Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 261058
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
355 AM PDT SUN OCT 26 2014

.SYNOPSIS...A COOL UPPER LEVEL TROUGH WILL MOVE THROUGH WESTERN
WASHINGTON TODAY. A WARM FRONT WILL BRUSH THE COAST MONDAY WITH THE
TRAILING COLD FRONT MOVING THROUGH WESTERN WASHINGTON TUESDAY
MORNING. THIS SYSTEM HAS THE POTENTIAL TO BRING SIGNIFICANT RAINS TO
THE AREA WITH THE REMAINS OF HURRICANE ANA EMBEDDED IN THE SYSTEM.
ADDITIONAL WEATHER SYSTEMS WILL ARRIVE LATER IN THE WEEK.

&&

.SHORT TERM...SATELLITE IMAGERY AND SURFACE OBSERVATIONS SHOW THE
LOW THAT MOVE THROUGH WESTERN WASHINGTON SATURDAY EVENING IS NOW
HEADED TOWARDS SOUTHERN ALBERTA. THE KPDX-KBLI GRADIENT PEAKED OUT
AT 17.2 MB AND THE KOLM-KBLI GRADIENT PEAKED OUT AT 9.8 MB. WINDS
HAVE BEEN EASING SINCE AROUND 05Z/10PM LAST NIGHT AND WILL CONTINUE
TO EASE THIS MORNING. DOPPLER RADAR SHOWS PLENTY OF SHOWERS ALONG
THE COAST EARLY THIS MORNING. MOSTLY CLOUDY SKIES ARE BEING REPORTED
ELSEWHERE. TEMPERATURES WERE IN THE MID 40S TO MID 50S AT 10Z/3AM.

COOL UPPER LEVEL TROUGH MOVING OVER WESTERN WASHINGTON TODAY.
SATELLITE IMAGERY SHOWS PLENTY OF SHOWERS OFFSHORE. THESE SHOWERS
WILL BE MOVING THROUGH THE AREA TODAY. THE TEMPERATURE AT PARADISE
ON MOUNT RAINIER IS ALREADY DOWN TO 30 DEGREES WITH THE TEMPERATURE
AT WASHINGTON PASS AT 31 DEGREES. SNOW LEVELS WILL BE NEAR 4500 FEET
TODAY SO THE HIGHER LOCATIONS LIKE PARADISE COULD SEE UP TO 4 INCHES
OF NEW SNOW. WITH THE TROUGH MOVING THROUGH HIGH TEMPERATURES WILL
BE NEAR OR A COUPLE OF DEGREES BELOW NORMAL...MOSTLY IN THE MID 50S.

SHOWERS ACTIVITY DRYING UP THIS EVENING WITH A WEAK UPPER LEVEL
RIDGE OUT AHEAD OF THE NEXT SYSTEM MOVING OVER THE AREA. LOWS IN THE
40S WILL BE COMMON.

EVEN THOUGH THE PARENT LOW WILL STILL WELL BACK NEAR 48N/139W AT 18Z
MONDAY THE WARM FRONT OUT AHEAD OF THE LOW WILL BRUSH THE COAST
PUTTING A CHANCE OF RAIN IN THE FORECAST. RAIN OUT AHEAD OF THE
TRAILING COLD FRONT REACHING THE COAST LATE IN THE DAY. HIGHS ONCE
AGAIN WILL BE IN THE 50S.

COLD FRONT SLOWLY MOVING EASTWARD MONDAY NIGHT AND STILL OFFSHORE AT
12Z TUESDAY. THE REMAINS OF HURRICANE ANA WILL BE EMBEDDED IN THE
COLD FRONT BRINGING UP THE POSSIBILITY OF MODERATE TO HEAVY RAINS
ESPECIALLY ALONG THE COAST AND OVER THE MOUNTAINS MONDAY NIGHT. UP
TO THREE INCHES OF RAIN IS POSSIBLE ALONG THE SOUTHWEST SLOPES OF
THE OLYMPICS. SNOW LEVELS WILL BE ON THE RISE AND BY TUESDAY MORNING
WILL BE WELL ABOVE PARADISE AND THE NORTH CASCADES HIGHWAY. IN
ADDITION TO THE SIGNIFICANT RAINFALL ANOTHER ROUND OF WINDS IS
POSSIBLE FOR THE COAST AND POSSIBLY THE NORTHWEST INTERIOR. WITH
THE SURFACE LOW NEAR 50N AND ABOUT 985 MB NOT EXPECTING HIGH WIND
WARNING SPEEDS AT THIS TIME BUT WIND ADVISORIES ARE A POSSIBILITY.
LOWS WILL MOSTLY BE THE MID 40S TO LOWER 50S.

COLD FRONT MOVING THROUGH WESTERN WASHINGTON TUESDAY MORNING WITH
PLENTY OF SHOWERS BEHIND THE FRONT FOR LATER TUESDAY MORNING INTO
TUESDAY AFTERNOON.  HIGHS WILL ONCE AGAIN BE IN THE 40S.

