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000
FXUS66 KSEW 121053
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
350 AM PDT WED JUN 12 2013

.SYNOPSIS...A WEAK UPPER LEVEL LOW OVER THE NORTHERN PORTION OF
VANCOUVER ISLAND WILL MOVE DOWN OVER WESTERN WASHINGTON LATER TODAY.
THE LOW WILL REMAIN OVER WESTERN WASHINGTON TONIGHT THEN MOVE INTO
EASTERN WASHINGTON AND EASTERN OREGON THURSDAY. THE LOW WILL
CONTINUE TO DRIFT EAST ON FRIDAY. THE LOW WILL BRING CLOUDS...COOL
TEMPERATURES...AND SHOWERY WEATHER INTO FRIDAY. WARMER AND DRIER
CONDITIONS ARE EXPECTED ON SATURDAY.

&&

.SHORT TERM...SATELLITE IMAGERY SHOWS UPPER LEVEL LOW JUST SOUTH OF
PORT HARDY ON VANCOUVER ISLAND EARLY THIS MORNING WITH CLOUDY SKIES
OVER WESTERN WASHINGTON. NOT MUCH IN THE WAY OF SHOWERS ON THE
DOPPLER RADARS WITH THE SHOWER ACTIVITY CONFINED TO THE NORTH COAST
AND NORTHWEST INTERIOR AT 10Z.

UPPER LEVEL LOW DRIFTING SOUTHEAST TODAY WITH THE SHOWERS CHANCES
INCREASING OVER THE AREA THE CLOSER THE LOW GETS TO THE REGION. AIR
MASS SOMEWHAT UNSTABLE THIS AFTERNOON WITH THE LIFTED INDEXES IN THE
0 TO -2 RANGE BUT CAPE VALUES ARE BELOW 300 J/KG...WINDS ALOFT ARE
SOUTHWESTERLY 10 TO 20 KNOTS FROM 5000 TO 20000 FEET AND MODEL
SOUNDINGS SHOW A BIT OF AN INVERSION AROUND 10000 FEET. GIVEN THESE
VARIABLES WILL KEEP THUNDERSTORMS OUT OF THE FORECAST THIS
AFTERNOON. WITH THE COOL AIR MASS OVER WESTERN WASHINGTON EVEN WITH
SOME SUNBREAKS THIS AFTERNOON HIGH TEMPERATURES WILL CONTINUE TO BE
BELOW NORMAL WITH HIGHS MOSTLY IN THE UPPER 50S TO MID 60S.

LOW CONTINUING TO DRIFT SLOWLY SOUTH SOUTHEAST OVER THE AREA TONIGHT
KEEPING A CHANCE OF SHOWERS IN THE FORECAST. A BIT OF A WESTERLY
PUSH THROUGH THE STRAIT THIS EVENING COULD RESULT IN A CONVERGENCE
ZONE FORMING OVER SKAGIT AND SNOHOMISH COUNTY. WILL GO WITH SLIGHTLY
HIGHER POPS THERE VERSUS THE REST OF THE AREA. IT WILL BE A LITTLE
CHILLY FOR THIS TIME OF YEAR THURSDAY MORNING WITH MANY LOCATIONS IN
THE 40S.

LOW KICKING OFF TO THE EAST ON THURSDAY WITH THE FLOW ALOFT BECOMING
NORTHERLY OVER THE AREA. AIR MASS STILL SOMEWHAT UNSTABLE WITH
LIFTED INDEXES NEAR 0. THIS WILL KEEP A CHANCE OF SHOWERS IN THE
FORECAST. EVEN WITH THE LOW MOVING OFF TO THE EAST TEMPERATURES
ALOFT ONLY WARM SLIGHTLY ON THURSDAY WITH PLENTY OF ONSHORE FLOW AT
THE LOWER LEVELS. THIS WILL KEEP HIGH TEMPERATURES ON THURSDAY
SIMILAR TO TODAYS READINGS.

