Weather Service Report


329 
FXUS66 KSEW 191025
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
325 AM PDT SAT APR 19 2014

.SYNOPSIS...A COLD FRONT WILL MOVE THROUGH THE AREA THIS AFTERNOON. 
SHOWERS WILL FOLLOW THE FRONT TONIGHT THEN TAPER OFF EARLY SUNDAY 
MORNING. THE NEXT APPROACHING FRONT WILL STALL OFF THE COAST ON 
SUNDAY WITH JUST A CHANCE OF RAIN ALONG THE NORTH COAST. THE FRONT 
WILL CONTINUE TO HAVE A HARD TIME MOVING EAST SUNDAY NIGHT INTO 
MONDAY BEFORE MOVING THROUGH THE AREA MONDAY NIGHT. THE WEATHER WILL 
REMAIN COOL AND UNSETTLED THROUGH THROUGH THE END OF NEXT WEEK. 

&&

.SHORT TERM...SATELLITE IMAGERY SHOWS THE COLD FRONT OFFSHORE NEAR 
129W AT 10Z/3AM. MID LEVEL CLOUD DECK OUT AHEAD OF THE FRONT IS 
ALREADY SPREADING OVER WESTERN WASHINGTON. LANGLEY HILL DOPPLER 
RADAR PICKING UP RAIN NEAR CAPE FLATTERY. OBSERVATIONS FROM KUIL NOT 
REPORTING ANY RAIN YET. TEMPERATURES AT 3 AM WERE IN THE MID 30S TO 
MID 40S. 

RAIN OUT AHEAD OF THE FRONT SPREADING INLAND THIS MORNING WITH THE 
LEADING EDGE OF THE PRECIPITATION MOVING INTO THE CASCADES BY NOON. 
FRONT MOVING THROUGH THE AREA THIS AFTERNOON MAKING FOR A WET START 
TO THE WEEKEND ACROSS WESTERN WASHINGTON. WITH ALL OF THE CLOUD 
COVER AND PRECIPITATION HIGH TEMPERATURES IN THE 50S TODAY.

UPPER LEVEL TROUGH MOVING INLAND QUICKLY BEHIND THE FRONT LATE THIS 
AFTERNOON AND THIS EVENING KEEPING SHOWERS IN THE FORECAST. PUGET 
SOUND CONVERGENCE ZONE FORMING IN THE EVENING. WITH THE FLOW IN THE 
LOWER LEVEL REMAINING SOUTHWESTERLY EXPECT THE CONVERGENCE ZONE TO 
STAY IN SNOHOMISH AND SKAGIT COUNTIES INTO THE EARLY MORNING HOURS. 
FOR THE REMAINDER OF THE AREA SHOWER ACTIVITY DECREASING OVERNIGHT 
WITH A TRANSITORY UPPER LEVEL RIDGE JUST OFF THE COAST BY 12Z/5AM. 
LOW TEMPERATURE WILL MOSTLY BE IN THE LOWER TO MID 40S.

SOME CHANGES TO THE FORECAST ON SUNDAY AS THE NEXT APPROACHING FRONT 
STALLS OFF THE COAST DUE TO A DEEP UPPER LEVEL TROUGH DIGGING BACK 
OUT BETWEEN 140-150W. FRONT NOT FAR ENOUGH TO THE WEST TO TAKE THE 
CHANCE POPS OUT OF THE NORTH COAST AND THERE STILL COULD BE SOME 
LINGERING CONVERGENCE ZONE SHOWERS IN THE NORTH CASCADES BUT OUTSIDE 
OF THOSE AREAS HAVE GONE WITH A DRY FORECAST FOR SUNDAY. WITH THE 
FRONT JUST OFFSHORE PLENTY OF MID LEVEL CLOUDS SO WILL WORD THE 
FORECAST JUST PARTLY SUNNY FOR SUNDAY. WITH THE FRONT STALLING LOOK 
FOR TEMPERATURES ON SUNDAY TO BE ABOUT 5 DEGREES WARMER VERSUS 
SATURDAY...MID 50S TO MID 60S. 

FRONT CONTINUING TO TO BECOME MORE NORTH SOUTH ORIENTED SUNDAY 
NIGHT WITH THE DEEP UPPER LEVEL TROUGH MOVING EAST A BIT. THIS WILL 
CONFINE THE THREAT OF RAIN TO THE NORTH COAST SUNDAY NIGHT. LOWS 
WILL BE IN THE 40S. 

FRONT CONTINUING TO STALL OFF THE COAST MONDAY WITH THE FLOW ALOFT 
BECOMING MORE SOUTHERLY. AIR MASS BECOMING SOMEWHAT UNSTABLE IN THE 
AFTERNOON ESPECIALLY OVER THE CASCADES SO EVEN THROUGH THE FRONT IS 
STILL OFFSHORE WILL HAVE TO INCLUDE A CHANCE OF SHOWERS IN THE 
FORECAST FOR THE ENTIRE AREA. HIGH TEMPERATURES ON MONDAY ARE A 
LITTLE TRICKY WITH THE POSSIBLE CONVECTION IN THE AFTERNOON COMBINED 
WITH THE FRONT JUST OFFSHORE. FOR NOW HAVE GONE PRETTY MUCH WITH 
PERSISTENCE FOR THE HIGHS ON MONDAY...MID 50S TO MID 60S AGAIN.

