AREA FORECAST DISCUSSION

 
 FXUS66 KSEW 100525
 AFDSEW
 
 AREA FORECAST DISCUSSION 
 NATIONAL WEATHER SERVICE SEATTLE WA
 925 PM PST TUE FEB 9 2010
 
 .SYNOPSIS...AN APPROACHING FRONT WILL BRING INCREASING CLOUDS 
 TONIGHT AND RAIN BY LATE WEDNESDAY MORNING. A STRONGER AND WETTER 
 FRONTAL SYSTEM WILL AFFECT THE AREA LATE WEDNESDAY NIGHT AND 
 THURSDAY. STRONGER SOUTHWEST FLOW ALOFT OVER THE REGION WILL SEND 
 MORE QUICK-MOVING WEATHER SYSTEMS ACROSS THE AREA FRIDAY THROUGH THE 
 WEEKEND.
 
 &&
 
 .SHORT TERM...OUR FIRST STRETCH OF MODERATELY ACTIVE WEATHER IN A 
 FEW WEEKS IS ABOUT TO BEGIN. A SHORTWAVE TROUGH NEAR THE LEADING 
 EDGE OF A MORE CONSOLIDATED MID-LATITUDE PACIFIC JET IS NOW QUICKLY 
 MOVING PAST 140W. THE LATEST ISALLOBARIC ANALYSIS SHOWS AN AREA OF 
 PRESSURE FALLS OVER THE OFFSHORE WATERS ADVANCING TOWARD THE COAST. 
 MANY LOCALES WILL HAVE THEIR LOW TEMPERATURES AND PERHAPS THEIR 
 THICKEST FOG DURING THE OVERNIGHT HOURS...BUT THEN TIGHTENING OF 
 SELY PRES GRADS AND A GRADUAL INCREASE IN BOUNDARY LAYER WIND SHOULD 
 START TO MECHANICALLY MIX OUT SOME FOG AND WEAKEN LOW-LEVEL 
 INVERSIONS BEFORE THE SUN EVEN COMES UP. THE REST OF TONIGHT LOOKS 
 DRY...BUT CLOUDS WILL QUICKLY THICKEN EARLY ON WED MORNING. 
 
 AN APPROACHING WARM FRONT AND SHORTWAVE TROUGH WILL SPREAD RAIN ONTO 
 THE COAST AROUND THE FIRST LIGHT OF DAY AND INTO THE INTERIOR NEAR 
 THE END OF MORNING COMMUTING HOURS. RAIN SHOULD PREVAIL FOR MUCH OF 
 THE DAY WITH SOME MODEST RAINFALL AMOUNTS EXPECTED. 
 
 THE SHORTWAVE TROUGH WILL PASS EAST LATE IN THE AFTERNOON WITH RAIN 
 TAPERING OFF EARLY IN THE EVENING. THIS WILL PROVIDE A BRIEF BREAK 
 ON WED EVNG AND NIGHT IN A FAIRLY ACTIVE PATTERN.
 
 YET ANOTHER WARM FRONT WILL LIFT NORTH ACROSS WRN WA ON THU... 
 SPREADING MORE RAIN THROUGH THE REGION FROM SW TO NE ON THU MORNING. 
 A 1000 MB LOW CENTER WILL THEN LIFT NNE OFF THE COAST ON THU 
 NIGHT...PUSHING A COLD FRONT AND MORE RAIN THROUGH WRN WA ON THU 
 NIGHT. PASSAGE OF THIS COLD FRONT COULD ALSO BRING A FEW HOURS OF 
 BREEZY OR WINDY WEATHER TO MANY PLACES.     
 
 BEHIND THE THU EVNG COLD FRONT...ANOTHER BRIEF BREAK IS EXPECTED 
 LATE THU NIGHT AND EARLY FRI MORNING...THEN ANOTHER IN THE SERIES OF 
 QUICK-MOVING WEATHER SYSTEMS WILL GLIDE BY WITH MORE RAIN ON FRI 
 MORNING...FOLLOWED BY ANOTHER BREAK ON FRI NIGHT.    HANER
 
 .LONG TERM...FROM PREVIOUS DISCUSSION...AFTER ANOTHER LULL FRIDAY 
 NIGHT AND SATURDAY MORNING...MODELS BRING ANOTHER SYSTEM INTO THE 
 PACIFIC NORTHWEST. THE EURO SENDS MOST MOISTURE INTO BRITISH 
 COLUMBIA AND THEN BRINGS A FRONT THROUGH WASHINGTON ON SUNDAY. THE 
 GFS BRINGS A MORE CONSOLIDATED FRONT DIRECTLY THROUGH WASHINGTON 
 SATURDAY NIGHT. NEITHER ONE IS ALL THAT IMPRESSIVE WITH RAINFALL 
 AMOUNTS...EVEN IN THE OLYMPIC MOUNTAINS. THUS WILL OPT FOR NO 
 STATEMENT ABOUT POTENTIAL FLOODING.
 
