Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 271108
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
405 AM PDT MON OCT 27 2014

.SYNOPSIS...HIGH PRESSURE WILL GIVE RELATIVELY DRY WEATHER THIS
MORNING. A WET WEATHER SYSTEM WILL REACH THE COAST THIS AFTERNOON
AND MOVE INLAND TUESDAY MORNING. THIS SYSTEM COULD BRING SIGNIFICANT
RAIN TO THE AREA WITH THE REMAINS OF HURRICANE ANA EMBEDDED IN THE
SYSTEM. AFTER A BREAK ON WEDNESDAY ANOTHER WEATHER SYSTEM WILL
ARRIVE THURSDAY INTO FRIDAY.

&&

.SHORT TERM...SATELLITE IMAGERY SHOWS PLENTY OF HIGH CLOUDS MOVING
OVER WESTERN WASHINGTON EARLY THIS MORNING DOPPLER RADARS INDICATE
SHOWER ACTIVITY OVER THE AREA HAS COME TO AN END. PRECIPITATION
ECHOES ARE BEGINNING TO SHOW UP OFFSHORE ASSOCIATED WITH AN INCOMING
WARM FRONT. SKIES WERE MOSTLY CLEAR EARLIER WHICH ALLOWED
TEMPERATURES TO DROP INTO THE UPPER 30S TO MID 40S. TEMPERATURES
HAVE REBOUNDED A COUPLE OF DEGREES WITH THE INCREASING HIGH CLOUDS
AT 3 AM.

LOTS OF CLOUD COVER OVER THE AREA TODAY WITH THE MID AND HIGH LEVEL
CLOUDS OUT AHEAD OF THE APPROACHING WARM FRONT. RAIN ASSOCIATED WITH
THE FRONT OFFSHORE THIS MORNING BUT WITH THE SLOW EASTWARD MOVEMENT
OF THE FRONT EXPECT THE CHANCE OF RAIN TO HOLD OFF FOR THE INTERIOR
UNTIL THE AFTERNOON WITH RAIN LIKELY ALONG THE COAST.

RAIN SPREADING OVER THE ENTIRE AREA THIS EVENING WITH SOUTHEASTERLY
WINDS INCREASING. EVEN WITH THE PARENT LOW WELL OFFSHORE AS THE WARM
FRONT MOVES IN OVERNIGHT WINDS INCREASING ENOUGH ALONG THE COAST AND
OVER WHATCOM AND SAN JUAN COUNTIES FOR A WIND ADVISORY TO BE ISSUED
FOR THESE AREAS. SIGNIFICANT RAIN IS POSSIBLE WITH THE SYSTEM
OVERNIGHT WITH THE REMAINS OF HURRICANE ANA EMBEDDED. THE HEAVIEST
RAINS ARE EXPECTED OVER THE SOUTHWEST SLOPES OF THE OLYMPICS WITH
SOUTHWEST 850 MB WINDS TO 45 KNOTS ENHANCING THE OROGRAPHICS.

TRAILING COLD FRONT RIGHT IN BEHIND THE WARM FRONT AND WILL MOVE
THROUGH WESTERN WASHINGTON TUESDAY MORNING. THIS WILL BRING ABOUT AN
END TO THE STEADY RAIN. CURRENT SATELLITE IMAGERY DOES NOT SHOW A
VERY IMPRESSIVE COLD POOL BEHIND THE FRONT SO WHILE A CHANCE OF
SHOWERS WILL STILL EXIST IN THE AFTERNOON RAINFALL AMOUNTS WITH THE
SHOWERS WILL BE LOW.

SHOWER ACTIVITY DRYING UP TUESDAY NIGHT INTO WEDNESDAY MORNING WITH
WEAK RIDGING ALOFT MOVING INTO THE AREA PROVIDING A SMALL BREAK IN
THE PRECIPITATION WEDNESDAY AFTERNOON. HIGH TEMPERATURES THROUGH THE
SHORT TERM WILL BE MOSTLY IN THE 55-60 DEGREE RANGE WITH LOWS IN THE
MID 40S TO LOWER 50S.

.LONG TERM...EXTENDED MODELS CONTINUING WITH THE IDEA OF SHOWING THE
FRONT FROM TUESDAY MORNING MOVING SOUTHEAST AND OUT OF THE AREA FOR
A COUPLE OF DAYS BUT THEN GETTING REENERGIZED AND MOVING BACK NORTH
OVER THE AREA ON THURSDAY. WILL KEEP RAIN IN THE FORECAST FOR
WEDNESDAY NIGHT INTO THURSDAY. GOOD CONSISTENCY CONTINUING THURSDAY
NIGHT AND FRIDAY WITH A DEEP UPPER LEVEL TROUGH OFFSHORE KEEPING
RAIN IN THE FORECAST. TROUGH AXIS MOVING THROUGH FRIDAY NIGHT .
MODEL SOLUTIONS START TO DIVERGE OVER THE WEEKEND WITH THE ECMWF
BRINGING ANOTHER SYSTEM INTO THE AREA ON SUNDAY WHILE THE GFS IS
SLOWER WITH THIS FEATURE. THE 00Z RUN OF BOTH MODELS IS STRONGER AND
MORE INTACT WITH THIS FEATURE VERSUS PREVIOUS RUNS. WILL WAIT FOR
ANOTHER RUN OR TWO BEFORE INCREASING POPS FOR SUNDAY. FELTON

