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000
FXUS66 KSEW 272127
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
230 PM PDT WED MAY 27 2015

.SYNOPSIS...RELATIVELY WEAK LOW LEVEL ONSHORE FLOW WILL PREVAIL FOR
THE NEXT SEVERAL DAYS...WITH ABOVE NORMAL TEMPERATURES AND MOSTLY
SUNNY DAYS. AN UPPER LOW WILL BRING SHOWERS AND COOLER WEATHER THE
FIRST PART OF NEXT WEEK.

&&

.SHORT TERM...WEAK HIGH PRESSURE ALOFT WILL BUILD OVER WESTERN
WASHINGTON TONIGHT AND THURSDAY. AT THE SAME TIME...LOW LEVEL
ONSHORE FLOW WILL WEAKEN A BIT AND TURN MORE NORTHERLY. THE UPSHOT
IS AREAS OF MORNING LOW CLOUDS THEN MOSTLY SUNNY THURSDAY. HIGHS
WILL BE IN THE 70S TO LOWER 80S INLAND.

500 MB HEIGHTS WILL FALL SLIGHTLY FRIDAY AND SATURDAY AS AN UPPER
LOW OVER BRITISH COLUMBIA SAGS SOUTH AND THEN EAST. THIS WILL CAUSE
LOW LEVEL ONSHORE FLOW TO INCREASE A BIT. THAT SAID...IT DOES NOT
LOOK LIKE THESE CHANGES WILL HAVE MUCH AFFECT ON THE WEATHER. LOW
LEVEL MOISTURE WILL BE LIMITED FOR MOSTLY SUNNY DAYS AFTER SOME
MORNING LOW CLOUDS. 850 MB TEMPERATURES WILL REMAIN ABOUT THE SAME
FRIDAY AND HIGHS SHOULD ONCE AGAIN BE IN THE 70S TO LOWER 80S FOR
THE INTERIOR. THERE WILL PROBABLY BE A FEW DEGREES OF COOLING
SATURDAY BUT TEMPERATURES WILL STILL BE ABOVE NORMAL.

THERE WILL BE ENOUGH INSTABILITY OVER THE CASCADES FOR A CHANCE OF
AFTERNOON AND EVENING SHOWERS THURSDAY AND FRIDAY WITH THE BEST
CHANCES WILL BE NEAR THE CREST. SCHNEIDER

.LONG TERM...SUNDAY WILL BE ANOTHER MOSTLY SUNNY AFTER SOME MORNING
LOW CLOUDS. HIGHS MIGHT EVEN WARM A LITTLE AS AN UPPER LOW
APPROACHES FROM THE SOUTHWEST AND LOW LEVEL ONSHORE FLOW EASES.

THE AFOREMENTIONED UPPER LOW WILL MOVE OVER OREGON ON MONDAY.
MOISTURE COMING UP FROM THE SOUTH WITH THIS LOW WILL BRING AN
INCREASING CHANCE OF SHOWERS TO THE AREA. HIGHS WILL COOL INTO THE
60S. THE UPPER LOW WILL MOVE INLAND TO THE SOUTH...CLOSE ENOUGH TO
KEEP SHOWERS AND CLOUDS OVER THE AREA THROUGH TUESDAY WITH HIGHS
REMAINING IN THE 60S.

WEAK HIGH PRESSURE ALOFT WILL BUILD OVER THE REGION ON WEDNESDAY.
THIS SHOULD ALLOW THINGS TO DRY OUT AND THERE WILL PROBABLY BE SOME
SUNSHINE BY AFTERNOON. SCHNEIDER

&&

.AVIATION...NORTHERLY FLOW ALOFT. LIGHT ONSHORE FLOW. MARINE STRATUS
IS ALONG THE COAST THIS AFTERNOON BUT MOST OF IT HAS BURNED OFF IN
THE INTERIOR. AREAS OF LOW CLOUDS ARE LIKELY TO DEVELOP OVERNIGHT
AND BURN OFF BY MIDDAY THURSDAY.

KSEA...MOSTLY CLEAR SKIES TONIGHT AND A FEW HOURS OF MORNING LOW
CLOUDS THURSDAY.

&&

.MARINE...HIGH PRESSURE IS OFFSHORE WITH LOWER PRESSURE INLAND.
WESTERLY FLOW IN THE STRAIT OF JUAN DE FUCA COULD INCREASE TO SMALL
CRAFT ADVISORY STRENGTH BY EVENING.

&&

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

&&

$$

WWW.WEATHER.GOV/SEATTLE

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












000
FXUS66 KSEW 272127
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
230 PM PDT WED MAY 27 2015

.SYNOPSIS...RELATIVELY WEAK LOW LEVEL ONSHORE FLOW WILL PREVAIL FOR
THE NEXT SEVERAL DAYS...WITH ABOVE NORMAL TEMPERATURES AND MOSTLY
SUNNY DAYS. AN UPPER LOW WILL BRING SHOWERS AND COOLER WEATHER THE
FIRST PART OF NEXT WEEK.

&&

.SHORT TERM...WEAK HIGH PRESSURE ALOFT WILL BUILD OVER WESTERN
WASHINGTON TONIGHT AND THURSDAY. AT THE SAME TIME...LOW LEVEL
ONSHORE FLOW WILL WEAKEN A BIT AND TURN MORE NORTHERLY. THE UPSHOT
IS AREAS OF MORNING LOW CLOUDS THEN MOSTLY SUNNY THURSDAY. HIGHS
WILL BE IN THE 70S TO LOWER 80S INLAND.

500 MB HEIGHTS WILL FALL SLIGHTLY FRIDAY AND SATURDAY AS AN UPPER
LOW OVER BRITISH COLUMBIA SAGS SOUTH AND THEN EAST. THIS WILL CAUSE
LOW LEVEL ONSHORE FLOW TO INCREASE A BIT. THAT SAID...IT DOES NOT
LOOK LIKE THESE CHANGES WILL HAVE MUCH AFFECT ON THE WEATHER. LOW
LEVEL MOISTURE WILL BE LIMITED FOR MOSTLY SUNNY DAYS AFTER SOME
MORNING LOW CLOUDS. 850 MB TEMPERATURES WILL REMAIN ABOUT THE SAME
FRIDAY AND HIGHS SHOULD ONCE AGAIN BE IN THE 70S TO LOWER 80S FOR
THE INTERIOR. THERE WILL PROBABLY BE A FEW DEGREES OF COOLING
SATURDAY BUT TEMPERATURES WILL STILL BE ABOVE NORMAL.

THERE WILL BE ENOUGH INSTABILITY OVER THE CASCADES FOR A CHANCE OF
AFTERNOON AND EVENING SHOWERS THURSDAY AND FRIDAY WITH THE BEST
CHANCES WILL BE NEAR THE CREST. SCHNEIDER

.LONG TERM...SUNDAY WILL BE ANOTHER MOSTLY SUNNY AFTER SOME MORNING
LOW CLOUDS. HIGHS MIGHT EVEN WARM A LITTLE AS AN UPPER LOW
APPROACHES FROM THE SOUTHWEST AND LOW LEVEL ONSHORE FLOW EASES.

THE AFOREMENTIONED UPPER LOW WILL MOVE OVER OREGON ON MONDAY.
MOISTURE COMING UP FROM THE SOUTH WITH THIS LOW WILL BRING AN
INCREASING CHANCE OF SHOWERS TO THE AREA. HIGHS WILL COOL INTO THE
60S. THE UPPER LOW WILL MOVE INLAND TO THE SOUTH...CLOSE ENOUGH TO
KEEP SHOWERS AND CLOUDS OVER THE AREA THROUGH TUESDAY WITH HIGHS
REMAINING IN THE 60S.

WEAK HIGH PRESSURE ALOFT WILL BUILD OVER THE REGION ON WEDNESDAY.
THIS SHOULD ALLOW THINGS TO DRY OUT AND THERE WILL PROBABLY BE SOME
SUNSHINE BY AFTERNOON. SCHNEIDER

&&

.AVIATION...NORTHERLY FLOW ALOFT. LIGHT ONSHORE FLOW. MARINE STRATUS
IS ALONG THE COAST THIS AFTERNOON BUT MOST OF IT HAS BURNED OFF IN
THE INTERIOR. AREAS OF LOW CLOUDS ARE LIKELY TO DEVELOP OVERNIGHT
AND BURN OFF BY MIDDAY THURSDAY.

KSEA...MOSTLY CLEAR SKIES TONIGHT AND A FEW HOURS OF MORNING LOW
CLOUDS THURSDAY.

&&

.MARINE...HIGH PRESSURE IS OFFSHORE WITH LOWER PRESSURE INLAND.
WESTERLY FLOW IN THE STRAIT OF JUAN DE FUCA COULD INCREASE TO SMALL
CRAFT ADVISORY STRENGTH BY EVENING.

