Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 240503
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
1000 PM PDT THU OCT 23 2014

.SYNOPSIS...AN UPPER TROUGH WILL GIVE WAY TO WEAK HIGH PRESSURE
FRIDAY. A WARM FRONT WILL BRING SOME RAIN BACK TO THE AREA FRIDAY
NIGHT AND SATURDAY. A LOW PRESSURE SYSTEM WILL BRING RAIN AND WINDY
CONDITIONS TO THE AREA SATURDAY NIGHT. A SERIES OF SYSTEMS WILL KEEP
THE WEATHER WET AND BREEZY AT TIMES NEXT WEEK.

&&

.SHORT TERM....THAT LINE OF SHOWERS AND ISOLATED TSTMS MOVING ONTO
THE SOUTH WA COAST AT 10PM IS HOLDING TOGETHER...SO IT WILL LIKELY
REACH THE CENTRAL AND THEN THE NORTH WA COAST OVER THE NEXT SEVERAL
HOURS...FORECASTS UPDATED FOR THAT. BUT FOR THE INTERIOR THE
SCATTERED SHOWERS SHOULD END OVERNIGHT. FRIDAY WILL BE A DRY DAY AS
A LITTLE UPPER RIDGING AND OFFSHORE FLOW DEVELOP OVER THE AREA. THE
NEXT SYSTEM WILL HAVE A WARM FRONT DRAPED FROM A DEEP LOW CENTER OFF
NRN CALIF LATE FRIDAY...ACROSS NW OREGON AND ALONG THE WA/ORE
BORDER. THE FRONT MOVES NORTH OVERNIGHT FRIDAY NIGHT AND SHOULD BE
INTO VANCOUVER ISLAND AND SW B.C. BY MIDDAY SAT. THE NAM SHOWS THAT
THE LOW PRESSURE AREA GETS STRETCHED OUT ALONG THE WA AND ORE
COASTAL WATERS BY THAT TIME AS PRECIP FILLS IN OVER MOST OF WRN WA.
THE SURFACE LOW WILL MOVE TO THE INTERIOR OF WRN WA SATURDAY EVENING
AND GIVE BLUSTERY CONDITIONS IN STRONG ONSHORE FLOW. SUNDAY LOOKS
LIKE A COOL DAY WITH SCATTERED SHOWERS AND PERHAPS A PSCZ...SHOWERS
LIKELY IN THE MOUNTAINS...AND A SNOW LEVEL NEAR PASS LEVEL.

.LONG TERM...AFTER A BRIEF LULL IN PRECIPITATION ON MONDAY...ANOTHER
LOW WILL MOVE INLAND OVER VANCOUVER ISLAND ON TUESDAY BRINGING WET
AND POSSIBLY BREEZY WEATHER TO THE AREA. WET AND LOCALLY BREEZY
CONDITIONS IS EXPECTED TO CONTINUE WEDNESDAY AND THURSDAY AS YET
MORE FEATURES MOVE INTO THE AREA.

&&

.HYDROLOGY...PERIODS OF RAIN ARE EXPECTED OVER THE NEXT SEVERAL
DAYS...BUT RAINFALL AMOUNTS ARE NOT EXPECTED TO BE HYDROLOGICALLY
SIGNIFICANT. THE SKOKOMISH RIVER IN MASON COUNTY FELL BELOW FLOOD
STAGE THIS EVENING.

&&

.AVIATION...STRONG SOUTHWESTERLY FLOW TONIGHT WEAKENING ON FRIDAY.
AIR MASS REMAINING UNSTABLE OVERNIGHT THEN STABILIZING FRIDAY
MORNING. WARM FRONT MOVING UP FROM THE SOUTH FRIDAY NIGHT.

CEILINGS AOA 10000 FEET. THE EXCEPTION TO THIS WILL BE OVER THE NEXT
THREE HOURS AS ONE LAST BAND OF SHOWERS APPROACHING THE COAST AT 05Z
MOVES THROUGH THE AREA. CEILINGS LOWERING TO NEAR 4000 FEET IN THE
SHOWERS. BAND WILL BE THROUGH THE AREA BY 09Z. BETWEEN 10Z-16Z
ISOLATED VISIBILITIES 1-3SM WITH CEILINGS BELOW 500 FEET ALONG THE
I-5 CORRIDOR FROM ABOUT KOLM SOUTHWARD.

KSEA...BAND OF SHOWERS MOVING THROUGH AROUND 06Z TO 09Z WITH
CEILINGS LOWERING TO NEAR 5000 FEET. OUTSIDE OF THAT WINDOW CEILINGS
AOA 10000 FEET. SOUTHERLY WINDS 4 TO 8 KNOTS BECOMING SOUTHEAST
EARLY FRIDAY MORNING THEN NORTHEAST FRIDAY AFTERNOON. FELTON

&&

.MARINE...THE FLOW WILL WEAKEN AND BECOME MORE EASTERLY OVERNIGHT
DUE TO FALLING PRES OVER THE EASTERN PACIFIC. OFFSHORE FLOW WILL
PREVAIL ON FRIDAY AND WILL GRADUALLY STRENGTHEN IN RESPONSE TO A 992
MB LOW APPROACHING FROM THE SW. THIS LOW IS EXPECTED TO WEAKEN TO
996 MB AS IT MOVES ACROSS THE WASHINGTON COASTAL WATERS ON SATURDAY.
GALE FORCE WINDS ARE POSSIBLE OVER PARTS OF THE AREA SATURDAY AHEAD
OF AND BEHIND THE COLD OR OCCLUDED FRONT.

THERE CONTINUES TO BE SOME UNCERTAINTY IN REGARDS TO THE TRACK AND
STRENGTH OF THE LOW SATURDAY. THERE IS A POSSIBILITY OF GALE FORCE
WINDS OVER MUCH OF THE WATERS...IF THE NE MOVING LOW MOVES INTO FAR
SW BRITISH COLUMBIA. IF IT MOVES INTO NORTHERN OREGON OR TRACKS
ACROSS FAR SW WASHINGTON...THE THREAT OF GALE FORCE WINDS WILL BE
CONFINED TO A SMALL AREA. THE CURRENT FORECAST REFLECTS MODEL
CONSENSUS. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...FLOOD WARNING REMAINS IN EFFECT FOR THE SKOKOMISH RIVER IN
     MASON COUNTY.

PZ...GALE WATCH IN EFFECT FOR THE COASTAL WATERS FROM SATURDAY
     MORNING THROUGH SATURDAY AFTERNOON.

&&

$$

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