LOW CONTINUING TO MOVE EAST THURSDAY NIGHT INTO FRIDAY WITH A WEAK
UPPER LEVEL RIDGE MOVING OVER THE AREA AND ANOTHER UPPER LEVEL LOW
MOVING SOUTH TO NEAR 47N/136W BY THE END OF THE DAY. TEMPERATURES
FRIDAY MORNING WILL ONCE AGAIN BE ON THE COOL SIDE ESPECIALLY OVER
THE SOUTHWEST INTERIOR. LOW LEVEL ONSHORE FLOW WILL KEEP PLENTY OF
MOISTURE IN THE LOWER LEVELS. EVEN WITH THE WEAK RIDGE MODELS
CONTINUE TO SHOW A FEW SHOWERS AROUND THE AREA. WILL STICK WITH THE
LOW...20 PERCENT POPS...FOR NOW. IF THE TRENDS CONTINUE LOOK FOR THE
CHANCE OF SHOWERS TO BE TAKEN OUT OF THE FRIDAY FORECAST. WITH A
LITTLE MORE SUNSHINE ON FRIDAY DAYTIME HIGHS WILL GET BACK TO NEAR
NORMAL WITH A FEW PLACES IN THE LOWER 70S.

.LONG TERM...EXTENDED MODELS IN GOOD AGREEMENT THIS MORNING AND
SHOWING GOOD RUN TO RUN CONSISTENCY. NEXT UPPER LEVEL LOW WELL
OFFSHORE SATURDAY WITH THE LOW MOVING EAST TO NEAR 130W ON SUNDAY.
WITH THE SOUTHERLY FLOW ALOFT THERE IS A CHANCE FOR SOME CONVECTION
ON SUNDAY ESPECIALLY OVER THE CASCADES. LOW CONTINUES TO SLOWLY
DRIFT EAST ON MONDAY WITH THE MODELS INDICATING A VORT LOBE ROTATING
AROUND THE LOW MOVING INTO WESTERN WASHINGTON. THE LOW FINALLY MOVES
OVER THE AREA ON TUESDAY. CURRENT FORECAST OF WARMER TEMPERATURES
OVER THE WEEKEND FOLLOWED BY A COOL DOWN AND INCREASING SHOWER
CHANCES FOR THE FIRST PART OF NEXT WEEK STILL LOOKS GOOD. NO CHANGES
TO THE EXTENDED THIS MORNING. FELTON

&&

.AVIATION...AN UPPER TROUGH WILL BE OVER THE REGION TODAY AND
TONIGHT. SOUTHWEST FLOW ALOFT TODAY BECOMING VARIABLE TONIGHT. WEAK
LOW LEVEL ONSHORE FLOW. AIR MASS MOIST AND A SOMEWHAT UNSTABLE.

CEILINGS MOSTLY 4-5K FT THIS MORNING WITH SOME PATCHY LOWER STUFF
AROUND 2K FT...MOSTLY CENTRAL PUGET SOUND AND NORTH COAST. THERE
SHOULD BE SOME DIURNAL IMPROVEMENT LATER TODAY WITH LOW CLOUDS
LIFTING AND BREAKING UP A BIT. SCATTERED SHOWERS WILL CONTINUE.

KSEA...SOUTH WIND 6-10 KNOTS. SCHNEIDER

&&

.MARINE...WEAK ONSHORE FLOW WILL CONTINUE TODAY AND TONIGHT WITH A
WEAK TROUGH OVER THE OFFSHORE WATERS DISSIPATING TONIGHT. LOW LEVEL
FLOW WILL BECOME MORE WESTERLY LATER THURSDAY WITH SMALL CRAFT
ADVISORY WEST WINDS LIKELY RETURNING TO THE CENTRAL AND EASTERN
STRAIT OF JUAN DE FUCA. VARYING AMOUNTS OF ONSHORE FLOW WILL
CONTINUE INTO THE WEEKEND WITH HIGH PRESSURE OVER THE OFFSHORE
WATERS AND LOWER PRESSURE INLAND. SCHNEIDER

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...NONE.

&&

$$

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