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000
FXUS66 KSEW 021023
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
323 AM PDT WED SEP 2 2015

.SYNOPSIS...A LARGE UPPER LOW WILL MOVE SLOWLY SOUTH OVER WESTERN
WASHINGTON TONIGHT THROUGH THURSDAY...BRINGING COOL SHOWERY
WEATHER. THERE IS ALSO A CHANCE OF THUNDERSTORMS MAINLY THROUGH
THIS EVENING. THE LOW WILL MOVE SOUTHEAST OF THE AREA BEGINNING
FRIDAY...FOR A GRADUAL DRYING AND WARMING TREND OVER THE WEEKEND.
A WEAK SYSTEM MAY BRING A CHANCE OF SHOWERS EARLY NEXT WEEK.

&&

.SHORT TERM...A 5410 METER UPPER LOW IS ALONG THE CENTRAL BRITISH
COLUMBIA COAST EARLY THIS MORNING...WITH ITS TROUGH AXIS EXTENDING
SOUTH ACROSS THE OFFSHORE WATERS. SCATTERED SHOWERS CONTINUE
ACROSS WESTERN WASHINGTON IN THE MOIST UNSTABLE SOUTHWEST FLOW
AHEAD OF THE TROUGH.

THE UPPER LOW WILL CONTINUE TO DIG SLOWLY SOUTHEAST TODAY AND
TONIGHT...ENDING UP NEAR VANCOUVER ISLAND LATE TONIGHT. THE UPPER
TROUGH WILL MOVE EAST TO THE PACIFIC NORTHWEST COAST OR JUST
INLAND. IT WILL PRODUCE MORE SHOWERS ACROSS THE FORECAST AREA.
THERE ARE CURRENTLY THUNDERSTORMS NEAR THE TROUGH AXIS JUST SOUTH
OF THE UPPER LOW...AND THERE IS CERTAINLY A CHANCE THAT THEY WILL
SPREAD INTO OUR FORECAST AREA THROUGH THIS EVENING. HIGHS TODAY
WILL BE IN THE 60S.

THE UPPER LOW SHOULD TRACK SOUTH INTO WESTERN WASHINGTON THURSDAY
AND THURSDAY NIGHT. INSTABILITY AND MOISTURE WILL PRODUCE
SCATTERED SHOWERS...ESPECIALLY DURING THE AFTERNOON AND EVENING...
BUT PRECIPITATION AMOUNTS SHOULD BE LESS. ON FRIDAY AND FRIDAY
NIGHT THE LOW WILL MOVE INTO OREGON...WITH SHOWERS OVER WESTERN
WASHINGTON TAPERING OFF AND EVENTUALLY BECOMING LIMITED TO THE
CASCADES. HIGHS BOTH DAYS WILL AGAIN BE MAINLY IN THE 60S.

THE SNOW LEVEL WILL BE AROUND 5500 TO 6000 FT TODAY THROUGH
FRIDAY WITH SHOWERS IN THE MOUNTAINS...FALLING AS SNOW ABOVE THE
SNOW LEVEL. MOST OF THE PRECIPITATION WILL OCCUR TODAY THROUGH
THURSDAY NIGHT...WITH SEVERAL INCHES OF ADDITIONAL SNOW OVER THE
HIGH TERRAIN OF THE OLYMPICS AND CASCADES. MCDONNAL

.LONG TERM...THE UPPER LOW WILL MOVE EAST OF THE REGION
SATURDAY...AND A SMALL UPPER RIDGE WILL MOVE OVER THE PACIFIC
NORTHWEST. IT SHOULD BE A MOSTLY SUNNY DAY AND A BIT WARMER. ONCE
AGAIN...CONFIDENCE IS NOT ESPECIALLY HIGH FOR SUNDAY THROUGH
TUESDAY AS MODEL SOLUTIONS HAVE BEEN INCONSISTENT. THE LATEST RUNS
OF THE GFS...EUROPEAN...AND CANADIAN MODELS ARE NOW SHOWING A WEAK
PROGRESSIVE TROUGH MOVING THROUGH THE AREA SUNDAY...FOLLOWED BY
ANOTHER SMALL RIDGE EARLY NEXT WEEK. OUR FORECAST REFLECTS EARLIER
RUNS...WHICH SHOWED A WEAK RIDGE OVER THE AREA THROUGH THE END OF
THE WEEKEND AND A WEAK UPPER TROUGH ARRIVING AROUND MONDAY NIGHT
OR TUESDAY. WE WILL SIT ON THE CURRENT FORECAST FOR NOW GIVEN THE
UNCERTAINTY. MCDONNAL

&&

.AVIATION...SHOWERS CONTINUING OVER THE AREA EARLY THIS
MORNING AS AN UPPER LEVEL TROUGH TO THE NORTHWEST CONTINUES
TO SAG SOUTH. TROUGH WILL CONTINUE TO MOVE SOUTH AND EAST
TODAY KEEPING SHOWERS AND POSSIBLE THUNDERSTORMS IN THE
FORECAST. WIDE VARIETY OF CEILINGS EARLY THIS MORNING. IN
GENERAL MULTIPLE CLOUD LAYERS FROM 1500 TO 7000 FEET. CEILINGS
GENERALLY NEAR 1500 FEET KPAE TO KSEA WITH CEILINGS 5000-
7000 FEET ELSEWHERE. LITTLE CHANGE IN THE CEILINGS THROUGH
THE MORNING. WITH SHOWER ACTIVITY INCREASING 1500 FOOT
CEILINGS WILL BECOME MORE WIDESPREAD. THERE IS A CHANCE OF
THUNDERSTORMS OVER THE NORTHERN PORTION OF THE AREA EARLY
THIS MORNING AND OVER THE ENTIRE AREA LATER THIS MORNING
INTO THIS AFTERNOON. CEILINGS WILL SLOWLY LIFT THIS AFTERNOON INTO
THIS EVENING WITH THE SHOWER ACTIVITY DECREASING THIS EVENING.


KSEA...CEILINGS NEAR 1500 FEET FOR THE MOST PART THOUGH THE
MORNING HOURS. CEILINGS LIFTING INTO THE 3000-4000 FOOT RANGE
THIS AFTERNOON INTO THE EVENING HOURS. SOUTHERLY WINDS 10-15 KNOTS.
FELTON

&&

.MARINE...LOW LEVEL ONSHORE FLOW CONTINUING TODAY. SHOWER
ACTIVITY WILL KEEP THINGS BLUSTERY THROUGH THE AFTERNOON
HOURS BUT WINDS WILL STAY JUST BELOW SMALL CRAFT ADVISORY
CRITERIA. WINDS WILL EASE LATE TONIGHT INTO THURSDAY WITH LOW LEVEL
ONSHORE FLOW CONTINUING. THE ONSHORE FLOW WILL WEAKEN THURSDAY NIGHT
INTO FRIDAY AS A WEAK SURFACE LOW MOVES THROUGH THE OFFSHORE WATERS.
HIGH PRESSURE WILL BUILD OVER THE WATERS FRIDAY INTO THE WEEKEND.
FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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





000
FXUS66 KSEW 021023
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
323 AM PDT WED SEP 2 2015

.SYNOPSIS...A LARGE UPPER LOW WILL MOVE SLOWLY SOUTH OVER WESTERN
WASHINGTON TONIGHT THROUGH THURSDAY...BRINGING COOL SHOWERY
WEATHER. THERE IS ALSO A CHANCE OF THUNDERSTORMS MAINLY THROUGH
THIS EVENING. THE LOW WILL MOVE SOUTHEAST OF THE AREA BEGINNING
FRIDAY...FOR A GRADUAL DRYING AND WARMING TREND OVER THE WEEKEND.
A WEAK SYSTEM MAY BRING A CHANCE OF SHOWERS EARLY NEXT WEEK.

&&

.SHORT TERM...A 5410 METER UPPER LOW IS ALONG THE CENTRAL BRITISH
COLUMBIA COAST EARLY THIS MORNING...WITH ITS TROUGH AXIS EXTENDING
SOUTH ACROSS THE OFFSHORE WATERS. SCATTERED SHOWERS CONTINUE
ACROSS WESTERN WASHINGTON IN THE MOIST UNSTABLE SOUTHWEST FLOW
AHEAD OF THE TROUGH.

THE UPPER LOW WILL CONTINUE TO DIG SLOWLY SOUTHEAST TODAY AND
TONIGHT...ENDING UP NEAR VANCOUVER ISLAND LATE TONIGHT. THE UPPER
TROUGH WILL MOVE EAST TO THE PACIFIC NORTHWEST COAST OR JUST
INLAND. IT WILL PRODUCE MORE SHOWERS ACROSS THE FORECAST AREA.
THERE ARE CURRENTLY THUNDERSTORMS NEAR THE TROUGH AXIS JUST SOUTH
OF THE UPPER LOW...AND THERE IS CERTAINLY A CHANCE THAT THEY WILL
SPREAD INTO OUR FORECAST AREA THROUGH THIS EVENING. HIGHS TODAY
WILL BE IN THE 60S.

THE UPPER LOW SHOULD TRACK SOUTH INTO WESTERN WASHINGTON THURSDAY
AND THURSDAY NIGHT. INSTABILITY AND MOISTURE WILL PRODUCE
SCATTERED SHOWERS...ESPECIALLY DURING THE AFTERNOON AND EVENING...
BUT PRECIPITATION AMOUNTS SHOULD BE LESS. ON FRIDAY AND FRIDAY
NIGHT THE LOW WILL MOVE INTO OREGON...WITH SHOWERS OVER WESTERN
WASHINGTON TAPERING OFF AND EVENTUALLY BECOMING LIMITED TO THE
CASCADES. HIGHS BOTH DAYS WILL AGAIN BE MAINLY IN THE 60S.

THE SNOW LEVEL WILL BE AROUND 5500 TO 6000 FT TODAY THROUGH
FRIDAY WITH SHOWERS IN THE MOUNTAINS...FALLING AS SNOW ABOVE THE
SNOW LEVEL. MOST OF THE PRECIPITATION WILL OCCUR TODAY THROUGH
THURSDAY NIGHT...WITH SEVERAL INCHES OF ADDITIONAL SNOW OVER THE
HIGH TERRAIN OF THE OLYMPICS AND CASCADES. MCDONNAL

.LONG TERM...THE UPPER LOW WILL MOVE EAST OF THE REGION
SATURDAY...AND A SMALL UPPER RIDGE WILL MOVE OVER THE PACIFIC
NORTHWEST. IT SHOULD BE A MOSTLY SUNNY DAY AND A BIT WARMER. ONCE
AGAIN...CONFIDENCE IS NOT ESPECIALLY HIGH FOR SUNDAY THROUGH
TUESDAY AS MODEL SOLUTIONS HAVE BEEN INCONSISTENT. THE LATEST RUNS
OF THE GFS...EUROPEAN...AND CANADIAN MODELS ARE NOW SHOWING A WEAK
PROGRESSIVE TROUGH MOVING THROUGH THE AREA SUNDAY...FOLLOWED BY
ANOTHER SMALL RIDGE EARLY NEXT WEEK. OUR FORECAST REFLECTS EARLIER
RUNS...WHICH SHOWED A WEAK RIDGE OVER THE AREA THROUGH THE END OF
THE WEEKEND AND A WEAK UPPER TROUGH ARRIVING AROUND MONDAY NIGHT
OR TUESDAY. WE WILL SIT ON THE CURRENT FORECAST FOR NOW GIVEN THE
UNCERTAINTY. MCDONNAL

&&

.AVIATION...SHOWERS CONTINUING OVER THE AREA EARLY THIS
MORNING AS AN UPPER LEVEL TROUGH TO THE NORTHWEST CONTINUES
TO SAG SOUTH. TROUGH WILL CONTINUE TO MOVE SOUTH AND EAST
TODAY KEEPING SHOWERS AND POSSIBLE THUNDERSTORMS IN THE
FORECAST. WIDE VARIETY OF CEILINGS EARLY THIS MORNING. IN
GENERAL MULTIPLE CLOUD LAYERS FROM 1500 TO 7000 FEET. CEILINGS
GENERALLY NEAR 1500 FEET KPAE TO KSEA WITH CEILINGS 5000-
7000 FEET ELSEWHERE. LITTLE CHANGE IN THE CEILINGS THROUGH
THE MORNING. WITH SHOWER ACTIVITY INCREASING 1500 FOOT
CEILINGS WILL BECOME MORE WIDESPREAD. THERE IS A CHANCE OF
THUNDERSTORMS OVER THE NORTHERN PORTION OF THE AREA EARLY
THIS MORNING AND OVER THE ENTIRE AREA LATER THIS MORNING
INTO THIS AFTERNOON. CEILINGS WILL SLOWLY LIFT THIS AFTERNOON INTO
THIS EVENING WITH THE SHOWER ACTIVITY DECREASING THIS EVENING.


KSEA...CEILINGS NEAR 1500 FEET FOR THE MOST PART THOUGH THE
MORNING HOURS. CEILINGS LIFTING INTO THE 3000-4000 FOOT RANGE
THIS AFTERNOON INTO THE EVENING HOURS. SOUTHERLY WINDS 10-15 KNOTS.
FELTON

&&

.MARINE...LOW LEVEL ONSHORE FLOW CONTINUING TODAY. SHOWER
ACTIVITY WILL KEEP THINGS BLUSTERY THROUGH THE AFTERNOON
HOURS BUT WINDS WILL STAY JUST BELOW SMALL CRAFT ADVISORY
CRITERIA. WINDS WILL EASE LATE TONIGHT INTO THURSDAY WITH LOW LEVEL
ONSHORE FLOW CONTINUING. THE ONSHORE FLOW WILL WEAKEN THURSDAY NIGHT
INTO FRIDAY AS A WEAK SURFACE LOW MOVES THROUGH THE OFFSHORE WATERS.
HIGH PRESSURE WILL BUILD OVER THE WATERS FRIDAY INTO THE WEEKEND.
FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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




000
FXUS66 KSEW 021023
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
323 AM PDT WED SEP 2 2015

.SYNOPSIS...A LARGE UPPER LOW WILL MOVE SLOWLY SOUTH OVER WESTERN
WASHINGTON TONIGHT THROUGH THURSDAY...BRINGING COOL SHOWERY
WEATHER. THERE IS ALSO A CHANCE OF THUNDERSTORMS MAINLY THROUGH
THIS EVENING. THE LOW WILL MOVE SOUTHEAST OF THE AREA BEGINNING
FRIDAY...FOR A GRADUAL DRYING AND WARMING TREND OVER THE WEEKEND.
A WEAK SYSTEM MAY BRING A CHANCE OF SHOWERS EARLY NEXT WEEK.

&&

.SHORT TERM...A 5410 METER UPPER LOW IS ALONG THE CENTRAL BRITISH
COLUMBIA COAST EARLY THIS MORNING...WITH ITS TROUGH AXIS EXTENDING
SOUTH ACROSS THE OFFSHORE WATERS. SCATTERED SHOWERS CONTINUE
ACROSS WESTERN WASHINGTON IN THE MOIST UNSTABLE SOUTHWEST FLOW
AHEAD OF THE TROUGH.

THE UPPER LOW WILL CONTINUE TO DIG SLOWLY SOUTHEAST TODAY AND
TONIGHT...ENDING UP NEAR VANCOUVER ISLAND LATE TONIGHT. THE UPPER
TROUGH WILL MOVE EAST TO THE PACIFIC NORTHWEST COAST OR JUST
INLAND. IT WILL PRODUCE MORE SHOWERS ACROSS THE FORECAST AREA.
THERE ARE CURRENTLY THUNDERSTORMS NEAR THE TROUGH AXIS JUST SOUTH
OF THE UPPER LOW...AND THERE IS CERTAINLY A CHANCE THAT THEY WILL
SPREAD INTO OUR FORECAST AREA THROUGH THIS EVENING. HIGHS TODAY
WILL BE IN THE 60S.

THE UPPER LOW SHOULD TRACK SOUTH INTO WESTERN WASHINGTON THURSDAY
AND THURSDAY NIGHT. INSTABILITY AND MOISTURE WILL PRODUCE
SCATTERED SHOWERS...ESPECIALLY DURING THE AFTERNOON AND EVENING...
BUT PRECIPITATION AMOUNTS SHOULD BE LESS. ON FRIDAY AND FRIDAY
NIGHT THE LOW WILL MOVE INTO OREGON...WITH SHOWERS OVER WESTERN
WASHINGTON TAPERING OFF AND EVENTUALLY BECOMING LIMITED TO THE
CASCADES. HIGHS BOTH DAYS WILL AGAIN BE MAINLY IN THE 60S.

THE SNOW LEVEL WILL BE AROUND 5500 TO 6000 FT TODAY THROUGH
FRIDAY WITH SHOWERS IN THE MOUNTAINS...FALLING AS SNOW ABOVE THE
SNOW LEVEL. MOST OF THE PRECIPITATION WILL OCCUR TODAY THROUGH
THURSDAY NIGHT...WITH SEVERAL INCHES OF ADDITIONAL SNOW OVER THE
HIGH TERRAIN OF THE OLYMPICS AND CASCADES. MCDONNAL

.LONG TERM...THE UPPER LOW WILL MOVE EAST OF THE REGION
SATURDAY...AND A SMALL UPPER RIDGE WILL MOVE OVER THE PACIFIC
NORTHWEST. IT SHOULD BE A MOSTLY SUNNY DAY AND A BIT WARMER. ONCE
AGAIN...CONFIDENCE IS NOT ESPECIALLY HIGH FOR SUNDAY THROUGH
TUESDAY AS MODEL SOLUTIONS HAVE BEEN INCONSISTENT. THE LATEST RUNS
OF THE GFS...EUROPEAN...AND CANADIAN MODELS ARE NOW SHOWING A WEAK
PROGRESSIVE TROUGH MOVING THROUGH THE AREA SUNDAY...FOLLOWED BY
ANOTHER SMALL RIDGE EARLY NEXT WEEK. OUR FORECAST REFLECTS EARLIER
RUNS...WHICH SHOWED A WEAK RIDGE OVER THE AREA THROUGH THE END OF
THE WEEKEND AND A WEAK UPPER TROUGH ARRIVING AROUND MONDAY NIGHT
OR TUESDAY. WE WILL SIT ON THE CURRENT FORECAST FOR NOW GIVEN THE
UNCERTAINTY. MCDONNAL

&&

.AVIATION...SHOWERS CONTINUING OVER THE AREA EARLY THIS
MORNING AS AN UPPER LEVEL TROUGH TO THE NORTHWEST CONTINUES
TO SAG SOUTH. TROUGH WILL CONTINUE TO MOVE SOUTH AND EAST
TODAY KEEPING SHOWERS AND POSSIBLE THUNDERSTORMS IN THE
FORECAST. WIDE VARIETY OF CEILINGS EARLY THIS MORNING. IN
GENERAL MULTIPLE CLOUD LAYERS FROM 1500 TO 7000 FEET. CEILINGS
GENERALLY NEAR 1500 FEET KPAE TO KSEA WITH CEILINGS 5000-
7000 FEET ELSEWHERE. LITTLE CHANGE IN THE CEILINGS THROUGH
THE MORNING. WITH SHOWER ACTIVITY INCREASING 1500 FOOT
CEILINGS WILL BECOME MORE WIDESPREAD. THERE IS A CHANCE OF
THUNDERSTORMS OVER THE NORTHERN PORTION OF THE AREA EARLY
THIS MORNING AND OVER THE ENTIRE AREA LATER THIS MORNING
INTO THIS AFTERNOON. CEILINGS WILL SLOWLY LIFT THIS AFTERNOON INTO
THIS EVENING WITH THE SHOWER ACTIVITY DECREASING THIS EVENING.


KSEA...CEILINGS NEAR 1500 FEET FOR THE MOST PART THOUGH THE
MORNING HOURS. CEILINGS LIFTING INTO THE 3000-4000 FOOT RANGE
THIS AFTERNOON INTO THE EVENING HOURS. SOUTHERLY WINDS 10-15 KNOTS.
FELTON

&&

.MARINE...LOW LEVEL ONSHORE FLOW CONTINUING TODAY. SHOWER
ACTIVITY WILL KEEP THINGS BLUSTERY THROUGH THE AFTERNOON
HOURS BUT WINDS WILL STAY JUST BELOW SMALL CRAFT ADVISORY
CRITERIA. WINDS WILL EASE LATE TONIGHT INTO THURSDAY WITH LOW LEVEL
ONSHORE FLOW CONTINUING. THE ONSHORE FLOW WILL WEAKEN THURSDAY NIGHT
INTO FRIDAY AS A WEAK SURFACE LOW MOVES THROUGH THE OFFSHORE WATERS.
HIGH PRESSURE WILL BUILD OVER THE WATERS FRIDAY INTO THE WEEKEND.
FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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





000
FXUS66 KSEW 021023
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
323 AM PDT WED SEP 2 2015

.SYNOPSIS...A LARGE UPPER LOW WILL MOVE SLOWLY SOUTH OVER WESTERN
WASHINGTON TONIGHT THROUGH THURSDAY...BRINGING COOL SHOWERY
WEATHER. THERE IS ALSO A CHANCE OF THUNDERSTORMS MAINLY THROUGH
THIS EVENING. THE LOW WILL MOVE SOUTHEAST OF THE AREA BEGINNING
FRIDAY...FOR A GRADUAL DRYING AND WARMING TREND OVER THE WEEKEND.
A WEAK SYSTEM MAY BRING A CHANCE OF SHOWERS EARLY NEXT WEEK.

&&

.SHORT TERM...A 5410 METER UPPER LOW IS ALONG THE CENTRAL BRITISH
COLUMBIA COAST EARLY THIS MORNING...WITH ITS TROUGH AXIS EXTENDING
SOUTH ACROSS THE OFFSHORE WATERS. SCATTERED SHOWERS CONTINUE
ACROSS WESTERN WASHINGTON IN THE MOIST UNSTABLE SOUTHWEST FLOW
AHEAD OF THE TROUGH.

THE UPPER LOW WILL CONTINUE TO DIG SLOWLY SOUTHEAST TODAY AND
TONIGHT...ENDING UP NEAR VANCOUVER ISLAND LATE TONIGHT. THE UPPER
TROUGH WILL MOVE EAST TO THE PACIFIC NORTHWEST COAST OR JUST
INLAND. IT WILL PRODUCE MORE SHOWERS ACROSS THE FORECAST AREA.
THERE ARE CURRENTLY THUNDERSTORMS NEAR THE TROUGH AXIS JUST SOUTH
OF THE UPPER LOW...AND THERE IS CERTAINLY A CHANCE THAT THEY WILL
SPREAD INTO OUR FORECAST AREA THROUGH THIS EVENING. HIGHS TODAY
WILL BE IN THE 60S.

THE UPPER LOW SHOULD TRACK SOUTH INTO WESTERN WASHINGTON THURSDAY
AND THURSDAY NIGHT. INSTABILITY AND MOISTURE WILL PRODUCE
SCATTERED SHOWERS...ESPECIALLY DURING THE AFTERNOON AND EVENING...
BUT PRECIPITATION AMOUNTS SHOULD BE LESS. ON FRIDAY AND FRIDAY
NIGHT THE LOW WILL MOVE INTO OREGON...WITH SHOWERS OVER WESTERN
WASHINGTON TAPERING OFF AND EVENTUALLY BECOMING LIMITED TO THE
CASCADES. HIGHS BOTH DAYS WILL AGAIN BE MAINLY IN THE 60S.

THE SNOW LEVEL WILL BE AROUND 5500 TO 6000 FT TODAY THROUGH
FRIDAY WITH SHOWERS IN THE MOUNTAINS...FALLING AS SNOW ABOVE THE
SNOW LEVEL. MOST OF THE PRECIPITATION WILL OCCUR TODAY THROUGH
THURSDAY NIGHT...WITH SEVERAL INCHES OF ADDITIONAL SNOW OVER THE
HIGH TERRAIN OF THE OLYMPICS AND CASCADES. MCDONNAL

.LONG TERM...THE UPPER LOW WILL MOVE EAST OF THE REGION
SATURDAY...AND A SMALL UPPER RIDGE WILL MOVE OVER THE PACIFIC
NORTHWEST. IT SHOULD BE A MOSTLY SUNNY DAY AND A BIT WARMER. ONCE
AGAIN...CONFIDENCE IS NOT ESPECIALLY HIGH FOR SUNDAY THROUGH
TUESDAY AS MODEL SOLUTIONS HAVE BEEN INCONSISTENT. THE LATEST RUNS
OF THE GFS...EUROPEAN...AND CANADIAN MODELS ARE NOW SHOWING A WEAK
PROGRESSIVE TROUGH MOVING THROUGH THE AREA SUNDAY...FOLLOWED BY
ANOTHER SMALL RIDGE EARLY NEXT WEEK. OUR FORECAST REFLECTS EARLIER
RUNS...WHICH SHOWED A WEAK RIDGE OVER THE AREA THROUGH THE END OF
THE WEEKEND AND A WEAK UPPER TROUGH ARRIVING AROUND MONDAY NIGHT
OR TUESDAY. WE WILL SIT ON THE CURRENT FORECAST FOR NOW GIVEN THE
UNCERTAINTY. MCDONNAL

&&

.AVIATION...SHOWERS CONTINUING OVER THE AREA EARLY THIS
MORNING AS AN UPPER LEVEL TROUGH TO THE NORTHWEST CONTINUES
TO SAG SOUTH. TROUGH WILL CONTINUE TO MOVE SOUTH AND EAST
TODAY KEEPING SHOWERS AND POSSIBLE THUNDERSTORMS IN THE
FORECAST. WIDE VARIETY OF CEILINGS EARLY THIS MORNING. IN
GENERAL MULTIPLE CLOUD LAYERS FROM 1500 TO 7000 FEET. CEILINGS
GENERALLY NEAR 1500 FEET KPAE TO KSEA WITH CEILINGS 5000-
7000 FEET ELSEWHERE. LITTLE CHANGE IN THE CEILINGS THROUGH
THE MORNING. WITH SHOWER ACTIVITY INCREASING 1500 FOOT
CEILINGS WILL BECOME MORE WIDESPREAD. THERE IS A CHANCE OF
THUNDERSTORMS OVER THE NORTHERN PORTION OF THE AREA EARLY
THIS MORNING AND OVER THE ENTIRE AREA LATER THIS MORNING
INTO THIS AFTERNOON. CEILINGS WILL SLOWLY LIFT THIS AFTERNOON INTO
THIS EVENING WITH THE SHOWER ACTIVITY DECREASING THIS EVENING.


KSEA...CEILINGS NEAR 1500 FEET FOR THE MOST PART THOUGH THE
MORNING HOURS. CEILINGS LIFTING INTO THE 3000-4000 FOOT RANGE
THIS AFTERNOON INTO THE EVENING HOURS. SOUTHERLY WINDS 10-15 KNOTS.
FELTON

&&

.MARINE...LOW LEVEL ONSHORE FLOW CONTINUING TODAY. SHOWER
ACTIVITY WILL KEEP THINGS BLUSTERY THROUGH THE AFTERNOON
HOURS BUT WINDS WILL STAY JUST BELOW SMALL CRAFT ADVISORY
CRITERIA. WINDS WILL EASE LATE TONIGHT INTO THURSDAY WITH LOW LEVEL
ONSHORE FLOW CONTINUING. THE ONSHORE FLOW WILL WEAKEN THURSDAY NIGHT
INTO FRIDAY AS A WEAK SURFACE LOW MOVES THROUGH THE OFFSHORE WATERS.
HIGH PRESSURE WILL BUILD OVER THE WATERS FRIDAY INTO THE WEEKEND.
FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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




000
FXUS66 KSEW 020419
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
900 PM PDT TUE PEP 1 2015

.SYNOPSIS...A LARGE UPPER LEVEL LOW WILL MOVE SLOWLY SOUTH OVER
WESTERN WASHINGTON TONIGHT THROUGH THURSDAY. THE LOW WILL BRING
SHOWERS AT TIMES TO THE AREA ALONG WITH A CHANCE OF THUNDERSTORMS
MAINLY WEDNESDAY AFTERNOON AND EVENING. THE UPPER LEVEL LOW WILL
BEGIN SHIFTING SOUTHEASTWARD ON FRIDAY FOR A GRADUAL DRYING AND
WARMING TREND OVER THE WEEKEND. A WEAK SYSTEM MAY BRING A CHANCE OF
SHOWERS EARLY NEXT WEEK.

&&

.SHORT TERM...AN UPPER LEVEL LOW CENTERED ALONG THE CENTRAL B.C.
COAST WILL DRIVE SOUTHEASTWARD TONIGHT AND MEANDER OVER THE PAC NW
WEDNESDAY AND THURSDAY. THE AIR MASS WILL BECOME INCREASINGLY
UNSTABLE WITH SHOWERS CONTINUING ACROSS THE AREA. AN EMBEDDED SHORT
WAVE AND ASSOCIATED FRONTAL BAND IS PRODUCING SOME BETTER ORGANIZED
RAIN BANDS THIS EVENING ACROSS WRN WA. A LULL IN SHOWERS IS
PROBABLE LATER TONIGHT BEFORE THE NEXT SHORT WAVE AND MAIN UPPER
LOW MOVE OVERHEAD.

THE -25C COLD POOL AT 500 MB MOVES OVER WRN WA WEDNESDAY AFTERNOON.
LI`S DROP OFF TO -2 TO -3C INDICATING ENOUGH DIURNAL INSTABILITY
AND A THREAT OF THUNDERSTORMS. VORTICITY ADVECTION WILL AID IN LIFT
BUT OTHER LARGER SCALE FORCING MECHANISMS ARE NOT PRESENT.
THEREFORE...THUNDERSTORMS SHOULD GENERALLY REMAIN ISOLATED EXCEPT
CLOSER TO THE LOW NEAR THE COAST WHERE SCATTERED COVERAGE IS
POSSIBLE. SHOWERS COULD BE BRIEFLY HEAVY. QPF AMOUNTS WILL VARY
CONSIDERABLY THE NEXT COUPLE DAYS WITH THE MOUNTAINS PICKING UP THE
MOST...OVER A HALF INCH THROUGH THURSDAY. HIGHER ELEVATIONS ABOVE
ABOUT 5500 TO 6000 FEET COULD PICK UP A FEW INCHES OF SNOW WITH OVER
6 INCHES POSSIBLE ON THE HIGHER PEAKS OVER THE CASCADES AND
OLYMPICS. A SPECIAL WEATHER STATEMENT REMAINS IN EFFECT HIGHLIGHTING
THIS CHANGE IN THE PATTERN WITH EARLY SEASON SNOWFALL POSSIBLE AT
HIGHER ELEVATIONS.

A FEW SHOWERS MAY LINGER INTO FRIDAY BUT THE UPPER TROUGH AXIS WILL
START TO SHIFT EAST AWAY FROM THE REGION. DECREASING MOISTURE AND
LIFT MEANS LESS SHOWER ACTIVITY AND A BIT MORE SUNSHINE.
TEMPERATURES WILL STAY BELOW AVERAGE ACROSS THE AREA THROUGH FRIDAY
WITH HIGHS MAINLY IN THE MID 60S.

.LONG TERM...THE GFS ECMWF AND CANADIAN ALL AGREE THAT THE UPPER
LEVEL LOW WILL BE OVER W OREGON 18Z FRIDAY AND WILL THEN HEAD
GENERALLY E FRIDAY NIGHT...ENDING UP OVER SE OREGON 12Z SATURDAY.
WITH DRIER N FLOW ALOFT DEVELOPING OVER W WA FRIDAY NIGHT...SHOWERS
WERE PHASED OUT...LEADING TO A MOSTLY SUNNY DAY ON SATURDAY. MAX
TEMPS WILL REBOUND...BUT JUST UP TO AROUND 70.