&&

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

&&

$$

WWW.WEATHER.GOV/SEATTLE

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











000
FXUS66 KSEW 271530
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
830 AM PDT WED MAY 27 2015

.SYNOPSIS...LOW LEVEL ONSHORE FLOW WILL WEAKEN SLIGHTLY OVER THE
NEXT COUPLE OF DAYS...ALLOWING FOR WARMER AND SUNNIER WEATHER. AN
UPPER LOW WILL BRING SOME SHOWERS AND COOLER WEATHER EARLY NEXT WEEK.

&&

.SHORT TERM...AN UPPER LOW OVER EASTERN WASHINGTON WILL SLOWLY PULL
AWAY FROM THE AREA WITH WEAK HIGH PRESSURE ALOFT BUILDING OVER
WESTERN WASHINGTON TODAY AND THURSDAY. AT THE SAME TIME...LOW LEVEL
ONSHORE FLOW WILL WEAKEN A BIT AND TURN MORE NORTHERLY. THE UPSHOT
IS LOW CLOUDS OVER THE AREA THIS MORNING SHOULD SCATTER THIS
AFTERNOON AND HIGHS WILL WARM INTO THE 70S. THERE SHOULD BE LESS LOW
CLOUDS THURSDAY MORNING WITH HIGHS IN THE 70S TO LOWER 80S.

500 MB HEIGHTS WILL BEGIN TO FALL ACROSS THE AREA FRIDAY AS AN UPPER
LOW OVER BRITISH COLUMBIA SAGS SOUTH TOWARDS WESTERN WASHINGTON.
THIS WILL ALSO CAUSE LOW LEVEL ONSHORE FLOW TO INCREASE AGAIN. THAT
SAID...IT DOES NOT LOOK LIKE THESE CHANGES WILL HAVE MUCH AFFECT ON
THE WEATHER. LOW LEVEL MOISTURE WILL BE LIMITED FOR ANOTHER MOSTLY
SUNNY DAY. 850 MB TEMPERATURES ACTUALLY WARM SLIGHTLY AND HIGHS
SHOULD ONCE AGAIN BE IN THE 70S TO LOWER 80S.

THERE WILL BE ENOUGH INSTABILITY OVER THE CASCADES FOR A CHANCE OF
AFTERNOON AND EVENING SHOWERS FOR THE NEXT FEW DAYS. SCHNEIDER

.LONG TERM...PREVIOUS DISCUSSION...500 MB HEIGHTS WILL SLOWLY LOWER
THIS WEEKEND WITH A BIT OF AN INCREASE IN LOW LEVEL ONSHORE FLOW.
THIS WILL CAUSE HIGHS TO COOL SLIGHTLY BUT TEMPERATURES WILL REMAIN
ABOVE NORMAL.

AN UPPER LOW OFF THE FAR NORTHERN CA COAST WILL EITHER MOVE INTO
OREGON OR WA ON MONDAY. NOT SURPRISINGLY...THE MODELS WERE NOT IN
VERY GOOD AGREEMENT WITH HOW THIS WILL UNFOLD. THE GENERAL IDEA
WAS THAT MOISTURE COMING UP FROM THE SOUTH WILL START TO IMPACT
THE CWA ON MONDAY AS THE UPPER LOW APPROACHES. THE UPPER LOW WILL
REMAIN IN THE VICINITY FOR A CONTINUED CHANCE OF SHOWERS ON
TUESDAY. HIGH TEMPS WILL COOL TO NEAR NORMAL BY TUESDAY AS
CLOUDS AND ONSHORE FLOW INCREASE. SCHNEIDER/05

&&

.AVIATION...NORTHERLY FLOW ALOFT. LIGHT ONSHORE FLOW. THE AIR IS
MOIST WITH AREAS OF MARINE STRATUS THAT FOR THE MOST PART WILL LIFT
AND BURN OFF INTO THE AFTERNOON HOURS.

KSEA...THE MORNING CLOUDS SHOULD SCATTER OUT MIDDAY.

&&

.MARINE...HIGH PRESSURE WILL REMAIN OFFSHORE WITH LOWER PRESSURE
INLAND THROUGH THE WEEK. ONSHORE GRADIENTS INCREASE FRIDAY AFTERNOON
AND EVENING FOR POSSIBLE SMALL CRAFT ADVISORY STRENGTH WEST WINDS IN
THE STRAIT.

&&

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

&&

$$

WWW.WEATHER.GOV/SEATTLE

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








000
FXUS66 KSEW 271530
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
830 AM PDT WED MAY 27 2015

.SYNOPSIS...LOW LEVEL ONSHORE FLOW WILL WEAKEN SLIGHTLY OVER THE
NEXT COUPLE OF DAYS...ALLOWING FOR WARMER AND SUNNIER WEATHER. AN
UPPER LOW WILL BRING SOME SHOWERS AND COOLER WEATHER EARLY NEXT WEEK.

&&

.SHORT TERM...AN UPPER LOW OVER EASTERN WASHINGTON WILL SLOWLY PULL
AWAY FROM THE AREA WITH WEAK HIGH PRESSURE ALOFT BUILDING OVER
WESTERN WASHINGTON TODAY AND THURSDAY. AT THE SAME TIME...LOW LEVEL
ONSHORE FLOW WILL WEAKEN A BIT AND TURN MORE NORTHERLY. THE UPSHOT
IS LOW CLOUDS OVER THE AREA THIS MORNING SHOULD SCATTER THIS
AFTERNOON AND HIGHS WILL WARM INTO THE 70S. THERE SHOULD BE LESS LOW
CLOUDS THURSDAY MORNING WITH HIGHS IN THE 70S TO LOWER 80S.

500 MB HEIGHTS WILL BEGIN TO FALL ACROSS THE AREA FRIDAY AS AN UPPER
LOW OVER BRITISH COLUMBIA SAGS SOUTH TOWARDS WESTERN WASHINGTON.
THIS WILL ALSO CAUSE LOW LEVEL ONSHORE FLOW TO INCREASE AGAIN. THAT
SAID...IT DOES NOT LOOK LIKE THESE CHANGES WILL HAVE MUCH AFFECT ON
THE WEATHER. LOW LEVEL MOISTURE WILL BE LIMITED FOR ANOTHER MOSTLY
SUNNY DAY. 850 MB TEMPERATURES ACTUALLY WARM SLIGHTLY AND HIGHS
SHOULD ONCE AGAIN BE IN THE 70S TO LOWER 80S.

THERE WILL BE ENOUGH INSTABILITY OVER THE CASCADES FOR A CHANCE OF
AFTERNOON AND EVENING SHOWERS FOR THE NEXT FEW DAYS. SCHNEIDER

.LONG TERM...PREVIOUS DISCUSSION...500 MB HEIGHTS WILL SLOWLY LOWER
THIS WEEKEND WITH A BIT OF AN INCREASE IN LOW LEVEL ONSHORE FLOW.
THIS WILL CAUSE HIGHS TO COOL SLIGHTLY BUT TEMPERATURES WILL REMAIN
ABOVE NORMAL.

AN UPPER LOW OFF THE FAR NORTHERN CA COAST WILL EITHER MOVE INTO
OREGON OR WA ON MONDAY. NOT SURPRISINGLY...THE MODELS WERE NOT IN
VERY GOOD AGREEMENT WITH HOW THIS WILL UNFOLD. THE GENERAL IDEA
WAS THAT MOISTURE COMING UP FROM THE SOUTH WILL START TO IMPACT
THE CWA ON MONDAY AS THE UPPER LOW APPROACHES. THE UPPER LOW WILL
REMAIN IN THE VICINITY FOR A CONTINUED CHANCE OF SHOWERS ON
TUESDAY. HIGH TEMPS WILL COOL TO NEAR NORMAL BY TUESDAY AS
CLOUDS AND ONSHORE FLOW INCREASE. SCHNEIDER/05

&&

.AVIATION...NORTHERLY FLOW ALOFT. LIGHT ONSHORE FLOW. THE AIR IS
MOIST WITH AREAS OF MARINE STRATUS THAT FOR THE MOST PART WILL LIFT
AND BURN OFF INTO THE AFTERNOON HOURS.

KSEA...THE MORNING CLOUDS SHOULD SCATTER OUT MIDDAY.

&&

.MARINE...HIGH PRESSURE WILL REMAIN OFFSHORE WITH LOWER PRESSURE
INLAND THROUGH THE WEEK. ONSHORE GRADIENTS INCREASE FRIDAY AFTERNOON
AND EVENING FOR POSSIBLE SMALL CRAFT ADVISORY STRENGTH WEST WINDS IN
THE STRAIT.

