Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 172227
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
330 PM PDT FRI OCT 17 2014

.SYNOPSIS...RAIN AT TIMES WILL TAPER TO SHOWERS LATE TONIGHT THEN
COME TO AN END SATURDAY MORNING AS HIGH PRESSURE BUILDS. AN UPPER
LEVEL RIDGE AND OFFSHORE FLOW WILL BRING PARTLY SUNNY AND WARMER
WEATHER ON SUNDAY. A SERIES OF FRONTS WILL GIVE PERIODS OF RAIN AND
WINDY CONDITIONS AT TIMES NEXT WEEK.

&&

.SHORT TERM...RADAR AND SATELLITE IMAGERY DEPICTS A FRONT JUST ABOUT
TO MOVE ONTO THE COAST. RAIN HAS NOT EXACTLY BEEN STEADY TODAY BUT
EVEN SO IT SHOULD BECOME MORE SHOWERY TONIGHT AFTER THE FRONT GOES
BY. WIND HAS BEEN STRONG OVER MARINE AREAS BUT NOT OVER LAND. HAVE
ENDED THE WIND ADVISORIES THOUGH THERE WILL STILL BE SOME WIND ON
THE COAST AND OVER THE NORTH...ESPECIALLY AS THE FRONT PASSES.

BY MORNING THE FRONT WILL BE LONG PAST AND HEIGHTS WILL BE BUILDING
SOMEWHAT. THIS SHOULD LIMIT SHOWERS MAINLY TO THE MOUNTAINS AND GIVE
PARTLY SUNNY CONDITIONS TO SOME PARTS OF THE INTERIOR LOWLANDS IN
THE AFTERNOON. HIGHS WILL BE IN THE 60S. A SUNNIER DAY IS LIKELY ON
SUNDAY OVER THE INTERIOR. CLOUDS WILL INCREASE OVER WESTERN SECTIONS
IN THE AFTERNOON AS THE NEXT FRONT APPROACHES...AND THERE IS A
CHANCE OF RAIN ON THE COAST. HIGHS SUNDAY WILL BE 65-70.

RAIN WILL SPREAD SLOWLY INLAND SUNDAY NIGHT AND MONDAY AS A NEARLY
NORTH-SOUTH ORIENTED FRONT ARRIVES. AT THIS POINT IT DOES APPEAR
THAT EVERYWHERE WILL GET AT LEAST SOME RAIN BY MONDAY AFTERNOON.
SHOWERS FOLLOW MONDAY NIGHT. HIGHS WILL BE IN THE LOW 60S. GRADIENTS
ARE NOT AS STRONG AS WITH THE PRESENT SYSTEM BUT THERE COULD BE
BREEZY CONDITIONS IN PLACES. BURKE

.LONG TERM...MODELS BRING A SERIES OF SYSTEMS THROUGH THE AREA NEXT
WEEK. THE GFS HAS A MORE PROGRESSIVE SOLUTION WITH THE WET AND WINDY
PERIODS TUESDAY NIGHT AND WEDNESDAY MORNING...WEDNESDAY NIGHT...AND
FRIDAY. THE EURO HAS AN ATMOSPHERIC RIVER SOLUTION WITH HEAVY RAIN
TUESDAY NIGHT THROUGH THURSDAY...MAINLY CONCENTRATED ON THE OLYMPIC
PENINSULA. THE CANADIAN MODEL IS MORE LIKE THE GFS...PROGRESSIVE.
FOR NOW HAVE A LOT OF LIKELY POPS IN THE EXTENDED. THERE COULD BE
SOME WINDY PERIODS AS WELL. BURKE

&&

.HYDROLOGY...NEITHER THE SYSTEM TODAY NOR THE ONE MONDAY HAVE
ANYWHERE NEAR ENOUGH RAIN TO CAUSE CONCERN ON AREA RIVERS.