 BOTH THE EURO AND GFS HAVE DRY SUNDAY NIGHTS AND MONDAYS AND WET 
 TUESDAYS. HAVE NOT COMPLETELY BOUGHT THESE SOLUTIONS AND KEPT THE 
 BROAD BRUSH LIKELY POPS FOR NOW. BURKE
  
 &&
 
 .HYDROLOGY...PREVIOUS DISCUSSION IS STILL VALID AND FOLLOWS... 
 NOTHING TOO SIGNIFICANT IN THE MODELS THROUGH FRIDAY. ANY RAIN WILL 
 BE LIGHT TO MODERATE AND RIVERS WILL RISE ONLY MODERATELY. THE MAIN 
 EFFECT OF THE REPEATED RAIN STORMS WILL BE TO MOISTEN THE SOIL AND 
 GET THE HYDROLOGICAL SYSTEMS PRIMED AGAIN. BOTH THE GFS AND EURO 
 HAVE BACKED OFF SOMEWHAT ON RAINFALL AMOUNTS OVER THE WEEKEND. MOST 
 OF THE MOISTURE IS SHOVED NORTH INTO BRITISH COLUMBIA. THERE IS 
 STILL A CHANCE OF HEAVY RAIN OVER THE OLYMPIC MOUNTAINS...ESPECIALLY 
 ON SUNDAY. THE CASCADES DO NOT APPEAR TO BE UNDER ANY THREAT AND THE 
 PROBABILITY OF FLOODING ON THE GREEN RIVER IS LOW.
 
 POSSIBLY THE ONLY SIGNIFICANT EFFECT OF ALL THESE STORMS WILL BE TO 
 INCREASE THE THREAT OF LANDSLIDES IN SATURATED SOIL SLIGHTLY BY NEXT 
 WEEK. BURKE
  
 &&
 
 .AVIATION...HIGH PRES ALOFT WILL PERSIST THROUGH TONIGHT.  MODERATE 
 SW FLOW ALOFT TONIGHT WILL BECOME STRONG THROUGH WED.  CLEAR SKIES 
 THIS EVENING IS ALLOWING FOG TO FORM SOME AREAS AND THIS WILL 
 CONTINUE FOR THE NEXT FEW HOURS...THEN INCREASING HIGH AND MID LEVEL 
 CLOUDINESS WILL LIMIT ITS SPREAD AND POTENTIALLY ALLOW IT TO 
 DISSIPATE SOMEWHAT DURING THE EARLY MORNING HOURS.  
 
 RAIN WILL DEVELOP WED MORNING ALONG THE COAST SPREADING INLAND BY 
 WED AFTERNOON AS A FRONT MOVES INTO WRN WA. 
  
 KSEA...LIGHT WIND BECOMING S 5-9 KT AFTER 08Z.  STILL WILL GO WITH 
 FOG BEING UNLIKELY DUE TO THE SLY BREEZE THAT WILL DEVELOP AND 
 INCREASING HIGH CLOUDS LATE TONIGHT.  LIGHT RAIN AND CIGS 3-4K FT 
 WILL DEVELOP AFTER 18Z THU.
 
 &&
 
 .MARINE...WIND GENERALLY LIGHT TONIGHT...EXCEPT PICKING UP LATE 
 TONIGHT AT THE W ENTRANCE TO THE STRAIT.  A FRONT WILL BRING SOLID 
 SMALL CRAFT WINDS TO THE COASTAL WATERS AND W ENTRANCE WED.  AS THE 
 FRONT PUSHES INLAND THE WIND WILL ALSO INCREASE FROM AROUND 
 ADMIRALTY INLET NWD LATER WED. 
 
 A STRONGER FRONT IS EXPECTED TO BRING MORE WIDESPREAD SMALL CRAFT 
 WINDS...WITH THE POTENTIAL FOR GALES OVER THE COASTAL WATERS THU AND 
 THU NIGHT.
 
 THEN A CONTINUATION OF THE SERIES OF FRONTS WILL AFFECT THE REGION 
 WITH ONE ON FRI...ONE LATE SAT INTO SUN THEN ANOTHER EARLY  NEXT 
 WEEK.  CERNIGLIA
 
 &&
 
 .SEW WATCHES/WARNINGS/ADVISORIES...
 WA...NONE. 
 PZ...SMALL CRAFT ADVISORY COAST AND WEST ENTRANCE WEDNESDAY MORNING  
      THROUGH WEDNESDAY AFTERNOON.
 
 

 
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