&&

.HYDROLOGY...A BREAK IN THE RAIN THROUGH MIDDAY WILL ALLOW THE
SKOKOMISH RIVER TO RECEDE. THE SYSTEM ARRIVING TONIGHT WILL BE A WET
ONE WITH ANOTHER TWO TO THREE INCHES OF RAIN EXPECTED OVER THE SOUTH
SLOPES OF THE OLYMPICS. THIS COULD PUSH THE SKOKOMISH RIVER BACK
ABOVE FLOOD STAGE ON TUESDAY. THE FLOOD WATCH WILL REMAIN IN EFFECT
FOR THE SKOKOMISH FOR TUESDAY AND TUESDAY NIGHT.

ON ALL OTHER RIVERS FLOODING IS UNLIKELY OVER THE NEXT 7 DAYS. FELTON

&&

.AVIATION...THE LOWER AIR MASS IS SOMEWHAT MOIST THIS MORNING...SO
DESPITE INCREASING HIGH CLOUDS FROM AN APPROACHING FRONTAL
SYSTEM...AREAS OF MVFR STRATUS HAVE FORMED IN SPOTS AS WELL AS SOME
LOCAL IFR CONDITIONS IN FOG. THE MVFR/IFR STRATUS AND FOG SHOULD
LIFT BY 17Z.

A STRONG FRONTAL SYSTEM APPROACHING FROM OFFSHORE WILL SPREAD MID
LEVEL CLOUDS BKN080-100 OVER W WA TODAY WITH CLOUD BASES GRADUALLY
LOWERING TO BKN050-080 OVER THE INTERIOR THIS AFTERNOON. LIGHT RAIN
WILL REACH THE COAST THIS AFTERNOON AND SPREAD INLAND EARLY THIS
EVENING. CIGS WILL LOWER TO OVC020-050 TONIGHT. INCREASING S-SE FLOW
AHEAD OF THE WARM FRONT WILL PRODUCE WINDY CONDITIONS OVER THE COAST
AND NORTH INTERIOR.

THE WARM FRONT WILL CROSS THE COAST AROUND 07Z WITH THE MUCH WEAKER
COLD FRONT FOLLOWING AROUND 12Z TUESDAY.

KSEA...AREAS OF MVFR STRATUS HAVE FORMED OVER CENTRAL PUGET SOUND
AND WILL PROBABLY PERSIST THROUGH 17Z. SE SURFACE WINDS 4-7KT THIS
MORNING SHOULD PREVENT FOG FROM FORMING AT KSEA. VFR CONDITIONS WITH
CIGS SCT-BKN050 OR HIGHER ARE EXPECTED AFTER 17Z. SURFACE WINDS WILL
REMAIN S 5-10 KT THIS AFTERNOON. KAM

&&

.MARINE...THE STRONG FRONTAL SYSTEM OFFSHORE IS STEADILY APPROACHING
THE REGION. MODELS HAVE BEEN CONSISTENT. THIS SYSTEM WILL BE ALMOST
ALL STRONG WARM FRONT WITH JUST A VERY WEAK TRAILING COLD FRONT.
SOUTHERLY GALES WILL DEVELOP OVER THE COASTAL WATERS
TODAY...SPREADING TO THE NORTHERN INTERIOR WATERS THIS EVENING. THE
WARM FRONT WILL CROSS THE COAST AROUND MIDNIGHT FOLLOWED BY THE WEAK
COLD FRONT BEFORE SUNRISE. GALE WARNINGS HAVE BEEN ISSUED FOR ALL
THESE WATERS...AND A SMALL CRAFT ADVISORY FOR ADMIRALTY INLET. PUGET
SOUND WILL END UP WITH SCA WINDS IN THE INCREASING S FLOW WITH AND
BEHIND THE COLD FRONT. WITH THE LARGE PARENT 994 MB LOW STILL
HANGING OUT AROUND THE CENTRAL B.C. COAST ON TUESDAY MODERATE S FLOW
WILL CONTINUE WITH SCA WINDS IN MOST AREAS. THE LOW WILL DISSIPATE
TUESDAY NIGHT...ALLOWING A SURFACE HIGH TO MOVE BRIEFLY OVER W WA
WEDNESDAY...RESULTING IN A SHORT PERIOD OF WEAK WINDS. KAM

&&

.SEW WATCHES/WARNINGS/ADVISORIES...

WA...WIND ADVISORY NORTH AND CENTRAL COAST TONIGHT.
     WIND ADVISORY WHATCOM AND SAN JUAN COUNTIES TONIGHT INTO
     TUESDAY MORNING.
PZ...GALE WARNING COAST...STRAIT OF JUAN DE FUCA...AND NORTHERN
      INLAND WATERS.
     SMALL CRAFT ADVISORY ADMIRALTY INLET.

&&

$$

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











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