THE DEPARTING LOW ALLOWS NW FLOW ALOFT OVER THE NE PACIFIC TO SPREAD
IN OVER W WA SUNDAY AND MONDAY. THE MODELS ARE SHOWING MAYBE A
COUPLE OF WEAK UPPER LEVEL SHORTWAVE TROUGHS REACHING W WA SUNDAY
THROUGH MONDAY. THE MODELS JUST TEASE THE AREA WITH THE 0.01 PRECIP
CONTOUR...SO I HAVE KEPT THE DRY FORECAST FOR THE TIME
BEING...ALTHOUGH IT MAY BE TEMPORARY. CLOUDS WERE INCREASED FOR
PARTLY SUNNY SKIES. A STRONGER SHORTWAVE REACHES THE AREA MONDAY
NIGHT OR TUESDAY SO A CHANCE OF SHOWERS WAS ADDED FOR THIS PERIOD.
KAM

&&

.AVIATION...SHOWERS CONTINUE TO LINGER BEHIND THE FRONTAL SYSTEM
THAT WORKED THROUGH THE AREA TUESDAY. MULTIPLE CLOUD LAYERS BETWEEN
2000 AND 10000 FEET. IN GENERAL CEILINGS 5000-7000 FEET EXCEPT NEAR
2000 FEET IN THE VICINITY OF SHOWERS. AN UPPER LEVEL LOW OVER
NORTHERN BRITISH COLUMBIA WILL SAG SOUTH TONIGHT WHILE A WEAK
SECONDARY SURFACE FRONT WILL MOVE THROUGH THE AREA BY 12Z. EXPECT
EVENING SHOWERS TO TRANSITION BACK TO RAIN AND LOWER CEILINGS AS
THIS FEATURE WORKS INLAND. ABUNDANT LOW LEVEL MOISTURE AND LINGERING
SHOWERS AND A CHANCE OF THUNDERSTORMS OVER MUCH OF THE AREA BY
WEDNESDAY AFTERNOON AS THE UPPER LEVEL TROUGH CONTINUES TO WORK
SOUTHWARD.

KSEA...CEILINGS AOA 5000 FEET LOWERING DOWN TO 2000-3000 FEET AFTER
09Z. MVFR CEILINGS CONTINUING THROUGH WEDNESDAY. THUNDERSTORMS ARE
POSSIBLE WEDNESDAY AFTERNOON AS THE UPPER LEVEL LOW MOVES OVERHEAD.
SOUTHERLY WINDS 8 TO 14 KNOTS. FELTON

&&

.MARINE...SHOWERS WILL CONTINUE OVER AREAS WATERS THIS EVENING
BEHIND THE FRONTAL SYSTEM THAT MOVED THROUGH EARLIER TODAY. AN UPPER
LEVEL LOW OVER NORTHERN BRITISH COLUMBIA WILL MOVE SOUTH OVER THE
PACIFIC NORTHWEST TONIGHT AND WEDNESDAY...HELPING BRING INSTABILITY
AND A CHANCE OF THUNDERSTORMS TO THE COASTAL WATERS LATE TONIGHT AND
INLAND WATERS BY WEDNESDAY AFTERNOON. A WEAK SURFACE FRONT WILL
ALSO MOVE SOUTH INTO THE COASTAL WATERS LATER THIS EVENING BRINGING
SMALL CRAFT ADVISORY SOUTHERLIES TO PARTS OF THE COASTAL WATERS AND
THE PUGET SOUND AND HOOD CANAL. THE UPPER LEVEL TROUGH WILL LINGER
OVER THE PACIFIC NORTHWEST INTO FRIDAY FOLLOWED BY WEAK HIGH
PRESSURE LATER FRIDAY INTO SATURDAY. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES NORTHERN AND CENTRAL OUTER COASTAL
     WATERS...PUGET SOUND AND HOOD CANAL...GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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





000
FXUS66 KSEW 020419
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
900 PM PDT TUE PEP 1 2015

.SYNOPSIS...A LARGE UPPER LEVEL LOW WILL MOVE SLOWLY SOUTH OVER
WESTERN WASHINGTON TONIGHT THROUGH THURSDAY. THE LOW WILL BRING
SHOWERS AT TIMES TO THE AREA ALONG WITH A CHANCE OF THUNDERSTORMS
MAINLY WEDNESDAY AFTERNOON AND EVENING. THE UPPER LEVEL LOW WILL
BEGIN SHIFTING SOUTHEASTWARD ON FRIDAY FOR A GRADUAL DRYING AND
WARMING TREND OVER THE WEEKEND. A WEAK SYSTEM MAY BRING A CHANCE OF
SHOWERS EARLY NEXT WEEK.

&&

.SHORT TERM...AN UPPER LEVEL LOW CENTERED ALONG THE CENTRAL B.C.
COAST WILL DRIVE SOUTHEASTWARD TONIGHT AND MEANDER OVER THE PAC NW
WEDNESDAY AND THURSDAY. THE AIR MASS WILL BECOME INCREASINGLY
UNSTABLE WITH SHOWERS CONTINUING ACROSS THE AREA. AN EMBEDDED SHORT
WAVE AND ASSOCIATED FRONTAL BAND IS PRODUCING SOME BETTER ORGANIZED
RAIN BANDS THIS EVENING ACROSS WRN WA. A LULL IN SHOWERS IS
PROBABLE LATER TONIGHT BEFORE THE NEXT SHORT WAVE AND MAIN UPPER
LOW MOVE OVERHEAD.

THE -25C COLD POOL AT 500 MB MOVES OVER WRN WA WEDNESDAY AFTERNOON.
LI`S DROP OFF TO -2 TO -3C INDICATING ENOUGH DIURNAL INSTABILITY
AND A THREAT OF THUNDERSTORMS. VORTICITY ADVECTION WILL AID IN LIFT
BUT OTHER LARGER SCALE FORCING MECHANISMS ARE NOT PRESENT.
THEREFORE...THUNDERSTORMS SHOULD GENERALLY REMAIN ISOLATED EXCEPT
CLOSER TO THE LOW NEAR THE COAST WHERE SCATTERED COVERAGE IS
POSSIBLE. SHOWERS COULD BE BRIEFLY HEAVY. QPF AMOUNTS WILL VARY
CONSIDERABLY THE NEXT COUPLE DAYS WITH THE MOUNTAINS PICKING UP THE
MOST...OVER A HALF INCH THROUGH THURSDAY. HIGHER ELEVATIONS ABOVE
ABOUT 5500 TO 6000 FEET COULD PICK UP A FEW INCHES OF SNOW WITH OVER
6 INCHES POSSIBLE ON THE HIGHER PEAKS OVER THE CASCADES AND
OLYMPICS. A SPECIAL WEATHER STATEMENT REMAINS IN EFFECT HIGHLIGHTING
THIS CHANGE IN THE PATTERN WITH EARLY SEASON SNOWFALL POSSIBLE AT
HIGHER ELEVATIONS.

A FEW SHOWERS MAY LINGER INTO FRIDAY BUT THE UPPER TROUGH AXIS WILL
START TO SHIFT EAST AWAY FROM THE REGION. DECREASING MOISTURE AND
LIFT MEANS LESS SHOWER ACTIVITY AND A BIT MORE SUNSHINE.
TEMPERATURES WILL STAY BELOW AVERAGE ACROSS THE AREA THROUGH FRIDAY
WITH HIGHS MAINLY IN THE MID 60S.

.LONG TERM...THE GFS ECMWF AND CANADIAN ALL AGREE THAT THE UPPER
LEVEL LOW WILL BE OVER W OREGON 18Z FRIDAY AND WILL THEN HEAD
GENERALLY E FRIDAY NIGHT...ENDING UP OVER SE OREGON 12Z SATURDAY.
WITH DRIER N FLOW ALOFT DEVELOPING OVER W WA FRIDAY NIGHT...SHOWERS
WERE PHASED OUT...LEADING TO A MOSTLY SUNNY DAY ON SATURDAY. MAX
TEMPS WILL REBOUND...BUT JUST UP TO AROUND 70.

THE DEPARTING LOW ALLOWS NW FLOW ALOFT OVER THE NE PACIFIC TO SPREAD
IN OVER W WA SUNDAY AND MONDAY. THE MODELS ARE SHOWING MAYBE A
COUPLE OF WEAK UPPER LEVEL SHORTWAVE TROUGHS REACHING W WA SUNDAY
THROUGH MONDAY. THE MODELS JUST TEASE THE AREA WITH THE 0.01 PRECIP
CONTOUR...SO I HAVE KEPT THE DRY FORECAST FOR THE TIME
BEING...ALTHOUGH IT MAY BE TEMPORARY. CLOUDS WERE INCREASED FOR
PARTLY SUNNY SKIES. A STRONGER SHORTWAVE REACHES THE AREA MONDAY
NIGHT OR TUESDAY SO A CHANCE OF SHOWERS WAS ADDED FOR THIS PERIOD.
KAM

&&

.AVIATION...SHOWERS CONTINUE TO LINGER BEHIND THE FRONTAL SYSTEM
THAT WORKED THROUGH THE AREA TUESDAY. MULTIPLE CLOUD LAYERS BETWEEN
2000 AND 10000 FEET. IN GENERAL CEILINGS 5000-7000 FEET EXCEPT NEAR
2000 FEET IN THE VICINITY OF SHOWERS. AN UPPER LEVEL LOW OVER
NORTHERN BRITISH COLUMBIA WILL SAG SOUTH TONIGHT WHILE A WEAK
SECONDARY SURFACE FRONT WILL MOVE THROUGH THE AREA BY 12Z. EXPECT
EVENING SHOWERS TO TRANSITION BACK TO RAIN AND LOWER CEILINGS AS
THIS FEATURE WORKS INLAND. ABUNDANT LOW LEVEL MOISTURE AND LINGERING
SHOWERS AND A CHANCE OF THUNDERSTORMS OVER MUCH OF THE AREA BY
WEDNESDAY AFTERNOON AS THE UPPER LEVEL TROUGH CONTINUES TO WORK
SOUTHWARD.

KSEA...CEILINGS AOA 5000 FEET LOWERING DOWN TO 2000-3000 FEET AFTER
09Z. MVFR CEILINGS CONTINUING THROUGH WEDNESDAY. THUNDERSTORMS ARE
POSSIBLE WEDNESDAY AFTERNOON AS THE UPPER LEVEL LOW MOVES OVERHEAD.
SOUTHERLY WINDS 8 TO 14 KNOTS. FELTON

&&

.MARINE...SHOWERS WILL CONTINUE OVER AREAS WATERS THIS EVENING
BEHIND THE FRONTAL SYSTEM THAT MOVED THROUGH EARLIER TODAY. AN UPPER
LEVEL LOW OVER NORTHERN BRITISH COLUMBIA WILL MOVE SOUTH OVER THE
PACIFIC NORTHWEST TONIGHT AND WEDNESDAY...HELPING BRING INSTABILITY
AND A CHANCE OF THUNDERSTORMS TO THE COASTAL WATERS LATE TONIGHT AND
INLAND WATERS BY WEDNESDAY AFTERNOON. A WEAK SURFACE FRONT WILL
ALSO MOVE SOUTH INTO THE COASTAL WATERS LATER THIS EVENING BRINGING
SMALL CRAFT ADVISORY SOUTHERLIES TO PARTS OF THE COASTAL WATERS AND
THE PUGET SOUND AND HOOD CANAL. THE UPPER LEVEL TROUGH WILL LINGER
OVER THE PACIFIC NORTHWEST INTO FRIDAY FOLLOWED BY WEAK HIGH
PRESSURE LATER FRIDAY INTO SATURDAY. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES NORTHERN AND CENTRAL OUTER COASTAL
     WATERS...PUGET SOUND AND HOOD CANAL...GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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




000
FXUS66 KSEW 020419
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
900 PM PDT TUE PEP 1 2015

.SYNOPSIS...A LARGE UPPER LEVEL LOW WILL MOVE SLOWLY SOUTH OVER
WESTERN WASHINGTON TONIGHT THROUGH THURSDAY. THE LOW WILL BRING
SHOWERS AT TIMES TO THE AREA ALONG WITH A CHANCE OF THUNDERSTORMS
MAINLY WEDNESDAY AFTERNOON AND EVENING. THE UPPER LEVEL LOW WILL
BEGIN SHIFTING SOUTHEASTWARD ON FRIDAY FOR A GRADUAL DRYING AND
WARMING TREND OVER THE WEEKEND. A WEAK SYSTEM MAY BRING A CHANCE OF
SHOWERS EARLY NEXT WEEK.

&&

.SHORT TERM...AN UPPER LEVEL LOW CENTERED ALONG THE CENTRAL B.C.
COAST WILL DRIVE SOUTHEASTWARD TONIGHT AND MEANDER OVER THE PAC NW
WEDNESDAY AND THURSDAY. THE AIR MASS WILL BECOME INCREASINGLY
UNSTABLE WITH SHOWERS CONTINUING ACROSS THE AREA. AN EMBEDDED SHORT
WAVE AND ASSOCIATED FRONTAL BAND IS PRODUCING SOME BETTER ORGANIZED
RAIN BANDS THIS EVENING ACROSS WRN WA. A LULL IN SHOWERS IS
PROBABLE LATER TONIGHT BEFORE THE NEXT SHORT WAVE AND MAIN UPPER
LOW MOVE OVERHEAD.

THE -25C COLD POOL AT 500 MB MOVES OVER WRN WA WEDNESDAY AFTERNOON.
LI`S DROP OFF TO -2 TO -3C INDICATING ENOUGH DIURNAL INSTABILITY
AND A THREAT OF THUNDERSTORMS. VORTICITY ADVECTION WILL AID IN LIFT
BUT OTHER LARGER SCALE FORCING MECHANISMS ARE NOT PRESENT.
THEREFORE...THUNDERSTORMS SHOULD GENERALLY REMAIN ISOLATED EXCEPT
CLOSER TO THE LOW NEAR THE COAST WHERE SCATTERED COVERAGE IS
POSSIBLE. SHOWERS COULD BE BRIEFLY HEAVY. QPF AMOUNTS WILL VARY
CONSIDERABLY THE NEXT COUPLE DAYS WITH THE MOUNTAINS PICKING UP THE
MOST...OVER A HALF INCH THROUGH THURSDAY. HIGHER ELEVATIONS ABOVE
ABOUT 5500 TO 6000 FEET COULD PICK UP A FEW INCHES OF SNOW WITH OVER
6 INCHES POSSIBLE ON THE HIGHER PEAKS OVER THE CASCADES AND
OLYMPICS. A SPECIAL WEATHER STATEMENT REMAINS IN EFFECT HIGHLIGHTING
THIS CHANGE IN THE PATTERN WITH EARLY SEASON SNOWFALL POSSIBLE AT
HIGHER ELEVATIONS.

A FEW SHOWERS MAY LINGER INTO FRIDAY BUT THE UPPER TROUGH AXIS WILL
START TO SHIFT EAST AWAY FROM THE REGION. DECREASING MOISTURE AND
LIFT MEANS LESS SHOWER ACTIVITY AND A BIT MORE SUNSHINE.
TEMPERATURES WILL STAY BELOW AVERAGE ACROSS THE AREA THROUGH FRIDAY
WITH HIGHS MAINLY IN THE MID 60S.

.LONG TERM...THE GFS ECMWF AND CANADIAN ALL AGREE THAT THE UPPER
LEVEL LOW WILL BE OVER W OREGON 18Z FRIDAY AND WILL THEN HEAD
GENERALLY E FRIDAY NIGHT...ENDING UP OVER SE OREGON 12Z SATURDAY.
WITH DRIER N FLOW ALOFT DEVELOPING OVER W WA FRIDAY NIGHT...SHOWERS
WERE PHASED OUT...LEADING TO A MOSTLY SUNNY DAY ON SATURDAY. MAX
TEMPS WILL REBOUND...BUT JUST UP TO AROUND 70.

THE DEPARTING LOW ALLOWS NW FLOW ALOFT OVER THE NE PACIFIC TO SPREAD
IN OVER W WA SUNDAY AND MONDAY. THE MODELS ARE SHOWING MAYBE A
COUPLE OF WEAK UPPER LEVEL SHORTWAVE TROUGHS REACHING W WA SUNDAY
THROUGH MONDAY. THE MODELS JUST TEASE THE AREA WITH THE 0.01 PRECIP
CONTOUR...SO I HAVE KEPT THE DRY FORECAST FOR THE TIME
BEING...ALTHOUGH IT MAY BE TEMPORARY. CLOUDS WERE INCREASED FOR
PARTLY SUNNY SKIES. A STRONGER SHORTWAVE REACHES THE AREA MONDAY
NIGHT OR TUESDAY SO A CHANCE OF SHOWERS WAS ADDED FOR THIS PERIOD.
KAM

&&

.AVIATION...SHOWERS CONTINUE TO LINGER BEHIND THE FRONTAL SYSTEM
THAT WORKED THROUGH THE AREA TUESDAY. MULTIPLE CLOUD LAYERS BETWEEN
2000 AND 10000 FEET. IN GENERAL CEILINGS 5000-7000 FEET EXCEPT NEAR
2000 FEET IN THE VICINITY OF SHOWERS. AN UPPER LEVEL LOW OVER
NORTHERN BRITISH COLUMBIA WILL SAG SOUTH TONIGHT WHILE A WEAK
SECONDARY SURFACE FRONT WILL MOVE THROUGH THE AREA BY 12Z. EXPECT
EVENING SHOWERS TO TRANSITION BACK TO RAIN AND LOWER CEILINGS AS
THIS FEATURE WORKS INLAND. ABUNDANT LOW LEVEL MOISTURE AND LINGERING
SHOWERS AND A CHANCE OF THUNDERSTORMS OVER MUCH OF THE AREA BY
WEDNESDAY AFTERNOON AS THE UPPER LEVEL TROUGH CONTINUES TO WORK
SOUTHWARD.

KSEA...CEILINGS AOA 5000 FEET LOWERING DOWN TO 2000-3000 FEET AFTER
09Z. MVFR CEILINGS CONTINUING THROUGH WEDNESDAY. THUNDERSTORMS ARE
POSSIBLE WEDNESDAY AFTERNOON AS THE UPPER LEVEL LOW MOVES OVERHEAD.
SOUTHERLY WINDS 8 TO 14 KNOTS. FELTON

&&

.MARINE...SHOWERS WILL CONTINUE OVER AREAS WATERS THIS EVENING
BEHIND THE FRONTAL SYSTEM THAT MOVED THROUGH EARLIER TODAY. AN UPPER
LEVEL LOW OVER NORTHERN BRITISH COLUMBIA WILL MOVE SOUTH OVER THE
PACIFIC NORTHWEST TONIGHT AND WEDNESDAY...HELPING BRING INSTABILITY
AND A CHANCE OF THUNDERSTORMS TO THE COASTAL WATERS LATE TONIGHT AND
INLAND WATERS BY WEDNESDAY AFTERNOON. A WEAK SURFACE FRONT WILL
ALSO MOVE SOUTH INTO THE COASTAL WATERS LATER THIS EVENING BRINGING
SMALL CRAFT ADVISORY SOUTHERLIES TO PARTS OF THE COASTAL WATERS AND
THE PUGET SOUND AND HOOD CANAL. THE UPPER LEVEL TROUGH WILL LINGER
OVER THE PACIFIC NORTHWEST INTO FRIDAY FOLLOWED BY WEAK HIGH
PRESSURE LATER FRIDAY INTO SATURDAY. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES NORTHERN AND CENTRAL OUTER COASTAL
     WATERS...PUGET SOUND AND HOOD CANAL...GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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





000
FXUS66 KSEW 020419
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
900 PM PDT TUE PEP 1 2015

.SYNOPSIS...A LARGE UPPER LEVEL LOW WILL MOVE SLOWLY SOUTH OVER
WESTERN WASHINGTON TONIGHT THROUGH THURSDAY. THE LOW WILL BRING
SHOWERS AT TIMES TO THE AREA ALONG WITH A CHANCE OF THUNDERSTORMS
MAINLY WEDNESDAY AFTERNOON AND EVENING. THE UPPER LEVEL LOW WILL
BEGIN SHIFTING SOUTHEASTWARD ON FRIDAY FOR A GRADUAL DRYING AND
WARMING TREND OVER THE WEEKEND. A WEAK SYSTEM MAY BRING A CHANCE OF
SHOWERS EARLY NEXT WEEK.

&&

.SHORT TERM...AN UPPER LEVEL LOW CENTERED ALONG THE CENTRAL B.C.
COAST WILL DRIVE SOUTHEASTWARD TONIGHT AND MEANDER OVER THE PAC NW
WEDNESDAY AND THURSDAY. THE AIR MASS WILL BECOME INCREASINGLY
UNSTABLE WITH SHOWERS CONTINUING ACROSS THE AREA. AN EMBEDDED SHORT
WAVE AND ASSOCIATED FRONTAL BAND IS PRODUCING SOME BETTER ORGANIZED
RAIN BANDS THIS EVENING ACROSS WRN WA. A LULL IN SHOWERS IS
PROBABLE LATER TONIGHT BEFORE THE NEXT SHORT WAVE AND MAIN UPPER
LOW MOVE OVERHEAD.

THE -25C COLD POOL AT 500 MB MOVES OVER WRN WA WEDNESDAY AFTERNOON.
LI`S DROP OFF TO -2 TO -3C INDICATING ENOUGH DIURNAL INSTABILITY
AND A THREAT OF THUNDERSTORMS. VORTICITY ADVECTION WILL AID IN LIFT
BUT OTHER LARGER SCALE FORCING MECHANISMS ARE NOT PRESENT.
THEREFORE...THUNDERSTORMS SHOULD GENERALLY REMAIN ISOLATED EXCEPT
CLOSER TO THE LOW NEAR THE COAST WHERE SCATTERED COVERAGE IS
POSSIBLE. SHOWERS COULD BE BRIEFLY HEAVY. QPF AMOUNTS WILL VARY
CONSIDERABLY THE NEXT COUPLE DAYS WITH THE MOUNTAINS PICKING UP THE
MOST...OVER A HALF INCH THROUGH THURSDAY. HIGHER ELEVATIONS ABOVE
ABOUT 5500 TO 6000 FEET COULD PICK UP A FEW INCHES OF SNOW WITH OVER
6 INCHES POSSIBLE ON THE HIGHER PEAKS OVER THE CASCADES AND
OLYMPICS. A SPECIAL WEATHER STATEMENT REMAINS IN EFFECT HIGHLIGHTING
THIS CHANGE IN THE PATTERN WITH EARLY SEASON SNOWFALL POSSIBLE AT
HIGHER ELEVATIONS.

A FEW SHOWERS MAY LINGER INTO FRIDAY BUT THE UPPER TROUGH AXIS WILL
START TO SHIFT EAST AWAY FROM THE REGION. DECREASING MOISTURE AND
LIFT MEANS LESS SHOWER ACTIVITY AND A BIT MORE SUNSHINE.
TEMPERATURES WILL STAY BELOW AVERAGE ACROSS THE AREA THROUGH FRIDAY
WITH HIGHS MAINLY IN THE MID 60S.

.LONG TERM...THE GFS ECMWF AND CANADIAN ALL AGREE THAT THE UPPER
LEVEL LOW WILL BE OVER W OREGON 18Z FRIDAY AND WILL THEN HEAD
GENERALLY E FRIDAY NIGHT...ENDING UP OVER SE OREGON 12Z SATURDAY.
WITH DRIER N FLOW ALOFT DEVELOPING OVER W WA FRIDAY NIGHT...SHOWERS
WERE PHASED OUT...LEADING TO A MOSTLY SUNNY DAY ON SATURDAY. MAX
TEMPS WILL REBOUND...BUT JUST UP TO AROUND 70.

THE DEPARTING LOW ALLOWS NW FLOW ALOFT OVER THE NE PACIFIC TO SPREAD
IN OVER W WA SUNDAY AND MONDAY. THE MODELS ARE SHOWING MAYBE A
COUPLE OF WEAK UPPER LEVEL SHORTWAVE TROUGHS REACHING W WA SUNDAY
THROUGH MONDAY. THE MODELS JUST TEASE THE AREA WITH THE 0.01 PRECIP
CONTOUR...SO I HAVE KEPT THE DRY FORECAST FOR THE TIME
BEING...ALTHOUGH IT MAY BE TEMPORARY. CLOUDS WERE INCREASED FOR
PARTLY SUNNY SKIES. A STRONGER SHORTWAVE REACHES THE AREA MONDAY
NIGHT OR TUESDAY SO A CHANCE OF SHOWERS WAS ADDED FOR THIS PERIOD.
KAM

&&

.AVIATION...SHOWERS CONTINUE TO LINGER BEHIND THE FRONTAL SYSTEM
THAT WORKED THROUGH THE AREA TUESDAY. MULTIPLE CLOUD LAYERS BETWEEN
2000 AND 10000 FEET. IN GENERAL CEILINGS 5000-7000 FEET EXCEPT NEAR
2000 FEET IN THE VICINITY OF SHOWERS. AN UPPER LEVEL LOW OVER
NORTHERN BRITISH COLUMBIA WILL SAG SOUTH TONIGHT WHILE A WEAK
SECONDARY SURFACE FRONT WILL MOVE THROUGH THE AREA BY 12Z. EXPECT
EVENING SHOWERS TO TRANSITION BACK TO RAIN AND LOWER CEILINGS AS
THIS FEATURE WORKS INLAND. ABUNDANT LOW LEVEL MOISTURE AND LINGERING
SHOWERS AND A CHANCE OF THUNDERSTORMS OVER MUCH OF THE AREA BY
WEDNESDAY AFTERNOON AS THE UPPER LEVEL TROUGH CONTINUES TO WORK
SOUTHWARD.

KSEA...CEILINGS AOA 5000 FEET LOWERING DOWN TO 2000-3000 FEET AFTER
09Z. MVFR CEILINGS CONTINUING THROUGH WEDNESDAY. THUNDERSTORMS ARE
POSSIBLE WEDNESDAY AFTERNOON AS THE UPPER LEVEL LOW MOVES OVERHEAD.
SOUTHERLY WINDS 8 TO 14 KNOTS. FELTON

&&

.MARINE...SHOWERS WILL CONTINUE OVER AREAS WATERS THIS EVENING
BEHIND THE FRONTAL SYSTEM THAT MOVED THROUGH EARLIER TODAY. AN UPPER
LEVEL LOW OVER NORTHERN BRITISH COLUMBIA WILL MOVE SOUTH OVER THE
PACIFIC NORTHWEST TONIGHT AND WEDNESDAY...HELPING BRING INSTABILITY
AND A CHANCE OF THUNDERSTORMS TO THE COASTAL WATERS LATE TONIGHT AND
INLAND WATERS BY WEDNESDAY AFTERNOON. A WEAK SURFACE FRONT WILL
ALSO MOVE SOUTH INTO THE COASTAL WATERS LATER THIS EVENING BRINGING
SMALL CRAFT ADVISORY SOUTHERLIES TO PARTS OF THE COASTAL WATERS AND
THE PUGET SOUND AND HOOD CANAL. THE UPPER LEVEL TROUGH WILL LINGER
OVER THE PACIFIC NORTHWEST INTO FRIDAY FOLLOWED BY WEAK HIGH
PRESSURE LATER FRIDAY INTO SATURDAY. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES NORTHERN AND CENTRAL OUTER COASTAL
     WATERS...PUGET SOUND AND HOOD CANAL...GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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




000
FXUS66 KSEW 012252
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
352 PM PDT TUE PEP 1 2015

.SYNOPSIS...A LARGE UPPER LEVEL LOW WILL MOVE SLOWLY SOUTH OVER
WESTERN WASHINGTON TONIGHT THROUGH THURSDAY THEN DROP DOWN OVER
OREGON ON FRIDAY. THE LOW WILL BRING SHOWERS AT TIMES TO THE AREA
ALONG WITH A CHANCE OF THUNDERSTORMS MAINLY WEDNESDAY AFTERNOON AND
EVENING. THE UPPER LEVEL LOW WILL MOVE EAST FRIDAY NIGHT FOR A
GRADUAL DRYING AND WARMING TREND OVER THE WEEKEND. A WEAK SYSTEM MAY
BRING A CHANCE OF SHOWERS EARLY NEXT WEEK.

&&

.SHORT TERM...RADAR SHOWS AREAS OF LIGHT RAIN OVER MOST OF W WA THIS
AFTERNOON. IR SATELLITE IMAGERY SHOWS AN UPPER LEVEL SHORTWAVE
TROUGH JUST W OF THE COAST CHARGING INLAND. THE PRECIPITATION WILL
BECOME MORE SHOWERY THIS EVENING AFTER THE SHORTWAVE TROUGH MOVES E
OF THE AREA.

THE MAIN PLAYER THROUGH FRIDAY NIGHT WILL BE THE COLD UPPER LEVEL
LOW CENTERED OVER THE CENTRAL B.C. COAST AT 3 PM. THE LOW WILL MOVE
DOWN OVER SW B.C. ON WEDNESDAY. A WEAK SHORTWAVE TROUGH ROTATING
AROUND THE LOW EXTENDED SW FROM THE N TIP OF VANCOUVER ISLAND AT 3
PM...AND IS EXPECTED TO BRING SCATTERED SHOWERS TO W WA LATER
TONIGHT.

AS THE LOW CENTER MOVES DOWN OVER SW B.C. ON WEDNESDAY THE UNSTABLE
SHOWERY AIR MASS CURRENTLY IN THE SW QUADRANT OF THE LOW WILL REACH
W WA FOR AREAS OF SHOWERS. THE GFS STILL SHOWS LIFTED INDICES -1 TO -
2 WITH SOME SMALL POCKETS OF -3. ISOLATED THUNDERSTORMS HAVE BEEN
ADDED TO THE COASTAL WATERS LATE TONIGHT...EXTENDING INLAND OVER THE
WA COAST WEDNESDAY MORNING. A CHANCE OF THUNDERSTORMS CONTINUES FOR
W WA WEST OF THE CASCADES WEDNESDAY AFTERNOON AND EVENING.

THE UPPER LEVEL LOW WILL MOVE DOWN OVER W WA ON THURSDAY THEN S OVER
OREGON ON FRIDAY. THERE ARE MINOR DIFFERENCES IN THE MODEL FORECAST
TRACK OF THE LOW AS IT HEADS S...WHICH WILL IMPACT WHERE THE
GREATEST CHANCE OF SHOWERS ENDS UP. IT MAY BE NECESSARY TO ADD A
CHANCE OF THUNDERSTORMS TO THURSDAY AFTERNOON. BUT OVERALL IT WILL
BE COOL WITH SCATTERED SHOWERS. MAX TEMPS WILL BE IN THE 60S WHICH
IS ABOUT 10 DEGREES COOLER THAN NORMAL. KAM

.LONG TERM...THE GFS ECMWF AND CANADIAN ALL AGREE THAT THE UPPER
LEVEL LOW WILL BE OVER W OREGON 18Z FRIDAY AND WILL THEN HEAD
GENERALLY E FRIDAY NIGHT...ENDING UP OVER SE OREGON 12Z SATURDAY.
WITH DRIER N FLOW ALOFT DEVELOPING OVER W WA FRIDAY NIGHT...SHOWERS
WERE PHASED OUT...LEADING TO A MOSTLY SUNNY DAY ON SATURDAY. MAX
TEMPS WILL REBOUND...BUT JUST UP TO AROUND 70.