&&

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

&&

$$

WWW.WEATHER.GOV/SEATTLE

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








000
FXUS66 KSEW 271530
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
830 AM PDT WED MAY 27 2015

.SYNOPSIS...LOW LEVEL ONSHORE FLOW WILL WEAKEN SLIGHTLY OVER THE
NEXT COUPLE OF DAYS...ALLOWING FOR WARMER AND SUNNIER WEATHER. AN
UPPER LOW WILL BRING SOME SHOWERS AND COOLER WEATHER EARLY NEXT WEEK.

&&

.SHORT TERM...AN UPPER LOW OVER EASTERN WASHINGTON WILL SLOWLY PULL
AWAY FROM THE AREA WITH WEAK HIGH PRESSURE ALOFT BUILDING OVER
WESTERN WASHINGTON TODAY AND THURSDAY. AT THE SAME TIME...LOW LEVEL
ONSHORE FLOW WILL WEAKEN A BIT AND TURN MORE NORTHERLY. THE UPSHOT
IS LOW CLOUDS OVER THE AREA THIS MORNING SHOULD SCATTER THIS
AFTERNOON AND HIGHS WILL WARM INTO THE 70S. THERE SHOULD BE LESS LOW
CLOUDS THURSDAY MORNING WITH HIGHS IN THE 70S TO LOWER 80S.

500 MB HEIGHTS WILL BEGIN TO FALL ACROSS THE AREA FRIDAY AS AN UPPER
LOW OVER BRITISH COLUMBIA SAGS SOUTH TOWARDS WESTERN WASHINGTON.
THIS WILL ALSO CAUSE LOW LEVEL ONSHORE FLOW TO INCREASE AGAIN. THAT
SAID...IT DOES NOT LOOK LIKE THESE CHANGES WILL HAVE MUCH AFFECT ON
THE WEATHER. LOW LEVEL MOISTURE WILL BE LIMITED FOR ANOTHER MOSTLY
SUNNY DAY. 850 MB TEMPERATURES ACTUALLY WARM SLIGHTLY AND HIGHS
SHOULD ONCE AGAIN BE IN THE 70S TO LOWER 80S.

THERE WILL BE ENOUGH INSTABILITY OVER THE CASCADES FOR A CHANCE OF
AFTERNOON AND EVENING SHOWERS FOR THE NEXT FEW DAYS. SCHNEIDER

.LONG TERM...PREVIOUS DISCUSSION...500 MB HEIGHTS WILL SLOWLY LOWER
THIS WEEKEND WITH A BIT OF AN INCREASE IN LOW LEVEL ONSHORE FLOW.
THIS WILL CAUSE HIGHS TO COOL SLIGHTLY BUT TEMPERATURES WILL REMAIN
ABOVE NORMAL.

AN UPPER LOW OFF THE FAR NORTHERN CA COAST WILL EITHER MOVE INTO
OREGON OR WA ON MONDAY. NOT SURPRISINGLY...THE MODELS WERE NOT IN
VERY GOOD AGREEMENT WITH HOW THIS WILL UNFOLD. THE GENERAL IDEA
WAS THAT MOISTURE COMING UP FROM THE SOUTH WILL START TO IMPACT
THE CWA ON MONDAY AS THE UPPER LOW APPROACHES. THE UPPER LOW WILL
REMAIN IN THE VICINITY FOR A CONTINUED CHANCE OF SHOWERS ON
TUESDAY. HIGH TEMPS WILL COOL TO NEAR NORMAL BY TUESDAY AS
CLOUDS AND ONSHORE FLOW INCREASE. SCHNEIDER/05

&&

.AVIATION...NORTHERLY FLOW ALOFT. LIGHT ONSHORE FLOW. THE AIR IS
MOIST WITH AREAS OF MARINE STRATUS THAT FOR THE MOST PART WILL LIFT
AND BURN OFF INTO THE AFTERNOON HOURS.

KSEA...THE MORNING CLOUDS SHOULD SCATTER OUT MIDDAY.

&&

.MARINE...HIGH PRESSURE WILL REMAIN OFFSHORE WITH LOWER PRESSURE
INLAND THROUGH THE WEEK. ONSHORE GRADIENTS INCREASE FRIDAY AFTERNOON
AND EVENING FOR POSSIBLE SMALL CRAFT ADVISORY STRENGTH WEST WINDS IN
THE STRAIT.

&&

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

&&

$$

WWW.WEATHER.GOV/SEATTLE

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









000
FXUS66 KSEW 271019
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
319 AM PDT WED MAY 27 2015

.SYNOPSIS...A LOW PRESSURE SYSTEM ALOFT OVER EASTERN WASHINGTON
WILL CONTINUE MOVING EAST. THIS WILL PLACE THE AREA MORE UNDER THE
INFLUENCE OF HIGH PRESSURE ALOFT LATER TODAY AND CONTINUING
THROUGH FRIDAY. THIS COMBINED WITH LIGHT LOW LEVEL ONSHORE FLOW
WILL RESULT IN WELL ABOVE NORMAL DAYTIME TEMPERATURES.

&&

.SHORT TERM...
THERE WERE MULTIPLE CLOUD LAYERS PRESENT OVER THE CWA AT THIS
TIME. CLOUDS SHOULD FILL IN OVER THE CLEAR AREAS BY OR SHORTLY
AFTER SUNRISE.

MEANWHILE...A CUT-OFF LOW OVER EASTERN WA WILL MOVE INTO ID
TONIGHT. THIS WILL PLACE WESTERN WA MORE UNDER THE INFLUENCE OF AN
UPPER LEVEL RIDGE CENTERED OFFSHORE. TODAY SHOULD BE A WARMER DAY
DUE TO WEAKER ONSHORE FLOW AND LESS CLOUD COVER IN THE AFTERNOON.
THE AIR MASS WILL ALSO DESTABILIZE OVER THE CASCADES IN THE
AFTERNOON FOR A RISK OF SHOWERS. THERE WILL ALSO BE A SLIGHT RISK
OF TSTMS NEAR THE CREST THIS AFTERNOON THROUGH EARLY EVENING.

THE RIDGE WILL WEAKEN ON THU...AND THIS WILL ALLOW A VIGOROUS
UPPER LEVEL LOW OVER FAR NORTHWEST BRITISH COLUMBIA TO SLOWLY MOVE
SOUTH DURING THE DAY. IT SHOULD HAVE LITTLE IMPACT ON OUR WEATHER.
A WEAKER ONSHORE PRES GRADIENT PLUS PLENTY OF SUNSHINE AND
WARMING OF THE AIR MASS WILL RESULT IN ABOVE NORMAL TEMPS AND LESS
CLOUD COVER IN THE MORNING OVER THE CWA. AFTERNOON INSTABILITY WILL
ONCE AGAIN LEAD TO A RISK OF SHOWERS OVER THE CASCADES.

IT LOOKS LIKE THE PACIFIC NORTHWEST WILL BECOME SLIGHTLY MORE
UNDER THE INFLUENCE OF THE CUT-OFF LOW OVER BRITISH COLUMBIA ON
FRI. THIS SHOULD INDUCE AN ONSHORE PUSH LATER IN THE DAY. THERE IS
A POSSIBILITY THAT TEMPS ON THE COAST COULD END UP COOLER THAN
FORECAST. OTHERWISE...CONDITIONS SHOULD BE FAIRLY SIMILAR TO THU
BUT MAX TEMPS WILL LIKELY BE A COUPLE OF DEGREES COOLER AT MOST
PLACES.

.LONG TERM...
500 MB HEIGHTS WILL SLOWLY LOWER THIS WEEKEND WITH A BIT OF AN
INCREASE IN LOW LEVEL ONSHORE FLOW. THIS WILL CAUSE HIGHS TO COOL
SLIGHTLY BUT TEMPERATURES WILL REMAIN ABOVE NORMAL.

AN UPPER LOW OFF THE FAR NORTHERN CA COAST WILL EITHER MOVE INTO
OREGON OR WA ON MONDAY. NOT SURPRISINGLY...THE MODELS WERE NOT IN
VERY GOOD AGREEMENT WITH HOW THIS WILL UNFOLD. THE GENERAL IDEA
WAS THAT MOISTURE COMING UP FROM THE SOUTH WILL START TO IMPACT
THE CWA ON MONDAY AS THE UPPER LOW APPROACHES. THE UPPER LOW WILL
REMAIN IN THE VICINITY FOR A CONTINUED CHANCE OF SHOWERS ON
TUESDAY. HIGH TEMPS WILL COOL TO NEAR NORMAL BY TUESDAY AS
CLOUDS AND ONSHORE FLOW INCREASE. SCHNEIDER/05

&&

.AVIATION...AN UPPER LEVEL LOW WILL MOVE SLOWLY SOUTHEAST THROUGH
EASTERN WASHINGTON TODAY WITH NORTHERLY FLOW ALOFT OVER WESTERN
WASHINGTON. AT THE SURFACE LIGHT TO MODERATE ONSHORE FLOW WILL
CONTINUE. AIR MASS IS MOIST WITH MID LEVEL MOISTURE AND ALSO MARINE
STRATUS OVER WESTERN SECTIONS AND IN THE STRAIT. A CLEARING TREND
WILL BEGIN WEDNESDAY AFTERNOON.

