Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 221142
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
342 AM PST SAT NOV 22 2014

.SYNOPSIS...WEAK HIGH PRESSURE ALOFT WILL MOVE OVER THE REGION
TODAY. HOWEVER THE AIR MASS WILL REMAIN UNSTABLE ENOUGH FOR
SCATTERED SHOWERS...MORE NUMEROUS OVER THE CASCADES. ANOTHER
STRONG...BUT FAST MOVING...STORM WILL IMPACT THE AREA ON SUNDAY
FOR THE POSSIBILITY OF HEAVY SNOW IN THE CASCADES. A WEAKER AND
WARMER SYSTEM IS EXPECTED ON MONDAY.

&&

.SHORT TERM...
A SHORT WAVE RIDGE WILL MOVE OVER THE REGION TODAY BUT THE AIR
MASS WILL REMAIN COOL AND UNSTABLE ENOUGH FOR SCATTERED SHOWERS...
ESPECIALLY IN THE MOUNTAINS. THE CENTRAL CASCADES /FROM SNOHOMISH
COUNTY SOUTHWARD/ COULD RECEIVE LOW END ADVISORY CRITERIA AMOUNTS
TODAY...THUS THE WINTER WEATHER ADVISORY WAS EXTENDED THROUGH THIS
AFTERNOON. ALSO...CANNOT RULE OUT AN ISOLATED LIGHTNING STRIKE OR
TWO OVER THE COAST TODAY...SO A RISK OF THUNDER WAS INCLUDED IN
THESE ZONES. THE BEST CHANCE OF TSTMS WILL PROBABLY BE OVER THE
COASTAL WATERS.

ANOTHER STRONG...BUT FAST-MOVING...LOW PRESSURE SYSTEM WILL IMPACT
THE REGION LATE TONIGHT AND SUNDAY FOR A PERIOD OF LOCALLY HEAVY
SNOW IN THE CASCADES. SNOWFALL AMOUNTS ARE EXPECTED TO MEET
WARNING CRITERIA...THEREFORE A WINTER STORM WATCH WAS ISSUED. IT
LOOKS LIKE THE HEAVIEST SNOW WILL FALL IN THE AREA FROM STEVENS
PASS SOUTHWARD AND ABOVE THE 3000 FOOT LEVEL.

ANTICIPATE IMPROVING CONDITIONS SUNDAY AFTERNOON...WITH THE RISK
OF SHOWERS BECOMING PRIMARILY CONFINED TO THE CASCADES SUNDAY
EVENING.

LOOK FOR ANOTHER SYSTEM TO BRING MORE PRECIP TO THE CWA ON MON.
THIS SYSTEM IS ANTICIPATED TO BE WARMER THAN THE RECENT ONES.

.LONG TERM...
CONFIDENCE IN THIS PERIOD WAS LOW DUE TO LACK OF MODEL AGREEMENT
AND CONSISTENCY. IT MIGHT BE DRY DURING MUCH OF THIS PERIOD OR IT
COULD BE WET...DEPENDING ON THE MODEL OF PREFERENCE. THERE IS A
POSSIBILITY OF SIGNIFICANT RAINFALL IN THE MOUNTAINS ABOUT THE
MIDDLE OF NEXT WEEK.

&&

.HYDROLOGY...
THE SKOKOMISH RIVER CRESTED AT 16.3 FEET OVERNIGHT...WHICH WAS
ONLY A COUPLE OF TENTHS SHY OF THE FLOOD STAGE. THE RIVER HAS
RECEDED AND WILL CONTINUE TO FALL.