THE DEPARTING LOW ALLOWS NW FLOW ALOFT OVER THE NE PACIFIC TO SPREAD
IN OVER W WA SUNDAY AND MONDAY. THE MODELS ARE SHOWING MAYBE A
COUPLE OF WEAK UPPER LEVEL SHORTWAVE TROUGHS REACHING W WA SUNDAY
THROUGH MONDAY. THE MODELS JUST TEASE THE AREA WITH THE 0.01 PRECIP
CONTOUR...SO I HAVE KEPT THE DRY FORECAST FOR THE TIME
BEING...ALTHOUGH IT MAY BE TEMPORARY. CLOUDS WERE INCREASED FOR
PARTLY SUNNY SKIES. A STRONGER SHORTWAVE REACHES THE AREA MONDAY
NIGHT OR TUESDAY SO A CHANCE OF SHOWERS WAS ADDED FOR THIS PERIOD.
KAM

&&

.AVIATION...SHOWERS CONTINUE TO LINGER BEHIND THE FRONTAL SYSTEM
THAT WORKED THROUGH THE AREA DURING THE DAY. CEILINGS HAVE GENERALLY
IMPROVED TO VFR LEVELS...EXPECT WITH SHOWERS WHERE CEILINGS ARE MVFR
AND POSSIBLY IFR. SHOWERS AND BREEZY CONDITIONS WILL LINGER THIS
EVENING. THE UPPER LEVEL LOW OVER NORTHERN BRITISH COLUMBIA WILL SAG
SOUTH TONIGHT WHILE A WEAK SECONDARY SURFACE FRONT WILL MOVE ONTO
THE NORTH COAST AROUND 06Z AND SOUTH AND EAST AFTER MIDNIGHT. EXPECT
EVENING SHOWERS TO TRANSITION BACK TO RAIN AND LOWER CEILINGS AS
THIS FEATURE WORKS INLAND. ABUNDANT LOW LEVEL MOISTURE AND LINGERING
SHOWERS AND A CHANCE OF THUNDERSTORMS OVER MUCH OF THE AREA BY
WEDNESDAY AFTERNOON AS THE UPPER LEVEL TROUGH CONTINUES TO WORK
SOUTHWARD.

KSEA...CLOUDY WITH SHOWERS AT TIMES THIS EVENING. CIGS WILL
GENERALLY REMAIN VFR THIS EVENING...LOWERING TO MVFR WITH
SHOWERS. A WEAK FRONT WILL BRING STEADIER RAIN AND MVFR CIGS
AFTER MIDNIGHT. THUNDERSTORM ARE POSSIBLE WEDNESDAY AFTERNOON
AS THE UPPER LEVEL LOW MOVES OVERHEAD. SOUTHERLY WINDS 6 TO 10
KNOTS.

&&

.MARINE...SHOWERS WILL CONTINUE OVER AREAS WATERS THIS EVENING BEHIND
THE FRONTAL SYSTEM THAT MOVED THROUGH EARLIER TODAY. AN UPPER LEVEL
LOW OVER NORTHERN BRITISH COLUMBIA WILL MOVE SOUTH OVER THE PACIFIC
NORTHWEST TONIGHT AND WEDNESDAY...HELPING BRING INSTABILITY AND A
CHANCE OF THUNDERSTORMS TO THE COASTAL WATERS LATE TONIGHT AND
INLAND WATERS BY WEDNESDAY AFTERNOON. A WEAK SURFACE FRONT WILL
ALSO MOVE SOUTH INTO THE COASTAL WATERS LATER THIS EVENING BRINGING
SMALL CRAFT ADVISORY SOUTHERLIES AND RAIN  TO THE COASTAL WATERS
OVERNIGHT. THE UPPER LEVEL TROUGH WILL LINGER OVER THE PACIFIC
NORTHWEST INTO SATURDAY FOLLOWED BY WEAK HIGH PRESSURE.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES COASTAL WATERS...GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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





000
FXUS66 KSEW 012252
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
352 PM PDT TUE PEP 1 2015

.SYNOPSIS...A LARGE UPPER LEVEL LOW WILL MOVE SLOWLY SOUTH OVER
WESTERN WASHINGTON TONIGHT THROUGH THURSDAY THEN DROP DOWN OVER
OREGON ON FRIDAY. THE LOW WILL BRING SHOWERS AT TIMES TO THE AREA
ALONG WITH A CHANCE OF THUNDERSTORMS MAINLY WEDNESDAY AFTERNOON AND
EVENING. THE UPPER LEVEL LOW WILL MOVE EAST FRIDAY NIGHT FOR A
GRADUAL DRYING AND WARMING TREND OVER THE WEEKEND. A WEAK SYSTEM MAY
BRING A CHANCE OF SHOWERS EARLY NEXT WEEK.

&&

.SHORT TERM...RADAR SHOWS AREAS OF LIGHT RAIN OVER MOST OF W WA THIS
AFTERNOON. IR SATELLITE IMAGERY SHOWS AN UPPER LEVEL SHORTWAVE
TROUGH JUST W OF THE COAST CHARGING INLAND. THE PRECIPITATION WILL
BECOME MORE SHOWERY THIS EVENING AFTER THE SHORTWAVE TROUGH MOVES E
OF THE AREA.

THE MAIN PLAYER THROUGH FRIDAY NIGHT WILL BE THE COLD UPPER LEVEL
LOW CENTERED OVER THE CENTRAL B.C. COAST AT 3 PM. THE LOW WILL MOVE
DOWN OVER SW B.C. ON WEDNESDAY. A WEAK SHORTWAVE TROUGH ROTATING
AROUND THE LOW EXTENDED SW FROM THE N TIP OF VANCOUVER ISLAND AT 3
PM...AND IS EXPECTED TO BRING SCATTERED SHOWERS TO W WA LATER
TONIGHT.

AS THE LOW CENTER MOVES DOWN OVER SW B.C. ON WEDNESDAY THE UNSTABLE
SHOWERY AIR MASS CURRENTLY IN THE SW QUADRANT OF THE LOW WILL REACH
W WA FOR AREAS OF SHOWERS. THE GFS STILL SHOWS LIFTED INDICES -1 TO -
2 WITH SOME SMALL POCKETS OF -3. ISOLATED THUNDERSTORMS HAVE BEEN
ADDED TO THE COASTAL WATERS LATE TONIGHT...EXTENDING INLAND OVER THE
WA COAST WEDNESDAY MORNING. A CHANCE OF THUNDERSTORMS CONTINUES FOR
W WA WEST OF THE CASCADES WEDNESDAY AFTERNOON AND EVENING.

THE UPPER LEVEL LOW WILL MOVE DOWN OVER W WA ON THURSDAY THEN S OVER
OREGON ON FRIDAY. THERE ARE MINOR DIFFERENCES IN THE MODEL FORECAST
TRACK OF THE LOW AS IT HEADS S...WHICH WILL IMPACT WHERE THE
GREATEST CHANCE OF SHOWERS ENDS UP. IT MAY BE NECESSARY TO ADD A
CHANCE OF THUNDERSTORMS TO THURSDAY AFTERNOON. BUT OVERALL IT WILL
BE COOL WITH SCATTERED SHOWERS. MAX TEMPS WILL BE IN THE 60S WHICH
IS ABOUT 10 DEGREES COOLER THAN NORMAL. KAM

.LONG TERM...THE GFS ECMWF AND CANADIAN ALL AGREE THAT THE UPPER
LEVEL LOW WILL BE OVER W OREGON 18Z FRIDAY AND WILL THEN HEAD
GENERALLY E FRIDAY NIGHT...ENDING UP OVER SE OREGON 12Z SATURDAY.
WITH DRIER N FLOW ALOFT DEVELOPING OVER W WA FRIDAY NIGHT...SHOWERS
WERE PHASED OUT...LEADING TO A MOSTLY SUNNY DAY ON SATURDAY. MAX
TEMPS WILL REBOUND...BUT JUST UP TO AROUND 70.

THE DEPARTING LOW ALLOWS NW FLOW ALOFT OVER THE NE PACIFIC TO SPREAD
IN OVER W WA SUNDAY AND MONDAY. THE MODELS ARE SHOWING MAYBE A
COUPLE OF WEAK UPPER LEVEL SHORTWAVE TROUGHS REACHING W WA SUNDAY
THROUGH MONDAY. THE MODELS JUST TEASE THE AREA WITH THE 0.01 PRECIP
CONTOUR...SO I HAVE KEPT THE DRY FORECAST FOR THE TIME
BEING...ALTHOUGH IT MAY BE TEMPORARY. CLOUDS WERE INCREASED FOR
PARTLY SUNNY SKIES. A STRONGER SHORTWAVE REACHES THE AREA MONDAY
NIGHT OR TUESDAY SO A CHANCE OF SHOWERS WAS ADDED FOR THIS PERIOD.
KAM

&&

.AVIATION...SHOWERS CONTINUE TO LINGER BEHIND THE FRONTAL SYSTEM
THAT WORKED THROUGH THE AREA DURING THE DAY. CEILINGS HAVE GENERALLY
IMPROVED TO VFR LEVELS...EXPECT WITH SHOWERS WHERE CEILINGS ARE MVFR
AND POSSIBLY IFR. SHOWERS AND BREEZY CONDITIONS WILL LINGER THIS
EVENING. THE UPPER LEVEL LOW OVER NORTHERN BRITISH COLUMBIA WILL SAG
SOUTH TONIGHT WHILE A WEAK SECONDARY SURFACE FRONT WILL MOVE ONTO
THE NORTH COAST AROUND 06Z AND SOUTH AND EAST AFTER MIDNIGHT. EXPECT
EVENING SHOWERS TO TRANSITION BACK TO RAIN AND LOWER CEILINGS AS
THIS FEATURE WORKS INLAND. ABUNDANT LOW LEVEL MOISTURE AND LINGERING
SHOWERS AND A CHANCE OF THUNDERSTORMS OVER MUCH OF THE AREA BY
WEDNESDAY AFTERNOON AS THE UPPER LEVEL TROUGH CONTINUES TO WORK
SOUTHWARD.

KSEA...CLOUDY WITH SHOWERS AT TIMES THIS EVENING. CIGS WILL
GENERALLY REMAIN VFR THIS EVENING...LOWERING TO MVFR WITH
SHOWERS. A WEAK FRONT WILL BRING STEADIER RAIN AND MVFR CIGS
AFTER MIDNIGHT. THUNDERSTORM ARE POSSIBLE WEDNESDAY AFTERNOON
AS THE UPPER LEVEL LOW MOVES OVERHEAD. SOUTHERLY WINDS 6 TO 10
KNOTS.

&&

.MARINE...SHOWERS WILL CONTINUE OVER AREAS WATERS THIS EVENING BEHIND
THE FRONTAL SYSTEM THAT MOVED THROUGH EARLIER TODAY. AN UPPER LEVEL
LOW OVER NORTHERN BRITISH COLUMBIA WILL MOVE SOUTH OVER THE PACIFIC
NORTHWEST TONIGHT AND WEDNESDAY...HELPING BRING INSTABILITY AND A
CHANCE OF THUNDERSTORMS TO THE COASTAL WATERS LATE TONIGHT AND
INLAND WATERS BY WEDNESDAY AFTERNOON. A WEAK SURFACE FRONT WILL
ALSO MOVE SOUTH INTO THE COASTAL WATERS LATER THIS EVENING BRINGING
SMALL CRAFT ADVISORY SOUTHERLIES AND RAIN  TO THE COASTAL WATERS
OVERNIGHT. THE UPPER LEVEL TROUGH WILL LINGER OVER THE PACIFIC
NORTHWEST INTO SATURDAY FOLLOWED BY WEAK HIGH PRESSURE.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES COASTAL WATERS...GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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




000
FXUS66 KSEW 011608
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
908 AM PDT TUE PEP 1 2015

.SYNOPSIS...A WEAK COLD FRONT WILL BRING RAIN AT TIMES TO WESTERN
WASHINGTON TODAY. A LARGE UPPER LEVEL LOW WILL BE OVER THE REGION
WEDNESDAY THROUGH FRIDAY FOR COOL SHOWERY WEATHER. THE UPPER LEVEL
LOW WILL MOVE EAST THIS WEEKEND FOR A GRADUAL DRYING AND WARMING
TREND.

&&

.SHORT TERM...A WEAK COLD FRONT IS OVER W WA THIS MORNING...
EXTENDING FROM CENTRAL PUGET SOUND ACROSS THE SW WA COAST. THE FRONT
WILL CONTINUE MOVING VERY SLOWLY E AND SE TODAY AND SHOULD DISSIPATE
OVER THE CASCADES TONIGHT. RAIN FROM THE FRONT HAS BEEN LIGHT AND
NOT THAT EXTENSIVE...BUT THAT SHOULD CHANGE THIS AFTERNOON. AN UPPER
LEVEL SHORTWAVE TROUGH OFFSHORE NEAR 135W AND EMBEDDED IN THE W FLOW
ALOFT WILL MOVE OVER W WA THIS AFTERNOON. THE GFS AND NAM SHOW
PRECIP INCREASING THIS AFTERNOON AND CONTINUING INTO EARLY THIS
EVENING...PARTICULARLY ON AND E OF A LINE FROM THE N CASCADES ACROSS
PUGET SOUND AND OVER THE CENTRAL AND S COAST.

THE COLD UPPER LEVEL LOW OVER THE CENTRAL B.C. COAST THIS MORNING
WILL CONTINUE MOVING SE...REACHING SOUTHERN B.C. ON WEDNESDAY. THE
GFS AND NAM BRING A WEAK SHORTWAVE TROUGH...ROTATING AROUND THE S
QUADRANT OF THE LOW...OVER W WA LATE THIS EVENING FOR MORE SHOWERS.

COLDER MORE UNSTABLE AIR THAT IS CURRENTLY ON THE W SIDE OF THE LOW
WILL FOLLOW THE SHORTWAVE TROUGH...MOVING OVER THE COASTAL WATERS
AND W WA WEDNESDAY MORNING. GFS SHOWS LIFTED INDICES IN THIS COOL
UNSTABLE AIR MASS ARE BETWEEN -1 AND -2...SO THERE IS A CHANCE OF
THUNDERSTORMS FOR THE LOWLANDS AND OLYMPICS WEDNESDAY AFTERNOON AND
EVENING. THERE WILL LIKELY BE ISOLATED THUNDERSTORMS OVER THE
COASTAL WATERS AND PERHAPS THE COASTAL STRIP WEDNESDAY MORNING. THIS
WILL BE ADDED IN THE NEXT FORECAST PACKAGE.

ALL MODELS MOVE THE COLD UPPER LEVEL LOW SLOWLY S OVER W WA ON
THURSDAY. SCATTERED SHOWERS WILL CONTINUE. THE GFS SHOWS SMALL AREAS
WHERE LIFTED INDICES ARE JUST A BIT BELOW ZERO...NOT QUITE ENOUGH TO
ADD THUNDERSTORMS TO THE FORECAST. MAX TEMPERATURES WEDNESDAY AND
THURSDAY WILL BE IN THE LOWER TO MID 60S WHICH IS ABOUT 10 DEGREES
BELOW NORMAL.

WITH COLD AIR MOVING S OVER W WA WEDNESDAY AND THURSDAY...SNOW
LEVELS OVER THE MOUNTAINS WILL LOWER TO 5500 TO 6000 FEET WEDNESDAY
AND 5000-6000 FEET THURSDAY. ALONG WITH UNSEASONABLY COLD
TEMPERATURES THE SHOWERS COULD BRING SEVERAL INCHES OF SNOW TO
HIGHER MOUNTAIN ELEVATIONS...PARTICULARLY THE N CASCADES. A SPECIAL
WEATHER STATEMENT REMAINS IN EFFECT HIGH-LIGHTING THIS ISSUE. KAM

.LONG TERM...PREVIOUS DISCUSSION FROM THE 319 AM AFD...THE LONGER
RANGE MODELS HAVE FALLEN INTO BETTER AGREEMENT FOR THE EXTENDED
PERIOD FRIDAY THROUGH MONDAY. THE UPPER TROUGH WILL REMAIN OVER THE
REGION FRIDAY...THEN DRIER NORTHWEST FLOW WILL DEVELOP SATURDAY AS
THE TROUGH MOVES EAST OR SOUTHEAST AND CONTINUE INTO MONDAY. LIGHTER
SHOWERS FRIDAY WILL BECOME LIMITED TO THE CASCADES BY SATURDAY
NIGHT...WITH MOSTLY SUNNY AND WARMER WEATHER SUNDAY AND MONDAY.
MCDONNAL

&&

.AVIATION...A FRONTAL SYSTEM MOVING THROUGH WESTERN WASHINGTON THIS
MORNING WILL PRODUCE LIGHT RAIN AT TIMES THROUGH TONIGHT. CEILINGS
OVER MUCH OF THE LOWLANDS HAVE BEEN RANGING BETWEEN MVFR TO IFR WITH
THE LIGHT RAIN. IN ADDITION TO RAIN WITH THE FRONT THERE HAVE BEEN
SOME BREEZY CONDITIONS WITH GUSTS UP AROUND 20 KNOTS. EXPECT RAIN TO
TRANSITION TO SHOWERS LATER THIS MORNING AS THE FRONT EXITS THE
AREA. THE HIGHER TERRAIN WILL REMAIN OBSCURED TODAY. THE AREAS OF
BREEZY SOUTHERLY WIND WILL DECREASE OVERNIGHT AND TUESDAY MORNING AS
THE FRONT WEAKENS.

KSEA...RAIN BAND ASSOCIATED WITH THE FRONT OVER THE TERMINAL AS OF
16Z. THIS BAND WILL SLOWLY WORK EAST THIS MORNING ALLOWING CEILINGS
TO IMPROVE TO MVFR AND THEN VFR THIS AFTERNOON. RAIN WILL GIVE WAY
TO SHOWERS AS THE FRONT WORKS EAST. SOUTHERLY WINDS 6 TO 10 KNOTS.

&&

.MARINE...A FRONTAL SYSTEM MOVING THROUGH WESTERN WASHINGTON THIS
MORNING BRINGING RAIN TO AREA WATERS. INCREASING SOUTHWESTERLY WINDS
OVER THE COASTAL WATERS TODAY WILL BECOME WESTERLY THIS AFTERNOON
AND EVENING. A SMALL CRAFT ADVISORY REMAINS IN PLACE FOR PARTS OF
THE COASTAL WATERS AND GRAYS HARBOR BAR THROUGH WEDNESDAY MORNING.
A BROAD TROUGH IN THE NORTHEAST PACIFIC WILL GRADUALLY SAG OVER THE
PACNW AND WEAKEN OVER THE NEXT SEVERAL DAYS AND THEN WEAK HIGH
PRESSURE WILL BUILD LATE IN THE WEEK.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES NORTHERN AND CENTRAL OUTER COASTAL
WATERS...GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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




000
FXUS66 KSEW 011608
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
908 AM PDT TUE PEP 1 2015

.SYNOPSIS...A WEAK COLD FRONT WILL BRING RAIN AT TIMES TO WESTERN
WASHINGTON TODAY. A LARGE UPPER LEVEL LOW WILL BE OVER THE REGION
WEDNESDAY THROUGH FRIDAY FOR COOL SHOWERY WEATHER. THE UPPER LEVEL
LOW WILL MOVE EAST THIS WEEKEND FOR A GRADUAL DRYING AND WARMING
TREND.

&&

.SHORT TERM...A WEAK COLD FRONT IS OVER W WA THIS MORNING...
EXTENDING FROM CENTRAL PUGET SOUND ACROSS THE SW WA COAST. THE FRONT
WILL CONTINUE MOVING VERY SLOWLY E AND SE TODAY AND SHOULD DISSIPATE
OVER THE CASCADES TONIGHT. RAIN FROM THE FRONT HAS BEEN LIGHT AND
NOT THAT EXTENSIVE...BUT THAT SHOULD CHANGE THIS AFTERNOON. AN UPPER
LEVEL SHORTWAVE TROUGH OFFSHORE NEAR 135W AND EMBEDDED IN THE W FLOW
ALOFT WILL MOVE OVER W WA THIS AFTERNOON. THE GFS AND NAM SHOW
PRECIP INCREASING THIS AFTERNOON AND CONTINUING INTO EARLY THIS
EVENING...PARTICULARLY ON AND E OF A LINE FROM THE N CASCADES ACROSS
PUGET SOUND AND OVER THE CENTRAL AND S COAST.

THE COLD UPPER LEVEL LOW OVER THE CENTRAL B.C. COAST THIS MORNING
WILL CONTINUE MOVING SE...REACHING SOUTHERN B.C. ON WEDNESDAY. THE
GFS AND NAM BRING A WEAK SHORTWAVE TROUGH...ROTATING AROUND THE S
QUADRANT OF THE LOW...OVER W WA LATE THIS EVENING FOR MORE SHOWERS.

COLDER MORE UNSTABLE AIR THAT IS CURRENTLY ON THE W SIDE OF THE LOW
WILL FOLLOW THE SHORTWAVE TROUGH...MOVING OVER THE COASTAL WATERS
AND W WA WEDNESDAY MORNING. GFS SHOWS LIFTED INDICES IN THIS COOL
UNSTABLE AIR MASS ARE BETWEEN -1 AND -2...SO THERE IS A CHANCE OF
THUNDERSTORMS FOR THE LOWLANDS AND OLYMPICS WEDNESDAY AFTERNOON AND
EVENING. THERE WILL LIKELY BE ISOLATED THUNDERSTORMS OVER THE
COASTAL WATERS AND PERHAPS THE COASTAL STRIP WEDNESDAY MORNING. THIS
WILL BE ADDED IN THE NEXT FORECAST PACKAGE.

ALL MODELS MOVE THE COLD UPPER LEVEL LOW SLOWLY S OVER W WA ON
THURSDAY. SCATTERED SHOWERS WILL CONTINUE. THE GFS SHOWS SMALL AREAS
WHERE LIFTED INDICES ARE JUST A BIT BELOW ZERO...NOT QUITE ENOUGH TO
ADD THUNDERSTORMS TO THE FORECAST. MAX TEMPERATURES WEDNESDAY AND
THURSDAY WILL BE IN THE LOWER TO MID 60S WHICH IS ABOUT 10 DEGREES
BELOW NORMAL.

WITH COLD AIR MOVING S OVER W WA WEDNESDAY AND THURSDAY...SNOW
LEVELS OVER THE MOUNTAINS WILL LOWER TO 5500 TO 6000 FEET WEDNESDAY
AND 5000-6000 FEET THURSDAY. ALONG WITH UNSEASONABLY COLD
TEMPERATURES THE SHOWERS COULD BRING SEVERAL INCHES OF SNOW TO
HIGHER MOUNTAIN ELEVATIONS...PARTICULARLY THE N CASCADES. A SPECIAL
WEATHER STATEMENT REMAINS IN EFFECT HIGH-LIGHTING THIS ISSUE. KAM

.LONG TERM...PREVIOUS DISCUSSION FROM THE 319 AM AFD...THE LONGER
RANGE MODELS HAVE FALLEN INTO BETTER AGREEMENT FOR THE EXTENDED
PERIOD FRIDAY THROUGH MONDAY. THE UPPER TROUGH WILL REMAIN OVER THE
REGION FRIDAY...THEN DRIER NORTHWEST FLOW WILL DEVELOP SATURDAY AS
THE TROUGH MOVES EAST OR SOUTHEAST AND CONTINUE INTO MONDAY. LIGHTER
SHOWERS FRIDAY WILL BECOME LIMITED TO THE CASCADES BY SATURDAY
NIGHT...WITH MOSTLY SUNNY AND WARMER WEATHER SUNDAY AND MONDAY.
MCDONNAL

&&

.AVIATION...A FRONTAL SYSTEM MOVING THROUGH WESTERN WASHINGTON THIS
MORNING WILL PRODUCE LIGHT RAIN AT TIMES THROUGH TONIGHT. CEILINGS
OVER MUCH OF THE LOWLANDS HAVE BEEN RANGING BETWEEN MVFR TO IFR WITH
THE LIGHT RAIN. IN ADDITION TO RAIN WITH THE FRONT THERE HAVE BEEN
SOME BREEZY CONDITIONS WITH GUSTS UP AROUND 20 KNOTS. EXPECT RAIN TO
TRANSITION TO SHOWERS LATER THIS MORNING AS THE FRONT EXITS THE
AREA. THE HIGHER TERRAIN WILL REMAIN OBSCURED TODAY. THE AREAS OF
BREEZY SOUTHERLY WIND WILL DECREASE OVERNIGHT AND TUESDAY MORNING AS
THE FRONT WEAKENS.

KSEA...RAIN BAND ASSOCIATED WITH THE FRONT OVER THE TERMINAL AS OF
16Z. THIS BAND WILL SLOWLY WORK EAST THIS MORNING ALLOWING CEILINGS
TO IMPROVE TO MVFR AND THEN VFR THIS AFTERNOON. RAIN WILL GIVE WAY
TO SHOWERS AS THE FRONT WORKS EAST. SOUTHERLY WINDS 6 TO 10 KNOTS.

&&

.MARINE...A FRONTAL SYSTEM MOVING THROUGH WESTERN WASHINGTON THIS
MORNING BRINGING RAIN TO AREA WATERS. INCREASING SOUTHWESTERLY WINDS
OVER THE COASTAL WATERS TODAY WILL BECOME WESTERLY THIS AFTERNOON
AND EVENING. A SMALL CRAFT ADVISORY REMAINS IN PLACE FOR PARTS OF
THE COASTAL WATERS AND GRAYS HARBOR BAR THROUGH WEDNESDAY MORNING.
A BROAD TROUGH IN THE NORTHEAST PACIFIC WILL GRADUALLY SAG OVER THE
PACNW AND WEAKEN OVER THE NEXT SEVERAL DAYS AND THEN WEAK HIGH
PRESSURE WILL BUILD LATE IN THE WEEK.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES NORTHERN AND CENTRAL OUTER COASTAL
WATERS...GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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




000
FXUS66 KSEW 011608
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
908 AM PDT TUE PEP 1 2015

.SYNOPSIS...A WEAK COLD FRONT WILL BRING RAIN AT TIMES TO WESTERN
WASHINGTON TODAY. A LARGE UPPER LEVEL LOW WILL BE OVER THE REGION
WEDNESDAY THROUGH FRIDAY FOR COOL SHOWERY WEATHER. THE UPPER LEVEL
LOW WILL MOVE EAST THIS WEEKEND FOR A GRADUAL DRYING AND WARMING
TREND.

&&

.SHORT TERM...A WEAK COLD FRONT IS OVER W WA THIS MORNING...
EXTENDING FROM CENTRAL PUGET SOUND ACROSS THE SW WA COAST. THE FRONT
WILL CONTINUE MOVING VERY SLOWLY E AND SE TODAY AND SHOULD DISSIPATE
OVER THE CASCADES TONIGHT. RAIN FROM THE FRONT HAS BEEN LIGHT AND
NOT THAT EXTENSIVE...BUT THAT SHOULD CHANGE THIS AFTERNOON. AN UPPER
LEVEL SHORTWAVE TROUGH OFFSHORE NEAR 135W AND EMBEDDED IN THE W FLOW
ALOFT WILL MOVE OVER W WA THIS AFTERNOON. THE GFS AND NAM SHOW
PRECIP INCREASING THIS AFTERNOON AND CONTINUING INTO EARLY THIS
EVENING...PARTICULARLY ON AND E OF A LINE FROM THE N CASCADES ACROSS
PUGET SOUND AND OVER THE CENTRAL AND S COAST.

THE COLD UPPER LEVEL LOW OVER THE CENTRAL B.C. COAST THIS MORNING
WILL CONTINUE MOVING SE...REACHING SOUTHERN B.C. ON WEDNESDAY. THE
GFS AND NAM BRING A WEAK SHORTWAVE TROUGH...ROTATING AROUND THE S
QUADRANT OF THE LOW...OVER W WA LATE THIS EVENING FOR MORE SHOWERS.

COLDER MORE UNSTABLE AIR THAT IS CURRENTLY ON THE W SIDE OF THE LOW
WILL FOLLOW THE SHORTWAVE TROUGH...MOVING OVER THE COASTAL WATERS
AND W WA WEDNESDAY MORNING. GFS SHOWS LIFTED INDICES IN THIS COOL
UNSTABLE AIR MASS ARE BETWEEN -1 AND -2...SO THERE IS A CHANCE OF
THUNDERSTORMS FOR THE LOWLANDS AND OLYMPICS WEDNESDAY AFTERNOON AND
EVENING. THERE WILL LIKELY BE ISOLATED THUNDERSTORMS OVER THE
COASTAL WATERS AND PERHAPS THE COASTAL STRIP WEDNESDAY MORNING. THIS
WILL BE ADDED IN THE NEXT FORECAST PACKAGE.

ALL MODELS MOVE THE COLD UPPER LEVEL LOW SLOWLY S OVER W WA ON
THURSDAY. SCATTERED SHOWERS WILL CONTINUE. THE GFS SHOWS SMALL AREAS
WHERE LIFTED INDICES ARE JUST A BIT BELOW ZERO...NOT QUITE ENOUGH TO
ADD THUNDERSTORMS TO THE FORECAST. MAX TEMPERATURES WEDNESDAY AND
THURSDAY WILL BE IN THE LOWER TO MID 60S WHICH IS ABOUT 10 DEGREES
BELOW NORMAL.

WITH COLD AIR MOVING S OVER W WA WEDNESDAY AND THURSDAY...SNOW
LEVELS OVER THE MOUNTAINS WILL LOWER TO 5500 TO 6000 FEET WEDNESDAY
AND 5000-6000 FEET THURSDAY. ALONG WITH UNSEASONABLY COLD
TEMPERATURES THE SHOWERS COULD BRING SEVERAL INCHES OF SNOW TO
HIGHER MOUNTAIN ELEVATIONS...PARTICULARLY THE N CASCADES. A SPECIAL
WEATHER STATEMENT REMAINS IN EFFECT HIGH-LIGHTING THIS ISSUE. KAM

.LONG TERM...PREVIOUS DISCUSSION FROM THE 319 AM AFD...THE LONGER
RANGE MODELS HAVE FALLEN INTO BETTER AGREEMENT FOR THE EXTENDED
PERIOD FRIDAY THROUGH MONDAY. THE UPPER TROUGH WILL REMAIN OVER THE
REGION FRIDAY...THEN DRIER NORTHWEST FLOW WILL DEVELOP SATURDAY AS
THE TROUGH MOVES EAST OR SOUTHEAST AND CONTINUE INTO MONDAY. LIGHTER
SHOWERS FRIDAY WILL BECOME LIMITED TO THE CASCADES BY SATURDAY
NIGHT...WITH MOSTLY SUNNY AND WARMER WEATHER SUNDAY AND MONDAY.
MCDONNAL

&&

.AVIATION...A FRONTAL SYSTEM MOVING THROUGH WESTERN WASHINGTON THIS
MORNING WILL PRODUCE LIGHT RAIN AT TIMES THROUGH TONIGHT. CEILINGS
OVER MUCH OF THE LOWLANDS HAVE BEEN RANGING BETWEEN MVFR TO IFR WITH
THE LIGHT RAIN. IN ADDITION TO RAIN WITH THE FRONT THERE HAVE BEEN
SOME BREEZY CONDITIONS WITH GUSTS UP AROUND 20 KNOTS. EXPECT RAIN TO
TRANSITION TO SHOWERS LATER THIS MORNING AS THE FRONT EXITS THE
AREA. THE HIGHER TERRAIN WILL REMAIN OBSCURED TODAY. THE AREAS OF
BREEZY SOUTHERLY WIND WILL DECREASE OVERNIGHT AND TUESDAY MORNING AS
THE FRONT WEAKENS.

