000 FXUS66 KSEW 041552 AFDSEW AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SEATTLE WA 900 AM PDT SAT JUL 4 2009 .SYNOPSIS...IT WILL CONTINUE TO BE WARM AND SUNNY FOR MOST OF WESTERN WASHINGTON TODAY. MORNING FOG AND LOW CLOUDS ON THE COAST WILL BURN OFF MIDDAY. A TROUGH IS APPROACHING THE REGION HOWEVER AND A MARINE PUSH WILL DEVELOP SUNDAY AFTERNOON. THERE IS A CHANCE OF SHOWERS WITH COOL WEATHER UNDER AN UPPER TROUGH THROUGH NEXT WEEK. && .SHORT TERM...COASTAL MARINE STRATUS A NOTCH MORE EXTENSIVE THAN YDY AND A SMALL PUDDLE OF STRATUS AND FOG MADE IT INTO SRN PUGET SOUND BASIN...INTO BREMERTON AT DAYBREAK THIS MORNING. WILL BURN OFF THERE BEFORE 10AM. THE MARINE AIR ISN'T DEEP...ONLY MADE IT AS FAR AS KELSO IN THE SOUTH AND STAYED OUT OVER THE STRAIT WEST OF PORT ANGELES. HIGHS TODAY WILL RANGE FROM THE 60S ON THE COASTAL BEACHES TO 70S JUST A LITTLE INLAND...WITH 80S TO LOWER 90S IN THE INTERIOR. A LITTLE COOLING INTO SUNDAY IS A BETTER BET NOW...NAM HAS OTH-SEA GRADIENT +3.5MB 8AM SUNDAY INCREASING TO +5MB AT 2PM. OUR FCST TEMPS SUNDAY PROBABLY DEPEND ON THE MARINE PUSH HOLDING OFF A FEW HOURS FROM WHAT THIS 12Z RUN OF THE NAM SHOWS. AS FAR AS THE CHANCE FOR SHOWERS OR A MOUNTAIN THUNDERSTORM SUN NITE...THE NAM CONTINUES TO SHOW A BAND OF RAIN DEVELOPING AROUND MIDNIGHT SUNDAY NIGHT/EARLY MONDAY...BUT MOST OF THE PRECIP IS FCST TO BE EAST OF THE CREST SO OUR POPS ARE FAIRLY LOW. BY MONDAY WESTERN WA WILL BE UNDER DEEP MARINE LAYER WILL BE A CHANCE OF LIGHT SHOWERS OR DRIZZLE...MOST OF THAT LIGHT RAIN IS FCST TO BE ALONG THE COAST ASSOCIATED WITH A SURFACE TROF OVER THE COASTAL WATERS. THE GFS ALSO HAS SOME PRECIP...ONLY ALONG THE COAST MONDAY...SO WILL LIKELY MOVE THE POP UP A NOTCH BUT JUST FOR THE COAST ON MON IN THE AFTERNOON FCST PACKAGE. 19 .LONG TERM...THE LONGER RANGE MODELS SHOW AN UPPER TROUGH PARKED OVER THE REGION. WE HAVE A BROAD BRUSH FORECAST FOR A CHANCE OF SHOWERS EACH DAY WITH ONSHORE FLOW...MARINE CLOUDINESS MOST DAYS...TEMPS ON THE COOL SIDE. FOR THE MOMENT THE CURRENT ECMWF SOLN SUGGESTS A GOOD CHANCE OF SHOWERS TUESDAY NIGHT THRU WED...THEN DRY THU AND FRI...AND ANOTHER BATCH OF SHOWERS NEXT SATURDAY. THE GFS LOOKS BEST FOR SHOWERS TUE NIGHT AND WED AS WELL BUT DOESN'T PROMISE A DRY SOLUTION FOR THU AND FRI WITH THE UPPER LOW STAYING OVER THE AREA WITH A FEW SHOWERS. THEN BY NEXT SATURDAY THE GFS IS SOMEWHAT OUT OF PHASE WITH THE TIMING OF THE NEXT UPPER TROF IN THE ECMWF. AS I SAID YDY...TROFS IN JULY ARE COOL BUT OFTEN NOT MORE THAN A LITTLE DAMP...PERHAPS MORNING DRIZZLE OUT OF A MARINE LAYER AND THEN THE MOISTURE OFTEN OVERTURNS IN THE AFTERNOON FOR