Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 010333
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
830 PM PDT TUE JUN 30 2015

.SYNOPSIS...HIGH PRESSURE ALOFT IS EXPECTED TO REMAIN OVER THE
PACIFIC NORTHWEST INTO EARLY NEXT WEEK FOR MORE QUITE WARM AND DRY
WEATHER.

&&

.SHORT TERM...UPPER HIGH OVER THE GREAT BASIN WITH 500 MB HEIGHTS
OVER WA IN THE 580S WITH WESTERLY FLOW ALOFT THIS EVENING. UPPER LOW
IN THE WESTERN GULF OF ALASKA CONTINUES TO SPIN SHORTWAVES AROUND IT
WITH THE LATEST QUITE WEAK ONE MOVING THROUGH WESTERN CANADA. NOT
MUCH IMPACT ON WESTERN WA THOUGH MAINTAINING LOW LEVEL ONSHORE FLOW.
SUBSIDENCE BEHIND PLAYING KEY ROLE IS DECREASING THE STRATUS AND FOG
NEAR THE BEACHES. MARINE CLOUDINESS WED MORNING LIKELY TO BE QUITE
LIMITED COMPARED TO TUE MORNING AND SHORTLIVED AS A RESULT.

WITH MORE FULL SUNSHINE ON WED...MOST WESTERN WA LOCATIONS SHOULD BE
WARMER PARTICULARLY THOSE AREAS THAT MARINE CLOUDS TUE MORNING SUCH
AS THE COAST. A LOT OF CENTRAL PUGET SOUND SOUTH INTO THE SW
INTERIOR LOCATIONS WERE BETWEEN 85 AND 90 TUE...SOME MAY BE 90 OR A
BIT MORE WED. WITH HIGHER HEIGHTS YET ON THU...THAT MAY BE OUR
WARMEST DAY OF THE WEEK WITH MANY CENTRAL PUGET SOUND SOUTHWARD
LOCATIONS ABOVE 90. MORE 00Z GUIDANCE YET TO COME IN...YET IT
APPEARS THE MAX TEMP FORECASTS MAY NEED TO BE BUMPED UP A BIT.

PROGS GENERALLY AGREE THAT THE PATTERN IS EXPECTED TO RETROGRAD A
BIT WITH THE UPPER RIDGE AXIS MOVING TO AROUND 140W. SO NW FLOW
ALOFT TO DEVELOP LATE IN THE WEEK AND HOLIDAY WEEKEND AS THE GULF OF
ALASKA UPPER LOW TRACKS INTO CANADA...WITH HEIGHTS FALLING A BIT
OVER WA. SO SOME MODERATING TEMPS THOUGH STILL WELL ABOVE AVERAGE
LATER IN THE WEEK. BUEHNER

.LONG TERM...FROM PREVIOUS DISCUSSION...COMPARED TO THE ECMWF AND
CANADIAN MODELS...THE GFS IS SLOWER IN MOVING THE NORTHERN B.C. LOW
OFF TO THE EAST ON SUNDAY AND IN ADDITION BRINGS ANOTHER TROUGH DOWN
THE B.C. COAST ON MONDAY. THIS KEEPS W WA UNDER AN UPPER LEVEL
TROUGH...WITH A COOLER AIR MASS AND LOWER 500 MB HEIGHTS. THE ECMWF
AND CANADIAN MODELS ARE FASTER WITH THE DEPARTING CANADIAN LOW AND
ARE ABLE TO REBUILD THE UPPER LEVEL RIDGE MORE QUICKLY...RESULTING
IN WARMER TEMPERATURES OVER W WA. THE GFS LOOKS A LITTLE TOO STRONG
WITH THE TROUGH SO THE TEMPERATURE FORECAST IS CLOSER TO THE OTHER
MODELS AND THE STATUS QUO FOR LATE THIS WEEK. WEAK ONSHORE FLOW WILL
CONTINUE. KAM

&&

.CLIMATE...AFTER TODAYS SEATAC AIRPORT HIGH OF 87 AND LOW OF 59 AS
OF 5 PM...HERE ARE SOME - WOW - MONTH OF JUNE STATISTICS. THESE NEW
RECORDS WERE NOT EVEN CLOSE.