KSEA...RAIN BAND ASSOCIATED WITH THE FRONT OVER THE TERMINAL AS OF
16Z. THIS BAND WILL SLOWLY WORK EAST THIS MORNING ALLOWING CEILINGS
TO IMPROVE TO MVFR AND THEN VFR THIS AFTERNOON. RAIN WILL GIVE WAY
TO SHOWERS AS THE FRONT WORKS EAST. SOUTHERLY WINDS 6 TO 10 KNOTS.

&&

.MARINE...A FRONTAL SYSTEM MOVING THROUGH WESTERN WASHINGTON THIS
MORNING BRINGING RAIN TO AREA WATERS. INCREASING SOUTHWESTERLY WINDS
OVER THE COASTAL WATERS TODAY WILL BECOME WESTERLY THIS AFTERNOON
AND EVENING. A SMALL CRAFT ADVISORY REMAINS IN PLACE FOR PARTS OF
THE COASTAL WATERS AND GRAYS HARBOR BAR THROUGH WEDNESDAY MORNING.
A BROAD TROUGH IN THE NORTHEAST PACIFIC WILL GRADUALLY SAG OVER THE
PACNW AND WEAKEN OVER THE NEXT SEVERAL DAYS AND THEN WEAK HIGH
PRESSURE WILL BUILD LATE IN THE WEEK.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES NORTHERN AND CENTRAL OUTER COASTAL
WATERS...GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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





000
FXUS66 KSEW 011608
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
908 AM PDT TUE PEP 1 2015

.SYNOPSIS...A WEAK COLD FRONT WILL BRING RAIN AT TIMES TO WESTERN
WASHINGTON TODAY. A LARGE UPPER LEVEL LOW WILL BE OVER THE REGION
WEDNESDAY THROUGH FRIDAY FOR COOL SHOWERY WEATHER. THE UPPER LEVEL
LOW WILL MOVE EAST THIS WEEKEND FOR A GRADUAL DRYING AND WARMING
TREND.

&&

.SHORT TERM...A WEAK COLD FRONT IS OVER W WA THIS MORNING...
EXTENDING FROM CENTRAL PUGET SOUND ACROSS THE SW WA COAST. THE FRONT
WILL CONTINUE MOVING VERY SLOWLY E AND SE TODAY AND SHOULD DISSIPATE
OVER THE CASCADES TONIGHT. RAIN FROM THE FRONT HAS BEEN LIGHT AND
NOT THAT EXTENSIVE...BUT THAT SHOULD CHANGE THIS AFTERNOON. AN UPPER
LEVEL SHORTWAVE TROUGH OFFSHORE NEAR 135W AND EMBEDDED IN THE W FLOW
ALOFT WILL MOVE OVER W WA THIS AFTERNOON. THE GFS AND NAM SHOW
PRECIP INCREASING THIS AFTERNOON AND CONTINUING INTO EARLY THIS
EVENING...PARTICULARLY ON AND E OF A LINE FROM THE N CASCADES ACROSS
PUGET SOUND AND OVER THE CENTRAL AND S COAST.

THE COLD UPPER LEVEL LOW OVER THE CENTRAL B.C. COAST THIS MORNING
WILL CONTINUE MOVING SE...REACHING SOUTHERN B.C. ON WEDNESDAY. THE
GFS AND NAM BRING A WEAK SHORTWAVE TROUGH...ROTATING AROUND THE S
QUADRANT OF THE LOW...OVER W WA LATE THIS EVENING FOR MORE SHOWERS.

COLDER MORE UNSTABLE AIR THAT IS CURRENTLY ON THE W SIDE OF THE LOW
WILL FOLLOW THE SHORTWAVE TROUGH...MOVING OVER THE COASTAL WATERS
AND W WA WEDNESDAY MORNING. GFS SHOWS LIFTED INDICES IN THIS COOL
UNSTABLE AIR MASS ARE BETWEEN -1 AND -2...SO THERE IS A CHANCE OF
THUNDERSTORMS FOR THE LOWLANDS AND OLYMPICS WEDNESDAY AFTERNOON AND
EVENING. THERE WILL LIKELY BE ISOLATED THUNDERSTORMS OVER THE
COASTAL WATERS AND PERHAPS THE COASTAL STRIP WEDNESDAY MORNING. THIS
WILL BE ADDED IN THE NEXT FORECAST PACKAGE.

ALL MODELS MOVE THE COLD UPPER LEVEL LOW SLOWLY S OVER W WA ON
THURSDAY. SCATTERED SHOWERS WILL CONTINUE. THE GFS SHOWS SMALL AREAS
WHERE LIFTED INDICES ARE JUST A BIT BELOW ZERO...NOT QUITE ENOUGH TO
ADD THUNDERSTORMS TO THE FORECAST. MAX TEMPERATURES WEDNESDAY AND
THURSDAY WILL BE IN THE LOWER TO MID 60S WHICH IS ABOUT 10 DEGREES
BELOW NORMAL.

WITH COLD AIR MOVING S OVER W WA WEDNESDAY AND THURSDAY...SNOW
LEVELS OVER THE MOUNTAINS WILL LOWER TO 5500 TO 6000 FEET WEDNESDAY
AND 5000-6000 FEET THURSDAY. ALONG WITH UNSEASONABLY COLD
TEMPERATURES THE SHOWERS COULD BRING SEVERAL INCHES OF SNOW TO
HIGHER MOUNTAIN ELEVATIONS...PARTICULARLY THE N CASCADES. A SPECIAL
WEATHER STATEMENT REMAINS IN EFFECT HIGH-LIGHTING THIS ISSUE. KAM

.LONG TERM...PREVIOUS DISCUSSION FROM THE 319 AM AFD...THE LONGER
RANGE MODELS HAVE FALLEN INTO BETTER AGREEMENT FOR THE EXTENDED
PERIOD FRIDAY THROUGH MONDAY. THE UPPER TROUGH WILL REMAIN OVER THE
REGION FRIDAY...THEN DRIER NORTHWEST FLOW WILL DEVELOP SATURDAY AS
THE TROUGH MOVES EAST OR SOUTHEAST AND CONTINUE INTO MONDAY. LIGHTER
SHOWERS FRIDAY WILL BECOME LIMITED TO THE CASCADES BY SATURDAY
NIGHT...WITH MOSTLY SUNNY AND WARMER WEATHER SUNDAY AND MONDAY.
MCDONNAL

&&

.AVIATION...A FRONTAL SYSTEM MOVING THROUGH WESTERN WASHINGTON THIS
MORNING WILL PRODUCE LIGHT RAIN AT TIMES THROUGH TONIGHT. CEILINGS
OVER MUCH OF THE LOWLANDS HAVE BEEN RANGING BETWEEN MVFR TO IFR WITH
THE LIGHT RAIN. IN ADDITION TO RAIN WITH THE FRONT THERE HAVE BEEN
SOME BREEZY CONDITIONS WITH GUSTS UP AROUND 20 KNOTS. EXPECT RAIN TO
TRANSITION TO SHOWERS LATER THIS MORNING AS THE FRONT EXITS THE
AREA. THE HIGHER TERRAIN WILL REMAIN OBSCURED TODAY. THE AREAS OF
BREEZY SOUTHERLY WIND WILL DECREASE OVERNIGHT AND TUESDAY MORNING AS
THE FRONT WEAKENS.

KSEA...RAIN BAND ASSOCIATED WITH THE FRONT OVER THE TERMINAL AS OF
16Z. THIS BAND WILL SLOWLY WORK EAST THIS MORNING ALLOWING CEILINGS
TO IMPROVE TO MVFR AND THEN VFR THIS AFTERNOON. RAIN WILL GIVE WAY
TO SHOWERS AS THE FRONT WORKS EAST. SOUTHERLY WINDS 6 TO 10 KNOTS.

&&

.MARINE...A FRONTAL SYSTEM MOVING THROUGH WESTERN WASHINGTON THIS
MORNING BRINGING RAIN TO AREA WATERS. INCREASING SOUTHWESTERLY WINDS
OVER THE COASTAL WATERS TODAY WILL BECOME WESTERLY THIS AFTERNOON
AND EVENING. A SMALL CRAFT ADVISORY REMAINS IN PLACE FOR PARTS OF
THE COASTAL WATERS AND GRAYS HARBOR BAR THROUGH WEDNESDAY MORNING.
A BROAD TROUGH IN THE NORTHEAST PACIFIC WILL GRADUALLY SAG OVER THE
PACNW AND WEAKEN OVER THE NEXT SEVERAL DAYS AND THEN WEAK HIGH
PRESSURE WILL BUILD LATE IN THE WEEK.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES NORTHERN AND CENTRAL OUTER COASTAL
WATERS...GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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





000
FXUS66 KSEW 011019
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
319 AM PDT TUE SEP 1 2015

.SYNOPSIS...A WEAK COLD FRONT WILL BRING RAIN AT TIMES TO WESTERN
WASHINGTON TODAY. A LARGE UPPER LOW WILL BE OVER THE REGION WEDNESDAY
THROUGH FRIDAY FOR COOL SHOWERY WEATHER. THE UPPER LOW WILL MOVE
EAST THIS WEEKEND FOR A GRADUAL DRYING AND WARMING TREND.

&&

.SHORT TERM...A WEAK COLD FRONT EXTENDS SOUTHWEST FROM SOUTHERN
BRITISH COLUMBIA ACROSS WESTERN WASHINGTON AND INTO THE OFFSHORE
WATERS OF OREGON. THE FRONT IS WITHIN THE DEEP BROAD UPPER TROUGH
OVER THE REGION WITH ITS 5330 METER LOW CENTER JUST NORTHWEST OF
HAIDA GWAII. THE FRONT IS BRINGING AREAS OF LIGHT PRECIPITATION TO
THE FORECAST AREA EARLY THIS MORNING...MAINLY NORTH AND WEST OF
SEATTLE.

THE COLD FRONT WILL MOVE SLOWLY ACROSS WESTERN WASHINGTON TODAY...
WHILE THE UPPER LOW DIGS SOUTHEAST JUST OFF THE COAST OF BRITISH
COLUMBIA. THE FRONT SHOULD BRING MEASURABLE PRECIPITATION TO MOST
ALL OF WESTERN WASHINGTON TODAY...WITH THE HEAVIEST AMOUNTS OVER
THE NORTH CASCADES. THE SNOW LEVEL WILL BE AROUND 9000 FT TODAY...
ALTHOUGH THE HIGHS IN THE LOWLANDS WILL BE ONLY IN THE 60S.

THE UPPER LOW WILL MOVE SLOWLY SOUTHEAST TONIGHT THROUGH THURSDAY.
THE UPPER TROUGH EXTENDS SOUTH FROM THE LOW...AND IT WILL MOVE
INTO OUR OFFSHORE WATERS TONIGHT AND WEDNESDAY AND THEN INLAND ON
THURSDAY. THE COOL MOIST AND UNSTABLE AIR MASS WITH THE UPPER
TROUGH WILL BRING SHOWERY WEATHER TO WESTERN WASHINGTON. WE ARE
ALSO FOLLOWING THE SPC GUIDANCE AND ADDING A CHANCE OF AFTERNOON
AND EVENING THUNDERSTORMS TO MOST OF THE FORECAST AREA WEDNESDAY.

DAYTIME HIGHS WILL BE IN THE LOWER TO MID 60S -- A GOOD 5 TO 10
DEGREES BELOW NORMAL. TOTAL RAINFALL FOR THE LOWLANDS TODAY
THROUGH THURSDAY WILL BE MOSTLY IN THE 0.25 TO 0.75 INCH RANGE.
THE SNOW LEVEL WILL BE AROUND 5500 TO 6000 FT WEDNESDAY THROUGH
THURSDAY. WATER EQUIVALENT PRECIPITATION AMOUNTS OF 0.50 TO 1.50
INCHES WILL FALL OVER MUCH OF THE HIGHER MOUNTAINS...WITH THE
HEAVIEST AMOUNTS NEAR MT BAKER. THAT MEANS THERE WILL BE LOCAL
ACCUMULATIONS OF A HALF FOOT OF SNOW ABOVE 6000 FT...WITH A FOOT
OR MORE OF SNOW NEAR THE TOP OF MT BAKER. MCDONNAL

.LONG TERM...THE LONGER RANGE MODELS HAVE FALLEN INTO BETTER
AGREEMENT FOR THE EXTENDED PERIOD FRIDAY THROUGH MONDAY. THE
UPPER TROUGH WILL REMAIN OVER THE REGION FRIDAY...THEN DRIER
NORTHWEST FLOW WILL DEVELOP SATURDAY AS THE TROUGH MOVES EAST OR
SOUTHEAST AND CONTINUE INTO MONDAY. LIGHTER SHOWERS FRIDAY WILL
BECOME LIMITED TO THE CASCADES BY SATURDAY NIGHT...WITH MOSTLY
SUNNY AND WARMER WEATHER SUNDAY AND MONDAY. MCDONNAL

&&

.AVIATION...A FRONTAL SYSTEM WILL DRAG ACROSS THE AREA TODAY. A COOL
UPPER LEVEL TROUGH WILL FOLLOW THE FRONT LATER TONIGHT INTO
WEDNESDAY. CEILINGS GENERALLY 3500-5000 THIS MORNING WITH BRIEF
CEILINGS AROUND 2000 FEET AND VISIBILITIES 3-5SM IN MODERATE RAIN.
LITTLE IF ANY IMPROVEMENT IN THE CEILINGS BEHIND THE FRONT LATER
THIS AFTERNOON INTO THE EVENING HOURS BEFORE THE UPPER LEVEL TROUGH
ARRIVES.

KSEA...CLOUDY WITH RAIN AT TIMES THROUGH THIS AFTERNOON. CEILINGS
35000-4500 FEET WITH POSSIBLE BRIEF CEILINGS NEAR 2000 FEET IN
MODERATE RAIN MID MORNING TO EARLY AFTERNOON. SOUTHERLY WINDS 6 TO
10 KNOTS. FELTON

&&

.MARINE...A FRONTAL SYSTEM OVER THE NORTH PORTION OF THE AREA WILL
MOVE THROUGH THE INLAND WATERS LATER TODAY. THE FRONT IS NOT STRONG
ENOUGH TO CAUSE SMALL CRAFT ADVISORY WINDS. A COOL UPPER LEVEL TROUGH
WILL MOVE INTO THE AREA LATER TONIGHT INTO WEDNESDAY WITH SMALL
CRAFT ADVISORY WINDS OVER THE NORTHERN AND CENTRAL PORTION OF THE
OUTER COASTAL WATERS. THE TROUGH WILL KICK OUT OF THE AREA ON
THURSDAY. HIGH PRESSURE WILL BUILD OVER THE WATERS FRIDAY AND
SATURDAY. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES NORTHERN AND CENTRAL OUTER COASTAL
WATERS...GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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




000
FXUS66 KSEW 011019
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
319 AM PDT TUE SEP 1 2015

.SYNOPSIS...A WEAK COLD FRONT WILL BRING RAIN AT TIMES TO WESTERN
WASHINGTON TODAY. A LARGE UPPER LOW WILL BE OVER THE REGION WEDNESDAY
THROUGH FRIDAY FOR COOL SHOWERY WEATHER. THE UPPER LOW WILL MOVE
EAST THIS WEEKEND FOR A GRADUAL DRYING AND WARMING TREND.

&&

.SHORT TERM...A WEAK COLD FRONT EXTENDS SOUTHWEST FROM SOUTHERN
BRITISH COLUMBIA ACROSS WESTERN WASHINGTON AND INTO THE OFFSHORE
WATERS OF OREGON. THE FRONT IS WITHIN THE DEEP BROAD UPPER TROUGH
OVER THE REGION WITH ITS 5330 METER LOW CENTER JUST NORTHWEST OF
HAIDA GWAII. THE FRONT IS BRINGING AREAS OF LIGHT PRECIPITATION TO
THE FORECAST AREA EARLY THIS MORNING...MAINLY NORTH AND WEST OF
SEATTLE.

THE COLD FRONT WILL MOVE SLOWLY ACROSS WESTERN WASHINGTON TODAY...
WHILE THE UPPER LOW DIGS SOUTHEAST JUST OFF THE COAST OF BRITISH
COLUMBIA. THE FRONT SHOULD BRING MEASURABLE PRECIPITATION TO MOST
ALL OF WESTERN WASHINGTON TODAY...WITH THE HEAVIEST AMOUNTS OVER
THE NORTH CASCADES. THE SNOW LEVEL WILL BE AROUND 9000 FT TODAY...
ALTHOUGH THE HIGHS IN THE LOWLANDS WILL BE ONLY IN THE 60S.

THE UPPER LOW WILL MOVE SLOWLY SOUTHEAST TONIGHT THROUGH THURSDAY.
THE UPPER TROUGH EXTENDS SOUTH FROM THE LOW...AND IT WILL MOVE
INTO OUR OFFSHORE WATERS TONIGHT AND WEDNESDAY AND THEN INLAND ON
THURSDAY. THE COOL MOIST AND UNSTABLE AIR MASS WITH THE UPPER
TROUGH WILL BRING SHOWERY WEATHER TO WESTERN WASHINGTON. WE ARE
ALSO FOLLOWING THE SPC GUIDANCE AND ADDING A CHANCE OF AFTERNOON
AND EVENING THUNDERSTORMS TO MOST OF THE FORECAST AREA WEDNESDAY.

DAYTIME HIGHS WILL BE IN THE LOWER TO MID 60S -- A GOOD 5 TO 10
DEGREES BELOW NORMAL. TOTAL RAINFALL FOR THE LOWLANDS TODAY
THROUGH THURSDAY WILL BE MOSTLY IN THE 0.25 TO 0.75 INCH RANGE.
THE SNOW LEVEL WILL BE AROUND 5500 TO 6000 FT WEDNESDAY THROUGH
THURSDAY. WATER EQUIVALENT PRECIPITATION AMOUNTS OF 0.50 TO 1.50
INCHES WILL FALL OVER MUCH OF THE HIGHER MOUNTAINS...WITH THE
HEAVIEST AMOUNTS NEAR MT BAKER. THAT MEANS THERE WILL BE LOCAL
ACCUMULATIONS OF A HALF FOOT OF SNOW ABOVE 6000 FT...WITH A FOOT
OR MORE OF SNOW NEAR THE TOP OF MT BAKER. MCDONNAL

.LONG TERM...THE LONGER RANGE MODELS HAVE FALLEN INTO BETTER
AGREEMENT FOR THE EXTENDED PERIOD FRIDAY THROUGH MONDAY. THE
UPPER TROUGH WILL REMAIN OVER THE REGION FRIDAY...THEN DRIER
NORTHWEST FLOW WILL DEVELOP SATURDAY AS THE TROUGH MOVES EAST OR
SOUTHEAST AND CONTINUE INTO MONDAY. LIGHTER SHOWERS FRIDAY WILL
BECOME LIMITED TO THE CASCADES BY SATURDAY NIGHT...WITH MOSTLY
SUNNY AND WARMER WEATHER SUNDAY AND MONDAY. MCDONNAL

&&

.AVIATION...A FRONTAL SYSTEM WILL DRAG ACROSS THE AREA TODAY. A COOL
UPPER LEVEL TROUGH WILL FOLLOW THE FRONT LATER TONIGHT INTO
WEDNESDAY. CEILINGS GENERALLY 3500-5000 THIS MORNING WITH BRIEF
CEILINGS AROUND 2000 FEET AND VISIBILITIES 3-5SM IN MODERATE RAIN.
LITTLE IF ANY IMPROVEMENT IN THE CEILINGS BEHIND THE FRONT LATER
THIS AFTERNOON INTO THE EVENING HOURS BEFORE THE UPPER LEVEL TROUGH
ARRIVES.

KSEA...CLOUDY WITH RAIN AT TIMES THROUGH THIS AFTERNOON. CEILINGS
35000-4500 FEET WITH POSSIBLE BRIEF CEILINGS NEAR 2000 FEET IN
MODERATE RAIN MID MORNING TO EARLY AFTERNOON. SOUTHERLY WINDS 6 TO
10 KNOTS. FELTON

&&

.MARINE...A FRONTAL SYSTEM OVER THE NORTH PORTION OF THE AREA WILL
MOVE THROUGH THE INLAND WATERS LATER TODAY. THE FRONT IS NOT STRONG
ENOUGH TO CAUSE SMALL CRAFT ADVISORY WINDS. A COOL UPPER LEVEL TROUGH
WILL MOVE INTO THE AREA LATER TONIGHT INTO WEDNESDAY WITH SMALL
CRAFT ADVISORY WINDS OVER THE NORTHERN AND CENTRAL PORTION OF THE
OUTER COASTAL WATERS. THE TROUGH WILL KICK OUT OF THE AREA ON
THURSDAY. HIGH PRESSURE WILL BUILD OVER THE WATERS FRIDAY AND
SATURDAY. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES NORTHERN AND CENTRAL OUTER COASTAL
WATERS...GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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




000
FXUS66 KSEW 011019
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
319 AM PDT TUE SEP 1 2015

.SYNOPSIS...A WEAK COLD FRONT WILL BRING RAIN AT TIMES TO WESTERN
WASHINGTON TODAY. A LARGE UPPER LOW WILL BE OVER THE REGION WEDNESDAY
THROUGH FRIDAY FOR COOL SHOWERY WEATHER. THE UPPER LOW WILL MOVE
EAST THIS WEEKEND FOR A GRADUAL DRYING AND WARMING TREND.

&&

.SHORT TERM...A WEAK COLD FRONT EXTENDS SOUTHWEST FROM SOUTHERN
BRITISH COLUMBIA ACROSS WESTERN WASHINGTON AND INTO THE OFFSHORE
WATERS OF OREGON. THE FRONT IS WITHIN THE DEEP BROAD UPPER TROUGH
OVER THE REGION WITH ITS 5330 METER LOW CENTER JUST NORTHWEST OF
HAIDA GWAII. THE FRONT IS BRINGING AREAS OF LIGHT PRECIPITATION TO
THE FORECAST AREA EARLY THIS MORNING...MAINLY NORTH AND WEST OF
SEATTLE.

THE COLD FRONT WILL MOVE SLOWLY ACROSS WESTERN WASHINGTON TODAY...
WHILE THE UPPER LOW DIGS SOUTHEAST JUST OFF THE COAST OF BRITISH
COLUMBIA. THE FRONT SHOULD BRING MEASURABLE PRECIPITATION TO MOST
ALL OF WESTERN WASHINGTON TODAY...WITH THE HEAVIEST AMOUNTS OVER
THE NORTH CASCADES. THE SNOW LEVEL WILL BE AROUND 9000 FT TODAY...
ALTHOUGH THE HIGHS IN THE LOWLANDS WILL BE ONLY IN THE 60S.

THE UPPER LOW WILL MOVE SLOWLY SOUTHEAST TONIGHT THROUGH THURSDAY.
THE UPPER TROUGH EXTENDS SOUTH FROM THE LOW...AND IT WILL MOVE
INTO OUR OFFSHORE WATERS TONIGHT AND WEDNESDAY AND THEN INLAND ON
THURSDAY. THE COOL MOIST AND UNSTABLE AIR MASS WITH THE UPPER
TROUGH WILL BRING SHOWERY WEATHER TO WESTERN WASHINGTON. WE ARE
ALSO FOLLOWING THE SPC GUIDANCE AND ADDING A CHANCE OF AFTERNOON
AND EVENING THUNDERSTORMS TO MOST OF THE FORECAST AREA WEDNESDAY.

DAYTIME HIGHS WILL BE IN THE LOWER TO MID 60S -- A GOOD 5 TO 10
DEGREES BELOW NORMAL. TOTAL RAINFALL FOR THE LOWLANDS TODAY
THROUGH THURSDAY WILL BE MOSTLY IN THE 0.25 TO 0.75 INCH RANGE.
THE SNOW LEVEL WILL BE AROUND 5500 TO 6000 FT WEDNESDAY THROUGH
THURSDAY. WATER EQUIVALENT PRECIPITATION AMOUNTS OF 0.50 TO 1.50
INCHES WILL FALL OVER MUCH OF THE HIGHER MOUNTAINS...WITH THE
HEAVIEST AMOUNTS NEAR MT BAKER. THAT MEANS THERE WILL BE LOCAL
ACCUMULATIONS OF A HALF FOOT OF SNOW ABOVE 6000 FT...WITH A FOOT
OR MORE OF SNOW NEAR THE TOP OF MT BAKER. MCDONNAL

.LONG TERM...THE LONGER RANGE MODELS HAVE FALLEN INTO BETTER
AGREEMENT FOR THE EXTENDED PERIOD FRIDAY THROUGH MONDAY. THE
UPPER TROUGH WILL REMAIN OVER THE REGION FRIDAY...THEN DRIER
NORTHWEST FLOW WILL DEVELOP SATURDAY AS THE TROUGH MOVES EAST OR
SOUTHEAST AND CONTINUE INTO MONDAY. LIGHTER SHOWERS FRIDAY WILL
BECOME LIMITED TO THE CASCADES BY SATURDAY NIGHT...WITH MOSTLY
SUNNY AND WARMER WEATHER SUNDAY AND MONDAY. MCDONNAL

&&

.AVIATION...A FRONTAL SYSTEM WILL DRAG ACROSS THE AREA TODAY. A COOL
UPPER LEVEL TROUGH WILL FOLLOW THE FRONT LATER TONIGHT INTO
WEDNESDAY. CEILINGS GENERALLY 3500-5000 THIS MORNING WITH BRIEF
CEILINGS AROUND 2000 FEET AND VISIBILITIES 3-5SM IN MODERATE RAIN.
LITTLE IF ANY IMPROVEMENT IN THE CEILINGS BEHIND THE FRONT LATER
THIS AFTERNOON INTO THE EVENING HOURS BEFORE THE UPPER LEVEL TROUGH
ARRIVES.

KSEA...CLOUDY WITH RAIN AT TIMES THROUGH THIS AFTERNOON. CEILINGS
35000-4500 FEET WITH POSSIBLE BRIEF CEILINGS NEAR 2000 FEET IN
MODERATE RAIN MID MORNING TO EARLY AFTERNOON. SOUTHERLY WINDS 6 TO
10 KNOTS. FELTON

&&

.MARINE...A FRONTAL SYSTEM OVER THE NORTH PORTION OF THE AREA WILL
MOVE THROUGH THE INLAND WATERS LATER TODAY. THE FRONT IS NOT STRONG
ENOUGH TO CAUSE SMALL CRAFT ADVISORY WINDS. A COOL UPPER LEVEL TROUGH
WILL MOVE INTO THE AREA LATER TONIGHT INTO WEDNESDAY WITH SMALL
CRAFT ADVISORY WINDS OVER THE NORTHERN AND CENTRAL PORTION OF THE
OUTER COASTAL WATERS. THE TROUGH WILL KICK OUT OF THE AREA ON
THURSDAY. HIGH PRESSURE WILL BUILD OVER THE WATERS FRIDAY AND
SATURDAY. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES NORTHERN AND CENTRAL OUTER COASTAL
WATERS...GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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





000
FXUS66 KSEW 011019
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
319 AM PDT TUE SEP 1 2015

.SYNOPSIS...A WEAK COLD FRONT WILL BRING RAIN AT TIMES TO WESTERN
WASHINGTON TODAY. A LARGE UPPER LOW WILL BE OVER THE REGION WEDNESDAY
THROUGH FRIDAY FOR COOL SHOWERY WEATHER. THE UPPER LOW WILL MOVE
EAST THIS WEEKEND FOR A GRADUAL DRYING AND WARMING TREND.

&&

.SHORT TERM...A WEAK COLD FRONT EXTENDS SOUTHWEST FROM SOUTHERN
BRITISH COLUMBIA ACROSS WESTERN WASHINGTON AND INTO THE OFFSHORE
WATERS OF OREGON. THE FRONT IS WITHIN THE DEEP BROAD UPPER TROUGH
OVER THE REGION WITH ITS 5330 METER LOW CENTER JUST NORTHWEST OF
HAIDA GWAII. THE FRONT IS BRINGING AREAS OF LIGHT PRECIPITATION TO
THE FORECAST AREA EARLY THIS MORNING...MAINLY NORTH AND WEST OF
SEATTLE.

THE COLD FRONT WILL MOVE SLOWLY ACROSS WESTERN WASHINGTON TODAY...
WHILE THE UPPER LOW DIGS SOUTHEAST JUST OFF THE COAST OF BRITISH
COLUMBIA. THE FRONT SHOULD BRING MEASURABLE PRECIPITATION TO MOST
ALL OF WESTERN WASHINGTON TODAY...WITH THE HEAVIEST AMOUNTS OVER
THE NORTH CASCADES. THE SNOW LEVEL WILL BE AROUND 9000 FT TODAY...
ALTHOUGH THE HIGHS IN THE LOWLANDS WILL BE ONLY IN THE 60S.

THE UPPER LOW WILL MOVE SLOWLY SOUTHEAST TONIGHT THROUGH THURSDAY.
THE UPPER TROUGH EXTENDS SOUTH FROM THE LOW...AND IT WILL MOVE
INTO OUR OFFSHORE WATERS TONIGHT AND WEDNESDAY AND THEN INLAND ON
THURSDAY. THE COOL MOIST AND UNSTABLE AIR MASS WITH THE UPPER
TROUGH WILL BRING SHOWERY WEATHER TO WESTERN WASHINGTON. WE ARE
ALSO FOLLOWING THE SPC GUIDANCE AND ADDING A CHANCE OF AFTERNOON
AND EVENING THUNDERSTORMS TO MOST OF THE FORECAST AREA WEDNESDAY.

DAYTIME HIGHS WILL BE IN THE LOWER TO MID 60S -- A GOOD 5 TO 10
DEGREES BELOW NORMAL. TOTAL RAINFALL FOR THE LOWLANDS TODAY
THROUGH THURSDAY WILL BE MOSTLY IN THE 0.25 TO 0.75 INCH RANGE.
THE SNOW LEVEL WILL BE AROUND 5500 TO 6000 FT WEDNESDAY THROUGH
THURSDAY. WATER EQUIVALENT PRECIPITATION AMOUNTS OF 0.50 TO 1.50
INCHES WILL FALL OVER MUCH OF THE HIGHER MOUNTAINS...WITH THE
HEAVIEST AMOUNTS NEAR MT BAKER. THAT MEANS THERE WILL BE LOCAL
ACCUMULATIONS OF A HALF FOOT OF SNOW ABOVE 6000 FT...WITH A FOOT
OR MORE OF SNOW NEAR THE TOP OF MT BAKER. MCDONNAL

.LONG TERM...THE LONGER RANGE MODELS HAVE FALLEN INTO BETTER
AGREEMENT FOR THE EXTENDED PERIOD FRIDAY THROUGH MONDAY. THE
UPPER TROUGH WILL REMAIN OVER THE REGION FRIDAY...THEN DRIER
NORTHWEST FLOW WILL DEVELOP SATURDAY AS THE TROUGH MOVES EAST OR
SOUTHEAST AND CONTINUE INTO MONDAY. LIGHTER SHOWERS FRIDAY WILL
BECOME LIMITED TO THE CASCADES BY SATURDAY NIGHT...WITH MOSTLY
SUNNY AND WARMER WEATHER SUNDAY AND MONDAY. MCDONNAL

&&

.AVIATION...A FRONTAL SYSTEM WILL DRAG ACROSS THE AREA TODAY. A COOL
UPPER LEVEL TROUGH WILL FOLLOW THE FRONT LATER TONIGHT INTO
WEDNESDAY. CEILINGS GENERALLY 3500-5000 THIS MORNING WITH BRIEF
CEILINGS AROUND 2000 FEET AND VISIBILITIES 3-5SM IN MODERATE RAIN.
LITTLE IF ANY IMPROVEMENT IN THE CEILINGS BEHIND THE FRONT LATER
THIS AFTERNOON INTO THE EVENING HOURS BEFORE THE UPPER LEVEL TROUGH
ARRIVES.