.LONG TERM...EXTENDED MODELS IN FAIRLY GOOD AGREEMENT THIS MORNING.
SHOWERS DECREASING ON WEDNESDAY WITH A WEAK RIDGE OF HIGH PRESSURE
BUILDING OVER THE AREA. THE GFS IS A LITTLE STRONGER WITH THE RIDGE
LEADING TO LESS SHOWER ACTIVITY VERSUS THE ECMWF BUT EVEN WITH THE
DRIER GFS SOLUTION WILL HAVE TO KEEP CHANCE POPS IN THE FORECAST.
BOTH THE GFS AND ECMWF SHOW A DEEP TROUGH DEVELOPING OFF THE WEST
COAST FOR THURSDAY AND FRIDAY WITH MOIST SOUTHWESTERLY FLOW ALOFT
OVER WESTERN WASHINGTON. THE TROUGH OFFSHORE WILL BE DIGGING SOUTH
WITH BRINGS UP THE CHANCE THAT ONE OF THE SYSTEMS SPINNING OUT OF
THE TROUGH COULD GET STALLED OVER WESTERN WASHINGTON. TIMING THESE
FEATURES AT THIS POINT WOULD BE TOUGH BUT THE 00Z RUN SOLUTIONS
INDICATE AT LEAST LIKELY POPS ARE WARRANTED FOR THURSDAY AND FRIDAY
AND HAVE GONE AHEAD AND MADE THESE CHANGES. UPPER LEVEL TROUGH
MOVING INLAND FRIDAY NIGHT AND SATURDAY FOR A CHANCE OF SHOWERS AT
THAT TIME. FELTON

&&

.HYDROLOGY...THE FLOOD WARNING FOR THE SKOKOMISH RIVER WILL COME TO
AN END THIS MORNING. THE RIVER CRESTED A TENTH OF A FOOT ABOVE FLOOD
STAGE AROUND 0830Z/130AM THIS MORNING.

A BREAK IN THE STEADY RAIN TODAY THROUGH MONDAY WILL ALLOW THE
SKOKOMISH RIVER TO RECEDE. WILL HAVE TO KEEP AN EYE ON THE RIVER
TUESDAY WITH UP TO ANOTHER THREE INCHES OF RAIN EXPECTED ALONG THE
SOUTH SLOPES OF THE OLYMPICS MONDAY NIGHT. THERE IS A POSSIBILITY
THAT THE SKOKOMISH COULD FLOOD AGAIN TUESDAY.

FOR THE REMAINDER OF THE RIVERS FLOODING IS UNLIKELY OVER THE NEXT 7
DAYS. FELTON

&&

.AVIATION...AN UPPER LEVEL TROUGH WILL REMAIN OVER W WA THROUGH 22Z
THEN SHIFT E AS AN UPPER LEVEL RIDGE MOVES INLAND 00Z-12Z. THE AIR
MASS IS UNSTABLE WITH A LARGE AREA OF SHOWERS OFFSHORE THAT WILL BE
MOVING INLAND OVER W WA THROUGH 00Z. CONDITIONS WILL BE
PREDOMINANTLY VFR BUT LOCAL MVFR CIGS MAY OCCUR AROUND SHOWERS.
SURFACE WINDS WILL REMAIN GUSTY IN SPOTS PARTICULARLY AROUND PUGET
SOUND...BUT THE OVERALL TREND IS FOR WINDS TO SLOWLY DIMINISH.

KSEA...MAINLY VFR CIGS TODAY...BUT OCCASIONALLY MVFR CIGS BKN015-030
AS SHOWERS ROLL THROUGH THE AREA. SURFACE WINDS WILL REMAIN SW 8-15
KT WITH GUSTS TO 20-22KT. KAM

&&

.MARINE...WESTERLY ONSHORE FLOW WILL CONTINUE TODAY AS HIGHER
PRESSURE GRADUALLY BUILDS INLAND OVER WESTERN WA. WINDS ARE
GRADUALLY WEAKENING BUT SCA LEVEL WINDS WILL CONTINUE FOR A WHILE
LONGER OVER THE COAST...STRAIT...AND PUGET SOUND. WINDS WILL WEAKEN
TONIGHT AS A SURFACE RIDGE MOVES OVER THE AREA. THE RIDGE WILL SHIFT
EAST ON MONDAY AS A FRONTAL SYSTEM APPROACHES.

SOUTHERLY GALES WILL DEVELOP OVER THE COASTAL WATERS MONDAY AND OVER
THE NORTH INTERIOR MONDAY NIGHT AS THE COLD FRONT APPROACHES. THIS
IS A TYPICAL VIGOROUS FALL SEASON FRONTAL SYSTEM. MODELS HAVE BEEN
FAIRLY CONSISTENT SHOWING FROPA ON THE COAST LATE MONDAY NIGHT. GALE
WINDS OVER THE N INTERIOR WILL LAST UNTIL THE FRONT PASSES TUESDAY
MORNING. A SURFACE TROUGH WILL BE OVER THE AREA TUESDAY...GIVING WAY
TO A SURFACE RIDGE ON WEDNESDAY. KAM

&&

.SEW WATCHES/WARNINGS/ADVISORIES...

WA...FLOOD WARNING SKOKOMISH RIVER EARLY THIS MORNING.
PZ...SMALL CRAFT ADVISORY ALL WATERS EXCEPT ADMIRALTY INLET.
     SMALL CRAFT ADVISORY FOR ROUGH BAR CONDITIONS GRAYS HARBOR.

&&

$$

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









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