KSEA...DISCUSSION ABOVE APPLIES. VFR CONDITIONS ARE LIKELY TODAY
WITH CEILINGS ABOVE 5K FT. THERE IS A CHANCE MARINE STRATUS WILL
REACH THE TERMINAL FOR A FEW HOURS THIS MORNING AND WILL COVER THAT
WITH A TEMPO GROUP IN THE TAF. CLEARING TREND IN THE AFTERNOON.
LIGHT SOUTHERLY WIND WILL BECOME NORTHWEST IN THE AFTERNOON. CHB

&&

.MARINE...HIGH PRESSURE WILL REMAIN OFFSHORE WITH LOWER PRESSURE
INLAND THROUGH THE WEEK. CURRENTLY MODELS KEEP WINDS BELOW 20 KT
TODAY AND THURSDAY IN THE STRAIT. ONSHORE GRADIENTS INCREASE FRIDAY
AFTERNOON AND EVENING FOR POSSIBLE SMALL CRAFT ADVISORY STRENGTH
WEST WINDS IN THE STRAIT.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY IN EFFECT TIL 5 AM THIS MORNING FOR
     THE CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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





000
FXUS66 KSEW 271019
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
319 AM PDT WED MAY 27 2015

.SYNOPSIS...A LOW PRESSURE SYSTEM ALOFT OVER EASTERN WASHINGTON
WILL CONTINUE MOVING EAST. THIS WILL PLACE THE AREA MORE UNDER THE
INFLUENCE OF HIGH PRESSURE ALOFT LATER TODAY AND CONTINUING
THROUGH FRIDAY. THIS COMBINED WITH LIGHT LOW LEVEL ONSHORE FLOW
WILL RESULT IN WELL ABOVE NORMAL DAYTIME TEMPERATURES.

&&

.SHORT TERM...
THERE WERE MULTIPLE CLOUD LAYERS PRESENT OVER THE CWA AT THIS
TIME. CLOUDS SHOULD FILL IN OVER THE CLEAR AREAS BY OR SHORTLY
AFTER SUNRISE.

MEANWHILE...A CUT-OFF LOW OVER EASTERN WA WILL MOVE INTO ID
TONIGHT. THIS WILL PLACE WESTERN WA MORE UNDER THE INFLUENCE OF AN
UPPER LEVEL RIDGE CENTERED OFFSHORE. TODAY SHOULD BE A WARMER DAY
DUE TO WEAKER ONSHORE FLOW AND LESS CLOUD COVER IN THE AFTERNOON.
THE AIR MASS WILL ALSO DESTABILIZE OVER THE CASCADES IN THE
AFTERNOON FOR A RISK OF SHOWERS. THERE WILL ALSO BE A SLIGHT RISK
OF TSTMS NEAR THE CREST THIS AFTERNOON THROUGH EARLY EVENING.

THE RIDGE WILL WEAKEN ON THU...AND THIS WILL ALLOW A VIGOROUS
UPPER LEVEL LOW OVER FAR NORTHWEST BRITISH COLUMBIA TO SLOWLY MOVE
SOUTH DURING THE DAY. IT SHOULD HAVE LITTLE IMPACT ON OUR WEATHER.
A WEAKER ONSHORE PRES GRADIENT PLUS PLENTY OF SUNSHINE AND
WARMING OF THE AIR MASS WILL RESULT IN ABOVE NORMAL TEMPS AND LESS
CLOUD COVER IN THE MORNING OVER THE CWA. AFTERNOON INSTABILITY WILL
ONCE AGAIN LEAD TO A RISK OF SHOWERS OVER THE CASCADES.

IT LOOKS LIKE THE PACIFIC NORTHWEST WILL BECOME SLIGHTLY MORE
UNDER THE INFLUENCE OF THE CUT-OFF LOW OVER BRITISH COLUMBIA ON
FRI. THIS SHOULD INDUCE AN ONSHORE PUSH LATER IN THE DAY. THERE IS
A POSSIBILITY THAT TEMPS ON THE COAST COULD END UP COOLER THAN
FORECAST. OTHERWISE...CONDITIONS SHOULD BE FAIRLY SIMILAR TO THU
BUT MAX TEMPS WILL LIKELY BE A COUPLE OF DEGREES COOLER AT MOST
PLACES.

.LONG TERM...
500 MB HEIGHTS WILL SLOWLY LOWER THIS WEEKEND WITH A BIT OF AN
INCREASE IN LOW LEVEL ONSHORE FLOW. THIS WILL CAUSE HIGHS TO COOL
SLIGHTLY BUT TEMPERATURES WILL REMAIN ABOVE NORMAL.

AN UPPER LOW OFF THE FAR NORTHERN CA COAST WILL EITHER MOVE INTO
OREGON OR WA ON MONDAY. NOT SURPRISINGLY...THE MODELS WERE NOT IN
VERY GOOD AGREEMENT WITH HOW THIS WILL UNFOLD. THE GENERAL IDEA
WAS THAT MOISTURE COMING UP FROM THE SOUTH WILL START TO IMPACT
THE CWA ON MONDAY AS THE UPPER LOW APPROACHES. THE UPPER LOW WILL
REMAIN IN THE VICINITY FOR A CONTINUED CHANCE OF SHOWERS ON
TUESDAY. HIGH TEMPS WILL COOL TO NEAR NORMAL BY TUESDAY AS
CLOUDS AND ONSHORE FLOW INCREASE. SCHNEIDER/05

&&

.AVIATION...AN UPPER LEVEL LOW WILL MOVE SLOWLY SOUTHEAST THROUGH
EASTERN WASHINGTON TODAY WITH NORTHERLY FLOW ALOFT OVER WESTERN
WASHINGTON. AT THE SURFACE LIGHT TO MODERATE ONSHORE FLOW WILL
CONTINUE. AIR MASS IS MOIST WITH MID LEVEL MOISTURE AND ALSO MARINE
STRATUS OVER WESTERN SECTIONS AND IN THE STRAIT. A CLEARING TREND
WILL BEGIN WEDNESDAY AFTERNOON.

KSEA...DISCUSSION ABOVE APPLIES. VFR CONDITIONS ARE LIKELY TODAY
WITH CEILINGS ABOVE 5K FT. THERE IS A CHANCE MARINE STRATUS WILL
REACH THE TERMINAL FOR A FEW HOURS THIS MORNING AND WILL COVER THAT
WITH A TEMPO GROUP IN THE TAF. CLEARING TREND IN THE AFTERNOON.
LIGHT SOUTHERLY WIND WILL BECOME NORTHWEST IN THE AFTERNOON. CHB

&&

.MARINE...HIGH PRESSURE WILL REMAIN OFFSHORE WITH LOWER PRESSURE
INLAND THROUGH THE WEEK. CURRENTLY MODELS KEEP WINDS BELOW 20 KT
TODAY AND THURSDAY IN THE STRAIT. ONSHORE GRADIENTS INCREASE FRIDAY
AFTERNOON AND EVENING FOR POSSIBLE SMALL CRAFT ADVISORY STRENGTH
WEST WINDS IN THE STRAIT.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY IN EFFECT TIL 5 AM THIS MORNING FOR
     THE CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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






000
FXUS66 KSEW 271019
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
319 AM PDT WED MAY 27 2015

.SYNOPSIS...A LOW PRESSURE SYSTEM ALOFT OVER EASTERN WASHINGTON
WILL CONTINUE MOVING EAST. THIS WILL PLACE THE AREA MORE UNDER THE
INFLUENCE OF HIGH PRESSURE ALOFT LATER TODAY AND CONTINUING
THROUGH FRIDAY. THIS COMBINED WITH LIGHT LOW LEVEL ONSHORE FLOW
WILL RESULT IN WELL ABOVE NORMAL DAYTIME TEMPERATURES.

&&

.SHORT TERM...
THERE WERE MULTIPLE CLOUD LAYERS PRESENT OVER THE CWA AT THIS
TIME. CLOUDS SHOULD FILL IN OVER THE CLEAR AREAS BY OR SHORTLY
AFTER SUNRISE.

MEANWHILE...A CUT-OFF LOW OVER EASTERN WA WILL MOVE INTO ID
TONIGHT. THIS WILL PLACE WESTERN WA MORE UNDER THE INFLUENCE OF AN
UPPER LEVEL RIDGE CENTERED OFFSHORE. TODAY SHOULD BE A WARMER DAY
DUE TO WEAKER ONSHORE FLOW AND LESS CLOUD COVER IN THE AFTERNOON.
THE AIR MASS WILL ALSO DESTABILIZE OVER THE CASCADES IN THE
AFTERNOON FOR A RISK OF SHOWERS. THERE WILL ALSO BE A SLIGHT RISK
OF TSTMS NEAR THE CREST THIS AFTERNOON THROUGH EARLY EVENING.