KSEA...CLOUDY WITH RAIN AT TIMES THROUGH THIS AFTERNOON. CEILINGS
35000-4500 FEET WITH POSSIBLE BRIEF CEILINGS NEAR 2000 FEET IN
MODERATE RAIN MID MORNING TO EARLY AFTERNOON. SOUTHERLY WINDS 6 TO
10 KNOTS. FELTON

&&

.MARINE...A FRONTAL SYSTEM OVER THE NORTH PORTION OF THE AREA WILL
MOVE THROUGH THE INLAND WATERS LATER TODAY. THE FRONT IS NOT STRONG
ENOUGH TO CAUSE SMALL CRAFT ADVISORY WINDS. A COOL UPPER LEVEL TROUGH
WILL MOVE INTO THE AREA LATER TONIGHT INTO WEDNESDAY WITH SMALL
CRAFT ADVISORY WINDS OVER THE NORTHERN AND CENTRAL PORTION OF THE
OUTER COASTAL WATERS. THE TROUGH WILL KICK OUT OF THE AREA ON
THURSDAY. HIGH PRESSURE WILL BUILD OVER THE WATERS FRIDAY AND
SATURDAY. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES NORTHERN AND CENTRAL OUTER COASTAL
WATERS...GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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





000
FXUS66 KSEW 010412 CCA
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
900 PM PDT MON AUG 31 2015

.SYNOPSIS...A FRONTAL SYSTEM WILL BRING RAIN AT TIMES TO WESTERN
WASHINGTON TONIGHT AND TUESDAY AS IT MOVES SLOWLY SOUTH ACROSS THE
AREA. A LARGE UPPER LEVEL LOW WILL SETTLE OVER THE REGION WEDNESDAY
THROUGH FRIDAY FOR COOL SHOWERY WEATHER. THE UPPER LEVEL LOW WILL
WEAKEN AND MOVE EAST EARLY THIS WEEKEND FOR A GRADUAL DRYING AND
WARMING TREND.

&&

.SHORT TERM...A LONG WAVE TROUGH WILL BROADEN OVER THE
PAC NW AND PERSIST THROUGH THE NEXT SEVERAL DAYS. ONE FRONTAL
FEATURE IS CURRENTLY DRAPED ACROSS WRN WA WITH AN ASSOCIATED BAND OF
RAIN PUSHING TO THE SE OF PUGET SOUND. STATION PRESSURES CONTINUE TO
FALL EXCEPT ALONG THE N WA COAST WITH KUIL REPORTING LITTLE CHANGE
THIS PAST HOUR. THE SURFACE FRONT IS NOT WELL DEFINED BUT IS
PROBABLY IN THE PROCESS OF PIVOTING ALONG THE N COAST AS THE MAIN
TROUGH DIGS SWD. QPF ON MOST MODELS IS PRETTY WIDESPREAD THROUGH AT
LEAST 12Z TONIGHT WHICH MAY BE OVERDONE. RAIN APPEARS TO HAVE
CHANGED OVER TO A MORE SHOWERY PATTERN BUT ANOTHER BAND OF
PERSISTANT RAIN COULD DEVELOP OVERNIGHT. SHOWERS SEEM LIKELY TO
CONTINUE THROUGH TUESDAY AS MODELS SHOW LITTLE MOVEMENT OF THE
MOISTURE BAND OVER THE AREA AND THE TROUGH DEEPENING OVER THE AREA.

UNSEASONABLY COOL AIR ALOFT WILL FILTER INTO WRN WA TUESDAY NIGHT
INTO WEDNESDAY AND THURSDAY. 1000-500 MB THICKNESS VALUES FALL DOWN
TO 5400M WHICH COULD COULD DROP SNOW LEVELS AS LOW AS 5500 TO 6000
FEET. BY THE TIME COLD AIR ARRIVES...THE DEEPER MOISTURE WILL HAVE
SHIFTED OFF TO THE E. IT WILL BECOME UNSTABLE WITH SOME SHOWERS
ACROSS THE AREA AND SNOW SHOWERS IN THE MOUNTAINS ABOVE PASS LEVELS.
A COUPLE INCHES OF EARLY SEASON SNOWFALL IS POSSIBLE ON HIGHER
PEAKS. IT WILL BE COOL OVER THE LOWLANDS WITH HIGHS STRUGGLING TO
REACH THE MID 60S BY THURSDAY. MERCER

.LONG TERM...FROM PREVIOUS DISCUSSION...THE CENTER OF THE LARGE
UPPER LEVEL TROUGH OVER B.C. WILL FORM A LOW WHICH WILL MOVE S OVER
W WA ON FRIDAY. WHILE THE LOW IS OVERHEAD FRIDAY AFTERNOON...THE GFS
HAS LIFTED INDICES DROPPING BELOW ZERO. THERE COULD BE ENOUGH
INSTABILITY FOR ISOLATED THUNDERSTORMS...BUT I WILL HOLD OFF
INCLUDING THEM IN THE FORECAST UNTIL THE MODELS BECOME A LITTLE MORE
CONSISTENT OR MORE UNSTABLE.

FRIDAY NIGHT AND SATURDAY THE GFS BEGINS MOVING THE WEAKENING TROUGH
TO THE EAST...WHILE THE ECMWF AND CANADIAN MOVE IT S OVER OREGON
SATURDAY THEN EAST SATURDAY NIGHT. THE CURRENT FORECASTS STILL
FOLLOW THE GFS SOLUTION WHICH ENDS THE SHOWERS OVER W WA A LITTLE
SOONER. ONCE THE TROUGH MOVES EAST A WARMING TREND WILL
DEVELOP...EITHER STARTING SATURDAY OR HOLDING OFF UNTIL SUNDAY. THE
MODEL SOLUTIONS DIFFER ON MONDAY AS WELL SO CONFIDENCE IN THE MOSTLY
SUNNY FORECAST IS A LITTLE SHAKY. KAM

&&

.AVIATION...A FRONTAL SYSTEM OVER THE AREA THROUGH TONIGHT WILL MOVE
INLAND LATER TUESDAY. LIGHT RAIN AT TIMES THROUGH TONIGHT SHOULD
TAPER OFF TO SCATTERED SHOWERS LATER TUESDAY. THE MOUNTAINS AND
HIGHER TERRAIN WILL REMAIN OBSCURED AND THE VISIBILITY WILL DROP AT
TIMES IN THE PRECIP AND MIST TUESDAY. THE AREAS OF BREEZY SOUTHERLY
WIND WILL DECREASE OVERNIGHT AND TUESDAY MORNING AS THE FRONT
WEAKENS. CLOUD LAYERS BETWEEN 4000-7000 FEET WITH LOWER CEILINGS
...1500-2500 FEET NORTH OF KPAE. CEILINGS LOWERING TO 2000-3000 FEET
AFTER 15Z TUESDAY AS WEAK FRONT MOVES THROUGH THE AREA.

KSEA...CLOUDY WITH RAIN AT TIMES THROUGH TUESDAY MORNING. CEILINGS
AOB 4000 FEET LOWERING TO 2000-3000 FEET TUESDAY MORNING.
SOUTHERLY WINDS 6 TO 10 KNOTS. FELTON

&&

.MARINE...A FRONTAL SYSTEM IS OVER THE NORTH PORTION OF THE AREA
WILL MOVE THROUGH THE INLAND WATERS TUESDAY. SOUTHERLY GRADIENTS
WILL EASE OVERNIGHT INTO TUESDAY MORNING. SMALL CRAFT ADVISORIES
REMAIN FOR THE COASTAL AND INLAND WATERS TONIGHT. A BROAD TROUGH IN
THE NORTHEAST PACIFIC WILL GRADUALLY SAG OVER THE PACNW AND WEAKEN
OVER THE NEXT SEVERAL DAYS AND THEN WEAK HIGH PRESSURE WILL BUILD
LATE IN THE WEEK. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES COASTAL WATERS...INLAND WATERS...GRAYS
     HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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




000
FXUS66 KSEW 010412 CCA
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
900 PM PDT MON AUG 31 2015

.SYNOPSIS...A FRONTAL SYSTEM WILL BRING RAIN AT TIMES TO WESTERN
WASHINGTON TONIGHT AND TUESDAY AS IT MOVES SLOWLY SOUTH ACROSS THE
AREA. A LARGE UPPER LEVEL LOW WILL SETTLE OVER THE REGION WEDNESDAY
THROUGH FRIDAY FOR COOL SHOWERY WEATHER. THE UPPER LEVEL LOW WILL
WEAKEN AND MOVE EAST EARLY THIS WEEKEND FOR A GRADUAL DRYING AND
WARMING TREND.

&&

.SHORT TERM...A LONG WAVE TROUGH WILL BROADEN OVER THE
PAC NW AND PERSIST THROUGH THE NEXT SEVERAL DAYS. ONE FRONTAL
FEATURE IS CURRENTLY DRAPED ACROSS WRN WA WITH AN ASSOCIATED BAND OF
RAIN PUSHING TO THE SE OF PUGET SOUND. STATION PRESSURES CONTINUE TO
FALL EXCEPT ALONG THE N WA COAST WITH KUIL REPORTING LITTLE CHANGE
THIS PAST HOUR. THE SURFACE FRONT IS NOT WELL DEFINED BUT IS
PROBABLY IN THE PROCESS OF PIVOTING ALONG THE N COAST AS THE MAIN
TROUGH DIGS SWD. QPF ON MOST MODELS IS PRETTY WIDESPREAD THROUGH AT
LEAST 12Z TONIGHT WHICH MAY BE OVERDONE. RAIN APPEARS TO HAVE
CHANGED OVER TO A MORE SHOWERY PATTERN BUT ANOTHER BAND OF
PERSISTANT RAIN COULD DEVELOP OVERNIGHT. SHOWERS SEEM LIKELY TO
CONTINUE THROUGH TUESDAY AS MODELS SHOW LITTLE MOVEMENT OF THE
MOISTURE BAND OVER THE AREA AND THE TROUGH DEEPENING OVER THE AREA.

UNSEASONABLY COOL AIR ALOFT WILL FILTER INTO WRN WA TUESDAY NIGHT
INTO WEDNESDAY AND THURSDAY. 1000-500 MB THICKNESS VALUES FALL DOWN
TO 5400M WHICH COULD COULD DROP SNOW LEVELS AS LOW AS 5500 TO 6000
FEET. BY THE TIME COLD AIR ARRIVES...THE DEEPER MOISTURE WILL HAVE
SHIFTED OFF TO THE E. IT WILL BECOME UNSTABLE WITH SOME SHOWERS
ACROSS THE AREA AND SNOW SHOWERS IN THE MOUNTAINS ABOVE PASS LEVELS.
A COUPLE INCHES OF EARLY SEASON SNOWFALL IS POSSIBLE ON HIGHER
PEAKS. IT WILL BE COOL OVER THE LOWLANDS WITH HIGHS STRUGGLING TO
REACH THE MID 60S BY THURSDAY. MERCER

.LONG TERM...FROM PREVIOUS DISCUSSION...THE CENTER OF THE LARGE
UPPER LEVEL TROUGH OVER B.C. WILL FORM A LOW WHICH WILL MOVE S OVER
W WA ON FRIDAY. WHILE THE LOW IS OVERHEAD FRIDAY AFTERNOON...THE GFS
HAS LIFTED INDICES DROPPING BELOW ZERO. THERE COULD BE ENOUGH
INSTABILITY FOR ISOLATED THUNDERSTORMS...BUT I WILL HOLD OFF
INCLUDING THEM IN THE FORECAST UNTIL THE MODELS BECOME A LITTLE MORE
CONSISTENT OR MORE UNSTABLE.

FRIDAY NIGHT AND SATURDAY THE GFS BEGINS MOVING THE WEAKENING TROUGH
TO THE EAST...WHILE THE ECMWF AND CANADIAN MOVE IT S OVER OREGON
SATURDAY THEN EAST SATURDAY NIGHT. THE CURRENT FORECASTS STILL
FOLLOW THE GFS SOLUTION WHICH ENDS THE SHOWERS OVER W WA A LITTLE
SOONER. ONCE THE TROUGH MOVES EAST A WARMING TREND WILL
DEVELOP...EITHER STARTING SATURDAY OR HOLDING OFF UNTIL SUNDAY. THE
MODEL SOLUTIONS DIFFER ON MONDAY AS WELL SO CONFIDENCE IN THE MOSTLY
SUNNY FORECAST IS A LITTLE SHAKY. KAM

&&

.AVIATION...A FRONTAL SYSTEM OVER THE AREA THROUGH TONIGHT WILL MOVE
INLAND LATER TUESDAY. LIGHT RAIN AT TIMES THROUGH TONIGHT SHOULD
TAPER OFF TO SCATTERED SHOWERS LATER TUESDAY. THE MOUNTAINS AND
HIGHER TERRAIN WILL REMAIN OBSCURED AND THE VISIBILITY WILL DROP AT
TIMES IN THE PRECIP AND MIST TUESDAY. THE AREAS OF BREEZY SOUTHERLY
WIND WILL DECREASE OVERNIGHT AND TUESDAY MORNING AS THE FRONT
WEAKENS. CLOUD LAYERS BETWEEN 4000-7000 FEET WITH LOWER CEILINGS
...1500-2500 FEET NORTH OF KPAE. CEILINGS LOWERING TO 2000-3000 FEET
AFTER 15Z TUESDAY AS WEAK FRONT MOVES THROUGH THE AREA.

KSEA...CLOUDY WITH RAIN AT TIMES THROUGH TUESDAY MORNING. CEILINGS
AOB 4000 FEET LOWERING TO 2000-3000 FEET TUESDAY MORNING.
SOUTHERLY WINDS 6 TO 10 KNOTS. FELTON

&&

.MARINE...A FRONTAL SYSTEM IS OVER THE NORTH PORTION OF THE AREA
WILL MOVE THROUGH THE INLAND WATERS TUESDAY. SOUTHERLY GRADIENTS
WILL EASE OVERNIGHT INTO TUESDAY MORNING. SMALL CRAFT ADVISORIES
REMAIN FOR THE COASTAL AND INLAND WATERS TONIGHT. A BROAD TROUGH IN
THE NORTHEAST PACIFIC WILL GRADUALLY SAG OVER THE PACNW AND WEAKEN
OVER THE NEXT SEVERAL DAYS AND THEN WEAK HIGH PRESSURE WILL BUILD
LATE IN THE WEEK. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES COASTAL WATERS...INLAND WATERS...GRAYS
     HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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





000
FXUS66 KSEW 312331 CCA
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
256 PM PDT MON AUG 31 2015

.SYNOPSIS...A FRONTAL SYSTEM WILL BRING RAIN AT TIMES TO WESTERN
WASHINGTON TONIGHT AND TUESDAY AS IT MOVES SLOWLY SOUTH ACROSS THE
AREA. A LARGE UPPER LEVEL LOW WILL SETTLE OVER THE REGION WEDNESDAY
THROUGH FRIDAY FOR COOL SHOWERY WEATHER. THE UPPER LEVEL LOW WILL
WEAKEN AND MOVE EAST EARLY THIS WEEKEND FOR A GRADUAL DRYING AND
WARMING TREND.

&&

.SHORT TERM...A BROAD UPPER LEVEL LONGWAVE TROUGH EXTENDS FROM THE
NE PACIFIC ACROSS WESTERN CANADA AND THE PACNW THIS AFTERNOON...WITH
FAIRLY STRONG W FLOW ALOFT OVER W WA FOR LATE AUGUST. A FRONTAL
SYSTEM IS HUNG UP OVER SW B.C. WITH THE COLD FRONT EXTENDING WSW
FROM ABOUT CENTRAL VANCOUVER ISLAND. RADAR STILL SHOWS AREAS OF RAIN
TRAVERSING THE NORTHERN HALF OF W WA THIS AFTERNOON.

WATER VAPOR IMAGERY SHOWS A WELL DEVELOPED SHORTWAVE TROUGH OFFSHORE
THAT HAS MOVED SE TO AROUND 47N/136W THIS AFTERNOON AND WILL
CONTINUE HEADING SE TOWARD N CA. AS THIS SHORTWAVE MOVES SE IT WILL
WILL DRAG THE SW B.C. COLD FRONT SLOWLY SE ACROSS W WA LATE TONIGHT
THROUGH TUESDAY. FOR W WA THIS MEANS PERIODS OF LIGHT RAIN THROUGH
TUESDAY AND BREEZY WINDS AT TIMES.

THE BROAD UPPER LEVEL LONGWAVE TROUGH OVER THE REGION...MENTIONED
ABOVE...WILL GRADUALLY DEEPEN AND GAIN AMPLITUDE OVER THE REGION
THIS WEEK. A SMALL UPPER LEVEL LOW OVER THE GULF OF AK TODAY WILL
MOVE SE ALONG THE B.C. COAST THROUGH TUESDAY...EVENTUALLY BECOMING
THE CENTER OF THIS LARGE DEEPENING LONGWAVE TROUGH OVER CENTRAL B.C.
ON WEDNESDAY. THIS WILL BE A COOL SHOWERY PERIOD FOR W WA. THE AIR
MASS WILL COOL AS COLD AIR ALOFT WITH THE TROUGH MOVES DOWN OVER THE
AREA. THIS WILL LOWER SNOW LEVELS OVER THE MOUNTAINS TO 5000-6000
FEET LATE TUESDAY NIGHT THROUGH THURSDAY NIGHT.

WHILE THE LARGE UPPER LEVEL TROUGH IS OVER THE REGION A NUMBER OF
SHORTWAVE TROUGHS EMBEDDED IN THE FLOW AROUND THE LOW WILL MOVE
ACROSS W WA. THE GFS SHOWS A SHORTWAVE TROUGH ASSOCIATED WITH THE
DEVELOPING LOW CENTER CROSSING W WA TUESDAY NIGHT...BRINGING AND
INCREASE IN SHOWERS. THE 06Z GFS RUN SHOWED ANOTHER WEAK SHORTWAVE
CROSSING W WA WEDNESDAY...BUT THIS FEATURE HAS DROPPED OUT OF THE
12Z RUN. MOIST W FLOW ALOFT WILL CONTINUE OVER THE AREA
WEDNESDAY...AND THERE COULD STILL BE A WEAK SHORTWAVE PROVIDING SOME
EXTRA LIFT...SO SCATTERED SHOWERS WILL CONTINUE. A LARGER MORE
DEVELOPED SHORTWAVE TROUGH IS EXPECTED TO MOVE ACROSS THE AREA ON
THURSDAY. SW PRESSURE GRADIENTS WILL REMAIN STRONG ENOUGH SO THAT
LOCALLY BREEZY WINDS ARE LIKELY AS EACH SHORTWAVE CROSSES THE AREA.
KAM

.LONG TERM...THE CENTER OF THE LARGE UPPER LEVEL TROUGH OVER B.C.
WILL FORM A LOW WHICH WILL MOVE S OVER W WA ON FRIDAY. WHILE THE LOW
IS OVERHEAD FRIDAY AFTERNOON...THE GFS HAS LIFTED INDICES DROPPING
BELOW ZERO. THERE COULD BE ENOUGH INSTABILITY FOR ISOLATED
THUNDERSTORMS...BUT I WILL HOLD OFF INCLUDING THEM IN THE FORECAST
UNTIL THE MODELS BECOME A LITTLE MORE CONSISTENT OR MORE UNSTABLE.

FRIDAY NIGHT AND SATURDAY THE GFS BEGINS MOVING THE WEAKENING TROUGH
TO THE EAST...WHILE THE ECMWF AND CANADIAN MOVE IT S OVER OREGON
SATURDAY THEN EAST SATURDAY NIGHT. THE CURRENT FORECASTS STILL
FOLLOW THE GFS SOLUTION WHICH ENDS THE SHOWERS OVER W WA A LITTLE
SOONER. ONCE THE TROUGH MOVES EAST A WARMING TREND WILL
DEVELOP...EITHER STARTING SATURDAY OR HOLDING OFF UNTIL SUNDAY. THE
MODEL SOLUTIONS DIFFER ON MONDAY AS WELL SO CONFIDENCE IN THE MOSTLY
SUNNY FORECAST IS A LITTLE SHAKY. KAM

&&

.AVIATION...A FRONTAL SYSTEM OVER THE AREA THROUGH TONIGHT WILL MOVE
INLAND LATER TUESDAY. RAIN AT TIMES THROUGH TONIGHT SHOULD TAPER OFF
TO SCATTERED SHOWERS LATER TUE. THE MOUNTAINS AND HIGHER TERRAIN
WILL REMAIN OBSCURED AND THE VSBY WILL DROP AT TIMES IN THE PRECIP
AND MIST. THE AREAS OF BREEZY SOUTHERLY WIND WILL DECREASE OVERNIGHT
AND TUESDAY MORNING AS THE FRONT WEAKENS.

KSEA...CLOUDY WITH RAIN AT TIMES AND A SLY BREEZE CONTINUES.

&&

.MARINE...A FRONTAL SYSTEM IS OVER THE AREA BUT IT WILL MOVE INLAND
TUESDAY. THE SOUTHERLY GRADIENTS TODAY WHICH ARE STRONG ENOUGH FOR
BREEZY WEATHER AND SMALL CRAFT ADVISORIES SHOULD GIVE OUT OVERNIGHT
OR TUESDAY MORNING. A BROAD TROUGH IN THE NORTHEAST PACIFIC WILL
GRADUALLY SAG OVER THE PACNW AND WEAKEN OVER THE NEXT SEVERAL DAYS
AND THEN WEAK HIGH PRESSURE WILL BUILD LATE IN THE WEEK.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY COAST...EAST ENTRANCE TO THE STRAIT...
      ADMIRALTY INLET...NORTHERN INLAND WATERS...PUGET SOUND.
     SMALL CRAFT ADVISORY FOR ROUGH GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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




000
FXUS66 KSEW 312156
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
256 PM PDT MON AUG 31 2015

.SYNOPSIS...A FRONTAL SYSTEM WILL BRING RAIN AT TIMES TO WESTERN
WASHINGTON TONIGHT AND TUESDAY AS IT MOVES SLOWLY SOUTH ACROSS THE
AREA. A LARGE UPPER LEVEL LOW WILL SETTLE OVER THE REGION WEDNESDAY
THROUGH FRIDAY FOR COOL SHOWERY WEATHER. THE UPPER LEVEL LOW WILL
WEAKEN AND MOVE EAST EARLY THIS WEEKEND FOR A GRADUAL DRYING AND
WARMING TREND.

&&

.SHORT TERM...A BROAD UPPER LEVEL LONGWAVE TROUGH EXTENDS FROM THE
NE PACIFIC ACROSS WESTERN CANADA AND THE PACNW THIS AFTERNOON...WITH
FAIRLY STRONG W FLOW ALOFT OVER W WA FOR LATE AUGUST. A FRONTAL
SYSTEM IS HUNG UP OVER SW B.C. WITH THE COLD FRONT EXTENDING WSW
FROM ABOUT CENTRAL VANCOUVER ISLAND. RADAR STILL SHOWS AREAS OF RAIN
TRAVERSING THE NORTHERN HALF OF W WA THIS AFTERNOON.

WATER VAPOR IMAGERY SHOWS A WELL DEVELOPED SHORTWAVE TROUGH OFFSHORE
THAT HAS MOVED SE TO AROUND 47N/136W THIS AFTERNOON AND WILL
COMEDIAN HEADING SE TOWARD N CA. AS THIS SHORTWAVE MOVES SE IT WILL
WILL DRAG THE SW B.C. COLD FRONT SLOWLY SE ACROSS W WA LATE TONIGHT
THROUGH TUESDAY. FOR W WA THIS MEANS PERIODS OF LIGHT RAIN THROUGH
TUESDAY AND BREEZY WINDS AT TIMES.

THE BROAD UPPER LEVEL LONGWAVE TROUGH OVER THE REGION...MENTIONED
ABOVE...WILL GRADUALLY DEEPEN AND GAIN AMPLITUDE OVER THE REGION
THIS WEEK. A SMALL UPPER LEVEL LOW OVER THE GULF OF AK TODAY WILL
MOVE SE ALONG THE B.C. COAST THROUGH TUESDAY...EVENTUALLY BECOMING
THE CENTER OF THIS LARGE DEEPENING LONGWAVE TROUGH OVER CENTRAL B.C.
ON WEDNESDAY. THIS WILL BE A COOL SHOWERY PERIOD FOR W WA. THE AIR
MASS WILL COOL AS COLD AIR ALOFT WITH THE TROUGH MOVES DOWN OVER THE
AREA. THIS WILL LOWER SNOW LEVELS OVER THE MOUNTAINS TO 5000-6000
FEET LATE TUESDAY NIGHT THROUGH THURSDAY NIGHT.

WHILE THE LARGE UPPER LEVEL TROUGH IS OVER THE REGION A NUMBER OF
SHORTWAVE TROUGHS EMBEDDED IN THE FLOW AROUND THE LOW WILL MOVE
ACROSS W WA. THE GFS SHOWS A SHORTWAVE TROUGH ASSOCIATED WITH THE
DEVELOPING LOW CENTER CROSSING W WA TUESDAY NIGHT...BRINGING AND
INCREASE IN SHOWERS. THE 06Z GFS RUN SHOWED ANOTHER WEAK SHORTWAVE
CROSSING W WA WEDNESDAY...BUT THIS FEATURE HAS DROPPED OUT OF THE
12Z RUN. MOIST W FLOW ALOFT WILL CONTINUE OVER THE AREA
WEDNESDAY...AND THERE COULD STILL BE A WEAK SHORTWAVE PROVIDING SOME
EXTRA LIFT...SO SCATTERED SHOWERS WILL CONTINUE. A LARGER MORE
DEVELOPED SHORTWAVE TROUGH IS EXPECTED TO MOVE ACROSS THE AREA ON
THURSDAY. SW PRESSURE GRADIENTS WILL REMAIN STRONG ENOUGH SO THAT
LOCALLY BREEZY WINDS ARE LIKELY AS EACH SHORTWAVE CROSSES THE AREA.
KAM

.LONG TERM...THE CENTER OF THE LARGE UPPER LEVEL TROUGH OVER B.C.
WILL FORM A LOW WHICH WILL MOVE S OVER W WA ON FRIDAY. WHILE THE LOW
IS OVERHEAD FRIDAY AFTERNOON...THE GFS HAS LIFTED INDICES DROPPING
BELOW ZERO. THERE COULD BE ENOUGH INSTABILITY FOR ISOLATED
THUNDERSTORMS...BUT I WILL HOLD OFF INCLUDING THEM IN THE FORECAST
UNTIL THE MODELS BECOME A LITTLE MORE CONSISTENT OR MORE UNSTABLE.

FRIDAY NIGHT AND SATURDAY THE GFS BEGINS MOVING THE WEAKENING TROUGH
TO THE EAST...WHILE THE ECMWF AND CANADIAN MOVE IT S OVER OREGON
SATURDAY THEN EAST SATURDAY NIGHT. THE CURRENT FORECASTS STILL
FOLLOW THE GFS SOLUTION WHICH ENDS THE SHOWERS OVER W WA A LITTLE
SOONER. ONCE THE TROUGH MOVES EAST A WARMING TREND WILL
DEVELOP...EITHER STARTING SATURDAY OR HOLDING OFF UNTIL SUNDAY. THE
MODEL SOLUTIONS DIFFER ON MONDAY AS WELL SO CONFIDENCE IN THE MOSTLY
SUNNY FORECAST IS A LITTLE SHAKY. KAM

&&

.AVIATION...A FRONTAL SYSTEM OVER THE AREA THROUGH TONIGHT WILL MOVE
INLAND LATER TUESDAY. RAIN AT TIMES THROUGH TONIGHT SHOULD TAPER OFF
TO SCATTERED SHOWERS LATER TUE. THE MOUNTAINS AND HIGHER TERRAIN
WILL REMAIN OBSCURED AND THE VSBY WILL DROP AT TIMES IN THE PRECIP
AND MIST. THE AREAS OF BREEZY SOUTHERLY WIND WILL DECREASE OVERNIGHT
AND TUESDAY MORNING AS THE FRONT WEAKENS.

KSEA...CLOUDY WITH RAIN AT TIMES AND A SLY BREEZE CONTINUES.

&&

.MARINE...A FRONTAL SYSTEM IS OVER THE AREA BUT IT WILL MOVE INLAND
TUESDAY. THE SOUTHERLY GRADIENTS TODAY WHICH ARE STRONG ENOUGH FOR
BREEZY WEATHER AND SMALL CRAFT ADVISORIES SHOULD GIVE OUT OVERNIGHT
OR TUESDAY MORNING. A BROAD TROUGH IN THE NORTHEAST PACIFIC WILL
GRADUALLY SAG OVER THE PACNW AND WEAKEN OVER THE NEXT SEVERAL DAYS
AND THEN WEAK HIGH PRESSURE WILL BUILD LATE IN THE WEEK.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY COAST...EAST ENTRANCE TO THE STRAIT...
      ADMIRALTY INLET...NORTHERN INLAND WATERS...PUGET SOUND.
     SMALL CRAFT ADVISORY FOR ROUGH GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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





000
FXUS66 KSEW 312156
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
256 PM PDT MON AUG 31 2015

.SYNOPSIS...A FRONTAL SYSTEM WILL BRING RAIN AT TIMES TO WESTERN
WASHINGTON TONIGHT AND TUESDAY AS IT MOVES SLOWLY SOUTH ACROSS THE
AREA. A LARGE UPPER LEVEL LOW WILL SETTLE OVER THE REGION WEDNESDAY
THROUGH FRIDAY FOR COOL SHOWERY WEATHER. THE UPPER LEVEL LOW WILL
WEAKEN AND MOVE EAST EARLY THIS WEEKEND FOR A GRADUAL DRYING AND
WARMING TREND.

&&

.SHORT TERM...A BROAD UPPER LEVEL LONGWAVE TROUGH EXTENDS FROM THE
NE PACIFIC ACROSS WESTERN CANADA AND THE PACNW THIS AFTERNOON...WITH
FAIRLY STRONG W FLOW ALOFT OVER W WA FOR LATE AUGUST. A FRONTAL
SYSTEM IS HUNG UP OVER SW B.C. WITH THE COLD FRONT EXTENDING WSW
FROM ABOUT CENTRAL VANCOUVER ISLAND. RADAR STILL SHOWS AREAS OF RAIN
TRAVERSING THE NORTHERN HALF OF W WA THIS AFTERNOON.