WHAT IS LEFT OF THE FRONT MOVING INLAND MONDAY NIGHT WITH THE UPPER 
LEVEL TROUGH OFFSHORE MOVING EAST OF 130W BY 12Z/5AM. WITH THE FRONT 
WEAKENING HAVE GONE WITH SHOWERS AS THE PRECIPITATION TYPE. FELTON

.LONG TERM...EXTENDED MODELS ARE IN GOOD AGREEMENT WITH THE COOL 
UPPER LEVEL TROUGH MOVING THROUGH ON TUESDAY. MODEL SOLUTION DIVERGE 
ON WEDNESDAY WITH THE GFS TRYING TO DRY THINGS OUT WHILE THE 
CANADIAN AND ECMWF CONTINUE THE CHANCE FOR SHOWERS. GOOD AGREEMENT 
AGAIN ON THURSDAY WITH AN ORGANIZED FRONT MOVING THROUGH THE AREA 
WITH AN UPPER LEVEL TROUGH OFFSHORE ON FRIDAY. CURRENT FORECAST HAS 
CHANCE POPS THROUGH THE PERIOD EXCEPT ON THURSDAY WHERE LIKELY POPS 
ARE IN THE FORECAST. SINCE THE ECMWF AND CANADIAN STILL HAVE 
PRECIPITATION OVER THE AREA ON WEDNESDAY WILL STAY REFRAIN FROM 
DRYING OUT WEDNESDAY AND STAY WITH THE CURRENT EXTENDED FORECAST. 
FELTON
 
&&

.HYDROLOGY...RIVER FLOODING IS UNLIKELY FOR THE NEXT 7 DAYS. 

THE EXCEPTION IS THE NORTH FORK OF THE STILLAGUAMISH RIVER EAST OF 
THE SR 530 LANDSLIDE NEAR OSO WHERE A FLOOD WARNING REMAINS IN 
EFFECT UNTIL FURTHER NOTICE. FLOODING CONTINUES FOR THIS RIVER AS A 
RESULT OF WATER POOLED BEHIND THE DEBRIS DAM THAT PARTIALLY BLOCKS 
THE RIVER.

AT 215 AM...THE NORTH FORK OF THE STILLAGUAMISH NEAR ARLINGTON IS AT 
4.9 FT...OR 3240 CFS AND IS FALLING. IT IS EXPECTED TO FALL TO 
AROUND 4.4 FT THIS AFTERNOON THEN RISE BACK UP TO AROUND 5.3 FEET 
MIDDAY SUNDAY BEFORE RESUMING A FALL BACK DOWN TO AROUND 4 FT EARLY 
NEXT WEEK. SIMILAR TRENDS ARE EXPECTED ON THE NORTH FORK OF THE 
STILLAGUAMISH NEAR OSO AND AT THE SR 530 SLIDE POOL TO THE EAST OF 
THE LANDSLIDE.  FELTON 

&&

.AVIATION...AN UPPER LEVEL TROUGH WILL MOVE THROUGH WRN WA THIS 
AFTERNOON AND EVENING. THE ASSOCIATED SURFACE FRONT REACHES THE 
COAST BY LATE MORNING...THEN PUSHES THROUGH INTERIOR WRN WA MIDDAY 
TO EARLY AFTERNOON. MODERATE SW FLOW ALOFT. STABLE CONDITIONS. 
BECOMING MOIST AT ALL LEVELS. RAIN ALONG THE COAST THIS 
MORNING...SPREADING INLAND BY MIDDAY. CIGS ACROSS THE INTERIOR WILL 
LOWER TO 3-5K FT AS RAIN DEVELOPS LATE THIS MORNING OR EARLY 
AFTERNOON AHEAD OF THE FRONT. THE FRONT WILL PUSH THROUGH PUGET 
SOUND ROUGHLY 20Z (1PM). 

KSEA...SCT-BKN MID/HIGH CLOUDS EARLY...THEN CIGS 3-5K FT DEVELOPING 
BY MID TO LATE MORNING. NE OR VARIABLE WINDS TO 5 KT...THEN SE 5-10 
KT AFTER 12Z...BECOMING SW 10-15 W/ GUSTS TO 22 KT AFTER 20Z. RAIN 
DEVELOPING BY MIDDAY. DTM

&&

.MARINE...A COLD FRONT MOVING INTO THE COASTAL WATERS THIS MORNING 
WILL PUSH ACROSS THE INLAND WATERS MIDDAY TO EARLY AFTERNOON. SMALL 
CRAFT ADVISORY WINDS ARE EXPECTED OVER ALL WATERS. HIGH PRESSURE 
WILL REBUILD ON SUNDAY. A WEAKER SYSTEM WILL ARRIVE LATER MONDAY OR 
MONDAY NIGHT. 

A LARGE SWELL TRAIN WILL ARRIVE ALONG THE WASHINGTON COAST THIS 
EVENING AND CONTINUE INTO SUNDAY. LARGE WAVES UP TO 15 FEET WILL 
IMPACT THIS COAST BY THIS EVENING...BUILDING TO 16 TO 19 FEET LATER 
TONIGHT INTO SUNDAY MORNING. A HIGH SURF ADVISORY IS IN EFFECT FOR 
THE COAST FROM THIS EVENING THROUGH SUNDAY. THIS IS A RAZOR CLAM DIG 
WEEKEND FOR TWIN HARBORS...COPALIS AND MOCLIPS BEACHES. EXTREME 
CAUTION SHOULD BE EXERCISED AS WAVES WILL LIKELY RACE FURTHER UP THE 
BEACH THAN NORMAL. 

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...FLOOD WARNING REMAINS IN EFFECT FOR THE NORTH FORK OF THE       
     STILLAGUAMISH RIVER EAST OF THE SR 530 LANDSLIDE.      
     HIGH SURF ADVISORY NORTH AND CENTRAL COAST THIS EVENING THROUGH 
     SUNDAY AFTERNOON.

PZ...SMALL CRAFT ADVISORY ALL WATERS THROUGH THIS EVENING. 
     SMALL CRAFT ADVISORY FOR ROUGH GRAYS HARBOR BAR TONIGHT.
     

&&

$$

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