Small Craft Advisory 874, NWS Seattle, WA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
840 PM PST SUN DEC 25 2011

.SYNOPSIS...SHOWERS WILL TAPER TONIGHT BEHIND THE COLD FRONT THAT
MOVED THROUGH THE AREA EARLIER TODAY. WEAK UPPER LEVEL RIDGING WILL
BUILD MONDAY AHEAD OF ANOTHER FRONT THAT WILL MOVE INLAND MONDAY
EVENING. THIS WET AND ACTIVE PATTERN WILL CONTINUE THROUGH THE WEEK.
STRONG ZONAL FLOW WILL SET UP OVER THE NORTH PACIFIC...ALLOWING A
SERIES OF PACIFIC FRONTAL SYSTEMS TO MOVE THROUGH THE AREA.

&&

.SHORT TERM...GRADIENTS HAVE WEAKENED CONSIDERABLY AND SO HAVE THE
WINDS. SKIES ARE PARTLY CLOUDY WITH ONLY ISOLATED SHOWERS. A PUGET
SOUND CONVERGENCE ZONE HAS BEEN PUSHED MOSTLY INTO THE CASCADES.
SNOW IS FALLING IN THE MOUNTAINS WITH 4-6 INCHES SO FAR IN THE
CENTRAL CASCADES AND 2-4 INCHES NORTH. A WINTER WEATHER ADVISORY
WILL CONTINUE THERE UNTIL LATE TONIGHT.

THE NEXT IN A SERIES OF WEATHER SYSTEMS WILL REACH THE COAST MONDAY
AFTERNOON AND SPREAD RAIN INLAND MONDAY EVENING. THIS SYSTEM DOES
NOT LOOK QUITE AS STRONG AS THE ONE TODAY BUT THERE WILL BE A BURST
OF SOUTH WINDS MONDAY NIGHT AND TUESDAY MORNING...WITH GALE WARNINGS
OVER MOST WATERS. WOULD EXPECT MOST ZONES WILL BE BREEZY MONDAY
NIGHT. NEXT ISSUANCE OF GRIDS AND FORECASTS SHOULD PROBABLY PUT SOME
BREEZY WORDING IN. BASICALLY THE SAME SCENARIO LOOKS LIKELY ON
TUESDAY NIGHT AS WELL. BURKE

.LONG TERM...PREVIOUS DISCUSSION...MODELS CONTINUE TO REINFORCE THE
WET AND ACTIVE PERIOD THROUGH THE WEEK INTO NEW YEARS DAY. LOCALLY
HEAVY RAINFALL IS POSSIBLE TUESDAY NIGHT INTO EARLY WEDNESDAY AND
AGAIN WEDNESDAY NIGHT INTO THURSDAY. THURSDAY NIGHT INTO FRIDAY MAY
SEE A BIT OF A BREAK BEFORE MEDIUM RANGE MODELS BRING A 970 MB LOW
INTO NORTHERN VANCOUVER ISLAND OR THE STRAIT OF JUAN DE
FUCA...DEPENDING ON THE MODEL. SEVERAL OF THE SYSTEMS LINING UP OVER
THE NEXT 5 DAYS HAVE THE POTENTIAL TO TAP DECENT EXTRATROPICAL
MOISTURE AS ITS TRANSPORTED EASTWARD FROM THE SUBTROPICAL WESTERN
PACIFIC. IN ADDITION A STRONG 300 MB JET STRETCHING ACROSS THE NORTH
PACIFIC MIDWEEK ON WILL ALSO ADD TO THE MIX. NEEDLESS TO SAY THERE
REMAINS A FAIR AMOUNT OF UNCERTAINTY IN TERMS OF THE
TRACK...TIMING...AND STRENGTH OF THESE SYSTEMS. THE ONLY CONSTANT IS
THE EXPECTATION OF AND ACTIVE PATTERN THROUGH THE END OF THE MONTH.
SNOW LEVELS WILL RISE TO ABOUT 5000 FEET MIDWEEK BEFORE FALLING BACK
TO ABOUT 3000 FEET BY THE WEEKEND.

