Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 291059
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
355 AM PDT TUE JUL 29 2014

.SYNOPSIS...HIGH PRESSURE ALOFT WILL BRING WARM SUNNY DAYS TO
WESTERN WASHINGTON THROUGH EARLY NEXT WEEK AT LEAST.

&&

.SHORT TERM...SEATTLE 103...NWS SEATTLE 105...CENTRALIA 107...
OLYMPIA 104...ELMA 104...EVERETT 100...BELLINGHAM 96...ABERDEEN 95.
THESE WERE THE HIGH TEMPERATURES FIVE YEARS AGO ON THIS DAY.
ARGUABLY THE WARMEST DAY ON RECORD IN WESTERN WASHINGTON. THIS WILL
NOT BE THE CASE TODAY ALTHOUGH IT WILL BE ANOTHER DAY OF ABOVE
NORMAL TEMPERATURES FOR MOST OF THE AREA.

SATELLITE IMAGERY SHOWS STRATUS ALONG THE COAST MOVING SLOWLY EAST
THROUGH THE LOWER CHEHALIS VALLEY WITH ANOTHER AREA OF STRATUS
COMING DOWN THE STRAIT. CLEAR SKIES OVER THE REMAINDER OF THE AREA
WITH TEMPERATURES RANGING FROM NEAR 50 TO THE MID 60S IN THE METRO
AREA AT 3 AM.

SURFACE GRADIENTS ARE A LITTLE MORE ONSHORE THIS MORNING VERSUS THE
LAST COUPLE OF MORNINGS BUT STILL NOT VERY STRONG SO DON`T EXPECT
THE STRATUS TO GET MUCH FURTHER THAN SHELTON IN THE SOUTH AND EXPECT
THE STRATUS TO REMAIN IN THE STRAIT TO THE NORTH. NO CHANGE TO THE
UPPER LEVEL PATTERN WITH WESTERN WASHINGTON ON THE BACK SIDE OF A
STRONG UPPER LEVEL RIDGE CENTERED OVER THE ROCKIES. 500 MB HEIGHTS
STILL IN THE MID 580 DMS. MODEL 850 MB TEMPERATURES SIMILAR TO
YESTERDAY...PLUS 15 TO 18C. WITH THE ONSHORE GRADIENTS ONLY SLIGHTLY
STRONGER AND THE TEMPERATURES ALOFT SIMILAR NOT GOING FOR MUCH IN
THE WAY OF COOLING OVER THE INTERIOR TODAY WITH 80S COMMON ONCE
AGAIN AND THE WARMEST LOCATIONS PUSHING 90 DEGREES.

LITTLE CHANGE IN THE PATTERN...BOTH SURFACE AND ALOFT...TONIGHT
THROUGH THURSDAY. 500 MB HEIGHTS REMAIN IN THE MID 580 DMS WITH
SOUTHWESTERLY FLOW ALOFT KEEPING THE POSSIBILITY OF CONVECTION OVER
THE CENTRAL WASHINGTON CASCADES MINIMAL. AT THE SURFACE ANOTHER
SLIGHT INCREASE IN THE ONSHORE FLOW OVERNIGHT INTO WEDNESDAY MORNING
WILL RESULT IN A COUPLE OF DEGREES OF COOLING FOR THE INTERIOR
DURING THE DAY ON WEDNESDAY WITH THE STRATUS BEING A LITTLE MORE
PERSISTENT ALONG THE COAST IN THE MORNING HOURS. THURSDAY LOOKS TO
BE A REPEAT OF WEDNESDAY. EACH NIGHT THE MARINE STRATUS WILL PUSH
WEAKLY INLAND FROM THE COAST JUST REACHING WHIDBEY ISLAND THROUGH
THE STRAIT OF JUAN DE FUCA...AND JUST TO THE SOUTH END OF PUGET
SOUND AND HOOD CANAL THROUGH THE CHEHALIS GAP. THE STRATUS WILL BURN
BACK TO THE COAST QUICKLY EACH MORNING.

.LONG TERM...AFTER A FEW RUNS OF GOOD AGREEMENT IN THE EXTENDED
MODELS A COUPLE OF WRINKLES IN THE PROGS THIS MORNING. THE GFS HAS
CHANGED SLIGHTLY OVER THE WEEKEND WITH SOME WEAK TROUGHINESS OVER
THE AREA. 500 MB HEIGHTS ARE STILL HIGH...MID 580S DMS SO THERE IS
STILL NO PRECIPITATION FORECAST. THE SLIGHT CHANGE IN THE FLOW ALOFT
COULD RESULT IN A LITTLE STRONGER ONSHORE FLOW AND SLIGHTLY COOLER
TEMPERATURES THAN CURRENTLY FORECAST. THE ECMWF BRINGS A SMALL LOW
UP FROM THE SOUTH ON SATURDAY WITH PRECIPITATION OVER THE NORTHERN
PORTION OF THE AREA. THE CANADIAN ALSO HAS THIS FEATURE ALTHOUGH IT
IS MUCH MORE DRIER THAN THE ECMWF SOLUTION. WITH THESE SOLUTIONS
BEING NEW TO THE MODEL RUNS WILL STAY WITH THE MORE CONSISTENT GFS
SOLUTION WHICH KEEPS THE WEAK ONSHORE FLOW PATTERN WITH TEMPERATURES
A FEW DEGREES ABOVE NORMAL GOING INTO THE FIRST PART OF NEXT WEEK.
FELTON

&&

.CLIMATE...A TOTAL OF 0.31 INCHES OF RAIN HAS BEEN REPORTED ON THIS
DAY SINCE RECORDS STARTED AT SEATTLE-TACOMA AIRPORT IN 1945 MAKING
THIS THE DRIEST DAY OF THE YEAR IN TERMS OF TOTAL RAINFALL FOR THE
DAY AT SEA-TAC.

&&

.AVIATION...UPPER RIDGE OVER THE WRN U.S. WILL PERSIST. SOUTHWEST
FLOW ALOFT. SURFACE HIGH PRESSURE OFFSHORE WITH THERMAL LOW PRESSURE
INLAND. AREAS OF FOG AND LOW CLOUDS ALONG THE COAST AND IN THE
STRAIT OF JUAN DE FUCA THIS MORNING...OTHERWISE THE AIR IS DRY AND
STABLE.

KSEA...CLEAR WITH A NLY BREEZE.

&&

.MARINE...HIGH PRESSURE OFFSHORE WITH THERMAL LOW PRESSURE INLAND
WILL RESULT IN A TYPICAL SUMMERTIME NW BREEZE FOR THE COASTAL WATERS
AND A WLY SEA BREEZE IN THE STRAIT EACH AFTERNOON AND EVENING. AREAS
OF LATE NIGHT AND MORNING FOG CAN BE EXPECTED OVER THE COASTAL
WATERS AND IN THE STRAIT OF JUAN DE FUCA.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY IN EFFECT FOR THE TWO SOUTHERN INNERMOST
COASTAL WATERS ZONES...JAMES ISLAND TO POINT GRENVILLE TO CAPE
SHOALWATER...AND FOR THE CENTRAL/EASTERN STRAIT OF JUAN DE FUCA.

&&

$$

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