Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS66 KSEW 011619
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
920 AM 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 RIDGE OVER THE PACIFIC NORTHWEST
WILL BUILD A LITTLE TODAY AS AN UPPER LEVEL SHORTWAVE RIDGE MOVES
THROUGH THE TOP OF THE LONGWAVE RIDGE. GFS 500 MB HEIGHTS RISE TO
AROUND 5900 METERS OVER THE PUGET SOUND REGION. PRESSURE GRADIENTS
ARE ACTUALLY WEAKLY OFFSHORE THIS MORNING. THE ONLY STRATUS AROUND
THIS MORNING IS OVER GRAYS HARBOR...OTHERWISE SKIES WILL REMAIN
CLOUD FREE TODAY. WITH THE FULL DOSE OF SUNSHINE TODAY MAX
TEMPERATURES OVER THE INTERIOR FROM SEATTLE SOUTHWARD ARE EXPECTED
TO REACH THE UPPER 80S AND LOWER 90S. THE N INTERIOR...STRAIT...AND
COAST WILL BE A LITTLE COOLER WITH HIGHS IN THE 70S TO MID 80S.

MOST OF W WA IS EXPECTED TO COOL OFF INTO THE 50S OVERNIGHT...BUT
RELIEF WILL BE LESS IN THE METRO CORRIDOR FROM SEATTLE TO TACOMA AND
EASTWARD ACROSS THE LOWLANDS...WHERE OVERNIGHT LOWS SHOULD ONLY DROP
OFF INTO THE UPPER 50S TO MID 60S. ONSHORE FLOW WILL BE WEAK NW
TONIGHT SO NO STRATUS OR COOLER MARINE AIR MASS IS EXPECTED TO REACH
INLAND AREAS.

THURSDAY IS EXPECTED TO BE SIMILAR TO TODAY WITH THE HOTTEST AREAS
ONCE AGAIN REACHING THE UPPER 80S AND LOWER 90S. A HEAT ADVISORY
WILL BE ISSUED FOR THE AREAS THAT HAVE BOTH THE HOTTEST DAYTIME
TEMPERATURES TODAY AND THURSDAY AND THE WARMEST LOWS OVERNIGHT. THIS
WOULD BE THE SEATTLE BELLEVUE TACOMA AREA AS WELL AS THE EAST PUGET
SOUND LOWLANDS. THE OTHER HOT AREAS OF THE INTERIOR ARE EXPECTED TO
COOL OFF A BIT MORE TONIGHT.

THERE IS A WEAK UPPER LEVEL TROUGH OFFSHORE NEAR 45N/133W THAT
SHOULD TRACK ENE ACROSS NW WA THURSDAY MORNING. IT DOES NOT LOOK
LIKE THIS FEATURE WILL HAVE ANY IMPACT ON MAX TEMPS THURSDAY...BUT
IT DOES LOOK LIKE IT WILL INCREASE THE WESTERLY ONSHORE FLOW
THURSDAY EVENING.

FOR FRIDAY...THE GFS AND ECMWF ARE IN GOOD AGREEMENT IN SLIGHTLY
WEAKENING THE UPPER LEVEL RIDGE OVER THE REGION...AS AN UPPER LEVEL
LOW MOVES ACROSS FAR NORTHERN B.C.  COMBINED WITH THE SOMEWHAT
STRONGER WESTERLY ONSHORE FLOW THURSDAY NIGHT...THIS SHOULD BE
ENOUGH TO COOL MAX TEMPS 3-5 DEGREES...LEAVING MAX TEMPS IN THE 80S.
KAM

.LONG TERM...THE UPPER RIDGE OVER THE AREA WILL RETROGRADE OFFSHORE
THIS WEEKEND AND EARLY NEXT WEEK. HEIGHTS WILL INITIALLY REMAIN HIGH
AND MODELS INDICATE A THERMAL TROUGH DEVELOPING ALONG THE COAST FOR
LOW LEVEL OFFSHORE FLOW. THIS COULD RESULT IN EVEN WARMER
TEMPERATURES WITH LOWER TO MID 90S POSSIBLE BY SUNDAY FOR PARTS OF
THE INTERIOR.

IT LOOKS LIKE THERE WILL BE SOME COOLING EARLY NEXT WEEK AS LOW
LEVEL ONSHORE FLOW INCREASES AGAIN AND UPPER HEIGHTS GRADUALLY LOWER
ACROSS THE REGION. TEMPERATURES WILL STILL BE A LITTLE ABOVE NORMAL
HOWEVER AND THERE IS NO PRECIPITATION EXPECTED THROUGH NEXT
TUESDAY. SCHNEIDER

&&

.AVIATION...HIGH PRESSURE ALOFT OVER THE PAC NW FOR THE NEXT COUPLE
DAYS. A WEAK SYSTEM WILL BRUSH BY TO THE NORTH OF WASHINGTON
TONIGHT. 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.

PATCHY STRATUS ALONG THE SOUTH WASHINGTON COAST WILL DISSIPATE BY
MIDDAY. MARINE STRATUS WILL REFORM ALONG THE COAST TONIGHT AND
THURSDAY MORNING. OTHERWISE...SKIES SHOULD BE GENERALLY CLEAR.

KSEA...NORTHERLY WIND 6-11 KT TODAY...BECOMING NORTH-NORTHEAST 4-7
KT TONIGHT. 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/MCDONNAL


&&

.SEW WATCHES/WARNINGS/ADVISORIES...

WA...NONE.
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.



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.