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

000
FXUS66 KSEW 261135 AAA
AFDSEW

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SEATTLE WA
334 AM PDT TUE APR 26 2016

UPDATED THE AVIATION SEGMENT.

.SYNOPSIS...A RIDGE WILL MOVE ACROSS WESTERN WASHINGTON TODAY
WITH MAINLY DRY WEATHER. A WEAK FRONT WILL CROSS OREGON TONIGHT
AND WEDNESDAY FOR AREAS OF LIGHT PRECIPITATION MAINLY COAST...
MOUNTAINS...AND SOUTH PART. ANOTHER UPPER RIDGE WILL BRING DRY
WEATHER THURSDAY...FOLLOWED BY AN UPPER TROUGH AND SOME SHOWERS
FRIDAY. DRY WARMER WEATHER IS EXPECTED SATURDAY THROUGH MONDAY.

&&

.SHORT TERM...A PROGRESSIVE UPPER LEVEL RIDGE IS ALONG THE PACIFIC
NORTHWEST COAST EARLY THIS MORNING. THE AIR MASS AHEAD OF THE
RIDGE AXIS IS FAIRLY DRY...WITH LITTLE CLOUD COVER OVER WESTERN
WASHINGTON AT 3 AM. THE AIR MASS OVER THE FORECAST AREA IS
COOL...WITH THE FREEZING LEVEL AROUND 4000 FT AND TEMPERATURES
OVER THE LOWLANDS IN THE MID 30S TO MID 40S.

THE RIDGE WILL MOVE ACROSS THE CASCADES LATE THIS MORNING...AND
THE WEAK FRONTAL SYSTEM CURRENTLY NEARING 130W WILL APPROACH THE
COAST. IT COULD BRING SOME LIGHT PRECIPITATION TO THE COAST AND
OLYMPICS IN THE AFTERNOON...BUT POPS THERE ARE ONLY IN THE LOW END
CHANCE AND IF ANY PRECIPITATION FALLS IT SHOULD AMOUNT TO ONLY A
FEW HUNDREDTHS OF AN INCH. FURTHER INLAND THE DAY WILL START
MOSTLY SUNNY WITH INCREASING HIGH CLOUDS IN THE AFTERNOON. HIGHS
WILL BE IN THE MID 50S TO LOWER 60S.

THE FRONT WILL WEAKEN CONSIDERABLY AS IT MOVES INLAND TONIGHT AND
WEDNESDAY...AND THE CORE OF THE SYSTEM WILL DIG SOUTHEAST ACROSS
OREGON. IT SHOULD BRING AREAS OF MAINLY LIGHT PRECIPITATION TO THE
FORECAST AREA ESPECIALLY THE COAST...MOUNTAINS...AND SOUTH PART.
MUCH OF THE PUGET SOUND REGION AND NORTH INTERIOR HAS A GOOD
CHANCE OF REMAINING DRY AS THIS SYSTEM MOVES THROUGH.

ANOTHER UPPER RIDGE -- EXTENDING NORTHEAST FROM A LARGE UPPER HIGH
WELL WEST OF CALIFORNIA -- WILL MOVE INTO THE OFFSHORE WATERS
WEDNESDAY NIGHT AND THEN ACROSS WESTERN WASHINGTON ON THURSDAY.
THURSDAY SHOULD BE A PARTLY SUNNY AND SLIGHTLY WARMER DAY...WITH
HIGHS IN THE UPPER 50S AND 60S. MCDONNAL

.LONG TERM...AN UPPER SHORTWAVE TROUGH WILL MOVE ACROSS THE AREA
LATER THURSDAY NIGHT AND FRIDAY...FOLLOWED BY MODERATE TO STRONG
ONSHORE FLOW AND PROBABLY A PUGET SOUND CONVERGENCE ZONE. A LARGE
UPPER RIDGE WILL START BUILDING OFFSHORE FRIDAY NIGHT AND
SATURDAY -- MOVING TO AROUND 130W LATE SATURDAY -- WITH DRIER
NORTHWEST FLOW ALOFT OVER WESTERN WASHINGTON. THE RIDGE WILL
BUILD FURTHER AS IT MOVES TO THE COAST SUNDAY AND THEN INLAND ON
MONDAY. SUNDAY AND MONDAY SHOULD BE MOSTLY SUNNY DAYS...WITH HIGHS
IN THE 70S OVER MUCH OF THE WESTERN WASHINGTON LOWLANDS ON MONDAY.
MCDONNAL

&&

.AVIATION...AN UPPER LEVEL RIDGE OVER THE AREA WILL WEAKEN AND
SHIFT E DURING THE DAY TODAY...ALLOWING A WEAK UPPER TROF OVER THE
NERN PAC TO APPROACH THE REGION. NLY FLOW ALOFT WILL BECOME SLY.
CONTD WEAK LOW LEVEL ONSHORE FLOW. THERE WILL BE PATCHY SHALLOW FOG
/VSBYS 1-3SM/ FROM ABOUT KOLM SWD AND BTWN KHQM AND KSHN TIL ABOUT
1700 UTC. OTHERWISE...EXPECT VFR CONDITIONS TO PREVAIL.

KSEA...VFR. WINDS WILL GENERALLY BE LIGHT AND VARIABLE.

&&

.MARINE...
AN AREA OF HIGH PRES ALONG THE WASHINGTON COAST WILL RESULT IN
WEAK ONSHORE FLOW TODAY. EXPECT A WEAKENING OCCLUDED FRONT OVER
THE OFFSHORE WATERS TO DISSIPATE BEFORE REACHING THE COASTAL
WATERS TONIGHT. ONSHORE OR WESTERLY FLOW WILL STRENGTHEN ON WED.


&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 AM PDT EARLY
     THIS MORNING FOR COASTAL WATERS FROM CAPE FLATTERY TO JAMES
     ISLAND 10 TO 60 NM-COASTAL WATERS FROM CAPE FLATTERY TO
     JAMES ISLAND OUT 10 NM-COASTAL WATERS FROM JAMES ISLAND TO
     POINT GRENVILLE 10 TO 60 NM-COASTAL WATERS FROM JAMES
     ISLAND TO POINT GRENVILLE OUT 10 NM-COASTAL WATERS FROM
     POINT GRENVILLE TO CAPE SHOALWATER 10 TO 60 NM-COASTAL
     WATERS FROM POINT GRENVILLE TO CAPE SHOALWATER OUT 10 NM.

&&

$$

WWW.WEATHER.GOV/SEATTLE

YOU CAN SEE AN ILLUSTRATED VERSION OF THIS DISCUSSION AT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML



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