Weather Service Report


821 
FXUS66 KSEW 011640
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
840 AM PST SUN FEB 1 2015

.SYNOPSIS...A WEAK COLD FRONT WILL MOVE THROUGH TODAY FOR RAIN AT 
TIMES. A BRIEF AND WEAK RIDGE WILL GIVE A DECREASING CHANCE OF 
SHOWERS TONIGHT. ANOTHER FRONTAL SYSTEM WILL MOVE THROUGH THE AREA 
ON MONDAY...WITH MORE LIGHT RAIN LIKELY. SOME LIGHT SHOWERS WILL 
LINGER TUESDAY INTO WEDNESDAY AS WEAK DISTURBANCES MOVE THROUGH THE 
AREA. A TRANSITION TO A FAIRLY WET AND MILD PATTERN WILL BEGIN 
THURSDAY AND CONTINUE THROUGH NEXT WEEKEND. 

&&

.SHORT TERM...SATELLITE IMAGERY AND RADARS SHOW A WEAK FRONT OVER 
THE OUTER COASTAL WATERS THIS MORNING MOVING SLOWLY EAST. THE FRONT 
WILL SLOW AND WEAKEN AS IT MOVES ONSHORE THIS AFTERNOON. TODAY WILL 
BE A CLOUDY DAY WITH OCCASIONAL LIGHT RAIN AND TEMPERATURES IN THE 
MID 40S TO NEAR 50 DEGREES. 

THE AIR MASS BEHIND THIS FRONT IS NOT PARTICULARLY COOL OR UNSTABLE 
ALOFT...SO EXPECT SHOWER ACTIVITY TO DIMINISH BEHIND THE FRONT THIS 
EVENING. THE LATE EVENING THROUGH PRE DAWN HOURS MAY BE DRY ACROSS 
THE AREA...JUST CLOUDY...BETWEEN THE FIRST FRONT AND THE NEXT 
INCOMING SYSTEM THAT IS NOW ALONG ABOUT 142W. WITH ALL THE CLOUD 
COVER AROUND...TEMPERATURES WILL HOLD MAINLY IN THE LOWER 40S 
TONIGHT.

ANOTHER WEAK FRONT WILL MOVE ACROSS THE AREA ON MONDAY. THE 12Z NAM 
AND 12Z GFS SOLUTIONS BOTH SHOW THE RAIN MOVING INTO THE AREA FROM 
THE SOUTHWEST DURING THE MORNING HOURS ON THE COAST AND THE SOUTHERN 
HALF OF THE INTERIOR THEN THROUGH THE AREA DURING THE AFTERNOON 
HOURS. THIS FRONTAL FEATURE WILL BE LOSING ITS IDENTITY AS IT MOVES 
ACROSS THE AREA LATER IN THE DAY. 

TUESDAY AND TUESDAY NIGHT WILL LIKELY SEE SHOWERS AT TIMES. A WARM 
FRONT IN THE SOUTHERN STREAM WILL AFFECT EXTREME NORTHERN CALIFORNIA 
INTO CENTRAL OREGON GIVING STEADIER RAIN DOWN THERE. BUT THE 
REMNANTS OF A WRAP AROUND FEATURE THAT IS SEEN MOVING AROUND THE 
DEEP AND MATURE LOW NOW CENTERED NEAR 46N 158W WILL SPLIT OFF AND 
MOVE ACROSS ESPECIALLY THE NORTHERN HALF OF WESTERN WASHINGTON 
ENHANCING SHOWER ACTIVITY AND POSSIBLY CONVERGENCE ZONE ACTIVITY 
INITIATED BY WNW FLOW ALOFT. 

SHOWER ACTIVITY WILL LIKELY COME TO AN END EARLY WEDNESDAY...BUT THE 
INCOMING GFS DOES SHOW WARM ADVECTION PRECIPITATION MOVING INTO THE 
SOUTHERN PORTIONS OF WESTERN WASHINGTON LATE WED AFTERNOON OR 
EVENING. 

CURRENT FORECASTS APPEAR TO BE GENERALLY ON TRACK. NO MORNING UPDATE 
IS PLANNED. ALBRECHT

.LONG TERM...FROM THE PREVIOUS LONG TERM SOLUTION...MODEL SOLUTIONS 
FOR WEDNESDAY CONTINUE TO SHOW A LACK OF CONSISTENCY AMONG THE 
MODELS. THE ECMWF HAS A WARM FRONT OVER OREGON TRYING TO LIFT NORTH 
INTO WESTERN WASHINGTON. THE GFS HAS A WEAK SHORTWAVE RIDING BY TO 
THE NORTH OF THE AREA. GFS ENSEMBLES SHOW LITTLE VARIATION IN THEIR 
SOLUTION ON WEDNESDAY WHICH LENDS SOME CONFIDENCE TO THE GFS 
SOLUTION BUT WITH THE LACK OF MODEL CONSENSUS WILL KEEP THE CHANCE 
POPS IN THE FORECAST. WHILE THERE ARE SOME DIFFERENCES IN THE TIMING 
OF THE SYSTEMS BEGINNING THURSDAY THE EXTENDED MODELS ARE IN MUCH 
BETTER AGREEMENT IN REGARD TO THE OVERALL PATTERN TURNING WARMER AND 
WETTER BEGINNING THURSDAY AND CONTINUING THROUGH NEXT WEEKEND. 
TIMING OF THE INDIVIDUAL FEATURES IS TOUGH AT THIS POINT SO A BROAD 
BRUSH RAIN LIKELY/RAIN AT TIMES FORECAST LOOKS GOD THURSDAY THROUGH 
SATURDAY. FELTON
 