THE RIDGE WILL WEAKEN ON THU...AND THIS WILL ALLOW A VIGOROUS
UPPER LEVEL LOW OVER FAR NORTHWEST BRITISH COLUMBIA TO SLOWLY MOVE
SOUTH DURING THE DAY. IT SHOULD HAVE LITTLE IMPACT ON OUR WEATHER.
A WEAKER ONSHORE PRES GRADIENT PLUS PLENTY OF SUNSHINE AND
WARMING OF THE AIR MASS WILL RESULT IN ABOVE NORMAL TEMPS AND LESS
CLOUD COVER IN THE MORNING OVER THE CWA. AFTERNOON INSTABILITY WILL
ONCE AGAIN LEAD TO A RISK OF SHOWERS OVER THE CASCADES.

IT LOOKS LIKE THE PACIFIC NORTHWEST WILL BECOME SLIGHTLY MORE
UNDER THE INFLUENCE OF THE CUT-OFF LOW OVER BRITISH COLUMBIA ON
FRI. THIS SHOULD INDUCE AN ONSHORE PUSH LATER IN THE DAY. THERE IS
A POSSIBILITY THAT TEMPS ON THE COAST COULD END UP COOLER THAN
FORECAST. OTHERWISE...CONDITIONS SHOULD BE FAIRLY SIMILAR TO THU
BUT MAX TEMPS WILL LIKELY BE A COUPLE OF DEGREES COOLER AT MOST
PLACES.

.LONG TERM...
500 MB HEIGHTS WILL SLOWLY LOWER THIS WEEKEND WITH A BIT OF AN
INCREASE IN LOW LEVEL ONSHORE FLOW. THIS WILL CAUSE HIGHS TO COOL
SLIGHTLY BUT TEMPERATURES WILL REMAIN ABOVE NORMAL.

AN UPPER LOW OFF THE FAR NORTHERN CA COAST WILL EITHER MOVE INTO
OREGON OR WA ON MONDAY. NOT SURPRISINGLY...THE MODELS WERE NOT IN
VERY GOOD AGREEMENT WITH HOW THIS WILL UNFOLD. THE GENERAL IDEA
WAS THAT MOISTURE COMING UP FROM THE SOUTH WILL START TO IMPACT
THE CWA ON MONDAY AS THE UPPER LOW APPROACHES. THE UPPER LOW WILL
REMAIN IN THE VICINITY FOR A CONTINUED CHANCE OF SHOWERS ON
TUESDAY. HIGH TEMPS WILL COOL TO NEAR NORMAL BY TUESDAY AS
CLOUDS AND ONSHORE FLOW INCREASE. SCHNEIDER/05

&&

.AVIATION...AN UPPER LEVEL LOW WILL MOVE SLOWLY SOUTHEAST THROUGH
EASTERN WASHINGTON TODAY WITH NORTHERLY FLOW ALOFT OVER WESTERN
WASHINGTON. AT THE SURFACE LIGHT TO MODERATE ONSHORE FLOW WILL
CONTINUE. AIR MASS IS MOIST WITH MID LEVEL MOISTURE AND ALSO MARINE
STRATUS OVER WESTERN SECTIONS AND IN THE STRAIT. A CLEARING TREND
WILL BEGIN WEDNESDAY AFTERNOON.

KSEA...DISCUSSION ABOVE APPLIES. VFR CONDITIONS ARE LIKELY TODAY
WITH CEILINGS ABOVE 5K FT. THERE IS A CHANCE MARINE STRATUS WILL
REACH THE TERMINAL FOR A FEW HOURS THIS MORNING AND WILL COVER THAT
WITH A TEMPO GROUP IN THE TAF. CLEARING TREND IN THE AFTERNOON.
LIGHT SOUTHERLY WIND WILL BECOME NORTHWEST IN THE AFTERNOON. CHB

&&

.MARINE...HIGH PRESSURE WILL REMAIN OFFSHORE WITH LOWER PRESSURE
INLAND THROUGH THE WEEK. CURRENTLY MODELS KEEP WINDS BELOW 20 KT
TODAY AND THURSDAY IN THE STRAIT. ONSHORE GRADIENTS INCREASE FRIDAY
AFTERNOON AND EVENING FOR POSSIBLE SMALL CRAFT ADVISORY STRENGTH
WEST WINDS IN THE STRAIT.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY IN EFFECT TIL 5 AM THIS MORNING FOR
     THE CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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





000
FXUS66 KSEW 271019
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
319 AM PDT WED MAY 27 2015

.SYNOPSIS...A LOW PRESSURE SYSTEM ALOFT OVER EASTERN WASHINGTON
WILL CONTINUE MOVING EAST. THIS WILL PLACE THE AREA MORE UNDER THE
INFLUENCE OF HIGH PRESSURE ALOFT LATER TODAY AND CONTINUING
THROUGH FRIDAY. THIS COMBINED WITH LIGHT LOW LEVEL ONSHORE FLOW
WILL RESULT IN WELL ABOVE NORMAL DAYTIME TEMPERATURES.

&&

.SHORT TERM...
THERE WERE MULTIPLE CLOUD LAYERS PRESENT OVER THE CWA AT THIS
TIME. CLOUDS SHOULD FILL IN OVER THE CLEAR AREAS BY OR SHORTLY
AFTER SUNRISE.

MEANWHILE...A CUT-OFF LOW OVER EASTERN WA WILL MOVE INTO ID
TONIGHT. THIS WILL PLACE WESTERN WA MORE UNDER THE INFLUENCE OF AN
UPPER LEVEL RIDGE CENTERED OFFSHORE. TODAY SHOULD BE A WARMER DAY
DUE TO WEAKER ONSHORE FLOW AND LESS CLOUD COVER IN THE AFTERNOON.
THE AIR MASS WILL ALSO DESTABILIZE OVER THE CASCADES IN THE
AFTERNOON FOR A RISK OF SHOWERS. THERE WILL ALSO BE A SLIGHT RISK
OF TSTMS NEAR THE CREST THIS AFTERNOON THROUGH EARLY EVENING.

THE RIDGE WILL WEAKEN ON THU...AND THIS WILL ALLOW A VIGOROUS
UPPER LEVEL LOW OVER FAR NORTHWEST BRITISH COLUMBIA TO SLOWLY MOVE
SOUTH DURING THE DAY. IT SHOULD HAVE LITTLE IMPACT ON OUR WEATHER.
A WEAKER ONSHORE PRES GRADIENT PLUS PLENTY OF SUNSHINE AND
WARMING OF THE AIR MASS WILL RESULT IN ABOVE NORMAL TEMPS AND LESS
CLOUD COVER IN THE MORNING OVER THE CWA. AFTERNOON INSTABILITY WILL
ONCE AGAIN LEAD TO A RISK OF SHOWERS OVER THE CASCADES.

IT LOOKS LIKE THE PACIFIC NORTHWEST WILL BECOME SLIGHTLY MORE
UNDER THE INFLUENCE OF THE CUT-OFF LOW OVER BRITISH COLUMBIA ON
FRI. THIS SHOULD INDUCE AN ONSHORE PUSH LATER IN THE DAY. THERE IS
A POSSIBILITY THAT TEMPS ON THE COAST COULD END UP COOLER THAN
FORECAST. OTHERWISE...CONDITIONS SHOULD BE FAIRLY SIMILAR TO THU
BUT MAX TEMPS WILL LIKELY BE A COUPLE OF DEGREES COOLER AT MOST
PLACES.

.LONG TERM...
500 MB HEIGHTS WILL SLOWLY LOWER THIS WEEKEND WITH A BIT OF AN
INCREASE IN LOW LEVEL ONSHORE FLOW. THIS WILL CAUSE HIGHS TO COOL
SLIGHTLY BUT TEMPERATURES WILL REMAIN ABOVE NORMAL.

AN UPPER LOW OFF THE FAR NORTHERN CA COAST WILL EITHER MOVE INTO
OREGON OR WA ON MONDAY. NOT SURPRISINGLY...THE MODELS WERE NOT IN
VERY GOOD AGREEMENT WITH HOW THIS WILL UNFOLD. THE GENERAL IDEA
WAS THAT MOISTURE COMING UP FROM THE SOUTH WILL START TO IMPACT
THE CWA ON MONDAY AS THE UPPER LOW APPROACHES. THE UPPER LOW WILL
REMAIN IN THE VICINITY FOR A CONTINUED CHANCE OF SHOWERS ON
TUESDAY. HIGH TEMPS WILL COOL TO NEAR NORMAL BY TUESDAY AS
CLOUDS AND ONSHORE FLOW INCREASE. SCHNEIDER/05

&&

.AVIATION...AN UPPER LEVEL LOW WILL MOVE SLOWLY SOUTHEAST THROUGH
EASTERN WASHINGTON TODAY WITH NORTHERLY FLOW ALOFT OVER WESTERN
WASHINGTON. AT THE SURFACE LIGHT TO MODERATE ONSHORE FLOW WILL
CONTINUE. AIR MASS IS MOIST WITH MID LEVEL MOISTURE AND ALSO MARINE
STRATUS OVER WESTERN SECTIONS AND IN THE STRAIT. A CLEARING TREND
WILL BEGIN WEDNESDAY AFTERNOON.