WATER VAPOR IMAGERY SHOWS A WELL DEVELOPED SHORTWAVE TROUGH OFFSHORE
THAT HAS MOVED SE TO AROUND 47N/136W THIS AFTERNOON AND WILL
COMEDIAN HEADING SE TOWARD N CA. AS THIS SHORTWAVE MOVES SE IT WILL
WILL DRAG THE SW B.C. COLD FRONT SLOWLY SE ACROSS W WA LATE TONIGHT
THROUGH TUESDAY. FOR W WA THIS MEANS PERIODS OF LIGHT RAIN THROUGH
TUESDAY AND BREEZY WINDS AT TIMES.

THE BROAD UPPER LEVEL LONGWAVE TROUGH OVER THE REGION...MENTIONED
ABOVE...WILL GRADUALLY DEEPEN AND GAIN AMPLITUDE OVER THE REGION
THIS WEEK. A SMALL UPPER LEVEL LOW OVER THE GULF OF AK TODAY WILL
MOVE SE ALONG THE B.C. COAST THROUGH TUESDAY...EVENTUALLY BECOMING
THE CENTER OF THIS LARGE DEEPENING LONGWAVE TROUGH OVER CENTRAL B.C.
ON WEDNESDAY. THIS WILL BE A COOL SHOWERY PERIOD FOR W WA. THE AIR
MASS WILL COOL AS COLD AIR ALOFT WITH THE TROUGH MOVES DOWN OVER THE
AREA. THIS WILL LOWER SNOW LEVELS OVER THE MOUNTAINS TO 5000-6000
FEET LATE TUESDAY NIGHT THROUGH THURSDAY NIGHT.

WHILE THE LARGE UPPER LEVEL TROUGH IS OVER THE REGION A NUMBER OF
SHORTWAVE TROUGHS EMBEDDED IN THE FLOW AROUND THE LOW WILL MOVE
ACROSS W WA. THE GFS SHOWS A SHORTWAVE TROUGH ASSOCIATED WITH THE
DEVELOPING LOW CENTER CROSSING W WA TUESDAY NIGHT...BRINGING AND
INCREASE IN SHOWERS. THE 06Z GFS RUN SHOWED ANOTHER WEAK SHORTWAVE
CROSSING W WA WEDNESDAY...BUT THIS FEATURE HAS DROPPED OUT OF THE
12Z RUN. MOIST W FLOW ALOFT WILL CONTINUE OVER THE AREA
WEDNESDAY...AND THERE COULD STILL BE A WEAK SHORTWAVE PROVIDING SOME
EXTRA LIFT...SO SCATTERED SHOWERS WILL CONTINUE. A LARGER MORE
DEVELOPED SHORTWAVE TROUGH IS EXPECTED TO MOVE ACROSS THE AREA ON
THURSDAY. SW PRESSURE GRADIENTS WILL REMAIN STRONG ENOUGH SO THAT
LOCALLY BREEZY WINDS ARE LIKELY AS EACH SHORTWAVE CROSSES THE AREA.
KAM

.LONG TERM...THE CENTER OF THE LARGE UPPER LEVEL TROUGH OVER B.C.
WILL FORM A LOW WHICH WILL MOVE S OVER W WA ON FRIDAY. WHILE THE LOW
IS OVERHEAD FRIDAY AFTERNOON...THE GFS HAS LIFTED INDICES DROPPING
BELOW ZERO. THERE COULD BE ENOUGH INSTABILITY FOR ISOLATED
THUNDERSTORMS...BUT I WILL HOLD OFF INCLUDING THEM IN THE FORECAST
UNTIL THE MODELS BECOME A LITTLE MORE CONSISTENT OR MORE UNSTABLE.

FRIDAY NIGHT AND SATURDAY THE GFS BEGINS MOVING THE WEAKENING TROUGH
TO THE EAST...WHILE THE ECMWF AND CANADIAN MOVE IT S OVER OREGON
SATURDAY THEN EAST SATURDAY NIGHT. THE CURRENT FORECASTS STILL
FOLLOW THE GFS SOLUTION WHICH ENDS THE SHOWERS OVER W WA A LITTLE
SOONER. ONCE THE TROUGH MOVES EAST A WARMING TREND WILL
DEVELOP...EITHER STARTING SATURDAY OR HOLDING OFF UNTIL SUNDAY. THE
MODEL SOLUTIONS DIFFER ON MONDAY AS WELL SO CONFIDENCE IN THE MOSTLY
SUNNY FORECAST IS A LITTLE SHAKY. KAM

&&

.AVIATION...A FRONTAL SYSTEM OVER THE AREA THROUGH TONIGHT WILL MOVE
INLAND LATER TUESDAY. RAIN AT TIMES THROUGH TONIGHT SHOULD TAPER OFF
TO SCATTERED SHOWERS LATER TUE. THE MOUNTAINS AND HIGHER TERRAIN
WILL REMAIN OBSCURED AND THE VSBY WILL DROP AT TIMES IN THE PRECIP
AND MIST. THE AREAS OF BREEZY SOUTHERLY WIND WILL DECREASE OVERNIGHT
AND TUESDAY MORNING AS THE FRONT WEAKENS.

KSEA...CLOUDY WITH RAIN AT TIMES AND A SLY BREEZE CONTINUES.

&&

.MARINE...A FRONTAL SYSTEM IS OVER THE AREA BUT IT WILL MOVE INLAND
TUESDAY. THE SOUTHERLY GRADIENTS TODAY WHICH ARE STRONG ENOUGH FOR
BREEZY WEATHER AND SMALL CRAFT ADVISORIES SHOULD GIVE OUT OVERNIGHT
OR TUESDAY MORNING. A BROAD TROUGH IN THE NORTHEAST PACIFIC WILL
GRADUALLY SAG OVER THE PACNW AND WEAKEN OVER THE NEXT SEVERAL DAYS
AND THEN WEAK HIGH PRESSURE WILL BUILD LATE IN THE WEEK.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY COAST...EAST ENTRANCE TO THE STRAIT...
      ADMIRALTY INLET...NORTHERN INLAND WATERS...PUGET SOUND.
     SMALL CRAFT ADVISORY FOR ROUGH GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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




000
FXUS66 KSEW 312156
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
256 PM PDT MON AUG 31 2015

.SYNOPSIS...A FRONTAL SYSTEM WILL BRING RAIN AT TIMES TO WESTERN
WASHINGTON TONIGHT AND TUESDAY AS IT MOVES SLOWLY SOUTH ACROSS THE
AREA. A LARGE UPPER LEVEL LOW WILL SETTLE OVER THE REGION WEDNESDAY
THROUGH FRIDAY FOR COOL SHOWERY WEATHER. THE UPPER LEVEL LOW WILL
WEAKEN AND MOVE EAST EARLY THIS WEEKEND FOR A GRADUAL DRYING AND
WARMING TREND.

&&

.SHORT TERM...A BROAD UPPER LEVEL LONGWAVE TROUGH EXTENDS FROM THE
NE PACIFIC ACROSS WESTERN CANADA AND THE PACNW THIS AFTERNOON...WITH
FAIRLY STRONG W FLOW ALOFT OVER W WA FOR LATE AUGUST. A FRONTAL
SYSTEM IS HUNG UP OVER SW B.C. WITH THE COLD FRONT EXTENDING WSW
FROM ABOUT CENTRAL VANCOUVER ISLAND. RADAR STILL SHOWS AREAS OF RAIN
TRAVERSING THE NORTHERN HALF OF W WA THIS AFTERNOON.

WATER VAPOR IMAGERY SHOWS A WELL DEVELOPED SHORTWAVE TROUGH OFFSHORE
THAT HAS MOVED SE TO AROUND 47N/136W THIS AFTERNOON AND WILL
COMEDIAN HEADING SE TOWARD N CA. AS THIS SHORTWAVE MOVES SE IT WILL
WILL DRAG THE SW B.C. COLD FRONT SLOWLY SE ACROSS W WA LATE TONIGHT
THROUGH TUESDAY. FOR W WA THIS MEANS PERIODS OF LIGHT RAIN THROUGH
TUESDAY AND BREEZY WINDS AT TIMES.

THE BROAD UPPER LEVEL LONGWAVE TROUGH OVER THE REGION...MENTIONED
ABOVE...WILL GRADUALLY DEEPEN AND GAIN AMPLITUDE OVER THE REGION
THIS WEEK. A SMALL UPPER LEVEL LOW OVER THE GULF OF AK TODAY WILL
MOVE SE ALONG THE B.C. COAST THROUGH TUESDAY...EVENTUALLY BECOMING
THE CENTER OF THIS LARGE DEEPENING LONGWAVE TROUGH OVER CENTRAL B.C.
ON WEDNESDAY. THIS WILL BE A COOL SHOWERY PERIOD FOR W WA. THE AIR
MASS WILL COOL AS COLD AIR ALOFT WITH THE TROUGH MOVES DOWN OVER THE
AREA. THIS WILL LOWER SNOW LEVELS OVER THE MOUNTAINS TO 5000-6000
FEET LATE TUESDAY NIGHT THROUGH THURSDAY NIGHT.

WHILE THE LARGE UPPER LEVEL TROUGH IS OVER THE REGION A NUMBER OF
SHORTWAVE TROUGHS EMBEDDED IN THE FLOW AROUND THE LOW WILL MOVE
ACROSS W WA. THE GFS SHOWS A SHORTWAVE TROUGH ASSOCIATED WITH THE
DEVELOPING LOW CENTER CROSSING W WA TUESDAY NIGHT...BRINGING AND
INCREASE IN SHOWERS. THE 06Z GFS RUN SHOWED ANOTHER WEAK SHORTWAVE
CROSSING W WA WEDNESDAY...BUT THIS FEATURE HAS DROPPED OUT OF THE
12Z RUN. MOIST W FLOW ALOFT WILL CONTINUE OVER THE AREA
WEDNESDAY...AND THERE COULD STILL BE A WEAK SHORTWAVE PROVIDING SOME
EXTRA LIFT...SO SCATTERED SHOWERS WILL CONTINUE. A LARGER MORE
DEVELOPED SHORTWAVE TROUGH IS EXPECTED TO MOVE ACROSS THE AREA ON
THURSDAY. SW PRESSURE GRADIENTS WILL REMAIN STRONG ENOUGH SO THAT
LOCALLY BREEZY WINDS ARE LIKELY AS EACH SHORTWAVE CROSSES THE AREA.
KAM

.LONG TERM...THE CENTER OF THE LARGE UPPER LEVEL TROUGH OVER B.C.
WILL FORM A LOW WHICH WILL MOVE S OVER W WA ON FRIDAY. WHILE THE LOW
IS OVERHEAD FRIDAY AFTERNOON...THE GFS HAS LIFTED INDICES DROPPING
BELOW ZERO. THERE COULD BE ENOUGH INSTABILITY FOR ISOLATED
THUNDERSTORMS...BUT I WILL HOLD OFF INCLUDING THEM IN THE FORECAST
UNTIL THE MODELS BECOME A LITTLE MORE CONSISTENT OR MORE UNSTABLE.

FRIDAY NIGHT AND SATURDAY THE GFS BEGINS MOVING THE WEAKENING TROUGH
TO THE EAST...WHILE THE ECMWF AND CANADIAN MOVE IT S OVER OREGON
SATURDAY THEN EAST SATURDAY NIGHT. THE CURRENT FORECASTS STILL
FOLLOW THE GFS SOLUTION WHICH ENDS THE SHOWERS OVER W WA A LITTLE
SOONER. ONCE THE TROUGH MOVES EAST A WARMING TREND WILL
DEVELOP...EITHER STARTING SATURDAY OR HOLDING OFF UNTIL SUNDAY. THE
MODEL SOLUTIONS DIFFER ON MONDAY AS WELL SO CONFIDENCE IN THE MOSTLY
SUNNY FORECAST IS A LITTLE SHAKY. KAM

&&

.AVIATION...A FRONTAL SYSTEM OVER THE AREA THROUGH TONIGHT WILL MOVE
INLAND LATER TUESDAY. RAIN AT TIMES THROUGH TONIGHT SHOULD TAPER OFF
TO SCATTERED SHOWERS LATER TUE. THE MOUNTAINS AND HIGHER TERRAIN
WILL REMAIN OBSCURED AND THE VSBY WILL DROP AT TIMES IN THE PRECIP
AND MIST. THE AREAS OF BREEZY SOUTHERLY WIND WILL DECREASE OVERNIGHT
AND TUESDAY MORNING AS THE FRONT WEAKENS.

KSEA...CLOUDY WITH RAIN AT TIMES AND A SLY BREEZE CONTINUES.

&&

.MARINE...A FRONTAL SYSTEM IS OVER THE AREA BUT IT WILL MOVE INLAND
TUESDAY. THE SOUTHERLY GRADIENTS TODAY WHICH ARE STRONG ENOUGH FOR
BREEZY WEATHER AND SMALL CRAFT ADVISORIES SHOULD GIVE OUT OVERNIGHT
OR TUESDAY MORNING. A BROAD TROUGH IN THE NORTHEAST PACIFIC WILL
GRADUALLY SAG OVER THE PACNW AND WEAKEN OVER THE NEXT SEVERAL DAYS
AND THEN WEAK HIGH PRESSURE WILL BUILD LATE IN THE WEEK.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY COAST...EAST ENTRANCE TO THE STRAIT...
      ADMIRALTY INLET...NORTHERN INLAND WATERS...PUGET SOUND.
     SMALL CRAFT ADVISORY FOR ROUGH GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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





000
FXUS66 KSEW 312156
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
256 PM PDT MON AUG 31 2015

.SYNOPSIS...A FRONTAL SYSTEM WILL BRING RAIN AT TIMES TO WESTERN
WASHINGTON TONIGHT AND TUESDAY AS IT MOVES SLOWLY SOUTH ACROSS THE
AREA. A LARGE UPPER LEVEL LOW WILL SETTLE OVER THE REGION WEDNESDAY
THROUGH FRIDAY FOR COOL SHOWERY WEATHER. THE UPPER LEVEL LOW WILL
WEAKEN AND MOVE EAST EARLY THIS WEEKEND FOR A GRADUAL DRYING AND
WARMING TREND.

&&

.SHORT TERM...A BROAD UPPER LEVEL LONGWAVE TROUGH EXTENDS FROM THE
NE PACIFIC ACROSS WESTERN CANADA AND THE PACNW THIS AFTERNOON...WITH
FAIRLY STRONG W FLOW ALOFT OVER W WA FOR LATE AUGUST. A FRONTAL
SYSTEM IS HUNG UP OVER SW B.C. WITH THE COLD FRONT EXTENDING WSW
FROM ABOUT CENTRAL VANCOUVER ISLAND. RADAR STILL SHOWS AREAS OF RAIN
TRAVERSING THE NORTHERN HALF OF W WA THIS AFTERNOON.

WATER VAPOR IMAGERY SHOWS A WELL DEVELOPED SHORTWAVE TROUGH OFFSHORE
THAT HAS MOVED SE TO AROUND 47N/136W THIS AFTERNOON AND WILL
COMEDIAN HEADING SE TOWARD N CA. AS THIS SHORTWAVE MOVES SE IT WILL
WILL DRAG THE SW B.C. COLD FRONT SLOWLY SE ACROSS W WA LATE TONIGHT
THROUGH TUESDAY. FOR W WA THIS MEANS PERIODS OF LIGHT RAIN THROUGH
TUESDAY AND BREEZY WINDS AT TIMES.

THE BROAD UPPER LEVEL LONGWAVE TROUGH OVER THE REGION...MENTIONED
ABOVE...WILL GRADUALLY DEEPEN AND GAIN AMPLITUDE OVER THE REGION
THIS WEEK. A SMALL UPPER LEVEL LOW OVER THE GULF OF AK TODAY WILL
MOVE SE ALONG THE B.C. COAST THROUGH TUESDAY...EVENTUALLY BECOMING
THE CENTER OF THIS LARGE DEEPENING LONGWAVE TROUGH OVER CENTRAL B.C.
ON WEDNESDAY. THIS WILL BE A COOL SHOWERY PERIOD FOR W WA. THE AIR
MASS WILL COOL AS COLD AIR ALOFT WITH THE TROUGH MOVES DOWN OVER THE
AREA. THIS WILL LOWER SNOW LEVELS OVER THE MOUNTAINS TO 5000-6000
FEET LATE TUESDAY NIGHT THROUGH THURSDAY NIGHT.

WHILE THE LARGE UPPER LEVEL TROUGH IS OVER THE REGION A NUMBER OF
SHORTWAVE TROUGHS EMBEDDED IN THE FLOW AROUND THE LOW WILL MOVE
ACROSS W WA. THE GFS SHOWS A SHORTWAVE TROUGH ASSOCIATED WITH THE
DEVELOPING LOW CENTER CROSSING W WA TUESDAY NIGHT...BRINGING AND
INCREASE IN SHOWERS. THE 06Z GFS RUN SHOWED ANOTHER WEAK SHORTWAVE
CROSSING W WA WEDNESDAY...BUT THIS FEATURE HAS DROPPED OUT OF THE
12Z RUN. MOIST W FLOW ALOFT WILL CONTINUE OVER THE AREA
WEDNESDAY...AND THERE COULD STILL BE A WEAK SHORTWAVE PROVIDING SOME
EXTRA LIFT...SO SCATTERED SHOWERS WILL CONTINUE. A LARGER MORE
DEVELOPED SHORTWAVE TROUGH IS EXPECTED TO MOVE ACROSS THE AREA ON
THURSDAY. SW PRESSURE GRADIENTS WILL REMAIN STRONG ENOUGH SO THAT
LOCALLY BREEZY WINDS ARE LIKELY AS EACH SHORTWAVE CROSSES THE AREA.
KAM

.LONG TERM...THE CENTER OF THE LARGE UPPER LEVEL TROUGH OVER B.C.
WILL FORM A LOW WHICH WILL MOVE S OVER W WA ON FRIDAY. WHILE THE LOW
IS OVERHEAD FRIDAY AFTERNOON...THE GFS HAS LIFTED INDICES DROPPING
BELOW ZERO. THERE COULD BE ENOUGH INSTABILITY FOR ISOLATED
THUNDERSTORMS...BUT I WILL HOLD OFF INCLUDING THEM IN THE FORECAST
UNTIL THE MODELS BECOME A LITTLE MORE CONSISTENT OR MORE UNSTABLE.

FRIDAY NIGHT AND SATURDAY THE GFS BEGINS MOVING THE WEAKENING TROUGH
TO THE EAST...WHILE THE ECMWF AND CANADIAN MOVE IT S OVER OREGON
SATURDAY THEN EAST SATURDAY NIGHT. THE CURRENT FORECASTS STILL
FOLLOW THE GFS SOLUTION WHICH ENDS THE SHOWERS OVER W WA A LITTLE
SOONER. ONCE THE TROUGH MOVES EAST A WARMING TREND WILL
DEVELOP...EITHER STARTING SATURDAY OR HOLDING OFF UNTIL SUNDAY. THE
MODEL SOLUTIONS DIFFER ON MONDAY AS WELL SO CONFIDENCE IN THE MOSTLY
SUNNY FORECAST IS A LITTLE SHAKY. KAM

&&

.AVIATION...A FRONTAL SYSTEM OVER THE AREA THROUGH TONIGHT WILL MOVE
INLAND LATER TUESDAY. RAIN AT TIMES THROUGH TONIGHT SHOULD TAPER OFF
TO SCATTERED SHOWERS LATER TUE. THE MOUNTAINS AND HIGHER TERRAIN
WILL REMAIN OBSCURED AND THE VSBY WILL DROP AT TIMES IN THE PRECIP
AND MIST. THE AREAS OF BREEZY SOUTHERLY WIND WILL DECREASE OVERNIGHT
AND TUESDAY MORNING AS THE FRONT WEAKENS.

KSEA...CLOUDY WITH RAIN AT TIMES AND A SLY BREEZE CONTINUES.

&&

.MARINE...A FRONTAL SYSTEM IS OVER THE AREA BUT IT WILL MOVE INLAND
TUESDAY. THE SOUTHERLY GRADIENTS TODAY WHICH ARE STRONG ENOUGH FOR
BREEZY WEATHER AND SMALL CRAFT ADVISORIES SHOULD GIVE OUT OVERNIGHT
OR TUESDAY MORNING. A BROAD TROUGH IN THE NORTHEAST PACIFIC WILL
GRADUALLY SAG OVER THE PACNW AND WEAKEN OVER THE NEXT SEVERAL DAYS
AND THEN WEAK HIGH PRESSURE WILL BUILD LATE IN THE WEEK.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY COAST...EAST ENTRANCE TO THE STRAIT...
      ADMIRALTY INLET...NORTHERN INLAND WATERS...PUGET SOUND.
     SMALL CRAFT ADVISORY FOR ROUGH GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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




000
FXUS66 KSEW 311610
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
910 AM PDT MON AUG 31 2015

.SYNOPSIS...A FRONTAL SYSTEM WILL BRING RAIN TO WESTERN WASHINGTON
MAINLY FROM PUGET SOUND NORTHWARD TODAY THROUGH TUESDAY. A LARGE
UPPER LEVEL LOW WILL SETTLE OVER THE REGION WEDNESDAY THROUGH FRIDAY
FOR COOL SHOWERY WEATHER. THE UPPER LEVEL LOW WILL WEAKEN AND MOVE
EAST EARLY THIS WEEKEND FOR A GRADUAL DRYING AND WARMING TREND.

&&

.SHORT TERM...A BROAD UPPER LEVEL LONGWAVE TROUGH EXTENDS FROM THE
NE PACIFIC ACROSS WESTERN CANADA AND THE PACNW THIS MORNING...WITH
FAIRLY STRONG W FLOW ALOFT OVER W WA FOR LATE AUGUST. A FRONTAL
SYSTEM IS HUNG UP OVER SW B.C. THIS MORNING WITH THE COLD FRONT
EXTENDING WSW FROM ABOUT CENTRAL VANCOUVER ISLAND. RADAR IS SHOWING
STEADIER LIGHT RAIN OVER THE N COAST AND N INTERIOR AND SMALLER
AREAS OF LIGHT RAIN CROSSING THE CENTRAL COAST AND PUGET SOUND
REGION.

WATER VAPOR IMAGERY SHOWS A WELL DEVELOPED SHORTWAVE TROUGH OUT NEAR
49N/140W AND THE TAIL END OF THE COLD FRONT....THAT IS DIGGING SE
TOWARD N CA. AS THE SHORTWAVE MOVES SE IT WILL WILL DRAG THE
VANCOUVER ISLAND COLD FRONT WITH IT...SOUTHEASTWARD ACROSS W
WA...WEAKENING THE FRONT IN THE PROCESS. FOR W WA THIS MEANS THE
PERIODS OF RAIN...MAINLY OVER THE N PART WILL CONTINUE TODAY...BUT
SHOULD BE LIGHTER IN INTENSITY AND PROBABLY MORE INTERMITTENT
TONIGHT AND TUESDAY. PER THE GFS THE MUCH WEAKER FRONT SHOULD BE
JUST E OF THE AREA TUESDAY AFTERNOON. S WINDS WILL REMAIN BREEZY
THROUGH THIS EVENING THEN GRADUALLY WEAKEN AND BECOME SW THROUGH
TUESDAY.

THE BROAD UPPER LEVEL LONGWAVE TROUGH OVER THE REGION WILL GRADUALLY
DEEPEN AND GAIN AMPLITUDE OVER THE REGION THIS WEEK. THE TRIGGER FOR
THIS IS A SMALL UPPER LEVEL LOW OVER THE GULF OF AK TODAY. THIS
SMALL LOW WILL MOVE SE ALONG THE B.C. COAST THROUGH
TUESDAY...EVENTUALLY BECOMING THE CENTER OF THIS LARGE LONGWAVE
TROUGH OVER CENTRAL B.C. ON WEDNESDAY. THE GFS SHOWS A SHORTWAVE
TROUGH ASSOCIATED WITH THE DEVELOPING LOW CENTER CROSSING W WA
TUESDAY NIGHT. THIS SHORTWAVE WILL PROBABLY BRING AN INCREASE IN
SHOWERS OVER W WA. THE GFS SHOWS ANOTHER WEAK SHORTWAVE CROSSING W
WA WEDNESDAY...FOLLOWED BY A LARGER MORE DEVELOPED SHORTWAVE TROUGH
WEDNESDAY NIGHT. THIS MEANS THE WEATHER WILL BECOME SHOWERY TUESDAY
NIGHT ONWARD AND THERE WILL BE A COOLING TREND AS THE LARGE TROUGH
DEEPENS OVER THE REGION. WINDS WILL BE BREEZY AT TIMES AS EACH
SHORTWAVE TROUGH CROSSES W WA. KAM

THE SNOW LEVEL WILL BE NEAR 9000 FT TODAY BUT FALL TO 5000 TO 6000
FT BY WEDNESDAY. CONTINUING MOIST WESTERLY FLOW OF ROUGHLY 25 KT
BETWEEN 5000 AND 10000 FT WILL BRING A FOOT OR MORE OF SNOW TO SOME
OF THE HIGH TERRAIN OF THE CASCADES AND OLYMPICS OVER THE NEXT THREE
DAYS. TERRAIN ABOVE 8000 FT ON MT BAKER WILL PROBABLY GET 2 TO 3
FEET OF SNOW BETWEEN TODAY AND WEDNESDAY. MCDONNAL

.LONG TERM...PREVIOUS DISCUSSION FROM THE 320 AM AFD...MODELS ALL
SHOW ANOTHER SHORTWAVE DIGGING INTO THE BASE OF THE UPPER
TROUGH...WHICH WILL KEEP IT OVER SOUTHERN BRITISH COLUMBIA AND THE
PACIFIC NORTHWEST THROUGH AT LEAST THURSDAY. MODEL SOLUTIONS
SEPARATE BEYOND THURSDAY THOUGH. THE 00Z MON GFS SHOWS THE UPPER
TROUGH MOVING EAST OF THE CASCADES FRIDAY...WITH DRY NORTHWEST FLOW
OVER WESTERN WASHINGTON SATURDAY AND SUNDAY. THE CANADIAN AND
EUROPEAN MODELS ARE SIMILAR...KEEPING AN UPPER LOW OVER THE REGION
THROUGH SATURDAY AND HOLDING OFF DRY WEATHER UNTIL AT LEAST SUNDAY.
OUR FORECAST...FOR NOW ANYWAY... LEANS HEAVILY TOWARD THE GFS
SOLUTION. MCDONNAL

&&

.AVIATION...A FRONTAL SYSTEM WILL BE OVER THE AREA TODAY AND
TUESDAY. AREAS OF RAIN WILL FALL...ESPECIALLY OVER THE COAST AND
MOUNTAINS...BUT THE RAIN SHOULD SPREAD TO MOST OF THE LOWLANDS BY
AFTERNOON. THE MOUNTAINS AND HIGHER TERRAIN WILL REMAIN OBSCURED AND
THE VSBY WILL DROP AT TIMES IN THE PRECIP AND MIST...ESPECIALLY
COAST. THIS LAST DAY OF AUGUST IS MORE LIKE A TYPICAL DAY IN THE
RAINY SEASON.

KSEA...CLOUDY WITH RAIN AT TIMES...CIGS WILL DROP A BIT MORE AS
THE RAIN STARTS UP TODAY. SOUTHERLY WIND A BIT BREEZY AT TIMES.

&&

.MARINE...A FRONTAL SYSTEM WILL BE HUNG UP OVER THE AREA
TODAY AND TUE. SOUTHERLY GRADIENTS TODAY ARE STRONG ENOUGH FOR
BREEZY WEATHER AND SMALL CRAFT ADVISORIES. WINDS WILL PROBABLY EASE
OVERNIGHT AS THE FRONT STALLS OVER THE AREA AND STARTS TO WEAKEN.
A TROUGH WILL MOVE OVER THE AREA LATER TUE AND WED. WEAK HIGH
PRESSURE WILL BUILD LATE IN THE WEEK.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY COAST...EAST ENTRANCE TO THE STRAIT...
      ADMIRALTY INLET...NORTHERN INLAND WATERS...PUGET SOUND.
     SMALL CRAFT ADVISORY FOR ROUGH GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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





000
FXUS66 KSEW 311610
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
910 AM PDT MON AUG 31 2015

.SYNOPSIS...A FRONTAL SYSTEM WILL BRING RAIN TO WESTERN WASHINGTON
MAINLY FROM PUGET SOUND NORTHWARD TODAY THROUGH TUESDAY. A LARGE
UPPER LEVEL LOW WILL SETTLE OVER THE REGION WEDNESDAY THROUGH FRIDAY
FOR COOL SHOWERY WEATHER. THE UPPER LEVEL LOW WILL WEAKEN AND MOVE
EAST EARLY THIS WEEKEND FOR A GRADUAL DRYING AND WARMING TREND.

&&

.SHORT TERM...A BROAD UPPER LEVEL LONGWAVE TROUGH EXTENDS FROM THE
NE PACIFIC ACROSS WESTERN CANADA AND THE PACNW THIS MORNING...WITH
FAIRLY STRONG W FLOW ALOFT OVER W WA FOR LATE AUGUST. A FRONTAL
SYSTEM IS HUNG UP OVER SW B.C. THIS MORNING WITH THE COLD FRONT
EXTENDING WSW FROM ABOUT CENTRAL VANCOUVER ISLAND. RADAR IS SHOWING
STEADIER LIGHT RAIN OVER THE N COAST AND N INTERIOR AND SMALLER
AREAS OF LIGHT RAIN CROSSING THE CENTRAL COAST AND PUGET SOUND
REGION.

WATER VAPOR IMAGERY SHOWS A WELL DEVELOPED SHORTWAVE TROUGH OUT NEAR
49N/140W AND THE TAIL END OF THE COLD FRONT....THAT IS DIGGING SE
TOWARD N CA. AS THE SHORTWAVE MOVES SE IT WILL WILL DRAG THE
VANCOUVER ISLAND COLD FRONT WITH IT...SOUTHEASTWARD ACROSS W
WA...WEAKENING THE FRONT IN THE PROCESS. FOR W WA THIS MEANS THE
PERIODS OF RAIN...MAINLY OVER THE N PART WILL CONTINUE TODAY...BUT
SHOULD BE LIGHTER IN INTENSITY AND PROBABLY MORE INTERMITTENT
TONIGHT AND TUESDAY. PER THE GFS THE MUCH WEAKER FRONT SHOULD BE
JUST E OF THE AREA TUESDAY AFTERNOON. S WINDS WILL REMAIN BREEZY
THROUGH THIS EVENING THEN GRADUALLY WEAKEN AND BECOME SW THROUGH
TUESDAY.

