Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 020003 CCA
AFDSEW

AREA FORECAST DISCUSSION...CORRECTED WARNINGS SECTION
NATIONAL WEATHER SERVICE SEATTLE WA
308 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...THE BROAD UPPER LEVEL LONGWAVE RIDGE OVER THE PACIFIC
NORTHWEST WILL REMAIN OVER THE REGION THURSDAY THEN WEAKEN A LITTLE
FRIDAY AND SATURDAY. THE WEAK UPPER LEVEL SHORTWAVE TROUGH NEAR
47N/130W WILL MOVE ACROSS W WA AROUND 12Z THURSDAY BUT WILL HAVE NO
REAL IMPACT ON TEMPERATURES THURSDAY. THE HOT AIR MASS CURRENTLY IN
PLACE OVER THE AREA SHOULD PRODUCE INLAND HIGHS IN THE MID 80S TO
LOWER 90S ON THURSDAY...MUCH LIKE TODAY. PRESSURE GRADIENTS REMAIN
FLAT OR WEAKLY OFFSHORE THIS AFTERNOON...AND WITH NO VISIBLE STRATUS
ON THE COAST...ONLY PATCHY STRATUS IS LIKELY ALONG THE COAST
THURSDAY MORNING WITH NO COOLING HELP INLAND TONIGHT. LOW
TEMPERATURES TONIGHT WILL DROP INTO THE 50S FOR MOST AREAS...BUT
LOWS IN THE SEATTLE...BELLEVUE...TACOMA METRO AREA CORRIDOR AS WELL
AS PARTS OF THE EAST PUGET SOUND LOWLANDS WILL ONLY REACH THE UPPER
50S TO MID 60S. THE HOT TEMPERATURES TODAY THURSDAY COMBINED WITH
THE WARMER METRO CORRIDOR LOWS TONIGHT MERIT KEEPING THE HEAT
ADVISORY IN PLACE THROUGH AT LEAST THURSDAY EVENING.

THURSDAY MORNINGS UPPER LEVEL TROUGH FINALLY SEEMS TO HAVE AN EFFECT
THURSDAY NIGHT...AS WESTERLY ONSHORE FLOW INCREASES BEHIND THE
DEPARTING TROUGH. STRATUS SHOULD RETURN TO THE COAST AND THE ONSHORE
FLOW SHOULD PUSH SOME COOLER AIR PARTWAY INLAND. THE UPPER LEVEL
LONGWAVE RIDGE OVER THE REGION ALSO WEAKENS A LITTLE AS A LARGE LOW
MOVES E ACROSS FAR NORTHERN B.C.  THE COMBINED COOLING EFFECTS
SHOULD ALLOW MAX TEMPS TO COOL INTO THE UPPER 70S AND MAINLY 80S
BOTH FRIDAY AND SATURDAY. WEAK WESTERLY ONSHORE FLOW WILL PREVAIL
THROUGH FRIDAY NIGHT BUT THE MARINE INFLUENCE WILL BE RESTRICTED TO
MAINLY THE COAST. KAM

.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

&&

.AVIATION...A WEAK SYSTEM WILL BRUSH BY TO THE NORTH OF WASHINGTON
TONIGHT. HIGH PRESSURE WILL DOMINATE THE WEATHER PATTERN ACROSS
WESTERN WASHINGTON FOR THE NEXT SEVERAL DAYS. LIGHT WESTERLY FLOW
ALOFT...BECOMING MORE NORTHERLY LATER TONIGHT AND THURSDAY. WEAK LOW
LEVEL ONSHORE FLOW WILL CONTINUE. THE AIR MASS WILL REMAIN DRY
EXCEPT FOR A SHALLOW SURFACE-BASED MARINE LAYER.

STRATUS HAS CLEARED EVEN FROM THE COAST THIS AFTERNOON. MARINE
STRATUS WILL REFORM ALONG THE COAST TONIGHT AND THURSDAY MORNING.
IFR STRATUS MAY AFFECT THE KHQM TERMINAL AT TIMES BY LATER THIS
EVENING. OTHERWISE...SKIES SHOULD BE GENERALLY CLEAR.

KSEA...NORTHERLY WIND 6-11 KT...BECOMING NORTH-NORTHEAST 4-7 KT
AFTER SUNSET. DTM

&&

.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 MARGINAL SMALL CRAFT
ADVISORY WESTERLIES IN THE CENTRAL AND EAST STRAIT DURING THE
EVENING HOURS.

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

&&

.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.

&&

$$

YOU CAN SEE AN ILLUSTRATED VERSION OF THIS FORECAST DISCUSSION AT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML - TEMPORARILY OUT OF
SERVICE BUT SHOULD RETURN BY THE END OF THIS WEEK.



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