Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 271650
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
900 AM PST TUE JAN 27 2015

.SYNOPSIS...A WEAK FRONT WILL MOVE INTO WESTERN WASHINGTON TODAY AND
DISSIPATE OVER THE AREA TONIGHT. AN UPPER RIDGE WILL PROVIDE DRY AND
MILD WEATHER WEDNESDAY THROUGH SATURDAY. THE NEXT FRONT BRINGS A
CHANCE OF RAIN BACK INTO THE AREA SUNDAY AND EARLY NEXT WEEK.

&&

.SHORT TERM...A WEAK COLD FRONT IS MOVING INLAND THIS MORNING FOR
CLOUDY SKIES AND A FEW LIGHT SPRINKLES ACROSS WESTERN WA. RAINFALL
AMOUNTS WILL REMAIN LIGHT WITH A TRACE TO A FEW HUNDREDTHS EXPECTED.
TEMPS WILL BE COOLER TODAY UNDER MOSTLY CLOUDY SKIES. ISOLATED LIGHT
SHOWERS WILL CONTINUE TONIGHT.

AN UPPER LEVEL RIDGE WILL BRING CLOUDY BUT STABLE WEATHER ON
WEDNESDAY. THE LOW LEVEL AIR MASS WILL REMAIN MOIST FOR CLOUDY AND
COOLER CONDITIONS. MODELS SHOW A WEAK FRONTAL BOUNDARY STALLING NEAR
THE WA/OR BORDER FOR A CHANCE OF LIGHT RAIN OR DRIZZLE.

THE UPPER LEVEL RIDGE WILL STRENGTHEN OVER THE PAC NW THU AND FRI
FOR DRIER AND SLIGHTLY WARMER WEATHER. WE WILL LIKELY SEE MORNING
LOW CLOUDS AND FOG IN THE LOWLANDS...WITH PARTLY TO MOSTLY SUNNY
SKIES DURING THE AFTERNOON. HIGHS WILL RANGE FROM THE MID TO UPPER
50S. 33

.LONG TERM...PREVIOUS DISCUSSION...A STRONG UPPER RIDGE WILL PROVIDE
DRY WEATHER AND ABOVE AVERAGE TEMPERATURES THROUGH SATURDAY. HIGHS
WILL WARM SLIGHTLY EACH DAY WITH MOSTLY SUNNY SKIES...EXCEPT FOR
SOME LATE NIGHT AND MORNING FOG. THE RIDGE AXIS MOVES DIRECTLY OVER
WRN WA ON SATURDAY WITH THE MID/UPPER LEVEL FLOW TURNING SLY AS A
FRONT APPROACHES OFFSHORE. HIGH TEMPERATURES ON SATURDAY HAVE THE
POTENTIAL TO SURPRISE TO THE UPSIDE. HOWEVER...IF INVERSIONS REMAIN
INTACT IT WILL BE COOLER WHICH IS INDICATED BY BOTH THE ECE/MEX
GUIDANCE. WILL GO WITH HIGHS IN THE UPPER 50S WHICH IS ABOVE MOS BUT
BELOW THE POTENTIAL IN THIS SLY FLOW PATTERN.

THE FIRST IN A SERIES OF FRONTAL SYSTEMS WILL REACH THE AREA
WEDNESDAY. ANOTHER SYSTEM WILL PROBABLY FOLLOW EARLY NEXT WEEK.
THERE IS SOME UNCERTAINTY ON TIMING AND STRENGTH GIVEN THE AMPLIFIED
RIDGE OVER THE WRN U.S. SO THE CHANCE POPS WILL REMAIN IN PLACE.
MERCER

&&

.HYDROLOGY...FLOODING IS NOT EXPECTED FOR THE NEXT 7 DAYS.

&&

.AVIATION...A BROAD UPPER LEVEL RIDGE CENTERED OVER IDAHO TODAY WILL
MAINTAIN SW FLOW ALOFT OVER WESTERN WASHINGTON. A WEAK FRONT ALONG
THE COAST THIS MORNING WILL DISSIPATE OVER THE AREA TODAY. AT THE
SURFACE FLOW WILL BE MODERATELY ONSHORE THIS AFTERNOON AND EVENING
THEN TURN WEAKLY OFFSHORE OVERNIGHT.

CEILINGS ARE GENERALLY 1-2K FT WITH SOME IFR IN THE SOUTHWEST AND
ALONG THE COAST. THIS PATTERN WILL CONTINUE TODAY WITH SPRINKLES AT
TIMES. LITTLE IMPROVEMENT IS LIKELY TONIGHT AS ONSHORE FLOW BRINGS
MOISTURE INLAND AT FIRST...THEN LIGHT FLOW KEEPS THE AIR MASS MOIST
AND STAGNANT. IFR CONDITIONS MAY BE BRIEFLY WIDESPREAD WEDNESDAY
MORNING...BUT OFFSHORE FLOW SHOULD CLEAR THINGS BY AFTERNOON.

KSEA...MVFR CEILINGS ARE LIKELY TODAY AND TONIGHT WITH A FEW HOURS
OF IFR CONDITIONS POSSIBLE WEDNESDAY MORNING. SIGNIFICANT
IMPROVEMENT WILL OCCUR WEDNESDAY AFTERNOON. SURFACE WINDS WILL
REMAIN SOUTHERLY 5-8 KT. CHB

&&

.MARINE...A WEAK FRONT WILL DISSIPATE OVER THE AREA TODAY. WESTERLY
FLOW WILL DEVELOP BEHIND THE FRONT AND WILL LIKELY GIVE A FEW HOURS
OF SMALL CRAFT ADVISORY WINDS IN THE STRAIT. AN ADVISORY IS NOW IN
EFFECT FOR THIS AFTERNOON AND EVENING.

THE ONSHORE FLOW WILL WEAKEN TONIGHT. THE FLOW WILL BECOME WEAK
OFFSHORE ON WEDNESDAY AND THIS PATTERN WILL PERSIST THROUGH
SATURDAY. NEXT WEAK ARRIVES AROUND SUNDAY. CHB

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND WEST STRAIT.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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





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