THE AVERAGE HIGH FOR JUNE WAS 78.9 DEGREES...WARMEST EVER. THE
PREVIOUS RECORD WAS 75.5 DEGREES IN 1992. THE AVERAGE LOW FOR THE
MONTH WAS 56.4 DEGREES...THE OLD RECORD WAS 55.7 DEGREES IN 2013.
AND FOR THE OVERALL AVERAGE MONTHLY TEMPERATURE...JUNE 2015 FINISHED
WITH A NEW ALL-TIME RECORD OF 68.0 DEGREES BREAKING THE OLD JUNE
MONTHLY RECORD SET IN 1969 OF 65.8 DEGREES - AGAIN NOT EVEN CLOSE.

TO PUT THIS WARM JUNE IN PERSPECTIVE...THE MONTH WOULD BE THE 12TH
WARMEST JULY ON RECORD AND THE 9TH WARMEST AUGUST ON RECORD.
SEATAC AIRPORT RECORDS BEGAN IN 1945.

NOT ONLY HAS IT BEEN WARM BUT ALSO QUITE DRY. JUNE 2015 FINISHED
WITH ONLY 0.23 INCHES OF RAIN MAKING IT THE 4TH DRIEST JUNE ON
RECORD. THE MAY 1ST THROUGH JUNE 30TH RAINFALL TOTAL WAS 0.81 INCHES
- THE DRIEST ON RECORD. THE OLD RECORD WAS 1.26 INCHES IN 1992.

NUMEROUS OTHER RECORDS HAVE BEEN BROKEN ACROSS WESTERN WASHINGTON
THIS JUNE. THESE RECORDS WILL BE SUMMARIZED WED IN A PUBLIC
INFORMATION STATEMENT. FELTON/BUEHNER

$$

.AVIATION...WESTERLY FLOW ALOFT OVER WESTERN WASHINGTON THIS EVENING
WILL CONTINUE TONIGHT AND WEDNESDAY...WITH A SMALL UPPER RIDGE
MOVING OVER THE REGION LATE WEDNESDAY. MODERATELY STRONG LOW LEVEL
FLOW THIS EVENING WILL GRADUALLY WEAKEN THROUGH WEDNESDAY. THE AIR
MASS WILL REMAIN DRY EXCEPT FOR A SHALLOW SURFACE-BASED MARINE LAYER.

MARINE STRATUS DISSIPATED ALMOST ENTIRELY EVEN OVER THE COASTAL
WATERS THIS EVENING...LEAVING THE FORECAST AREA UNDER CLEAR SKIES.
STRATUS WILL PROBABLY FORM OVER THE COASTAL WATERS AGAIN TONIGHT...
BUT THERE IS LIKELY TO BE LITTLE IF ANY OVER THE WESTERN WASHINGTON
INTERIOR.

KSEA...NORTHERLY WIND 6-12 KT THROUGH WEDNESDAY. SKIES SHOULD REMAIN
GENERALLY CLEAR.   MCDONNAL

&&

.MARINE...MODERATELY STRONG ONSHORE FLOW IS PRODUCING GALE FORCE
WESTERLIES IN THE CENTRAL STRAIT OF JUAN DE FUCA AND EAST ENTRANCE
STRAIT THIS EVENING. IN ADDITION SMALL CRAFT ADVISORIES CONTINUE
TONIGHT FOR THE OUTER COASTAL WATERS AND ADMIRALTY INLET.

ONSHORE FLOW WILL WEAKEN SOMEWHAT ON WEDNESDAY AS THE PRESSURE
GRADIENT BECOMES NORTHWESTERLY...AND RELATIVELY LIGHT ONSHORE FLOW
WILL CONTINUE THURSDAY AND FRIDAY. A THERMALLY INDUCED TROUGH WILL
PROBABLY DEVELOP OVER WESTERN WASHINGTON THIS WEEKEND...WEAKENING
ONSHORE FLOW EVEN FURTHER.   MCDONNAL

&&

.SEW WATCHES/WARNINGS/ADVISORIES...

WA...NONE.
PZ...GALE WARNING CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA.
     SMALL CRAFT ADVISORY ADMIRALTY INLET AND THE OUTER COASTAL WATERS.

&&

$$

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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