KSEA...DISCUSSION ABOVE APPLIES. VFR CONDITIONS ARE LIKELY TODAY
WITH CEILINGS ABOVE 5K FT. THERE IS A CHANCE MARINE STRATUS WILL
REACH THE TERMINAL FOR A FEW HOURS THIS MORNING AND WILL COVER THAT
WITH A TEMPO GROUP IN THE TAF. CLEARING TREND IN THE AFTERNOON.
LIGHT SOUTHERLY WIND WILL BECOME NORTHWEST IN THE AFTERNOON. CHB

&&

.MARINE...HIGH PRESSURE WILL REMAIN OFFSHORE WITH LOWER PRESSURE
INLAND THROUGH THE WEEK. CURRENTLY MODELS KEEP WINDS BELOW 20 KT
TODAY AND THURSDAY IN THE STRAIT. ONSHORE GRADIENTS INCREASE FRIDAY
AFTERNOON AND EVENING FOR POSSIBLE SMALL CRAFT ADVISORY STRENGTH
WEST WINDS IN THE STRAIT.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY IN EFFECT TIL 5 AM THIS MORNING FOR
     THE CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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






000
FXUS66 KSEW 270358
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
900 PM PDT TUE MAY 26 2015

.SYNOPSIS...LOW LEVEL ONSHORE FLOW WILL WEAKEN OVER THE NEXT FEW
DAYS WITH WARMER AND SUNNIER WEATHER AS THE WEEK PROGRESSES. AN
UPPER TROUGH COULD BRING SOME SHOWERS AND COOLING EARLY NEXT WEEK.

&&

.SHORT TERM...AN UPPER LEVEL LOW IS SPINNING ALONG THE WA/ID BORDER
THIS EVENING. MOISTURE WRAPPING AROUND THE LOW IS MAINLY AFFECTING
EASTERN WA ALTHOUGH A FEW SHOWERS ARE POSSIBLE OVER THE CASCADES.
THE UPPER LOW WILL WEAKEN ON WEDNESDAY AS IT SHIFTS SE INTO CENTRAL
ID. MEANWHILE...WESTERN WA IS STILL UNDER THE INFLUENCE OF LOW LEVEL
ONSHORE FLOW WITH STRATUS CLOUDS ACROSS THE LOWLANDS. HOWEVER...IT
LOOKS LIKE WE WILL SEE MORE SUNBREAKS WEDNESDAY AFTERNOON AS A RIDGE
MOVES IN FROM THE WEST. TEMPS WILL BE A FEW DEGREES WARMER IN THE
INTERIOR WITH HIGHS IN THE LOWER TO MID 70S. MODELS CONTINUE TO SHOW
SOME MOISTURE AND INSTABILITY OVER THE CASCADES FOR ISOLATED
AFTERNOON AND EVENING SHOWERS...WITH A CHANCE OF THUNDERSTORMS NEAR
THE CREST. ONSHORE FLOW WILL BE WEAKER THURSDAY AND FRIDAY FOR LESS
CLOUD COVER AND WARMER WEATHER. 33

.LONG TERM...PREVIOUS DISCUSSION...UPPER HEIGHTS WILL SLOWLY LOWER
OVER THE AREA SATURDAY AND SUNDAY WITH A BIT OF AN INCREASE IN LOW
LEVEL ONSHORE FLOW. THIS WILL CAUSE HIGHS TO COOL SLIGHTLY BUT
TEMPERATURES WILL REMAIN ABOVE NORMAL.

AN UPPER LOW OFFSHORE NORTHERN CALIFORNIA WILL MOVE TO THE WEST
COAST MONDAY. NOT SURPRISINGLY...THE MODELS ARE NOT IN VERY GOOD
AGREEMENT WITH HOW THIS WILL UNFOLD. THE GENERAL IDEA IS THAT
MOISTURE COMING UP FROM THE SOUTH WILL START TO IMPACT WESTERN
WASHINGTON MONDAY AS THE UPPER LOW NEARS FOR A CHANCE OF SHOWERS.
THE UPPER LOW WILL REMAIN IN THE VICINITY FOR A CONTINUED CHANCE OF
SHOWERS TUESDAY. HIGHS WILL COOL TO NEAR NORMAL BY TUESDAY AS CLOUDS
AND ONSHORE FLOW INCREASE. SCHNEIDER

&&

.AVIATION...AN UPPER LEVEL LOW WILL MOVE SLOWLY SOUTHEAST THROUGH
EASTERN WASHINGTON TONIGHT AND WEDNESDAY WITH NORTHERLY FLOW ALOFT
OVER WESTERN WASHINGTON. MODERATE ONSHORE FLOW AT THE SURFACE WILL
EASE OVERNIGHT. AIR MASS IS MOIST WITH MAINLY MID LEVEL MOISTURE AND
IS SLIGHTLY UNSTABLE. MARINE STRATUS IS LIKELY TO RETURN TO AT LEAST
SOME AREAS BY MORNING WITH MVFR CEILINGS. A CLEARING TREND WILL
BEGIN WEDNESDAY AFTERNOON.

KSEA...DISCUSSION ABOVE APPLIES. CEILINGS 6-9K FT WILL PERSIST THIS
EVENING. ONSHORE FLOW DOES NOT SEEM STRONG ENOUGH TO BRING STRATUS
INLAND TO THE TERMINAL FROM THE COAST. BEST GUESS IS CONTINUED VFR
WITH CEILINGS PERHAPS GETTING AS LOW AS 4K FT. LIGHT NORTHWEST WIND
WILL BECOME SOUTHERLY OVERNIGHT. CHB

&&

.MARINE...HIGH PRESSURE WILL REMAIN OFFSHORE WITH LOWER PRESSURE
INLAND THROUGH THE WEEK. SMALL CRAFT ADVISORY STRENGTH WEST WINDS OF
15 TO 25 KT WILL CONTINUE TONIGHT THEN EASE BY MORNING. CURRENTLY
MODELS KEEP WINDS BELOW 20 KT FOR THE REST OF THE WEEK IN THE
STRAIT. CHB

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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







000
FXUS66 KSEW 270358
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
900 PM PDT TUE MAY 26 2015

.SYNOPSIS...LOW LEVEL ONSHORE FLOW WILL WEAKEN OVER THE NEXT FEW
DAYS WITH WARMER AND SUNNIER WEATHER AS THE WEEK PROGRESSES. AN
UPPER TROUGH COULD BRING SOME SHOWERS AND COOLING EARLY NEXT WEEK.

&&

.SHORT TERM...AN UPPER LEVEL LOW IS SPINNING ALONG THE WA/ID BORDER
THIS EVENING. MOISTURE WRAPPING AROUND THE LOW IS MAINLY AFFECTING
EASTERN WA ALTHOUGH A FEW SHOWERS ARE POSSIBLE OVER THE CASCADES.
THE UPPER LOW WILL WEAKEN ON WEDNESDAY AS IT SHIFTS SE INTO CENTRAL
ID. MEANWHILE...WESTERN WA IS STILL UNDER THE INFLUENCE OF LOW LEVEL
ONSHORE FLOW WITH STRATUS CLOUDS ACROSS THE LOWLANDS. HOWEVER...IT
LOOKS LIKE WE WILL SEE MORE SUNBREAKS WEDNESDAY AFTERNOON AS A RIDGE
MOVES IN FROM THE WEST. TEMPS WILL BE A FEW DEGREES WARMER IN THE
INTERIOR WITH HIGHS IN THE LOWER TO MID 70S. MODELS CONTINUE TO SHOW
SOME MOISTURE AND INSTABILITY OVER THE CASCADES FOR ISOLATED
AFTERNOON AND EVENING SHOWERS...WITH A CHANCE OF THUNDERSTORMS NEAR
THE CREST. ONSHORE FLOW WILL BE WEAKER THURSDAY AND FRIDAY FOR LESS
CLOUD COVER AND WARMER WEATHER. 33

.LONG TERM...PREVIOUS DISCUSSION...UPPER HEIGHTS WILL SLOWLY LOWER
OVER THE AREA SATURDAY AND SUNDAY WITH A BIT OF AN INCREASE IN LOW
LEVEL ONSHORE FLOW. THIS WILL CAUSE HIGHS TO COOL SLIGHTLY BUT
TEMPERATURES WILL REMAIN ABOVE NORMAL.