AT LEAST PART SUNNY SKIES. BLUE TARP CAMPERS WONT BE PUT OFF TOO MUCH BY THIS TROF. 19 && .AVIATION...HIGH PRESSURE ALOFT THROUGH TONIGHT WITH LIGHT SW FLOW. LIGHT ONSHORE LOW LEVEL FLOW TODAY WILL BECOME FLAT OR WEAK OFFSHORE OVERNIGHT...THEN TURN ONSHORE AGAIN ON SUN. THE ATMOSPHERE WILL BE DRY AND STABLE OVER MOST OF THE INTERIOR. IFR STRATUS AND FOG WILL HUG THE COAST...PARTS OF THE SW INTERIOR AND W STRAIT THIS MORNING. THIS WILL LIFT DURING THE AFTERNOON AND RETURN TONIGHT. .KSEA...STRATUS NOT EXPECTED THIS MORNING WITH CONTINUED VFR CONDITIONS. LIGHT WIND BECOMING NW 5-9 KT AFTER 18Z. && .MARINE... LIGHT ONSHORE FLOW WILL PREVAIL OVER THE AREA TODAY. WINDS SHOULD PICK UP AGAIN THROUGH THE CENTRAL/E STRAIT LATE THIS AFTERNOON AND EVENING. THE FLOW WILL BECOME WEAK OFFSHORE OVERNIGHT OVER THE INLAND WATERS BUT THIS WILL BE BRIEF. EXPECT LIGHT ONSHORE FLOW TO RETURN SUNDAY AFTERNOON...WITH A STRONG MARINE PUSH OCCURING SUNDAY NIGHT. WINDS COULD BRIEFLY REACH CLOSE TO GALE FORCE ACROSS THE INLAND WATERS WITH THE INITIAL PUSH. LIGHT TO MODERATE ONSHORE FLOW ACROSS THE AREA EARLY NEXT WEEK. && .FIRE WEATHER...A RED FLAG WARNING CONTINUES FOR ALL OF WESTERN WASHINGTON THROUGH MIDNIGHT SUNDAY NIGHT. MARINE AIR PUSHED FURTHER ISLAND THAN EXPECTED...ALL THE WAY INTO BREMERTON AND OLYMPIA. SO LOW LAND HUMIDITIES ALSO UP THE MORNING. WITH MARINE LAYER ONLY AROUND 1000 FEET DEEP...OVERNIGHT HUMIDITY RECOVERIES ABOVE AND OUT OF IT REMAINED POOR...IN THE 30 TO 50 PERCENT RANGE. WITH PLENTY OF SUNSHINE ABOVE THE LOW CLOUDS AND FOG...ANY GAINS IN FUEL MOISTURE WILL BE QUICKLY LOST IN THE WARMTH OF THE AFTERNOON SUNSHINE AGAIN. THEREFORE...THE RED FLAG WARNING FOR WARM...DRY AND UNSTABLE CONDITIONS REMAINS IN EFFECT. THE LATEST COMPUTER MODELS HOLD SUNDAYS TROUGH FURTHER OFFSHORE AND DELAY THE MOISTURE MOVING IN FROM THE SOUTHWEST. WITH THIS IN MIND...I HAVE LESSENED THE THUNDERSTORM THREAT TO OUR SIDE OF THE CASCADES. MORE ON THIS WITH THE AFTERNOON FORECAST PACKAGE. SCREAMING MESSAGE FOR THE WEEKEND REMAINS THE SAME...EVERY ONE NEEDS TO CONTINUE TO BE EXTREMELY CAREFUL WITH FIREWORKS AND CAMPFIRES TODAY AND SUNDAY. ALSO...USE YOUR VEHICLES ASHTRAY. PRANGE && .SEW WATCHES/WARNINGS/ADVISORIES... WA...RED FLAG WARNING IN EFFECT FOR THE ENTIRE CWA UNTIL MIDNIGHT SUNDAY NIGHT. PZ...SMALL CRAFT ADVISORY FOR WINDS IN EFFECT FOR THE CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA FROM 3 PM THIS AFTERNOON UNTIL MIDNIGHT TONIGHT. $$ WWW.WEATHER.GOV/SEATTLE FOR AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION PLEASE SEE WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML (ALL LOWERCASE)