THE EURO SOLUTION WITH ITS ATMOSPHERIC RIVER DURING THE MIDDLE OF
NEXT WEEK PROBABLY HAS ENOUGH RAIN TO FLOOD RIVERS ON THE OLYMPIC
PENINSULA. THE OTHER MODELS ARE MORE PROGRESSIVE AND WOULD CAUSE
RISES BUT NOT FLOODING. HURRICANES IN THE PACIFIC OCEAN...THERE ARE
SEVERAL...GENERALLY WREAK HAVOC WITH LONG RANGE MODELS AND THERE IS
SO FAR NO REASON TO FAVOR THE EURO SOLUTION OVER THE OTHERS. THINGS
MAY BECOME CLEARER BY NEXT WEEK. BURKE

&&

.AVIATION...A WEAKENING COLD FRONT WILL MOVE INLAND ACROSS WESTERN
WA THIS EVNG. MODERATE TO STRONG SLY FLOW ALOFT WILL SHIFT TO SWLY
BEHIND THE FRONT AND THEN WEAKEN OVERNIGHT. THE AIR MASS WILL BE
MOIST AND STABLE. FAIRLY WIDESPREAD RAIN THIS AFTN WILL BECOME LESS
WIDESPREAD AND MORE SHOWERY THIS EVNG. EASTERLY SFC FLOW IS KEEPING
INLAND CIGS THIS AFTERNOON UP IN THE VFR CATEGORY...BUT A WEAKENING
OF THE EASTERLY COMPONENT THIS EVNG WILL ALLOW CIGS TO FALL STARTING
THIS EVNG...WITH IFR CONDS PREVAILING BY SUNRISE ON SAT. INDEED...
IFR CONDS HAVE ALREADY COMMENCED ALONG THE COAST. DURING THE DAY
SAT...LARGE-SCALE LIFT WILL BE LARGELY ABSENT...BUT THE AIR MASS
WILL REMAIN MOIST. WOULD EXPECT A FEW MORE BREAKS IN THE CLOUDS AND
A LACK OF RAIN ON SAT...BUT BKN CIGS IN MVFR RANGES WILL PERSIST AT
MANY WRN WA LOCALES ON SAT AFTN.

KSEA...DRYING EASTERLY COMPONENT OF THE LOW-LEVEL FLOW WILL WEAKEN
THIS EVNG...SO CIGS WILL HAVE THE OPPORTUNITY TO FALL BLO 050 ARND
00Z. CIGS WILL CONTINUE TO FALL THROUGH THE NIGHT AS WINDS ALOFT
GRADUALLY VEER FROM SOUTHERLY TO SOUTHWESTERLY...WITH CIGS POSSIBLY
BELOW 010 FROM 12Z-17Z ON SAT MORNING. LOW-LEVEL AIR MASS WILL
REMAIN MOIST ON SAT AFTN...SO SCT-BKN CLOUDS WILL PERSIST...BUT CIGS
WILL LIFT INTO THE 030-040 RANGE DURING THE AFTN.   HANER

&&

.MARINE...985 MB SFC LOW NEAR THE NORTH TIP OF HAIDA GWAII IS
LIFTING NORTH AND FILLING THIS AFTERNOON. A TRAILING COLD FRONT IS
NEARLY HALFWAY BTWN 130W AND THE COAST NOW...RESULTING IN MAINLY
EAST-SOUTHEAST PRESSURE GRADIENTS OVER THE WATERS. THIS HAS RESULTED
IN GALES OVER THE SOUTH-AND SOUTHEAST-WIND PRONE COASTAL
WATERS... EASTERN STRAIT AND AND NORTHERN INLAND WATERS. THE COLD
FRONT ALONG 130W WILL REACH THE COAST LATE THIS AFTN AND MOVE INLAND
THIS EVNG...BUT THE FRONT WILL BE WEAKENING AND FILLING ALONG THE
WAY. AS THE FRONT MOVES INLAND THIS EVNG... GRADIENTS WILL
TRANSITION FROM MODERATE EASTERLY TO WEAKER SOUTHEASTERLY. WINDS
WILL EASE THIS EVNG...FIRST ALONG THE COAST EARLY THIS EVNG...THEN
OVER THE INLAND WATERS LATER THIS EVNG.

ON SATURDAY...WEAKER SE GRADIENTS WILL CONTINUE WITH SFC HIGH
PRESSURE OVER THE NORTHERN U.S. ROCKIES. ON SUNDAY...A SIMILAR
NORTH-SOUTH ORIENTED COLD FRONT WILL MOVE PAST 130W...WITH
INCREASING SOUTHERLY WINDS OVER THE COASTAL WATERS.     HANER

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...

PZ...GALE WARNING COAST...ENTRANCES...AND NORTHERN INLAND WATERS.
     SMALL CRAFT ADVISORY ALL OTHER WATERS.
     SMALL CRAFT FOR ROUGH GRAYS HARBOR BAR.

&&

$$

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