Area Forecast Discussion 
FXUS66 KSEW 181034
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
334 AM PDT FRI MAY 18 2012
.SYNOPSIS...ONSHORE FLOW AND AN UPPER LEVEL TROUGH WILL BRING COOLER
WEATHER AND CLOUDS AT TIMES TODAY. WEAK HIGH PRESSURE WILL BRING DRY
AND SOMEWHAT WARMER WEATHER SATURDAY. WETTER WEATHER WILL DEVELOP
EARLY NEXT WEEK AS A SERIES OF FRONTS MOVE THROUGH.
&&
.SHORT TERM...ONSHORE FLOW CONTINUES ACROSS WESTERN WA TODAY THANKS
TO HIGH PRES OVER THE NE PAC. THE INTERIOR IS SEEING A FEW LIGHT
SPRINKLES EARLY THIS MORNING BUT SHOULD NOT AMOUNT TO MUCH. THE
INSANELY NARROW YET POTENT PSCZ THAT FORMED LAST EVENING FIZZLED OUT
OVERNIGHT. BOEING FIELD REPORTED 0.47 INCHES /AND A CLAP OF THUNDER/
FROM THIS THIN BAND OF SHOWERS WHILE SEATAC ONLY HAD A TRACE. THERE
WAS NOTHING HERE AT THE OFFICE IN NORTH SEATTLE. BUT THE UPPER LEVEL
TROUGH IS NOW OVER EASTERN WA AND THE AIR MASS IS PRETTY STABLE OVER
THE WEST SIDE. THE STRATUS DECK IS SHALLOW SO WE SHOULD SEE BREAKS
IN THE CLOUDS TODAY FOR PARTLY SUNNY SKIES. TEMPS WILL RANGE FROM
THE 50S ALONG THE COAST TO LOWER 60S IN THE INTERIOR.
A WEAK UPPER LEVEL RIDGE WILL BRING DRY AND WARMER WEATHER TO
WESTERN WA ON SATURDAY. TEMPS SHOULD REBOUND BACK INTO THE MID TO
UPPER 60S FOR MOST SPOTS.
SKIES WILL REMAIN CLOUDY ON SUNDAY AS OUR NEXT PAC SYSTEM ARRIVES.
THE WARM FRONT WILL BRING A FEW LIGHT SHOWERS TO THE AREA DURING THE
AFTERNOON. HOWEVER PRECIP AMOUNTS ARE FAIRLY LIGHT AND THE INTERIOR
MAY NOT SEE ANYTHING AT ALL. THE COLD FRONT WILL SLOWLY PUSH THROUGH
THE COASTAL WATERS SUNDAY NIGHT FOR A FEW MORE LIGHT SHOWERS.
ONSHORE FLOW WILL INCREASE ON MONDAY AS THIS FRONT FINALLY MOVES
INLAND. SO EXPECT AN INCREASE IN SHOWERS ACROSS THE AREA...ALONG
WITH BELOW NORMAL TEMPS. 33
.LONG TERM...THE MODELS MAINTAIN A COOL AND WET WEATHER PATTERN
ACROSS WESTERN WA THROUGH MUCH OF NEXT WEEK. LOW LEVEL ONSHORE FLOW
WILL KEEP SKIES MOSTLY CLOUDY WITH TEMPS STICKING BELOW NORMAL. THE
AIR MASS WILL REMAIN UNSTABLE AS A DEEP UPPER LOW OVER THE NE PAC
SPINS TOWARD AND OVER WA. MODELS DISAGREE ON WHEN THIS SYSTEM WILL
EXIT...SO CONFIDENCE IS LOW BEYOND THURSDAY. 33
&&
.AVIATION...AN UPPER TROUGH EAST OF THE AREA THIS MORNING WITH ZONAL
FLOW ALOFT. SURFACE HIGH PRESSURE OFFSHORE WITH LOWER PRESSURE
INLAND GIVING LOW LEVEL ONSHORE FLOW.
WEAK CONVERGENCE STILL OVER THE CENTRAL SOUND THIS MORNING WITH
CEILINGS RANGING FROM 2500 TO 5000 FEET. CEILINGS NEAR 2500 FEET
ALONG THE COAST WITH A SCATTERED TO BROKEN LAYER NEAR 6000 FEET OVER
THE NORTHWEST INTERIOR. SURFACE GRADIENTS ONSHORE THIS MORNING WHICH
SHOULD ALLOW THE 2500 FOOT DECK TO BECOME MORE WIDESPREAD OVER THE
CENTRAL SOUND LATER THIS MORNING. ONSHORE GRADIENTS WEAKENING THIS
MORNING. THIS COMBINED WITH THE MID MAY SUNSHINE WILL DISSIPATE THE
STRATUS DECK IN THE LATE MORNING/EARLY AFTERNOON HOURS. CONVERGENCE
PATTERN SETTING UP AGAIN LATER THIS AFTERNOON INTO THE EVENING HOURS
FOR ANOTHER ROUND OF 5000 FOOT CEILINGS FOR THE CENTRAL SOUND LATE
IN THE DAY. FOR THE REMAINDER OF THE AREA JUST SCATTERED CLOUDS THIS
AFTERNOON INTO THE EVENING HOURS.
KSEA...CEILINGS NEAR 6000 FEET AT 10Z BUT A FEW LOCATIONS IN THE
CENTRAL SOUND ALREADY REPORTING CEILINGS NEAR 2500 FEET. EXPECT
THESE CEILINGS TO ARRIVE AT SEA-TAC BY 13Z. STRATUS DECK SCATTERING
OUT MIDDAY WITH 5000 FOOT CEILINGS REDEVELOPING LATE IN THE
AFTERNOON. SOUTHERLY WIND 4 TO 8 KNOTS BECOMING NORTHWEST AROUND 00Z
SATURDAY. FELTON
&&
.MARINE...HIGH PRESSURE OFFSHORE AND LOWER PRESSURE INLAND WILL
PERSIST THROUGH SATURDAY GIVING SMALL CRAFT ADVISORY WESTERLIES TO
THE CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA DURING THE LATE
AFTERNOON AND EVENING HOURS. SURFACE HIGH MOVING INLAND SUNDAY FOR
LIGHT WINDS. A WEAK FRONT WILL REACH THE COASTAL WATERS ON MONDAY
WITH POSSIBLE SMALL CRAFT ADVISORY WINDS IN THAT AREA DURING THE
DAY. THE FRONT WILL MOVE INLAND MONDAY NIGHT WITH A SURGE OF
WESTERLIES THROUGH THE STRAIT BEHIND THE FRONT. FELTON
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES ARE IN EFFECT FOR THE CENTRAL AND
EASTERN STRAIT OF JUAN DE FUCA.
&&
WWW.WEATHER.GOV/SEATTLE
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