THE BROAD UPPER LEVEL LONGWAVE TROUGH OVER THE REGION WILL GRADUALLY
DEEPEN AND GAIN AMPLITUDE OVER THE REGION THIS WEEK. THE TRIGGER FOR
THIS IS A SMALL UPPER LEVEL LOW OVER THE GULF OF AK TODAY. THIS
SMALL LOW WILL MOVE SE ALONG THE B.C. COAST THROUGH
TUESDAY...EVENTUALLY BECOMING THE CENTER OF THIS LARGE LONGWAVE
TROUGH OVER CENTRAL B.C. ON WEDNESDAY. THE GFS SHOWS A SHORTWAVE
TROUGH ASSOCIATED WITH THE DEVELOPING LOW CENTER CROSSING W WA
TUESDAY NIGHT. THIS SHORTWAVE WILL PROBABLY BRING AN INCREASE IN
SHOWERS OVER W WA. THE GFS SHOWS ANOTHER WEAK SHORTWAVE CROSSING W
WA WEDNESDAY...FOLLOWED BY A LARGER MORE DEVELOPED SHORTWAVE TROUGH
WEDNESDAY NIGHT. THIS MEANS THE WEATHER WILL BECOME SHOWERY TUESDAY
NIGHT ONWARD AND THERE WILL BE A COOLING TREND AS THE LARGE TROUGH
DEEPENS OVER THE REGION. WINDS WILL BE BREEZY AT TIMES AS EACH
SHORTWAVE TROUGH CROSSES W WA. KAM

THE SNOW LEVEL WILL BE NEAR 9000 FT TODAY BUT FALL TO 5000 TO 6000
FT BY WEDNESDAY. CONTINUING MOIST WESTERLY FLOW OF ROUGHLY 25 KT
BETWEEN 5000 AND 10000 FT WILL BRING A FOOT OR MORE OF SNOW TO SOME
OF THE HIGH TERRAIN OF THE CASCADES AND OLYMPICS OVER THE NEXT THREE
DAYS. TERRAIN ABOVE 8000 FT ON MT BAKER WILL PROBABLY GET 2 TO 3
FEET OF SNOW BETWEEN TODAY AND WEDNESDAY. MCDONNAL

.LONG TERM...PREVIOUS DISCUSSION FROM THE 320 AM AFD...MODELS ALL
SHOW ANOTHER SHORTWAVE DIGGING INTO THE BASE OF THE UPPER
TROUGH...WHICH WILL KEEP IT OVER SOUTHERN BRITISH COLUMBIA AND THE
PACIFIC NORTHWEST THROUGH AT LEAST THURSDAY. MODEL SOLUTIONS
SEPARATE BEYOND THURSDAY THOUGH. THE 00Z MON GFS SHOWS THE UPPER
TROUGH MOVING EAST OF THE CASCADES FRIDAY...WITH DRY NORTHWEST FLOW
OVER WESTERN WASHINGTON SATURDAY AND SUNDAY. THE CANADIAN AND
EUROPEAN MODELS ARE SIMILAR...KEEPING AN UPPER LOW OVER THE REGION
THROUGH SATURDAY AND HOLDING OFF DRY WEATHER UNTIL AT LEAST SUNDAY.
OUR FORECAST...FOR NOW ANYWAY... LEANS HEAVILY TOWARD THE GFS
SOLUTION. MCDONNAL

&&

.AVIATION...A FRONTAL SYSTEM WILL BE OVER THE AREA TODAY AND
TUESDAY. AREAS OF RAIN WILL FALL...ESPECIALLY OVER THE COAST AND
MOUNTAINS...BUT THE RAIN SHOULD SPREAD TO MOST OF THE LOWLANDS BY
AFTERNOON. THE MOUNTAINS AND HIGHER TERRAIN WILL REMAIN OBSCURED AND
THE VSBY WILL DROP AT TIMES IN THE PRECIP AND MIST...ESPECIALLY
COAST. THIS LAST DAY OF AUGUST IS MORE LIKE A TYPICAL DAY IN THE
RAINY SEASON.

KSEA...CLOUDY WITH RAIN AT TIMES...CIGS WILL DROP A BIT MORE AS
THE RAIN STARTS UP TODAY. SOUTHERLY WIND A BIT BREEZY AT TIMES.

&&

.MARINE...A FRONTAL SYSTEM WILL BE HUNG UP OVER THE AREA
TODAY AND TUE. SOUTHERLY GRADIENTS TODAY ARE STRONG ENOUGH FOR
BREEZY WEATHER AND SMALL CRAFT ADVISORIES. WINDS WILL PROBABLY EASE
OVERNIGHT AS THE FRONT STALLS OVER THE AREA AND STARTS TO WEAKEN.
A TROUGH WILL MOVE OVER THE AREA LATER TUE AND WED. WEAK HIGH
PRESSURE WILL BUILD LATE IN THE WEEK.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY COAST...EAST ENTRANCE TO THE STRAIT...
      ADMIRALTY INLET...NORTHERN INLAND WATERS...PUGET SOUND.
     SMALL CRAFT ADVISORY FOR ROUGH GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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




000
FXUS66 KSEW 311020
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
320 AM PDT MON AUG 31 2015

.SYNOPSIS...A FRONTAL SYSTEM WILL BRING MORE RAIN TO WESTERN
WASHINGTON TODAY THROUGH TUESDAY...ESPECIALLY THE COAST AND NORTH
PART. COOL SHOWERY WEATHER WILL CONTINUE WEDNESDAY AND THURSDAY
AS AN UPPER TROUGH DROPS SOUTHEAST INTO THE AREA. THE UPPER
TROUGH WILL PROBABLY MOVE EAST LATE THIS WEEK...FOR DRIER AND
WARMER WEATHER FRIDAY AND ESPECIALLY OVER THE WEEKEND.

&&

.SHORT TERM...A LARGE DEEP UPPER TROUGH REMAINS OVER THE REGION...
WITH ITS 5270 METER LOW CENTERED OVER THE NORTHWEST CORNER OF
BRITISH COLUMBIA EARLY THIS MORNING. THE LEADING NOSE OF THE NEXT
FRONTAL SYSTEM IS MOVING INTO THE REGION...WITH ITS WEAK WARM
FRONT EXTENDING FROM VANCOUVER ISLAND INTO WASHINGTON AND THE COLD
FRONT TRAILING WEST-SOUTHWEST FROM VANCOUVER ISLAND ACROSS THE
OFFSHORE WATERS. THIS FEATURE IS BRINGING SOME LIGHT RAIN TO THE
NORTHWEST PART OF THE FORECAST AREA...WITH BREEZY CONDITIONS FROM
AROUND SEATTLE NORTHWARD.

THE WARM FRONT WILL MOVE EAST OF THE CASCADES LATER TODAY...AND
THE COLD FRONT WILL MOVE SLOWLY THROUGH THE FORECAST AREA LATER TONIGHT
AND TUESDAY. MOST OF THE PRECIPITATION TODAY AND TONIGHT WILL BE
ALONG THE NORTH COAST AND IN THE OLYMPICS...NORTHWEST INTERIOR...
AND NORTH CASCADES WITH A HALF INCH TO AN INCH IN MANY PLACES. THE
PUGET SOUND REGION AND SOUTHWEST INTERIOR WILL MOSTLY RECEIVE A
QUARTER INCH OR LESS. PRECIPITATION WITH THE COLD FRONT ON TUESDAY
WILL BE MORE WIDESPREAD. THE FRONT WILL BRING BREEZY CONDITIONS TO
MOST OF THE FORECAST AREA.

THE UPPER TROUGH ITSELF WILL DIG SOUTHEAST ALONG THE COAST OF
BRITISH COLUMBIA TODAY THROUGH TUESDAY. IT WILL SWING THROUGH
WESTERN WASHINGTON TUESDAY NIGHT AND WEDNESDAY...BRINGING SHOWERS
TO THE AREA WITHOUT MUCH OR ANY DISCERNIBLE BREAK BEHIND THE COLD
FRONT. HIGHS TODAY THROUGH WEDNESDAY WILL BE MAINLY IN THE MID
60S TO LOWER 70S...WHICH IS SEVERAL DEGREES BELOW NORMAL.

THE SNOW LEVEL WILL BE NEAR 9000 FT TODAY BUT FALL TO 5000 TO
6000 FT BY WEDNESDAY. CONTINUING MOIST WESTERLY FLOW OF ROUGHLY
25 KT BETWEEN 5000 AND 10000 FT WILL BRING A FOOT OR MORE OF SNOW
TO SOME OF THE HIGH TERRAIN OF THE CASCADES AND OLYMPICS OVER THE
NEXT THREE DAYS. TERRAIN ABOVE 8000 FT ON MT BAKER WILL PROBABLY
GET 2 TO 3 FEET OF SNOW BETWEEN TODAY AND WEDNESDAY. MCDONNAL

.LONG TERM...MODELS ALL SHOW ANOTHER SHORTWAVE DIGGING INTO THE
BASE OF THE UPPER TROUGH...WHICH WILL KEEP IT OVER SOUTHERN
BRITISH COLUMBIA AND THE PACIFIC NORTHWEST THROUGH AT LEAST
THURSDAY. MODEL SOLUTIONS SEPARATE BEYOND THURSDAY THOUGH. THE 00Z
MON GFS SHOWS THE UPPER TROUGH MOVING EAST OF THE CASCADES
FRIDAY...WITH DRY NORTHWEST FLOW OVER WESTERN WASHINGTON SATURDAY
AND SUNDAY. THE CANADIAN AND EUROPEAN MODELS ARE SIMILAR...KEEPING
AN UPPER LOW OVER THE REGION THROUGH SATURDAY AND HOLDING OFF DRY
WEATHER UNTIL AT LEAST SUNDAY. OUR FORECAST...FOR NOW ANYWAY...
LEANS HEAVILY TOWARD THE GFS SOLUTION. MCDONNAL

&&

.AVIATION...A WEAK FRONT WILL HANG UP OVER THE NORTHERN PORTION OF
THE AREA TODAY. LIGHT RAIN WILL SLOWLY SPREAD SOUTH THIS MORNING
FINALLY REACHING KOLM AROUND 18Z. AHEAD OF THE RAIN CEILINGS 4500-
6000 FEET. CEILINGS LOWERING TO 3000-4000 FEET WITH THE LIGHT
RAIN...2000-3000 FEET ALONG THE COAST AND NORTH INTERIOR. LIGHT RAIN
WILL CONTINUE INTO THE AFTERNOON HOURS THEN DISSIPATE IN THE
EVENING WITH LITTLE CHANGE IN THE CEILINGS.

KSEA...CEILINGS NEAR 5000 FEET LOWERING TO NEAR 3000 FEET WITH THE
ONSET OF THE LIGHT RAIN AROUND 15Z. CEILINGS REMAINING NEAR 3000 FEET
INTO THE EVENING HOURS. SOUTHERLY WINDS 10 TO 15 KNOTS. FELTON

&&

.MARINE...FRONTAL SYSTEM HUNG UP OVER THE NORTHERN PORTION OF THE
WATERS WILL KEEP SOUTHERLY GRADIENTS INTACT TODAY. EXPECT SMALL
CRAFT ADVISORY SOUTHERLY WINDS OVER THE INLAND WATERS...ADMIRALTY
INLET AND THE EAST ENTRANCE TO THE STRAIT. WINDS WILL EASE TONIGHT.
A PAIR OF WEAK SYSTEMS WILL MOVE THROUGH THE WATERS TUESDAY AND
WEDNESDAY. WEAK HIGH PRESSURE WILL BUILD OVER THE WATERS ON THURSDAY
AND REMAIN THROUGH FRIDAY. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES EAST ENTRANCE TO THE STRAIT...
     ADMIRALTY INLET...AND THE INLAND WATERS.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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





000
FXUS66 KSEW 311020
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
320 AM PDT MON AUG 31 2015

.SYNOPSIS...A FRONTAL SYSTEM WILL BRING MORE RAIN TO WESTERN
WASHINGTON TODAY THROUGH TUESDAY...ESPECIALLY THE COAST AND NORTH
PART. COOL SHOWERY WEATHER WILL CONTINUE WEDNESDAY AND THURSDAY
AS AN UPPER TROUGH DROPS SOUTHEAST INTO THE AREA. THE UPPER
TROUGH WILL PROBABLY MOVE EAST LATE THIS WEEK...FOR DRIER AND
WARMER WEATHER FRIDAY AND ESPECIALLY OVER THE WEEKEND.

&&

.SHORT TERM...A LARGE DEEP UPPER TROUGH REMAINS OVER THE REGION...
WITH ITS 5270 METER LOW CENTERED OVER THE NORTHWEST CORNER OF
BRITISH COLUMBIA EARLY THIS MORNING. THE LEADING NOSE OF THE NEXT
FRONTAL SYSTEM IS MOVING INTO THE REGION...WITH ITS WEAK WARM
FRONT EXTENDING FROM VANCOUVER ISLAND INTO WASHINGTON AND THE COLD
FRONT TRAILING WEST-SOUTHWEST FROM VANCOUVER ISLAND ACROSS THE
OFFSHORE WATERS. THIS FEATURE IS BRINGING SOME LIGHT RAIN TO THE
NORTHWEST PART OF THE FORECAST AREA...WITH BREEZY CONDITIONS FROM
AROUND SEATTLE NORTHWARD.

THE WARM FRONT WILL MOVE EAST OF THE CASCADES LATER TODAY...AND
THE COLD FRONT WILL MOVE SLOWLY THROUGH THE FORECAST AREA LATER TONIGHT
AND TUESDAY. MOST OF THE PRECIPITATION TODAY AND TONIGHT WILL BE
ALONG THE NORTH COAST AND IN THE OLYMPICS...NORTHWEST INTERIOR...
AND NORTH CASCADES WITH A HALF INCH TO AN INCH IN MANY PLACES. THE
PUGET SOUND REGION AND SOUTHWEST INTERIOR WILL MOSTLY RECEIVE A
QUARTER INCH OR LESS. PRECIPITATION WITH THE COLD FRONT ON TUESDAY
WILL BE MORE WIDESPREAD. THE FRONT WILL BRING BREEZY CONDITIONS TO
MOST OF THE FORECAST AREA.

THE UPPER TROUGH ITSELF WILL DIG SOUTHEAST ALONG THE COAST OF
BRITISH COLUMBIA TODAY THROUGH TUESDAY. IT WILL SWING THROUGH
WESTERN WASHINGTON TUESDAY NIGHT AND WEDNESDAY...BRINGING SHOWERS
TO THE AREA WITHOUT MUCH OR ANY DISCERNIBLE BREAK BEHIND THE COLD
FRONT. HIGHS TODAY THROUGH WEDNESDAY WILL BE MAINLY IN THE MID
60S TO LOWER 70S...WHICH IS SEVERAL DEGREES BELOW NORMAL.

THE SNOW LEVEL WILL BE NEAR 9000 FT TODAY BUT FALL TO 5000 TO
6000 FT BY WEDNESDAY. CONTINUING MOIST WESTERLY FLOW OF ROUGHLY
25 KT BETWEEN 5000 AND 10000 FT WILL BRING A FOOT OR MORE OF SNOW
TO SOME OF THE HIGH TERRAIN OF THE CASCADES AND OLYMPICS OVER THE
NEXT THREE DAYS. TERRAIN ABOVE 8000 FT ON MT BAKER WILL PROBABLY
GET 2 TO 3 FEET OF SNOW BETWEEN TODAY AND WEDNESDAY. MCDONNAL

.LONG TERM...MODELS ALL SHOW ANOTHER SHORTWAVE DIGGING INTO THE
BASE OF THE UPPER TROUGH...WHICH WILL KEEP IT OVER SOUTHERN
BRITISH COLUMBIA AND THE PACIFIC NORTHWEST THROUGH AT LEAST
THURSDAY. MODEL SOLUTIONS SEPARATE BEYOND THURSDAY THOUGH. THE 00Z
MON GFS SHOWS THE UPPER TROUGH MOVING EAST OF THE CASCADES
FRIDAY...WITH DRY NORTHWEST FLOW OVER WESTERN WASHINGTON SATURDAY
AND SUNDAY. THE CANADIAN AND EUROPEAN MODELS ARE SIMILAR...KEEPING
AN UPPER LOW OVER THE REGION THROUGH SATURDAY AND HOLDING OFF DRY
WEATHER UNTIL AT LEAST SUNDAY. OUR FORECAST...FOR NOW ANYWAY...
LEANS HEAVILY TOWARD THE GFS SOLUTION. MCDONNAL

&&

.AVIATION...A WEAK FRONT WILL HANG UP OVER THE NORTHERN PORTION OF
THE AREA TODAY. LIGHT RAIN WILL SLOWLY SPREAD SOUTH THIS MORNING
FINALLY REACHING KOLM AROUND 18Z. AHEAD OF THE RAIN CEILINGS 4500-
6000 FEET. CEILINGS LOWERING TO 3000-4000 FEET WITH THE LIGHT
RAIN...2000-3000 FEET ALONG THE COAST AND NORTH INTERIOR. LIGHT RAIN
WILL CONTINUE INTO THE AFTERNOON HOURS THEN DISSIPATE IN THE
EVENING WITH LITTLE CHANGE IN THE CEILINGS.

KSEA...CEILINGS NEAR 5000 FEET LOWERING TO NEAR 3000 FEET WITH THE
ONSET OF THE LIGHT RAIN AROUND 15Z. CEILINGS REMAINING NEAR 3000 FEET
INTO THE EVENING HOURS. SOUTHERLY WINDS 10 TO 15 KNOTS. FELTON

&&

.MARINE...FRONTAL SYSTEM HUNG UP OVER THE NORTHERN PORTION OF THE
WATERS WILL KEEP SOUTHERLY GRADIENTS INTACT TODAY. EXPECT SMALL
CRAFT ADVISORY SOUTHERLY WINDS OVER THE INLAND WATERS...ADMIRALTY
INLET AND THE EAST ENTRANCE TO THE STRAIT. WINDS WILL EASE TONIGHT.
A PAIR OF WEAK SYSTEMS WILL MOVE THROUGH THE WATERS TUESDAY AND
WEDNESDAY. WEAK HIGH PRESSURE WILL BUILD OVER THE WATERS ON THURSDAY
AND REMAIN THROUGH FRIDAY. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES EAST ENTRANCE TO THE STRAIT...
     ADMIRALTY INLET...AND THE INLAND WATERS.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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





000
FXUS66 KSEW 311020
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
320 AM PDT MON AUG 31 2015

.SYNOPSIS...A FRONTAL SYSTEM WILL BRING MORE RAIN TO WESTERN
WASHINGTON TODAY THROUGH TUESDAY...ESPECIALLY THE COAST AND NORTH
PART. COOL SHOWERY WEATHER WILL CONTINUE WEDNESDAY AND THURSDAY
AS AN UPPER TROUGH DROPS SOUTHEAST INTO THE AREA. THE UPPER
TROUGH WILL PROBABLY MOVE EAST LATE THIS WEEK...FOR DRIER AND
WARMER WEATHER FRIDAY AND ESPECIALLY OVER THE WEEKEND.

&&

.SHORT TERM...A LARGE DEEP UPPER TROUGH REMAINS OVER THE REGION...
WITH ITS 5270 METER LOW CENTERED OVER THE NORTHWEST CORNER OF
BRITISH COLUMBIA EARLY THIS MORNING. THE LEADING NOSE OF THE NEXT
FRONTAL SYSTEM IS MOVING INTO THE REGION...WITH ITS WEAK WARM
FRONT EXTENDING FROM VANCOUVER ISLAND INTO WASHINGTON AND THE COLD
FRONT TRAILING WEST-SOUTHWEST FROM VANCOUVER ISLAND ACROSS THE
OFFSHORE WATERS. THIS FEATURE IS BRINGING SOME LIGHT RAIN TO THE
NORTHWEST PART OF THE FORECAST AREA...WITH BREEZY CONDITIONS FROM
AROUND SEATTLE NORTHWARD.

THE WARM FRONT WILL MOVE EAST OF THE CASCADES LATER TODAY...AND
THE COLD FRONT WILL MOVE SLOWLY THROUGH THE FORECAST AREA LATER TONIGHT
AND TUESDAY. MOST OF THE PRECIPITATION TODAY AND TONIGHT WILL BE
ALONG THE NORTH COAST AND IN THE OLYMPICS...NORTHWEST INTERIOR...
AND NORTH CASCADES WITH A HALF INCH TO AN INCH IN MANY PLACES. THE
PUGET SOUND REGION AND SOUTHWEST INTERIOR WILL MOSTLY RECEIVE A
QUARTER INCH OR LESS. PRECIPITATION WITH THE COLD FRONT ON TUESDAY
WILL BE MORE WIDESPREAD. THE FRONT WILL BRING BREEZY CONDITIONS TO
MOST OF THE FORECAST AREA.

THE UPPER TROUGH ITSELF WILL DIG SOUTHEAST ALONG THE COAST OF
BRITISH COLUMBIA TODAY THROUGH TUESDAY. IT WILL SWING THROUGH
WESTERN WASHINGTON TUESDAY NIGHT AND WEDNESDAY...BRINGING SHOWERS
TO THE AREA WITHOUT MUCH OR ANY DISCERNIBLE BREAK BEHIND THE COLD
FRONT. HIGHS TODAY THROUGH WEDNESDAY WILL BE MAINLY IN THE MID
60S TO LOWER 70S...WHICH IS SEVERAL DEGREES BELOW NORMAL.

THE SNOW LEVEL WILL BE NEAR 9000 FT TODAY BUT FALL TO 5000 TO
6000 FT BY WEDNESDAY. CONTINUING MOIST WESTERLY FLOW OF ROUGHLY
25 KT BETWEEN 5000 AND 10000 FT WILL BRING A FOOT OR MORE OF SNOW
TO SOME OF THE HIGH TERRAIN OF THE CASCADES AND OLYMPICS OVER THE
NEXT THREE DAYS. TERRAIN ABOVE 8000 FT ON MT BAKER WILL PROBABLY
GET 2 TO 3 FEET OF SNOW BETWEEN TODAY AND WEDNESDAY. MCDONNAL

.LONG TERM...MODELS ALL SHOW ANOTHER SHORTWAVE DIGGING INTO THE
BASE OF THE UPPER TROUGH...WHICH WILL KEEP IT OVER SOUTHERN
BRITISH COLUMBIA AND THE PACIFIC NORTHWEST THROUGH AT LEAST
THURSDAY. MODEL SOLUTIONS SEPARATE BEYOND THURSDAY THOUGH. THE 00Z
MON GFS SHOWS THE UPPER TROUGH MOVING EAST OF THE CASCADES
FRIDAY...WITH DRY NORTHWEST FLOW OVER WESTERN WASHINGTON SATURDAY
AND SUNDAY. THE CANADIAN AND EUROPEAN MODELS ARE SIMILAR...KEEPING
AN UPPER LOW OVER THE REGION THROUGH SATURDAY AND HOLDING OFF DRY
WEATHER UNTIL AT LEAST SUNDAY. OUR FORECAST...FOR NOW ANYWAY...
LEANS HEAVILY TOWARD THE GFS SOLUTION. MCDONNAL

&&

.AVIATION...A WEAK FRONT WILL HANG UP OVER THE NORTHERN PORTION OF
THE AREA TODAY. LIGHT RAIN WILL SLOWLY SPREAD SOUTH THIS MORNING
FINALLY REACHING KOLM AROUND 18Z. AHEAD OF THE RAIN CEILINGS 4500-
6000 FEET. CEILINGS LOWERING TO 3000-4000 FEET WITH THE LIGHT
RAIN...2000-3000 FEET ALONG THE COAST AND NORTH INTERIOR. LIGHT RAIN
WILL CONTINUE INTO THE AFTERNOON HOURS THEN DISSIPATE IN THE
EVENING WITH LITTLE CHANGE IN THE CEILINGS.

KSEA...CEILINGS NEAR 5000 FEET LOWERING TO NEAR 3000 FEET WITH THE
ONSET OF THE LIGHT RAIN AROUND 15Z. CEILINGS REMAINING NEAR 3000 FEET
INTO THE EVENING HOURS. SOUTHERLY WINDS 10 TO 15 KNOTS. FELTON

&&

.MARINE...FRONTAL SYSTEM HUNG UP OVER THE NORTHERN PORTION OF THE
WATERS WILL KEEP SOUTHERLY GRADIENTS INTACT TODAY. EXPECT SMALL
CRAFT ADVISORY SOUTHERLY WINDS OVER THE INLAND WATERS...ADMIRALTY
INLET AND THE EAST ENTRANCE TO THE STRAIT. WINDS WILL EASE TONIGHT.
A PAIR OF WEAK SYSTEMS WILL MOVE THROUGH THE WATERS TUESDAY AND
WEDNESDAY. WEAK HIGH PRESSURE WILL BUILD OVER THE WATERS ON THURSDAY
AND REMAIN THROUGH FRIDAY. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES EAST ENTRANCE TO THE STRAIT...
     ADMIRALTY INLET...AND THE INLAND WATERS.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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




000
FXUS66 KSEW 311020
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
320 AM PDT MON AUG 31 2015

.SYNOPSIS...A FRONTAL SYSTEM WILL BRING MORE RAIN TO WESTERN
WASHINGTON TODAY THROUGH TUESDAY...ESPECIALLY THE COAST AND NORTH
PART. COOL SHOWERY WEATHER WILL CONTINUE WEDNESDAY AND THURSDAY
AS AN UPPER TROUGH DROPS SOUTHEAST INTO THE AREA. THE UPPER
TROUGH WILL PROBABLY MOVE EAST LATE THIS WEEK...FOR DRIER AND
WARMER WEATHER FRIDAY AND ESPECIALLY OVER THE WEEKEND.

&&

.SHORT TERM...A LARGE DEEP UPPER TROUGH REMAINS OVER THE REGION...
WITH ITS 5270 METER LOW CENTERED OVER THE NORTHWEST CORNER OF
BRITISH COLUMBIA EARLY THIS MORNING. THE LEADING NOSE OF THE NEXT
FRONTAL SYSTEM IS MOVING INTO THE REGION...WITH ITS WEAK WARM
FRONT EXTENDING FROM VANCOUVER ISLAND INTO WASHINGTON AND THE COLD
FRONT TRAILING WEST-SOUTHWEST FROM VANCOUVER ISLAND ACROSS THE
OFFSHORE WATERS. THIS FEATURE IS BRINGING SOME LIGHT RAIN TO THE
NORTHWEST PART OF THE FORECAST AREA...WITH BREEZY CONDITIONS FROM
AROUND SEATTLE NORTHWARD.

THE WARM FRONT WILL MOVE EAST OF THE CASCADES LATER TODAY...AND
THE COLD FRONT WILL MOVE SLOWLY THROUGH THE FORECAST AREA LATER TONIGHT
AND TUESDAY. MOST OF THE PRECIPITATION TODAY AND TONIGHT WILL BE
ALONG THE NORTH COAST AND IN THE OLYMPICS...NORTHWEST INTERIOR...
AND NORTH CASCADES WITH A HALF INCH TO AN INCH IN MANY PLACES. THE
PUGET SOUND REGION AND SOUTHWEST INTERIOR WILL MOSTLY RECEIVE A
QUARTER INCH OR LESS. PRECIPITATION WITH THE COLD FRONT ON TUESDAY
WILL BE MORE WIDESPREAD. THE FRONT WILL BRING BREEZY CONDITIONS TO
MOST OF THE FORECAST AREA.

THE UPPER TROUGH ITSELF WILL DIG SOUTHEAST ALONG THE COAST OF
BRITISH COLUMBIA TODAY THROUGH TUESDAY. IT WILL SWING THROUGH
WESTERN WASHINGTON TUESDAY NIGHT AND WEDNESDAY...BRINGING SHOWERS
TO THE AREA WITHOUT MUCH OR ANY DISCERNIBLE BREAK BEHIND THE COLD
FRONT. HIGHS TODAY THROUGH WEDNESDAY WILL BE MAINLY IN THE MID
60S TO LOWER 70S...WHICH IS SEVERAL DEGREES BELOW NORMAL.

THE SNOW LEVEL WILL BE NEAR 9000 FT TODAY BUT FALL TO 5000 TO
6000 FT BY WEDNESDAY. CONTINUING MOIST WESTERLY FLOW OF ROUGHLY
25 KT BETWEEN 5000 AND 10000 FT WILL BRING A FOOT OR MORE OF SNOW
TO SOME OF THE HIGH TERRAIN OF THE CASCADES AND OLYMPICS OVER THE
NEXT THREE DAYS. TERRAIN ABOVE 8000 FT ON MT BAKER WILL PROBABLY
GET 2 TO 3 FEET OF SNOW BETWEEN TODAY AND WEDNESDAY. MCDONNAL

.LONG TERM...MODELS ALL SHOW ANOTHER SHORTWAVE DIGGING INTO THE
BASE OF THE UPPER TROUGH...WHICH WILL KEEP IT OVER SOUTHERN
BRITISH COLUMBIA AND THE PACIFIC NORTHWEST THROUGH AT LEAST
THURSDAY. MODEL SOLUTIONS SEPARATE BEYOND THURSDAY THOUGH. THE 00Z
MON GFS SHOWS THE UPPER TROUGH MOVING EAST OF THE CASCADES
FRIDAY...WITH DRY NORTHWEST FLOW OVER WESTERN WASHINGTON SATURDAY
AND SUNDAY. THE CANADIAN AND EUROPEAN MODELS ARE SIMILAR...KEEPING
AN UPPER LOW OVER THE REGION THROUGH SATURDAY AND HOLDING OFF DRY
WEATHER UNTIL AT LEAST SUNDAY. OUR FORECAST...FOR NOW ANYWAY...
LEANS HEAVILY TOWARD THE GFS SOLUTION. MCDONNAL

&&

.AVIATION...A WEAK FRONT WILL HANG UP OVER THE NORTHERN PORTION OF
THE AREA TODAY. LIGHT RAIN WILL SLOWLY SPREAD SOUTH THIS MORNING
FINALLY REACHING KOLM AROUND 18Z. AHEAD OF THE RAIN CEILINGS 4500-
6000 FEET. CEILINGS LOWERING TO 3000-4000 FEET WITH THE LIGHT
RAIN...2000-3000 FEET ALONG THE COAST AND NORTH INTERIOR. LIGHT RAIN
WILL CONTINUE INTO THE AFTERNOON HOURS THEN DISSIPATE IN THE
EVENING WITH LITTLE CHANGE IN THE CEILINGS.

KSEA...CEILINGS NEAR 5000 FEET LOWERING TO NEAR 3000 FEET WITH THE
ONSET OF THE LIGHT RAIN AROUND 15Z. CEILINGS REMAINING NEAR 3000 FEET
INTO THE EVENING HOURS. SOUTHERLY WINDS 10 TO 15 KNOTS. FELTON

&&

.MARINE...FRONTAL SYSTEM HUNG UP OVER THE NORTHERN PORTION OF THE
WATERS WILL KEEP SOUTHERLY GRADIENTS INTACT TODAY. EXPECT SMALL
CRAFT ADVISORY SOUTHERLY WINDS OVER THE INLAND WATERS...ADMIRALTY
INLET AND THE EAST ENTRANCE TO THE STRAIT. WINDS WILL EASE TONIGHT.
A PAIR OF WEAK SYSTEMS WILL MOVE THROUGH THE WATERS TUESDAY AND
WEDNESDAY. WEAK HIGH PRESSURE WILL BUILD OVER THE WATERS ON THURSDAY
AND REMAIN THROUGH FRIDAY. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES EAST ENTRANCE TO THE STRAIT...
     ADMIRALTY INLET...AND THE INLAND WATERS.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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




000
FXUS66 KSEW 310422
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
920 PM PDT SUN AUG 30 2015

.SYNOPSIS...AN UPPER LEVEL TROUGH WITH EMBEDDED DISTURBANCES WILL
KEEP THE WEATHER COOLER AND WETTER THAN NORMAL THROUGH WEDNESDAY.
THURSDAY AND FRIDAY WILL BE A BIT DRIER BUT STILL UNSTABLE AS AN
UPPER LOW MOVES SE THROUGH THE AREA. THE LOW WILL MOVE INLAND OVER
THE WEEKEND FOR WARMER AND DRIER CONDITIONS.