AN UPPER LOW OFFSHORE NORTHERN CALIFORNIA WILL MOVE TO THE WEST
COAST MONDAY. NOT SURPRISINGLY...THE MODELS ARE NOT IN VERY GOOD
AGREEMENT WITH HOW THIS WILL UNFOLD. THE GENERAL IDEA IS THAT
MOISTURE COMING UP FROM THE SOUTH WILL START TO IMPACT WESTERN
WASHINGTON MONDAY AS THE UPPER LOW NEARS FOR A CHANCE OF SHOWERS.
THE UPPER LOW WILL REMAIN IN THE VICINITY FOR A CONTINUED CHANCE OF
SHOWERS TUESDAY. HIGHS WILL COOL TO NEAR NORMAL BY TUESDAY AS CLOUDS
AND ONSHORE FLOW INCREASE. SCHNEIDER

&&

.AVIATION...AN UPPER LEVEL LOW WILL MOVE SLOWLY SOUTHEAST THROUGH
EASTERN WASHINGTON TONIGHT AND WEDNESDAY WITH NORTHERLY FLOW ALOFT
OVER WESTERN WASHINGTON. MODERATE ONSHORE FLOW AT THE SURFACE WILL
EASE OVERNIGHT. AIR MASS IS MOIST WITH MAINLY MID LEVEL MOISTURE AND
IS SLIGHTLY UNSTABLE. MARINE STRATUS IS LIKELY TO RETURN TO AT LEAST
SOME AREAS BY MORNING WITH MVFR CEILINGS. A CLEARING TREND WILL
BEGIN WEDNESDAY AFTERNOON.

KSEA...DISCUSSION ABOVE APPLIES. CEILINGS 6-9K FT WILL PERSIST THIS
EVENING. ONSHORE FLOW DOES NOT SEEM STRONG ENOUGH TO BRING STRATUS
INLAND TO THE TERMINAL FROM THE COAST. BEST GUESS IS CONTINUED VFR
WITH CEILINGS PERHAPS GETTING AS LOW AS 4K FT. LIGHT NORTHWEST WIND
WILL BECOME SOUTHERLY OVERNIGHT. CHB

&&

.MARINE...HIGH PRESSURE WILL REMAIN OFFSHORE WITH LOWER PRESSURE
INLAND THROUGH THE WEEK. SMALL CRAFT ADVISORY STRENGTH WEST WINDS OF
15 TO 25 KT WILL CONTINUE TONIGHT THEN EASE BY MORNING. CURRENTLY
MODELS KEEP WINDS BELOW 20 KT FOR THE REST OF THE WEEK IN THE
STRAIT. CHB

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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






000
FXUS66 KSEW 262127
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
230 PM PDT TUE MAY 26 2015

.SYNOPSIS...LOW LEVEL ONSHORE FLOW WILL WEAKEN OVER THE NEXT FEW
DAYS WITH WARMER AND SUNNIER WEATHER AS THE WEEK PROGRESSES. AN
UPPER TROUGH COULD BRING SOME SHOWERS AND COOLING EARLY NEXT WEEK.

&&

.SHORT TERM...AN UPPER LOW OVER EASTERN WASHINGTON WILL SHIFT INLAND
OVER THE NEXT FEW DAYS WITH WEAK HIGH PRESSURE ALOFT BUILDING OVER
WESTERN WASHINGTON. THERE WILL BE A THREAT OF AFTERNOON AND EVENING
SHOWERS OVER THE CASCADES EACH DAY WHERE THE AIR IS MOST UNSTABLE.

OTHERWISE...LOW LEVEL ONSHORE FLOW WILL CONTINUE...BUT IT WILL
WEAKEN A LITTLE EACH DAY. PARTLY CLOUDY SKIES SHOULD BECOME MOSTLY
CLOUDY AGAIN TONIGHT...THEN BECOME PARTLY TO MOSTLY SUNNY WEDNESDAY
AS THE LOW LEVELS DRY. HIGHS WILL WARM SEVERAL DEGREES.

WEDNESDAY AND THURSDAY SHOULD BE SIMILAR BUT WITH A LITTLE LESS LOW
CLOUDS THURSDAY MORNING AND MORE SUNSHINE DURING THE DAY. HIGHS WILL
NUDGE UP A FEW MORE DEGREES. FRIDAY SHOULD BE MOSTLY SUNNY WITH JUST
A FEW MORNING CLOUDS AND HIGHS ONCE AGAIN IN THE 70S TO LOWER 80S.
SCHNEIDER

.LONG TERM...UPPER HEIGHTS WILL SLOWLY LOWER OVER THE AREA SATURDAY
AND SUNDAY WITH A BIT OF AN INCREASE IN LOW LEVEL ONSHORE FLOW. THIS
WILL CAUSE HIGHS TO COOL SLIGHTLY BUT TEMPERATURES WILL REMAIN ABOVE
NORMAL.

AN UPPER LOW OFFSHORE NORTHERN CALIFORNIA WILL MOVE TO THE WEST
COAST MONDAY. NOT SURPRISINGLY...THE MODELS ARE NOT IN VERY GOOD
AGREEMENT WITH HOW THIS WILL UNFOLD. THE GENERAL IDEA IS THAT
MOISTURE COMING UP FROM THE SOUTH WILL START TO IMPACT WESTERN
WASHINGTON MONDAY AS THE UPPER LOW NEARS FOR A CHANCE OF SHOWERS.
THE UPPER LOW WILL REMAIN IN THE VICINITY FOR A CONTINUED CHANCE OF
SHOWERS TUESDAY. HIGHS WILL COOL TO NEAR NORMAL BY TUESDAY AS CLOUDS
AND ONSHORE FLOW INCREASE. SCHNEIDER

&&

.AVIATION...AN UPPER LEVEL LOW WILL REMAIN OVER EASTERN WASHINGTON
TONIGHT WITH NORTHERLY FLOW ALOFT OVER WESTERN WASHINGTON. FOR THE
MOST PART THE AREAS OF MORNING LOW CLOUDS BURNED OFF OR LIFTED. SOME
MID LEVEL MOISTURE IS DRIFTING SOUTH FROM B.C. IN THE NLY FLOW
ALOFT. AREAS OF LOW CLOUDS WILL DEVELOP AGAIN OVERNIGHT.

KSEA...LOOKS LIKE A MIX OF SUNSHINE AND CLOUDS...SOME CUMULUS AND A
FEW HIGHER CLOUDS THIS AFTERNOON. SOME MID LEVEL CLOUDS OUGHT TO
DRIFT DOWN FROM B.C...THEN LOW CLOUDS ARE LIKELY TO FORM AGAIN LATE
TONIGHT.

&&

.MARINE...HIGH PRESSURE WILL REMAIN OFFSHORE WITH LOWER PRESSURE
INLAND THROUGH THE WEEK. SMALL CRAFT ADVISORY STRENGTH WEST WINDS OF
15 TO 25 KT WILL DEVELOP IN THE STRAIT OF JUAN DE FUCA LATE THIS
AFTERNOON OR EVENING.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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
















000
FXUS66 KSEW 261533
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
830 AM PDT TUE MAY 26 2015

.SYNOPSIS...LOW LEVEL ONSHORE FLOW WILL WEAKEN THIS WEEK WITH WARMER
AND SUNNIER WEATHER AS THE WEEK PROGRESSES. A WEAK UPPER LOW COULD
BRING SOME SHOWERS AND COOLING EARLY NEXT WEEK.

&&

.SHORT TERM...AN UPPER LOW OVER EASTERN WASHINGTON WILL SHIFT INLAND
OVER THE NEXT FEW DAYS WITH WEAK HIGH PRESSURE ALOFT BUILDING OVER
WESTERN WASHINGTON. THERE IS A THREAT OF AFTERNOON AND EVENING
SHOWERS OVER THE CASCADES THROUGH THURSDAY WHERE THE AIR IS MOST
UNSTABLE AND WITH POSSIBLE WRAP AROUND MOISTURE FROM THE UPPER LOW.

ELSEWHERE...LOW LEVEL ONSHORE FLOW WILL CONTINUE...BUT IT WILL
WEAKEN A LITTLE EACH DAY. SKIES ARE CURRENTLY FAIRLY CLOUDY ALTHOUGH
THERE IS A GOOD HOLE IN THE CLOUDS OVER THE SOUTHWEST INTERIOR.
LOOKING OUT THE WINDOW...THERE IS ALREADY SOME BLUE POKING THROUGH
THE CLOUDS. THE NEWEST GFS CROSS SECTION FORECAST SUGGESTS CLOUDS
WILL THIN AND BREAK UP THIS AFTERNOON. THE FORECAST HAS ALREADY BEEN
UPDATED TO REFLECT A LITTLE MORE SUNSHINE TODAY.

