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 230455
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
900 PM PST SUN FEB 22 2015

.SYNOPSIS...AN UPPER RIDGE WILL KEEP THE WEATHER DRY TONIGHT AND
MONDAY. A WEAK UPPER TROUGH WILL BRING A RETURN TO ONSHORE FLOW ON
TUESDAY. MOIST NORTHWEST FLOW ALOFT WILL PREVAIL WEDNESDAY THROUGH
FRIDAY. DRIER NORTHERLY FLOW ALOFT WILL DEVELOP NEXT WEEKEND.

&&

.SHORT TERM...DRY WEATHER WILL CONTINUE ACROSS WESTERN WA TONIGHT
AND MONDAY WITH HIGH PRES IN THE REGION AND LOW LEVEL OFFSHORE FLOW.
WESTERN WA IS ON THE EASTERN PERIPHERY OF THE RIDGE WHICH IS
CENTERED ALONG 130W. THERE HAS BEEN OCCASIONAL HIGH CLOUDS DRIFTING
DOWN FROM B.C. BUT SATELLITE SHOWS A BREAK TONIGHT. WITH CLEAR SKIES
EXPECT LOWS DIPPING DOWN INTO THE 30S ONCE AGAIN...WITH UPPER 20S IN
THE SHELTERED AREAS LIKE KOLM AND KSHN. MODELS SHOW A FEW MORE HIGH
CLOUDS ON MONDAY WITH TEMPS AGAIN MAINLY IN THE LOWER TO MID 50S.

THE UPPER LEVEL RIDGE WILL WEAKEN OVER WESTERN WA ON TUE AS AN
UPPER LEVEL SHORT WAVE TROUGH TRACKS THROUGH. THIS SYSTEM IS DRY BUT
WE WILL SEE AN INCREASE IN CLOUDS AS THE FLOW FLIPS BACK TO
ONSHORE...ESPECIALLY TUE NIGHT. A WEAK WARM FRONT WILL BRING MORE
CLOUDS AND A CHANCE OF RAIN AS IT REACHES WESTERN WA ON WEDNESDAY. 33

.LONG TERM...PREVIOUS DISCUSSION...MOIST NORTHWEST FLOW ALOFT WILL
PREVAIL WEDNESDAY NIGHT THROUGH ABOUT FRIDAY. THIS PERIOD LOOKS
RAINY AT TIMES AND POPS WERE RAISED A BIT FOR MOST AREAS. TRYING TO
TIME INDIVIDUAL UPPER SHORT WAVES WHICH MIGHT ENHANCE THE RAIN
CHANCES IS TRICKY THIS FAR OUT AND THE FORECAST IS FAIRLY BROADBRUSH
FOR NOW.

DRIER NORTHERLY FLOW ALOFT WILL DEVELOP FRIDAY NIGHT WITH SHOWERS
GENERALLY ENDING FROM NORTH TO SOUTH. THE WEEKEND LOOKS DRY WITH AN
UPPER RIDGE OVER THE NORTHEAST PACIFIC ALTHOUGH SOME RAIN MIGHT
REACH THE AREA LATE SUNDAY AS THE NEXT SYSTEM DROPS DOWN FROM THE
NORTHWEST SCHNEIDER

&&

.HYDROLOGY...FLOODING IS UNLIKELY THE NEXT 7 DAYS.

&&

.AVIATION...A STRONG UPPER RIDGE OFF THE COAST WILL KEEP DRY
NORTHERLY FLOW OVER WASHINGTON TONIGHT AND MONDAY. THE RIDGE WILL
START TO WEAKEN MONDAY AFTERNOON...SO NORTHERLY FLOW WILL WEAKEN.
LOW-LEVEL OFFSHORE FLOW WILL WEAKEN ON MONDAY AS WELL. THE AIR MASS
WILL BE DRY AND STABLE.

FOG ON MONDAY MORNING WILL BE LIMITED TO THE MOST FOG-PRONE
LOCATIONS SUCH AS THE SOUTHWEST INTERIOR AND THE SNOHOMISH VALLEY.
ANY FOG ON MONDAY MORNING WILL BE SHALLOW.

KSEA...OTHER THAN A FEW THIN HIGH CLOUDS SKIES ARE CLEAR. NORTHERLY
WINDS 8-12 KT WILL DIMINISH TO 4-8 KT AFTER MIDNIGHT. NORTHERLY WIND
ON MONDAY WILL GENERALLY REMAIN BELOW 6 KT. NO FOG AT KSEA MONDAY
MORNING. CHB

&&

.MARINE...EASTERLY GRADIENTS WILL GRADUALLY WEAKEN TONIGHT WITH FLAT
GRADIENTS OVER THE AREA MONDAY. ONSHORE FLOW WILL RETURN ON TUESDAY
AND SHOULD BECOME STRONG ENOUGH FOR SMALL CRAFT ADVISORY WEST WINDS
IN THE STRAIT TUESDAY NIGHT. WEAK ONSHORE FLOW WILL CONTINUE
WEDNESDAY AND THURSDAY. MODELS ARE SHOWING STRENGTHENING NORTHEAST
GRADIENTS FRIDAY. CHB

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...NONE.

&&

$$

WWW.WEATHER.GOV/SEATTLE/

YOU CAN SEE AN ILLUSTRATED VERSION OF THIS FORECAST 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.