&&

.SHORT TERM...AS A BROAD UPPER TROUGH REMAINS OVER THE
REGION...EXPECT THE WEATHER TO REMAIN COOL AND UNSETTLED. TONIGHT
MAY BRING A BRIEF HIATUS FROM SHOWERS IN SOME AREAS...HOWEVER AS
ADDITIONAL SHORTWAVE DISTURBANCES MOVE THROUGH THE UPPER
TROUGH...EXPECT RAIN AT TIMES THROUGH WEDNESDAY. THE SURFACE
GRADIENT WILL REMAIN SOUTHERLY THROUGH WEDNESDAY AS WELL...KEEPING
LOW LEVEL WINDS FROM THE SOUTH. HOWEVER...THE GRADIENT WILL NOT BE
NEARLY AS STRONG AS THIS PAST SATURDAY AND ANY SURFACE WINDS WILL BE
LIMITED TO 20 MPH FOR THE MOST PART. JSMITH

.LONG TERM...ON THURSDAY AND FRIDAY AN UPPER LOW EMBEDDED IN THE
UPPER TROUGH WILL SWOOP SOUTHEAST THROUGH THE AREA...BRINGING A FEW
MORE PERIODS OF SHOWER ACTIVITY...AND THE MOUNTAINS AND PUGET SOUND
CONVERGENCE ZONE WILL HAVE THE GREATEST THREAT OF SHOWERS. SURFACE
GRADIENTS WILL BE WEAK DURING THIS TIME AND SURFACE WINDS WILL BE
LIGHT. OVER THE WEEKEND THE UPPER LOW WILL MOVE EAST OUT OF THE AREA
FOR DRY WEATHER AND SOME MORE SUNSHINE. JSMITH

&&

.AVIATION...A WEAK FRONT WILL APPROACH THE AREA FROM THE NORTHWEST
TONIGHT MOVING THROUGH THE NORTHERN PORTION OF THE AREA ON MONDAY.
LIGHT RAIN HAS ALREADY BEGUN ALONG THE NORTH COAST AND NORTHWEST
INTERIOR AS OF 04Z. LIGHT RAIN WILL SLOWLY SPREAD SOUTH THROUGH THE
AREA OVERNIGHT INTO MONDAY MORNING WITH THE RAIN FINALLY REACHING
KOLM 15Z-18Z. AHEAD OF THE RAIN CEILINGS 6000-8000 FEET. CEILINGS
LOWERING TO 3000-4000 FEET WITH THE LIGHT RAIN...2000-3000 FEET
ALONG THE COAST AND NORTH INTERIOR. LIGHT RAIN WILL CONTINUE INTO
THE AFTERNOON HOURS.

KSEA...CEILINGS ABOVE 5000 FEET LOWERING DOWN TO 3000-4000 FEET WITH
THE ONSET OF LIGHT RAIN 12Z-15Z. CEILINGS REMAINING NEAR 3000 FEET
INTO THE AFTERNOON HOURS. SOUTHERLY WINDS 8 TO 12 KNOTS. FELTON

&&

.MARINE...SOUTHERLY PRESSURE GRADIENTS INCREASING TONIGHT AS ANOTHER
FRONTAL SYSTEM APPROACHES FROM THE NORTHWEST. EXPECT SMALL CRAFT
ADVISORY SOUTHERLY WINDS OVER ALL WATERS BUT THE CENTRAL STRAIT BY
LATE TONIGHT. SMALL CRAFT ADVISORY WINDS WILL CONTINUE OVER THE
INTERIOR WATERS MONDAY MORNING BEFORE EASING MONDAY AFTERNOON. A
SERIES OF WEAK SYSTEMS WILL MOVE THROUGH THE AREA TUESDAY AND
WEDNESDAY. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...

WA...NONE.

PZ...SMALL CRAFT ADVISORIES COAST...ENTRANCES TO THE STRAIT...
     ADMIRALTY INLET AND THE INLAND WATERS.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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




000
FXUS66 KSEW 310422
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
920 PM PDT SUN AUG 30 2015

.SYNOPSIS...AN UPPER LEVEL TROUGH WITH EMBEDDED DISTURBANCES WILL
KEEP THE WEATHER COOLER AND WETTER THAN NORMAL THROUGH WEDNESDAY.
THURSDAY AND FRIDAY WILL BE A BIT DRIER BUT STILL UNSTABLE AS AN
UPPER LOW MOVES SE THROUGH THE AREA. THE LOW WILL MOVE INLAND OVER
THE WEEKEND FOR WARMER AND DRIER CONDITIONS.

&&

.SHORT TERM...AS A BROAD UPPER TROUGH REMAINS OVER THE
REGION...EXPECT THE WEATHER TO REMAIN COOL AND UNSETTLED. TONIGHT
MAY BRING A BRIEF HIATUS FROM SHOWERS IN SOME AREAS...HOWEVER AS
ADDITIONAL SHORTWAVE DISTURBANCES MOVE THROUGH THE UPPER
TROUGH...EXPECT RAIN AT TIMES THROUGH WEDNESDAY. THE SURFACE
GRADIENT WILL REMAIN SOUTHERLY THROUGH WEDNESDAY AS WELL...KEEPING
LOW LEVEL WINDS FROM THE SOUTH. HOWEVER...THE GRADIENT WILL NOT BE
NEARLY AS STRONG AS THIS PAST SATURDAY AND ANY SURFACE WINDS WILL BE
LIMITED TO 20 MPH FOR THE MOST PART. JSMITH

.LONG TERM...ON THURSDAY AND FRIDAY AN UPPER LOW EMBEDDED IN THE
UPPER TROUGH WILL SWOOP SOUTHEAST THROUGH THE AREA...BRINGING A FEW
MORE PERIODS OF SHOWER ACTIVITY...AND THE MOUNTAINS AND PUGET SOUND
CONVERGENCE ZONE WILL HAVE THE GREATEST THREAT OF SHOWERS. SURFACE
GRADIENTS WILL BE WEAK DURING THIS TIME AND SURFACE WINDS WILL BE
LIGHT. OVER THE WEEKEND THE UPPER LOW WILL MOVE EAST OUT OF THE AREA
FOR DRY WEATHER AND SOME MORE SUNSHINE. JSMITH

&&

.AVIATION...A WEAK FRONT WILL APPROACH THE AREA FROM THE NORTHWEST
TONIGHT MOVING THROUGH THE NORTHERN PORTION OF THE AREA ON MONDAY.
LIGHT RAIN HAS ALREADY BEGUN ALONG THE NORTH COAST AND NORTHWEST
INTERIOR AS OF 04Z. LIGHT RAIN WILL SLOWLY SPREAD SOUTH THROUGH THE
AREA OVERNIGHT INTO MONDAY MORNING WITH THE RAIN FINALLY REACHING
KOLM 15Z-18Z. AHEAD OF THE RAIN CEILINGS 6000-8000 FEET. CEILINGS
LOWERING TO 3000-4000 FEET WITH THE LIGHT RAIN...2000-3000 FEET
ALONG THE COAST AND NORTH INTERIOR. LIGHT RAIN WILL CONTINUE INTO
THE AFTERNOON HOURS.

KSEA...CEILINGS ABOVE 5000 FEET LOWERING DOWN TO 3000-4000 FEET WITH
THE ONSET OF LIGHT RAIN 12Z-15Z. CEILINGS REMAINING NEAR 3000 FEET
INTO THE AFTERNOON HOURS. SOUTHERLY WINDS 8 TO 12 KNOTS. FELTON

&&

.MARINE...SOUTHERLY PRESSURE GRADIENTS INCREASING TONIGHT AS ANOTHER
FRONTAL SYSTEM APPROACHES FROM THE NORTHWEST. EXPECT SMALL CRAFT
ADVISORY SOUTHERLY WINDS OVER ALL WATERS BUT THE CENTRAL STRAIT BY
LATE TONIGHT. SMALL CRAFT ADVISORY WINDS WILL CONTINUE OVER THE
INTERIOR WATERS MONDAY MORNING BEFORE EASING MONDAY AFTERNOON. A
SERIES OF WEAK SYSTEMS WILL MOVE THROUGH THE AREA TUESDAY AND
WEDNESDAY. FELTON

&&

.SEW WATCHES/WARNINGS/ADVISORIES...

WA...NONE.

PZ...SMALL CRAFT ADVISORIES COAST...ENTRANCES TO THE STRAIT...
     ADMIRALTY INLET AND THE INLAND WATERS.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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





000
FXUS66 KSEW 302222
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
320 PM PDT SUN AUG 30 2015

.SYNOPSIS...AN UPPER LEVEL TROUGH WILL REMAIN OVER THE PACIFIC
NORTHWEST THROUGH THURSDAY. WEATHER SYSTEMS MOVING THROUGH THE
TROUGH WILL KEEP THE WEATHER COOL AND WET FOR THIS TIME OF YEAR.
THE TROUGH WILL WEAKEN AND MOVE INLAND TOWARD THE END OF THE WEEK.

&&

.SHORT TERM...SCATTERED SHOWERS AND PARTIAL CLEARING PERIODS THIS
EVENING WILL GIVE WAY TO WARM ADVECTION OVERNIGHT AS A FRONTAL
SYSTEM SAGS SOUTH TOWARD THE AREA. THE MOUNTAINS SHOULD GET A GOOD
SOAKING AND LIGHT RAIN IS A GOOD BET AT TIMES FOR THE LOWLANDS MON
AND TUE. SHOWERS OR RAIN BANDS WILL CONTINUE TO BE DIRECTED INTO THE
AREA BY THE UPPER TROUGH TUE NITE AND WED AND THE AIR COOLS ALOFT
AS AN UPPER LOW CENTER SHIFTS OVER SOUTHWEST BRITISH COLUMBIA.

.LONG TERM...WEAK IMPULSES ROTATING THROUGH THE UPPER TROUGH WILL
BRING A FEW PERIODS OF SHOWER ACTIVITY THROUGH LATE IN THE WEEK. THE
MONTAINS AND PSCZ SHOULD HAVE THE BEST CHANCE OF SHOWERS. THE
UPPER TROUGH SHOULD SHIFT INLAND IN TIME FOR THE WEEKEND FOR DRY
WEATHER AND SOME MORE SUNSHINE.

&&


.AAVIATION...ABUNDANT LOW LEVEL MOISTURE AND INSTABILITY SUPPORTING
SCATTERED SHOWERS OVER THE AREA...WITH VFR CEILINGS AND
VISIBILITIES. A WEAK FRONT WILL APPROACH THE AREA FROM THE NORTHWEST
TONIGHT...BRINING RAIN TO THE NORTH COAST AROUND
MIDNIGHT...SPREADING INLAND THROUGH THE MORNING. PREVIOUS MODEL RUNS
HAD RAIN INTO MOST OF THE INTERIOR TERMINALS BY 12Z. MID DAY RUNS A
BIT SLOWER...MORE LIKE MID MORNING FOR THE CENTRAL SOUND
TERMINALS...AND SOUTH BY MIDDAY. EXPECT VFR CONDITIONS TO LOWER TO
MVFR LEVELS THROUGH MONDAY MORNING AS THE FRONT WORKS INLAND. SOME
LOCATIONS MAY REACH IFR LEVELS...ESPECIALLY WITH RAINFALL OR JUST
AFTER RAIN.

KSEA...VFR CONDITIONS WILL PERSIST THIS AFTERNOON...POSSIBLY LOWERING
TO NEAR MVFR LEVELS WITH SHOWERS. OTHERWISE EXPECT PREVAILING VFR
THROUGH MUCH OF THE NIGHT...LOWERING EARLY MONDAY MORNING AS THE
FRONT WORKS INTO THE CENTRAL SOUND TO MVFR LEVELS. WINDS WILL REMAIN
SOUTHERLY 10 TO 12 KNOTS THIS EVENING...EASING SOMEWHAT TO 8 TO 10
KNOTS AROUND MIDNIGHT...THEN INCREASING AGAIN AROUND MIDDAY TO 10 TO
12 KNOTS.

&&

.MARINE...SOUTHERLY LOW LEVEL PRESSURE GRADIENTS WILL INCREASE
TONIGHT AS ANOTHER FRONTAL SYSTEM APPROACHES FROM THE NORTHWEST.
EXPECT SMALL CRAFT ADVISORY SOUTHERLY WINDS OVER ALL WATERS BUT THE
CENTRAL STRAIT BY LATE TONIGHT. SMALL CRAFT ADVISORY WINDS WILL
CONTINUE OVER THE INTERIOR WATERS MONDAY MORNING BEFORE EASING
MONDAY AFTERNOON. A SERIES OF WEAK SYSTEMS WILL MOVE THROUGH THE
AREA TUESDAY AND WEDNESDAY.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...

WA...NONE.

PZ...SMALL CRAFT ADVISORIES COAST...ENTRANCES TO THE STRAIT...
     ADMIRALTY INLET AND THE INLAND WATERS.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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




000
FXUS66 KSEW 302222
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
320 PM PDT SUN AUG 30 2015

.SYNOPSIS...AN UPPER LEVEL TROUGH WILL REMAIN OVER THE PACIFIC
NORTHWEST THROUGH THURSDAY. WEATHER SYSTEMS MOVING THROUGH THE
TROUGH WILL KEEP THE WEATHER COOL AND WET FOR THIS TIME OF YEAR.
THE TROUGH WILL WEAKEN AND MOVE INLAND TOWARD THE END OF THE WEEK.

&&

.SHORT TERM...SCATTERED SHOWERS AND PARTIAL CLEARING PERIODS THIS
EVENING WILL GIVE WAY TO WARM ADVECTION OVERNIGHT AS A FRONTAL
SYSTEM SAGS SOUTH TOWARD THE AREA. THE MOUNTAINS SHOULD GET A GOOD
SOAKING AND LIGHT RAIN IS A GOOD BET AT TIMES FOR THE LOWLANDS MON
AND TUE. SHOWERS OR RAIN BANDS WILL CONTINUE TO BE DIRECTED INTO THE
AREA BY THE UPPER TROUGH TUE NITE AND WED AND THE AIR COOLS ALOFT
AS AN UPPER LOW CENTER SHIFTS OVER SOUTHWEST BRITISH COLUMBIA.

.LONG TERM...WEAK IMPULSES ROTATING THROUGH THE UPPER TROUGH WILL
BRING A FEW PERIODS OF SHOWER ACTIVITY THROUGH LATE IN THE WEEK. THE
MONTAINS AND PSCZ SHOULD HAVE THE BEST CHANCE OF SHOWERS. THE
UPPER TROUGH SHOULD SHIFT INLAND IN TIME FOR THE WEEKEND FOR DRY
WEATHER AND SOME MORE SUNSHINE.

&&


.AAVIATION...ABUNDANT LOW LEVEL MOISTURE AND INSTABILITY SUPPORTING
SCATTERED SHOWERS OVER THE AREA...WITH VFR CEILINGS AND
VISIBILITIES. A WEAK FRONT WILL APPROACH THE AREA FROM THE NORTHWEST
TONIGHT...BRINING RAIN TO THE NORTH COAST AROUND
MIDNIGHT...SPREADING INLAND THROUGH THE MORNING. PREVIOUS MODEL RUNS
HAD RAIN INTO MOST OF THE INTERIOR TERMINALS BY 12Z. MID DAY RUNS A
BIT SLOWER...MORE LIKE MID MORNING FOR THE CENTRAL SOUND
TERMINALS...AND SOUTH BY MIDDAY. EXPECT VFR CONDITIONS TO LOWER TO
MVFR LEVELS THROUGH MONDAY MORNING AS THE FRONT WORKS INLAND. SOME
LOCATIONS MAY REACH IFR LEVELS...ESPECIALLY WITH RAINFALL OR JUST
AFTER RAIN.

KSEA...VFR CONDITIONS WILL PERSIST THIS AFTERNOON...POSSIBLY LOWERING
TO NEAR MVFR LEVELS WITH SHOWERS. OTHERWISE EXPECT PREVAILING VFR
THROUGH MUCH OF THE NIGHT...LOWERING EARLY MONDAY MORNING AS THE
FRONT WORKS INTO THE CENTRAL SOUND TO MVFR LEVELS. WINDS WILL REMAIN
SOUTHERLY 10 TO 12 KNOTS THIS EVENING...EASING SOMEWHAT TO 8 TO 10
KNOTS AROUND MIDNIGHT...THEN INCREASING AGAIN AROUND MIDDAY TO 10 TO
12 KNOTS.

&&

.MARINE...SOUTHERLY LOW LEVEL PRESSURE GRADIENTS WILL INCREASE
TONIGHT AS ANOTHER FRONTAL SYSTEM APPROACHES FROM THE NORTHWEST.
EXPECT SMALL CRAFT ADVISORY SOUTHERLY WINDS OVER ALL WATERS BUT THE
CENTRAL STRAIT BY LATE TONIGHT. SMALL CRAFT ADVISORY WINDS WILL
CONTINUE OVER THE INTERIOR WATERS MONDAY MORNING BEFORE EASING
MONDAY AFTERNOON. A SERIES OF WEAK SYSTEMS WILL MOVE THROUGH THE
AREA TUESDAY AND WEDNESDAY.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...

WA...NONE.

PZ...SMALL CRAFT ADVISORIES COAST...ENTRANCES TO THE STRAIT...
     ADMIRALTY INLET AND THE INLAND WATERS.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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





000
FXUS66 KSEW 301621
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
915 AM PDT SUN AUG 30 2015

.SYNOPSIS...AN UPPER LEVEL TROUGH WILL REMAIN OVER THE PACIFIC
NORTHWEST THROUGH THURSDAY. WEATHER SYSTEMS MOVING THROUGH THE
TROUGH WILL KEEP THE WEATHER COOL AND WET FOR THIS TIME OF YEAR.
THE TROUGH WILL LIKELY WEAKEN AND MOVE INLAND TOWARD THE END OF
THE WEEK.

&&

.SHORT TERM...ONE SHORTWAVE TROUGH IS MOVING INLAND TODAY AND ANOTHER
WEATHER SYSTEM IS APPROACHING. THE AIR MASS BEHIND THE TROUGH IS
COOL AND SHOWERY. THE NEXT FRONTAL SYSTEM IS SPREADING RAIN INTO B.C.
NORTH OF VANCOUVER ISLAND TODAY AND THE RAIN WILL SHIFT SOUTH THROUGH
MONDAY. THE HEAVIER RAIN GOES INTO SOUTHEST BRITISH COLUMBIA BUT THE
OLYMPICS AND NORTH CASCADES SHOULD GET ANOTHER SOAKING AND THERE IS A
GOOD CHANCE OF RAIN AT TIMES FOR THE LOWLANDS OF WRN WA MON AND MON NITE...
ESPECIALLY ON THE COAST AND IN THE NORTH. THE 12Z NAM SHOWS THE FRONT
BREAKING UP OVER WRN WA AND NW OREGON TUE MORNING AND THEN A LOT OF
SHOWER ACTIVITY OR RAIN BANDS ARRIVE TUE NITE AND WED AS AN UPPER LOW
SHIFTS OVER SOUTHWEST BRITISH COLUMBIA...REINFORCING THE BROAD UPPER
TROUGH WITH THE COOLEST AIR ALOFT SO FAR...700 MB TEMPS COOL TO ARND -8C.

.LONG TERM...THE UPPER TROUGH WILL LIKELY WEAKEN AND MOVE INLAND AROUND
THE END OF THE WEEK. SHOWERS SHOULD DECREASE AND THERE IS A CHANCE THAT
THE WEEKEND WILL SEE WARMER AND SUNNIER WEATHER. THE ECMWF IS A NOTCH
SLOWER WITH THE IMPROVEMENT AND KEEPS HEIGHTS LOWER...CLOUDS COULD
LINGER WITH A CHANCE OF SHOWERS IN THE MOUNTAINS. THE MODELS DIVERGE
A GREAT DEAL TOWARD THE END OF THE FIRST WEEK OF SEPTEMBER BUT OVERALL
THE WEATHER PATTERN COULD RETURN TO RATHER ACTIVE WET WEATHER AFTER
A SHORT RESPITE ON THE WEEKEND.

&&

.CLIMATE...THE 0.73 INCHES OF RAIN THAT FELL AT SEA-TAC AIRPORT
DURING THE LAST THREE HOURS OF THE DAY PUSHED THE RAINFALL TOTAL FOR
SATURDAY TO 1.28 INCHES. THIS IS THE 5TH WETTEST AUGUST DAY ON
RECORD AT SEA-TAC. WITH THE 1.20 INCHES THAT WAS RECORDED ON THE
14TH...NOW TIED FOR THE 7TH WETTEST DAY IN AUGUST AT SEA-TAC...THIS
IS THE FIRST TIME INCLUDING THE FEDERAL BUILDING RECORDS THAT GO
BACK TO 1891 THAT THERE HAS BEEN TWO DAYS IN AUGUST WITH 1 INCH OR
MORE OF RAIN. THROUGH THE 29TH THE RAINFALL TOTAL FOR THE MONTH AT
SEA-TAC IS 2.88 INCHES...TIED FOR THE 5TH WETTEST AUGUST ON RECORD.
FELTON

&&

.AVIATION...AN OFFSHORE UPPER LEVEL TROUGH WILL MOVE OVER WESTERN
WASHINGTON THIS MORNING KEEPING THE MOIST AIR MASS SOMEWHAT UNSTABLE
TODAY. ABUNDANT LOW LEVEL MOISTURE AND SHOWERS ARE SUPPORTING A
MIXED BAG OF CONDITIONS THIS MORNING RANGING FROM IFR TO VFR. THERE
ARE MULTIPLE CLOUD LAYERS BETWEEN 2000 AND 8000 FEET WITH CEILINGS
RANGING BETWEEN 3500 AND 4500 FEET...AND BELOW 1000 FEET WITH OR
JUST BEHIND SHOWERS. SIMILARLY VISIBILITIES RANGING FROM 3SM TO WELL
OVER 10SM. IN ADDITION THERE REMAINS A CHANCE OF THUNDERSTORMS THIS
MORNING AS THE UPPER LEVEL TROUGH WORKS ONSHORE. SHOWERS WILL
DECREASE AND CONDITIONS SHOULD IMPROVE TO VFR LEVELS OVER THE
LOWLANDS THIS AFTERNOON AS THE UPPER LEVEL TROUGH MOVES EAST OF THE
AREA. A WEAK FRONT WILL APPROACH THE AREA FROM THE NORTHWEST
TONIGHT...BRINING RAIN TO THE NORTH COAST AROUND
MIDNIGHT...SPREADING INLAND BY DAY BREAK. EXPECT VFR CONDITIONS TO
LOWER TO MVFR LEVELS EARLY MONDAY MORNING AS THE FRONT WORKS INLAND.
SOME LOCATIONS MAY REACH IFR LEVELS...ESPECIALLY WITH RAINFALL OR
JUST AFTER RAIN.

KSEA...CEILINGS HAVE COME DOWN TO BELOW 1000 FEET THIS MORNING
BEHIND THE BAND OF RAINFALL THAT WORKED THROUGH THE INTERIOR EARLY
THIS MORNING. EXPECT CEILINGS TO RETURN TO 3500 TO 4500 FEET OVER
THE NEXT FEW HOURS. WINDS WILL REMAIN SOUTHERLY 6 TO 8 KNOTS THIS
MORNING...INCREASING TO 10 TO 12 KNOTS THIS AFTERNOON.

&&

.MARINE...SURFACE GRADIENTS AND WINDS HAVE EASED THIS MORNING.
SOUTHERLY GRADIENTS WILL INCREASE THIS AFTERNOON AND EVENING AS
ANOTHER FRONTAL SYSTEM APPROACHES FROM THE NORTHWEST. EXPECT SMALL
CRAFT ADVISORY SOUTHERLY WINDS OVER ALL WATERS BUT THE CENTRAL
STRAIT BY LATE TONIGHT. SMALL CRAFT ADVISORY WINDS WILL CONTINUE
OVER THE INTERIOR WATERS MONDAY MORNING BEFORE EASING MONDAY
AFTERNOON. A SERIES OF WEAK SYSTEMS WILL MOVE THROUGH THE AREA
TUESDAY AND WEDNESDAY.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...

WA...NONE.

PZ...SMALL CRAFT ADVISORIES COAST...ENTRANCES TO THE STRAIT...
     ADMIRALTY INLET AND THE INLAND WATERS.


&&

$$

WWW.WEATHER.GOV/SEATTLE

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





000
FXUS66 KSEW 301621
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
915 AM PDT SUN AUG 30 2015

.SYNOPSIS...AN UPPER LEVEL TROUGH WILL REMAIN OVER THE PACIFIC
NORTHWEST THROUGH THURSDAY. WEATHER SYSTEMS MOVING THROUGH THE
TROUGH WILL KEEP THE WEATHER COOL AND WET FOR THIS TIME OF YEAR.
THE TROUGH WILL LIKELY WEAKEN AND MOVE INLAND TOWARD THE END OF
THE WEEK.

&&

.SHORT TERM...ONE SHORTWAVE TROUGH IS MOVING INLAND TODAY AND ANOTHER
WEATHER SYSTEM IS APPROACHING. THE AIR MASS BEHIND THE TROUGH IS
COOL AND SHOWERY. THE NEXT FRONTAL SYSTEM IS SPREADING RAIN INTO B.C.
NORTH OF VANCOUVER ISLAND TODAY AND THE RAIN WILL SHIFT SOUTH THROUGH
MONDAY. THE HEAVIER RAIN GOES INTO SOUTHEST BRITISH COLUMBIA BUT THE
OLYMPICS AND NORTH CASCADES SHOULD GET ANOTHER SOAKING AND THERE IS A
GOOD CHANCE OF RAIN AT TIMES FOR THE LOWLANDS OF WRN WA MON AND MON NITE...
ESPECIALLY ON THE COAST AND IN THE NORTH. THE 12Z NAM SHOWS THE FRONT
BREAKING UP OVER WRN WA AND NW OREGON TUE MORNING AND THEN A LOT OF
SHOWER ACTIVITY OR RAIN BANDS ARRIVE TUE NITE AND WED AS AN UPPER LOW
SHIFTS OVER SOUTHWEST BRITISH COLUMBIA...REINFORCING THE BROAD UPPER
TROUGH WITH THE COOLEST AIR ALOFT SO FAR...700 MB TEMPS COOL TO ARND -8C.

.LONG TERM...THE UPPER TROUGH WILL LIKELY WEAKEN AND MOVE INLAND AROUND
THE END OF THE WEEK. SHOWERS SHOULD DECREASE AND THERE IS A CHANCE THAT
THE WEEKEND WILL SEE WARMER AND SUNNIER WEATHER. THE ECMWF IS A NOTCH
SLOWER WITH THE IMPROVEMENT AND KEEPS HEIGHTS LOWER...CLOUDS COULD
LINGER WITH A CHANCE OF SHOWERS IN THE MOUNTAINS. THE MODELS DIVERGE
A GREAT DEAL TOWARD THE END OF THE FIRST WEEK OF SEPTEMBER BUT OVERALL
THE WEATHER PATTERN COULD RETURN TO RATHER ACTIVE WET WEATHER AFTER
A SHORT RESPITE ON THE WEEKEND.

&&

.CLIMATE...THE 0.73 INCHES OF RAIN THAT FELL AT SEA-TAC AIRPORT
DURING THE LAST THREE HOURS OF THE DAY PUSHED THE RAINFALL TOTAL FOR
SATURDAY TO 1.28 INCHES. THIS IS THE 5TH WETTEST AUGUST DAY ON
RECORD AT SEA-TAC. WITH THE 1.20 INCHES THAT WAS RECORDED ON THE
14TH...NOW TIED FOR THE 7TH WETTEST DAY IN AUGUST AT SEA-TAC...THIS
IS THE FIRST TIME INCLUDING THE FEDERAL BUILDING RECORDS THAT GO
BACK TO 1891 THAT THERE HAS BEEN TWO DAYS IN AUGUST WITH 1 INCH OR
MORE OF RAIN. THROUGH THE 29TH THE RAINFALL TOTAL FOR THE MONTH AT
SEA-TAC IS 2.88 INCHES...TIED FOR THE 5TH WETTEST AUGUST ON RECORD.
FELTON

&&

.AVIATION...AN OFFSHORE UPPER LEVEL TROUGH WILL MOVE OVER WESTERN
WASHINGTON THIS MORNING KEEPING THE MOIST AIR MASS SOMEWHAT UNSTABLE
TODAY. ABUNDANT LOW LEVEL MOISTURE AND SHOWERS ARE SUPPORTING A
MIXED BAG OF CONDITIONS THIS MORNING RANGING FROM IFR TO VFR. THERE
ARE MULTIPLE CLOUD LAYERS BETWEEN 2000 AND 8000 FEET WITH CEILINGS
RANGING BETWEEN 3500 AND 4500 FEET...AND BELOW 1000 FEET WITH OR
JUST BEHIND SHOWERS. SIMILARLY VISIBILITIES RANGING FROM 3SM TO WELL
OVER 10SM. IN ADDITION THERE REMAINS A CHANCE OF THUNDERSTORMS THIS
MORNING AS THE UPPER LEVEL TROUGH WORKS ONSHORE. SHOWERS WILL
DECREASE AND CONDITIONS SHOULD IMPROVE TO VFR LEVELS OVER THE
LOWLANDS THIS AFTERNOON AS THE UPPER LEVEL TROUGH MOVES EAST OF THE
AREA. A WEAK FRONT WILL APPROACH THE AREA FROM THE NORTHWEST
TONIGHT...BRINING RAIN TO THE NORTH COAST AROUND
MIDNIGHT...SPREADING INLAND BY DAY BREAK. EXPECT VFR CONDITIONS TO
LOWER TO MVFR LEVELS EARLY MONDAY MORNING AS THE FRONT WORKS INLAND.
SOME LOCATIONS MAY REACH IFR LEVELS...ESPECIALLY WITH RAINFALL OR
JUST AFTER RAIN.

KSEA...CEILINGS HAVE COME DOWN TO BELOW 1000 FEET THIS MORNING
BEHIND THE BAND OF RAINFALL THAT WORKED THROUGH THE INTERIOR EARLY
THIS MORNING. EXPECT CEILINGS TO RETURN TO 3500 TO 4500 FEET OVER
THE NEXT FEW HOURS. WINDS WILL REMAIN SOUTHERLY 6 TO 8 KNOTS THIS
MORNING...INCREASING TO 10 TO 12 KNOTS THIS AFTERNOON.

&&

.MARINE...SURFACE GRADIENTS AND WINDS HAVE EASED THIS MORNING.
SOUTHERLY GRADIENTS WILL INCREASE THIS AFTERNOON AND EVENING AS
ANOTHER FRONTAL SYSTEM APPROACHES FROM THE NORTHWEST. EXPECT SMALL
CRAFT ADVISORY SOUTHERLY WINDS OVER ALL WATERS BUT THE CENTRAL
STRAIT BY LATE TONIGHT. SMALL CRAFT ADVISORY WINDS WILL CONTINUE
OVER THE INTERIOR WATERS MONDAY MORNING BEFORE EASING MONDAY
AFTERNOON. A SERIES OF WEAK SYSTEMS WILL MOVE THROUGH THE AREA
TUESDAY AND WEDNESDAY.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...

WA...NONE.

PZ...SMALL CRAFT ADVISORIES COAST...ENTRANCES TO THE STRAIT...
     ADMIRALTY INLET AND THE INLAND WATERS.


&&

$$

WWW.WEATHER.GOV/SEATTLE

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




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