&&

.HYDROLOGY...A SERIES OF WET WEATHER SYSTEMS WILL ARRIVE OVER THE
NEXT WEEK OR SO. ALTHOUGH NO PARTICULAR SYSTEM LOOKS LIKE IT WILL
CAUSE WIDESPREAD FLOODING...RIVERS WILL CERTAINLY RISE. THE
SKOKOMISH RIVER IS LIKELY TO REACH ADVISORY STAGE AS EARLY AS
WEDNESDAY MORNING AND COULD RISE ABOVE FLOOD STAGE LATER AS MORE
SYSTEMS PASS THROUGH THE AREA. BURKE

&&

.AVIATION...THERE WILL BE A BREAK BETWEEN FRONTAL SYSTEMS LATER
TONIGHT AND MONDAY MORNING AS A TRANSITORY RIDGE MOVES ACROSS THE
PAC NW. LIGHT SW FLOW ALOFT BECOMING SLY. STRONG SLY FLOW WILL
DEVELOP ON MONDAY AHEAD OF A APPROACHING TROUGH AND ASSOCIATED
SURFACE FRONT. IT WILL BE SOMEWHAT MOIST TONIGHT AND BECOME MOIST AT
ALL LEVELS BY LATE MONDAY AFTERNOON AND NIGHT. THE NEXT SURFACE
FRONT WILL PUSH THROUGH PUGET SOUND MONDAY EVENING. GENERALLY STABLE
CONDITIONS.

KSEA...SW WIND 12-15 KT W/ GUSTS 22 KT...EASING TO S WIND 5-9 KT
AFTER 08Z. MAINLY VFR CIGS THROUGH MONDAY. ANOTHER BOUT OF STRONG SW
WINDS ARE LIKELY BEHIND THE FRONT MIDDAY NIGHT.

&&

.MARINE...GRADIENTS ARE EASING BEHIND A STRONG FRONTAL SYSTEM. SMALL
CRAFT WINDS WILL LINGER IN THE CENTRAL/E STRAIT FOR AT LEAST A FEW
MORE HOURS. ELSEWHERE WINDS HAVE SUBSIDED BUT SEAS ABOVE 10 FT
WARRANT A SMALL CRAFT FOR HAZARDOUS SEAS.

THE NEXT VIGOROUS SYSTEM COULD BRING MORE WIDESPREAD GALES TO THE
WATERS LATE MONDAY AFTERNOON THROUGH MONDAY NIGHT. A GALE WARNING IS
ISSUED FOR THE COAST...ENTRANCES TO THE STRAIT...AND N OF PUGET
SOUND. THE STRONGEST WINDS IN PUGET SOUND WILL AGAIN BE POST FRONTAL
LATER MONDAY NIGHT...POSSIBLY REACHING 30 KT. WILL NEED TO WATCH FOR
THE POTENTIAL FOR A SHORT LIVED GALE IN THE SOUND ALTHOUGH IT SEEM
UNLIKELY AT THIS POINT.

ADDITIONAL VIGOROUS FRONTAL SYSTEMS WILL AFFECT THE WATERS THROUGH
THE END OF THE WEEK. DTM

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...WINTER WEATHER ADVISORY WEST SLOPES OF THE NORTH AND CENTRAL
     CASCADES THROUGH 3 AM PST MONDAY.
PZ...SMALL CRAFT ADVISORY FROM ADMIRALTY INLET TO THE NORTH INLAND
     WATERS THROUGH 10 PM PST TONIGHT.
    .SMALL CRAFT ADVISORY FOR THE CENTRAL AND EAST STRAIT OF JUAN DE
     FUCA UNTIL 4 PST AM MONDAY MORNING.
    .SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS COASTAL WATERS AND
     WEST ENTRANCE THROUGH MONDAY AFTERNOON.
    .SMALL CRAFT ADVISORY FOR ROUGH BAR CONDITIONS THROUGH MONDAY
     NIGHT.
    .GALE WARNING FROM 1 PM PST MONDAY AFTERNOON THROUGH 4 AM
     PST TUESDAY MORNING FOR ALL WATERS EXCEPT THE CENTRAL STRAIT
     AND PUGET SOUND.

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

WWW.WEATHER.GOV/SEATTLE