Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 020344
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
900 PM PDT WED JUL 1 2015

.SYNOPSIS...HIGH PRESSURE ALOFT WILL REMAIN OVER THE PACIFIC
NORTHWEST INTO EARLY NEXT WEEK FOR HOT AND DRY WEATHER.

&&

.SHORT TERM...A BROAD UPPER LEVEL RIDGE REMAINS OVER THE AREA WITH
HEIGHTS IN THE 590 DM RANGE. A WEAK UPPER LEVEL SHORTWAVE TROUGH
WILL MOVE THROUGH THE AREA EARLY THURSDAY BUT HAVE LITTLE EFFECT ON
THE OBSERVED WEATHER...WITH HOT TEMPERATURES FORECAST. LATE THURSDAY
INTO EARLY FRIDAY...SOME WEAK ONSHORE FLOW IS POSSIBLE MODERATING
THE TEMPERATURES ON FRIDAY BY A FEW DEGREES.

FRIDAY INTO SATURDAY MORNING...STRONGER WEST SOUTHWESTERLY SURFACE
GRADIENTS WILL MAKE FOR SLIGHTLY STRONGER ONSHORE FLOW. IN
ADDITION...AN UPPER LEVEL LOW WILL MOVE OVER NORTHERN BC...PUSHING
UPPER LEVEL HEIGHTS DOWN TO THE 584 DM RANGE. SATURDAY WILL LIKELY
BE THE COOLEST DAY OF THE WEEKEND WITH HIGHS IN THE 80S AROUND THE
PUGET SOUND AREA. ALTHOUGH IT WILL BE SLIGHTLY COOLER...TEMPS WILL
STILL BE ABOVE AVERAGE FOR INDEPENDENCE DAY...AND FOLKS SHOULD
REMEMBER TO BRING WATER AND STAY HYDRATED DURING FESTIVITIES. JSMITH

.LONG TERM...THE GFS AND ECMWF ARE IN PRETTY GOOD AGREEMENT WITH THE
OVERALL PATTERN SUNDAY THROUGH WEDNESDAY...AND THIS EXTENDS TO THE
850 MB TEMPERATURE TREND. SUNDAY LOOKS LIKE ANOTHER HOT DAY. THIS
TIME WE HAVE A SURFACE RIDGE BUILDING BRIEFLY OVER B.C. SATURDAY
NIGHT...BEHIND THE DEPARTING NORTH B.C. UPPER LEVEL LOW. THE SURFACE
RIDGE CAUSES A BRIEF PERIOD OF OFFSHORE FLOW OVER W WA WHICH WILL
CAUSE MAX TEMPS TO SPIKE BACK INTO THE LOWER TO MID 90S OVER MUCH OF
THE INTERIOR ON SUNDAY. THE OFFSHORE FLOW SHOULD EXTEND SUNDAYS HOT
WEATHER TO THE COAST AS WELL...WITH READINGS IN THE 80S TO LOWER
90S. THE OFFSHORE FLOW WILL WEAKEN SUNDAY NIGHT WITH HIGHS BACKING
OFF INTO THE 80S TO NEAR 90 ON MONDAY.

TUESDAY AND WEDNESDAY WILL BE COOLER AS A DRY UPPER LEVEL TROUGH
MOVES S OVER W WA. OH YES...NO RAIN IS EXPECTED FOR THE NEXT SEVEN
DAYS AND OUTSIDE OF COASTAL STRATUS...SKIES SHOULD BE MOSTLY CLEAR.
KAM

&&

CLIMATE...THIS WAS THE WARMEST JUNE IN SEATTLE IN RECORDED HISTORY.
THE AVERAGE TEMPERATURE AT SEA-TAC AIRPORT WAS 67.7
DEGREES...BLOWING SECOND PLACE OUT OF THE WATER AT 64.9 DEGREES SET
IN 1992. IN ADDITION...THIS WAS THE SECOND WARMEST JANUARY THROUGH
JUNE IN SEATTLE HISTORY...WITH THE AVERAGE TEMPERATURE BEING 53.8
DEGREES AT SEA-TAC AIRPORT. THE RECORD STANDS AT 54.1 DEGREES SET IN
1934 WHEN RECORDS WERE KEPT AT THE SEATTLE FEDERAL BUILDING. JSMITH

&&

.AVIATION...A SMALL UPPER RIDGE ALONG THE CASCADES THIS EVENING WILL
MOVE EAST TONIGHT...WITH A SMALL UPPER TROUGH MOVING ACROSS THE
REGION LATE TONIGHT AND THURSDAY MORNING. WESTERLY FLOW ALOFT OVER
WESTERN WASHINGTON WILL CONTINUE...ALONG WITH LIGHT ONSHORE FLOW AT
LOW LEVELS. THE AIR MASS IS DRY EXCEPT FOR SHALLOW SURFACE-BASED
MARINE MOISTURE.

SKIES WILL BE GENERALLY CLEAR THROUGH THURSDAY...EXCEPT FOR AREAS OF
LATE NIGHT AND MORNING STRATUS ALONG THE COAST.

KSEA...NORTH TO NORTHEAST WIND 4-10 KT...BECOMING NORTHWEST MIDDAY
THURSDAY.   MCDONNAL

&&

.MARINE...RELATIVELY WEAK ONSHORE FLOW WILL CONTINUE THROUGH
FRIDAY...WITH HIGH PRESSURE WELL OFFSHORE AND LOWER PRESSURE EAST OF
THE CASCADES. THE RESULT SHOULD BE SMALL CRAFT ADVISORY NORTHWEST
WINDS OVER THE OUTER COASTAL WATERS...AND SMALL CRAFT ADVISORY
WESTERLIES IN THE CENTRAL AND EAST STRAIT DURING THE EVENING HOURS.

A THERMALLY INDUCED TROUGH OF LOW PRESSURE WILL DEVELOP OVER WESTERN
WASHINGTON THIS WEEKEND...AND WINDS SHOULD BE 20 KT OR LESS.
MCDONNAL

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...HEAT ADVISORY FOR SEATTLE...BELLEVUE...
     TACOMA...AND EAST PUGET SOUND LOWLANDS ZONES.
PZ...SMALL CRAFT ADVISORY OUTER COASTAL WATERS...CENTRAL
     AND EAST STRAIT OF JUAN DE FUCA.

&&

$$

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