&&

.HYDROLOGY...FLOODING IS NOT EXPECTED THROUGH AT LEAST THURSDAY. 

A SERIES OF SYSTEMS MOVING THROUGH THE AREA THURSDAY NIGHT THROUGH 
SATURDAY WILL CAUSE RIVERS TO RISE BUT WITH A FEW BREAKS IN THE 
STEADY PRECIPITATION THE ONLY THREAT OF FLOODING IN THIS SCENARIO 
LOOKS TO BE ON THE SKOKOMISH RIVER NEXT WEEKEND. FELTON/ALBRECHT
 
&&

.AVIATION...MOIST WESTERLY FLOW ALOFT PREVAILS OVER WESTERN 
WASHINGTON THIS MORNING...AS A WEAK FRONT MOVES INLAND FROM THE 
OFFSHORE WATERS. THE FRONT WILL MOVE EAST OF THE CASCADES THIS 
EVENING...BUT THE AIR MASS WILL REMAIN MOIST AT LOWER LEVELS. A FLAT 
UPPER RIDGE WILL REMAIN OVER THE PACIFIC NORTHWEST. 

CEILINGS ACROSS THE FORECAST AREA ARE MAINLY 6000 FT OR ABOVE AT 
PRESENT...BUT THERE IS SPOTTY LIGHT RAIN AND AREAS OF VISIBILITY 
3-5SM -RA BR. CONDITIONS WILL DETERIORATE DURING THE NEXT FEW HOURS 
AS PRECIPITATION INCREASES...AND WIDESPREAD 3-5SM -RA BR AND CEILING 
BKN-OVC025 IS LIKELY LATE THIS MORNING AND AFTERNOON. RAIN WILL 
MOSTLY END OVER THE LOWLANDS THIS EVENING...BUT CEILINGS WILL 
PROBABLY REMAIN LOW THROUGH TONIGHT AND MONDAY MORNING WITH 
WIDESPREAD STRATUS.

KSEA...SOUTHERLY WIND 6-10 KT. CEILING WILL FALL OVER THE NEXT FEW 
HOURS AS RAIN INCREASES...AND VISIBILITY 3-5SM -RA BR SEEMS LIKELY 
AT TIMES. RAIN WILL END LATE TODAY OR THIS EVENING...BUT STRATUS 
WILL PROBABLY CONTINUE TONIGHT AND MONDAY MORNING.   MCDONNAL

&&

.MARINE...A WEAK FRONT WILL MOVE THROUGH THE COASTAL WATERS OF 
WESTERN WASHINGTON THIS MORNING AND THEN INLAND THIS AFTERNOON. THIS 
FEATURE IS PRODUCING SMALL CRAFT ADVISORY SOUTHERLIES OVER THE 
COASTAL WATERS FROM AROUND DESTRUCTION ISLAND NORTHWARD...AND THESE 
SHOULD CONTINUE INTO THE AFTERNOON. THE FRONT WILL PROBABLY ALSO 
PRODUCE MARGINAL SMALL CRAFT ADVISORY WINDS OVER THE EAST ENTRANCE 
STRAIT OF JUAN DE FUCA...ADMIRALTY INLET...AND NORTHERN INLAND 
WATERS THIS AFTERNOON. 

A NEGATIVELY TILTED FRONT WILL MOVE THROUGH THE FORECAST AREA MONDAY 
AFTERNOON AND EVENING. THIS WILL ALSO BE A RELATIVELY WEAK 
FEATURE...BUT IT SHOULD RESULT IN SMALL CRAFT ADVISORY WINDS OVER 
MOST OF THE MARINE ZONES. WEAK HIGH PRESSURE WILL BE OVER THE REGION 
TUESDAY AND WEDNESDAY...AND A STRONGER FRONTAL SYSTEM WILL ARRIVE 
THURSDAY.   MCDONNAL

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY TODAY COASTAL WATERS ZONES 150 153 170 173.
     SMALL CRAFT ADVISORY THIS AFTERNOON EAST ENTRANCE STRAIT OF 
       JUAN DE FUCA...ADMIRALTY INLET...NORTHERN INLAND WATERS.

&&

$$

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