Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 192156
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
300 PM PDT SUN OCT 19 2014

.SYNOPSIS...A FRONT WILL SPREAD RAIN OVER THE AREA TONIGHT. SHOWERS
WILL FOLLOW MONDAY AND MONDAY NIGHT. A STRONGER AND WETTER FRONT
WILL REACH THE AREA TUESDAY AFTERNOON...WITH RAIN CONTINUING OFF AND
ON INTO THURSDAY. SHOWERS FRIDAY COULD BE FOLLOWED BY A DRYING TREND
OVER THE WEEKEND.

&&

.SHORT TERM...RAIN JUST BEGAN ON THE NORTH COAST AND IT WILL SPREAD
INLAND OVERNIGHT. POPS ARE CATEGORICAL EVERYWHERE MONDAY MORNING FOR
SHOWERS. SHOWERS WILL DIMINISH MONDAY NIGHT. THE RAINIEST AREA WILL
BE THE OLYMPIC MOUNTAINS WHERE UP TO TWO INCHES ARE LIKELY. LOWLANDS
WILL GENERALLY SEE A QUARTER TO A HALF INCH IN THE 24 HOURS ENDING
MONDAY AFTERNOON.

BY TUESDAY AFTERNOON THE NEXT SYSTEM WILL BE NEAR THE COAST. RAIN
WILL SPREAD INLAND TUESDAY NIGHT AND CONTINUE WEDNESDAY MORNING.
THERE WILL BE BREEZY CONDITIONS ASSOCIATED WITH THIS FRONT. THE GFS
AND NAM AND CANADIAN MODELS ALL SAG THE FRONT SOUTH ON WEDNESDAY
AFTERNOON. WHILE NOT EXACTLY DRY THERE SHOULD BE A LULL IN THE RAIN
OVER THE AREA MOST LIKELY TO GET HEAVY RAIN...THE OLYMPIC PENINSULA.
THE EURO MODEL KEEPS HEAVY RAIN GOING LONGER IN THE OLYMPICS BUT
DOES MOVE THE HEAVY RAIN AREA SOUTH INTO OREGON WEDNESDAY NIGHT.

THE UPSHOT IS THAT HEAVY RAIN SHOULD BE LIMITED TO TUESDAY NIGHT AND
WEDNESDAY...WITH A 4-5 INCH BULLSEYE OVER THE OLYMPICS AND UP TO AN
INCH OVER THE LOWLANDS. THE FORECAST WILL BE RAIN AT TIMES FOR
WEDNESDAY NIGHT AND THURSDAY. HIGHS ALL FOUR DAYS...MONDAY THROUGH
THURSDAY...WILL BE IN THE LOW TO MID 60S...WITH LOWS IN THE 50S.

.LONG TERM...THE PATTERN LOOKS MORE SHOWERY IN BOTH THE GFS AND EURO
MODELS ON FRIDAY. MODELS THEN DIVERGE WITH THE GFS STILL SHOWERY ON
THE WEEKEND BUT THE EURO BRINGING ANOTHER FRONT SATURDAY WITH
SHOWERS ON SUNDAY. FOR NOW HAVE STUCK WITH THE IDEA OF SHOWERS
LIKELY ON FRIDAY WITH A CHANCE OF SHOWERS ON SATURDAY AND SUNDAY.
SHOWERS MAY BE MORE LIKELY ON THE COAST. HEIGHTS DO FALL A BIT SO
OVERNIGHT LOWS WILL BE LOWER...MAYBE BELOW 50 DEGREES. BURKE

&&

.HYDROLOGY...THE SYSTEM TONIGHT AND MONDAY IS WET BUT DOES NOT HAVE
ENOUGH RAIN TO CAUSE FLOODING. THE OLYMPICS WILL GET THE MOST RAIN
WITH PERHAPS 2 INCHES. THIS WILL BE THE SECOND RAINY EVENT OVER THE
OLYMPICS IN THREE DAYS. YESTERDAY MORNING THE SKOKOMISH RIVER
REACHED 15.3 FEET AND IT IS LIKELY TO GET AROUND THAT HIGH AGAIN ON
MONDAY. FLOOD STAGE ON THE SKOKOMISH IS 16.5 FEET.

THE GFS AND WRF VERSION OF THE HEAVY RAIN BEGINNING TUESDAY NIGHT IS
PROBABLY ENOUGH TO BRING THE SKOKOMISH RIVER TO FLOOD STAGE. MODELS
CONFINE FLOOD-PRODUCING RAINFALL TO THE OLYMPIC PENINSULA AND
PROBABLY JUST TO THE SKOKOMISH RIVER BASIN. ANY FLOODING ON THE
SKOKOMISH RIVER WOULD PROBABLY OCCUR WEDNESDAY NIGHT OR THURSDAY.

&&

.AVIATION...SOUTHERLY FLOW ALOFT. A FRONT WILL MOVE ONSHORE TONIGHT
AND MONDAY MORNING. AIR MASS STABLE WITH INCREASING LOW LEVEL
MOISTURE TONIGHT AS THE FRONT MOVES IN. AIR MASS BECOMING UNSTABLE
MONDAY BEHIND THE FRONT AND REMAINING MOIST.

KSEA...MID OR HIGH CLOUDS THIS EVENING. CEILINGS WILL LOWER WITH
RAIN DEVELOPING MONDAY MORNING. THERE SHOULD BE SOME IMPROVEMENT
LATER MONDAY AS RAIN CHANGES TO SHOWERS. SOUTH WIND 5 TO 10 KNOTS.
SCHNEIDER

&&

.MARINE...GALES OVER THE COASTAL WATERS AND ENTRANCES TO THE STRAIT
ALONG WITH SMALL CRAFT ADVISORY WINDS MOST OTHER WATERS LATE THIS
AFTERNOON WILL SUBSIDE TONIGHT AS A FRONT MOVES INLAND. WINDS ARE
EXPECTED TO BE BELOW ADVISORY LEVEL MONDAY ALL WATERS IN BETWEEN
WEATHER SYSTEMS. 10 TO 13 FOOT WEST SWELLS WILL LINGER OVER THE
COASTAL WATERS HOWEVER.

ADDITIONAL STRONG FRONTAL SYSTEMS WILL AFFECT THE WATERS LATER THIS
WEEK. FOR NOW IT LOOKS LIKE ONE SYSTEM WILL MOVE THROUGH THE AREA
AROUND TUESDAY NIGHT WITH ANOTHER ONE AROUND WEDNESDAY NIGHT. EACH
OF THESE SYSTEMS WILL BRING AT LEAST SMALL CRAFT ADVISORY WINDS TO
MOST OF THE WATERS. GALES ARE LIKELY FOR THE COASTAL WATERS AND
ENTRANCES TO THE STRAIT AS EACH FRONT MOVES THROUGH. SCHNEIDER

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...GALE WARNING COASTAL WATERS AND ENTRANCES TO THE STRAIT OF
     JUAN DE FUCA.
    .SMALL CRAFT ADVISORY ALL OTHER WATERS EXCEPT PUGET SOUND
     AND HOOD CANAL.


&&

$$

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YOU CAN SEE AN ILLUSTRATED VERSION OF THIS FORECAST DISCUSSION AT
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