Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 011123
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
330 AM PST MON FEB 1 2016

.SYNOPSIS...A WEAK UPPER LEVEL DISTURBANCE WILL BRING ISOLATED TO
SCATTERED SHOWERS TO THE AREA TODAY. DRIER WEATHER IS FORECAST
TONIGHT INTO TUESDAY WITH A RIDGE. RAIN WILL INCREASE ON WEDNESDAY
AS THE NEXT FRONTAL SYSTEM MOVES INLAND. ANOTHER FRONT WILL ARRIVE
FRIDAY NIGHT INTO SATURDAY.

&&

.SHORT TERM...THE FLOW ALOFT OVER WESTERN WA IS NORTH/NORTHWEST WITH
AN UPPER LEVEL RIDGE OFFSHORE. A WEAK UPPER LEVEL DISTURBANCE WILL
BRING ISOLATED TO SCATTERED SHOWERS TODAY...MAINLY IN THE INTERIOR.
THERE IS STILL A WEAK CONVERGENCE ZONE IN KING COUNTY THIS MORNING.
SHOWERS WILL DIMINISH THIS EVENING AS THE RIDGE MOVES INLAND.

TUESDAY WILL START DRY...THEN INCREASING CLOUDS AND A CHANCE OF RAIN
IN THE EVENING AS A WARM FRONT BRUSHES THE AREA. RAIN WILL INCREASE
IN COVERAGE WEDNESDAY MORNING WITH A COLD FRONT. THE TRAILING UPPER
LEVEL TROUGH WILL MAINTAIN SHOWERS WEDNESDAY NIGHT. SNOW LEVELS IN
THE MOUNTAINS WILL HOVER AROUND 2000-3000 FT WITH A FEW MORE INCHES
OF SNOW EXPECTED.

ANOTHER RIDGE WILL FORM OVER THE PAC NW THURSDAY AFTERNOON AND THIS
SHOULD PUSH THE NEXT WARM FRONT INTO SOUTHERN BRITISH COLUMBIA.
HOWEVER WE COULD SEE LIGHT SPRINKLES ON THE NORTH COAST AND NORTH
CASCADES. A WARMER AIR MASS OVER THE REGION WILL BRING HIGHS NEAR
50. 33

.LONG TERM...AN UPPER LEVEL TROUGH WILL FORM OFFSHORE FRIDAY NIGHT
AND KICK THE RIDGE OVER THE PAC NW FARTHER INLAND. THE COLD FRONT
ASSOCIATED WITH THIS TROUGH WILL BRING RAIN AND MOUNTAIN SNOW
THROUGH SATURDAY MORNING. A WEAK UPPER LEVEL TROUGH WILL PRODUCE A
FEW MORE SHOWERS DURING THE DAY ON SATURDAY. A STRONG UPPER LEVEL
RIDGE WILL BUILD OVER THE REGION ON SUNDAY AND PERSIST THROUGH EARLY
NEXT WEEK FOR A DRY PERIOD OF WEATHER. BOTH GFS AND ECMWF
SOLUTIONS MATCH WELL OVER THE PERIOD. 33

&&

.HYDROLOGY...RIVER FLOODING IS NOT EXPECTED THE NEXT 7 DAYS.

&&

.AVIATION...UPPER RIDGE AND WEAK SURFACE HIGH PRESSURE OVER THE AREA
TODAY AND TONIGHT. WEAK CONVERGENCE OVER THE CENTRAL SOUND
DISSIPATING THIS MORNING.  THE AIR MASS IS MOIST AND SLIGHTLY
UNSTABLE...BECOMING STABLE THIS AFTERNOON. SCATTERED TO BROKEN LAYER
AROUND 2000 FEET WITH ANOTHER SCATTERED TO BROKEN LAYER AROUND 4000
FEET. LOCAL CEILINGS BELOW 1000 FEET OVER CENTRAL SOUND UNTIL 15Z.
LOWER LAYER BECOMING SCATTERED THIS AFTERNOON WITH JUST SOME HIGH
CLOUDS TONIGHT.

KSEA...CEILINGS BELOW 1000 FEET AS CONVERGENCE ZONE DISSIPATES NEAR
THE TERMINAL. CEILINGS IMPROVING AFTER 15Z UP TO NEAR 2000 FEET.
CEILINGS CONTINUING TO IMPROVE THIS AFTERNOON TO NEAR 4000 FEET.
JUST HIGH CLOUDS TONIGHT. LIGHT WIND THIS MORNING...SOUTHEASTERLY
WINDS THIS AFTERNOON AND TONIGHT. FELTON

&&

.MARINE...WEAK HIGH PRESSURE WILL BRIEFLY MOVE OVER THE WATERS
TODAY. A WEAK FRONT WILL APPROACH FROM THE WEST ON TUESDAY MORNING
THEN DISSIPATE OVER THE COASTAL WATERS TUESDAY NIGHT. A STRONGER
FRONTAL SYSTEM WILL MOVE THROUGH THE WATERS WEDNESDAY AND WEDNESDAY
NIGHT. HIGH PRESSURE WILL BUILD OVER THE AREA ON THURSDAY. ANOTHER
VIGOROUS FRONT WILL MOVE THROUGH THE AREA ON FRIDAY. GALE FORCE
WINDS ARE POSSIBLE WITH THIS SYSTEM OVER THE COASTAL WATERS. FELTON

&&

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

&&

$$

WWW.WEATHER.GOV/SEATTLE

AN ILLUSTRATED VERSION OF THIS FORECAST DISCUSSION CAN BE SEEN AT
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