGHT
CHANCE OF SHOWERS THROUGH THE WEEKEND.

&&

.SHORT TERM...A WEAK WARM FRONT WILL LIFT NORTH THROUGH WESTERN WA
THIS MORNING WITH LIGHT RAIN OR A FEW LIGHT SPRINKLES ACROSS THE
AREA. THE AIR MASS WILL THEN DRY THIS AFTERNOON AS THE FRONT PUSHES
INTO B.C. WESTERN WA WILL BE IN THE WARM SECTOR WITH FREEZING LEVELS
RISING TO AROUND 9000 FT. MODELS SHOW GOOD WARM AIR ADVECTION AND
ALL GUIDANCE SHOWS TEMPS RISING INTO THE 70S THIS AFTERNOON. IT WILL
BE A LITTLE COOLER ALONG THE COAST WITH HIGHS IN THE 60S.

TUESDAY WILL BE COOLER AND WETTER AS A COLD FRONT MOVES INLAND. RAIN
WILL REACH THE COAST TUESDAY MORNING...WITH SHOWERS IN THE INTERIOR
THROUGH THE AFTERNOON. HIGH TEMPS WILL BE ABOUT 10-15 DEGREES COOLER
COMPARED TO MONDAY...BUT CLOSE TO NORMAL. ONSHORE FLOW WILL INCREASE
BEHIND THIS FRONT TUESDAY NIGHT AND MODELS SHOW A PUGET SOUND
CONVERGENCE ZONE DEVELOPING OVER THE CENTRAL SOUND. SHOWERS FROM THE
PSCZ MAY LINGER THROUGH LATE TUESDAY NIGHT.

A SECOND COLD FRONT AND TRAILING UPPER TROUGH WILL MAINTAIN
SCATTERED SHOWERS AS IT PASSES THROUGH THE AREA ON WEDNESDAY.
ONSHORE FLOW WILL PREVAIL ON THURSDAY FOR A FEW MORE
SHOWERS...MAINLY COAST AND MOUNTAINS. BUT SHOWERS LOOK ISOLATED AT
THIS POINT. 33

.LONG TERM...THE FLOW ALOFT WILL REMAIN ZONAL THROUGH THE WEEKEND.
MODELS SHOW WEAK UPPER LEVEL DISTURBANCES CLIPPING SOUTHERN BRITISH
COLUMBIA...BUT NOT A WHOLE LOT OF ACTION OVER WESTERN WA. OVERALL
THE PATTERN IS LOOKING PRETTY QUIET. THE SURFACE FLOW IS ONSHORE AND
TEMPERATURES WILL BE CLOSE TO NORMAL. MODELS SHOW A MORE ORGANIZED
SYSTEM AFFECTING THE REGION EARLY NEXT WEEK. 33

&&

.AVIATION...AN UPPER RIDGE OVER THE PACIFIC NORTHWEST TODAY WILL
SHIFT EAST TONIGHT. A WEAK WARM FRONT STALLED OVER WESTERN
WASHINGTON WILL LIFT NORTH OF THE AREA BY THIS AFTERNOON. AIR MASS
STABLE.

CEILINGS GENERALLY IN THE 1500-2500 FOOT RANGE WITH ISOLATED
CEILINGS BELOW 1000 FEET AND VISIBILITIES 3-5SM IN LIGHT
RAIN/DRIZZLE. CONDITIONS IMPROVING MID TO LATE MORNING WITH CEILINGS
RISING ABOVE 3000 FEET BY 19Z. CONDITIONS IMPROVING RAPIDLY LATER
THIS AFTERNOON WITH THE CLOUDS SCATTERING OUT. SCATTERED CLOUDS
TONIGHT.

KSEA...CEILINGS NEAR 1000 FEET EARLY THIS MORNING RISING TO
2000-3000 FEET BY 16Z. CEILINGS CONTINUING TO IMPROVE RISING ABOVE
3000 FEET BY 19Z. CLOUDS SCATTERING OUT THIS AFTERNOON. SOUTHERLY
WIND 4-8 KNOTS SWITCHING TO NORTHWESTERLY 21Z-00Z. FELTON

&&

.MARINE...A WEAKENING WARM FRONT WILL BRING SMALL CRAFT SOUTHERLY
WINDS TO MOST OF THE COASTAL WATERS THIS MORNING. WINDS WILL EASE
LATER TODAY AS THE FRONT LIFTS NORTH INTO SOUTHERN BRITISH COLUMBIA.

A SECOND FRONTAL SYSTEM WILL BRING ANOTHER ROUND OF SMALL CRAFT
ADVISORY SOUTHERLY WINDS TO THE COASTAL WATERS TUESDAY. MODERATE
ONSHORE FLOW BEHIND THE FRONT LATER TUESDAY IS EXPECTED TO BRING
SMALL CRAFT ADVISORY WEST WINDS TO THE STRAIT. A THIRD FRONT WILL
REACH THE AREA WEDNESDAY. HIGH PRESSURE WILL BUILD OVER THE WATERS
THURSDAY AND REMAIN OVER THE AREA ON FRIDAY. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY COASTAL WATERS.

&&

$$

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








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