AT THIS TIME...RIVER FLOODING IS NOT EXPECTED THE NEXT 7 DAYS BUT
WILL NEED TO WATCH OUT FOR THE POSSIBILITY OF SIGNIFICANT RAINFALL
IN THE MOUNTAINS ABOUT THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...MODERATE WESTERLY FLOW AT THE SURFACE AND ALOFT WILL
RELAX SOMEWHAT THIS AFTERNOON...THEN WILL BECOME SWLY AND INCREASE
LATE TONIGHT AS A FRONTAL SYSTEM APPROACHES THE AREA FROM THE W. THE
AIR MASS IS SOMEWHAT MOIST AND UNSTABLE.

SHOWERS THIS MORNING ARE FOCUSED AROUND A CENTRAL PUGET SOUND
CONVERGENCE ZONE AND TO THE WEST SLOPES OF THE CASCADES AND
OLYMPICS. SHOWERS WILL INCREASE SOMEWHAT AS A WEAK SHORTWAVE TROUGH
IN THE OFFSHORE WATERS SWEEPS ACROSS THE AREA LATER THIS
MORNING. THE MOST UNSTABLE AIR WILL REMAIN OFFSHORE WITH A CHANCE OF
TSTMS TODAY OVER THE COASTAL WATERS. EXPECT VFR CONDITIONS...WITH
MVFR IN SHOWERS. ALBRECHT

KSEA...MAINLY MVFR FLIGHT CONDITIONS IN CIGS THIS MORNING WITH VFR
LATER THIS AFTERNOON AND TONIGHT. GUSTY SW WINDS 15 TO 25 KNOTS ARE
EXPECTED TO GRADUALLY RELAX DURING THE DAY TODAY...THE INCREASE
AGAIN TONIGHT. ALBRECHT

&&

.MARINE...A RATHER ACTIVE PERIOD IS EXPECTED OVER THE WATERS THROUGH
THE MIDDLE OF THE UPCOMING WEEK AS A SERIES OF SYSTEMS MOVE THROUGH
THE WATERS.

MODERATELY STRONG POST FRONTAL ONSHORE FLOW IS GIVING SMALL CRAFT
ADVISORY CONDITIONS TO ALL OF THE WATERS...EXCEPT GALES TO THE
CENTRAL AND EAST STRAIT OF JUAN DE FUCA. WINDS WILL SLOWLY RELAX
DURING THE DAY TODAY THEN WILL PICK BACK UP TONIGHT AS ANOTHER
RATHER VIGOROUS FRONTAL SYSTEM APPROACHES THE AREA.

THE FRONT THAT MOVES THROUGH THE WATERS LATE TONIGHT INTO SUNDAY
MORNING WILL BRING SMALL CRAFT ADVISORY CONDITIONS TO ALL OF THE
WATERS. THERE IS ABOUT A 30 PERCENT CHANCE THAT BRIEF GALE FORCE
WINDS WILL OCCUR OVER PORTIONS OF THE COASTAL WATERS WITH THE FRONT
LATE TONIGHT AND THROUGH THE STRAIT OF JUAN DE FUCA BEHIND THE FRONT
BEGINNING MIDDAY SUN.

ONSHORE FLOW MAY INCREASE AGAIN TUE NIGHT OR WED AS ANOTHER LOW
MOVES BY TO THE NORTH OF THE AREA. ALBRECHT

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...WINTER WEATHER ADVISORY IN EFFECT TIL 5 PM TODAY FOR THE
     CENTRAL CASCADES ABOVE 2500 FEET.

     WINTER STORM WATCH IN EFFECT FROM LATE TONIGHT THROUGH SUNDAY
     AFTERNOON FOR THE CASCADES ABOVE 3000 FEET.

PZ...GALE WARNING IN EFFECT TIL 6 AM THIS MORNING FOR THE CENTRAL
     AND EASTERN STRAIT OF JUAN DE FUCA.

     SMALL CRAFT ADVISORIES ARE IN EFFECT FOR THE REMAINING
     WATERS.

     SMALL CRAFT ADVISORY IN EFFECT FOR ROUGH BAR TIL 3 AM SUNDAY
     FOR THE GRAYS HARBOR BAR.

&&

$$

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