IT LOOK LIKE A GOOD BET THAT WEDNESDAY AND THURSDAY WILL SEE
SUNSHINE AFTER SOME MORNING LOW CLOUDS AS LOW LEVEL ONSHORE FLOW
WEAKENS AND THE LOW LEVELS DRY. HIGHS SHOULD WARM INTO THE 70S BOTH
DAYS. SCHNEIDER

.LONG TERM...PREVIOUS DISCUSSION...EXTENDED MODELS IN GOOD AGREEMENT
ON FRIDAY WITH AN UPPER LEVEL LOW MOVING SOUTH DOWN THE BRITISH
COLUMBIA COAST BUT STILL FAR ENOUGH NORTH TO NOT BRING ANY WEATHER
TO WESTERN WASHINGTON. LIGHT ONSHORE FLOW CONTINUING AT THE LOWER
LEVELS WITH THE TEMPERATURES ALOFT CONTINUING TO WARM SLIGHTLY.
FRIDAY LOOKS TO BE THE WARMEST DAY IN THE FORECAST PERIOD WITH HIGHS
IN THE 70S TO LOWER 80S. MODELS CONTINUE TO BE IN GOOD AGREEMENT ON
SATURDAY WITH THE ECMWF NOW MORE IN LINE WITH THE GFS SOLUTION OF
MOVING THE LOW OFF TO THE EAST OVER CENTRAL BRITISH COLUMBIA.
ANOTHER SUNNY DAY FORECAST BUT WITH A LITTLE INCREASE IN THE LOW
LEVEL ONSHORE FLOW MAX TEMPERATURES A COUPLE OF DEGREES COOLER THAN
FRIDAY. ONSHORE FLOW CONTINUES TO INCREASE ON SUNDAY WITH AN UPPER
LEVEL TROUGH DIGGING OFFSHORE AND THE UPPER LEVEL LOW CONTINUING TO
MOVE EAST. TEMPERATURES ALOFT BEGIN TO COOL AS THE UPPER LEVEL
TROUGH OFFSHORE APPROACHES WITH 500 MB HEIGHTS LOWERING FROM THE MID
TO UPPER 570 DMS DOWN TO NEAR 570 DMS. THIS WILL KEEP THE COOLING
TREND GOING OVER WESTERN WASHINGTON WITH HIGHS IN THE UPPER 60S TO
MID 70S. TROUGH SWINGING INLAND ON MONDAY CONTINUING THE COOLING
TREND AND ADDING A CHANCE OF SHOWERS TO THE FORECAST. FELTON

&&

.AVIATION...AN UPPER LEVEL LOW WILL REMAIN OVER EASTERN WASHINGTON
TODAY WITH NORTHERLY FLOW ALOFT OVER WESTERN WASHINGTON. THERE ARE
AREAS OF LOW CLOUDS THAT SHOULD BURN OFF FOR THE AFTERNOON. SOME MID
LEVEL MOISTURE WILL PROBABLY COME DOWN FROM B.C. IN THE NLY FLOW
LATER THIS AFTERNOON AND EVENING. AREAS OF LOW CLOUDS WILL DEVELOP
AGAIN OVERNIGHT.

KSEA...THE LOW CLOUDS SHOULD BURN OFF AND THEN LATER TODAY SOME MID
LEVEL CLOUDS OUGHT TO DRIFT DOWN FROM B.C...THEN LOW CLOUDS AGAIN
LATE TONIGHT.

&&

.MARINE...HIGH PRESSURE WILL REMAIN OFFSHORE WITH LOWER PRESSURE
INLAND THROUGH THE WEEK. SMALL CRAFT ADVISORY STRENGTH WEST WINDS OF
15 TO 25 KT WILL DEVELOP IN THE STRAIT OF JUAN DE FUCA LATE THIS
AFTERNOON OR EVENING.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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












000
FXUS66 KSEW 261533
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
830 AM PDT TUE MAY 26 2015

.SYNOPSIS...LOW LEVEL ONSHORE FLOW WILL WEAKEN THIS WEEK WITH WARMER
AND SUNNIER WEATHER AS THE WEEK PROGRESSES. A WEAK UPPER LOW COULD
BRING SOME SHOWERS AND COOLING EARLY NEXT WEEK.

&&

.SHORT TERM...AN UPPER LOW OVER EASTERN WASHINGTON WILL SHIFT INLAND
OVER THE NEXT FEW DAYS WITH WEAK HIGH PRESSURE ALOFT BUILDING OVER
WESTERN WASHINGTON. THERE IS A THREAT OF AFTERNOON AND EVENING
SHOWERS OVER THE CASCADES THROUGH THURSDAY WHERE THE AIR IS MOST
UNSTABLE AND WITH POSSIBLE WRAP AROUND MOISTURE FROM THE UPPER LOW.

ELSEWHERE...LOW LEVEL ONSHORE FLOW WILL CONTINUE...BUT IT WILL
WEAKEN A LITTLE EACH DAY. SKIES ARE CURRENTLY FAIRLY CLOUDY ALTHOUGH
THERE IS A GOOD HOLE IN THE CLOUDS OVER THE SOUTHWEST INTERIOR.
LOOKING OUT THE WINDOW...THERE IS ALREADY SOME BLUE POKING THROUGH
THE CLOUDS. THE NEWEST GFS CROSS SECTION FORECAST SUGGESTS CLOUDS
WILL THIN AND BREAK UP THIS AFTERNOON. THE FORECAST HAS ALREADY BEEN
UPDATED TO REFLECT A LITTLE MORE SUNSHINE TODAY.

IT LOOK LIKE A GOOD BET THAT WEDNESDAY AND THURSDAY WILL SEE
SUNSHINE AFTER SOME MORNING LOW CLOUDS AS LOW LEVEL ONSHORE FLOW
WEAKENS AND THE LOW LEVELS DRY. HIGHS SHOULD WARM INTO THE 70S BOTH
DAYS. SCHNEIDER

.LONG TERM...PREVIOUS DISCUSSION...EXTENDED MODELS IN GOOD AGREEMENT
ON FRIDAY WITH AN UPPER LEVEL LOW MOVING SOUTH DOWN THE BRITISH
COLUMBIA COAST BUT STILL FAR ENOUGH NORTH TO NOT BRING ANY WEATHER
TO WESTERN WASHINGTON. LIGHT ONSHORE FLOW CONTINUING AT THE LOWER
LEVELS WITH THE TEMPERATURES ALOFT CONTINUING TO WARM SLIGHTLY.
FRIDAY LOOKS TO BE THE WARMEST DAY IN THE FORECAST PERIOD WITH HIGHS
IN THE 70S TO LOWER 80S. MODELS CONTINUE TO BE IN GOOD AGREEMENT ON
SATURDAY WITH THE ECMWF NOW MORE IN LINE WITH THE GFS SOLUTION OF
MOVING THE LOW OFF TO THE EAST OVER CENTRAL BRITISH COLUMBIA.
ANOTHER SUNNY DAY FORECAST BUT WITH A LITTLE INCREASE IN THE LOW
LEVEL ONSHORE FLOW MAX TEMPERATURES A COUPLE OF DEGREES COOLER THAN
FRIDAY. ONSHORE FLOW CONTINUES TO INCREASE ON SUNDAY WITH AN UPPER
LEVEL TROUGH DIGGING OFFSHORE AND THE UPPER LEVEL LOW CONTINUING TO
MOVE EAST. TEMPERATURES ALOFT BEGIN TO COOL AS THE UPPER LEVEL
TROUGH OFFSHORE APPROACHES WITH 500 MB HEIGHTS LOWERING FROM THE MID
TO UPPER 570 DMS DOWN TO NEAR 570 DMS. THIS WILL KEEP THE COOLING
TREND GOING OVER WESTERN WASHINGTON WITH HIGHS IN THE UPPER 60S TO
MID 70S. TROUGH SWINGING INLAND ON MONDAY CONTINUING THE COOLING
TREND AND ADDING A CHANCE OF SHOWERS TO THE FORECAST. FELTON

&&

.AVIATION...AN UPPER LEVEL LOW WILL REMAIN OVER EASTERN WASHINGTON
TODAY WITH NORTHERLY FLOW ALOFT OVER WESTERN WASHINGTON. THERE ARE
AREAS OF LOW CLOUDS THAT SHOULD BURN OFF FOR THE AFTERNOON. SOME MID
LEVEL MOISTURE WILL PROBABLY COME DOWN FROM B.C. IN THE NLY FLOW
LATER THIS AFTERNOON AND EVENING. AREAS OF LOW CLOUDS WILL DEVELOP
AGAIN OVERNIGHT.

KSEA...THE LOW CLOUDS SHOULD BURN OFF AND THEN LATER TODAY SOME MID
LEVEL CLOUDS OUGHT TO DRIFT DOWN FROM B.C...THEN LOW CLOUDS AGAIN
LATE TONIGHT.

&&

.MARINE...HIGH PRESSURE WILL REMAIN OFFSHORE WITH LOWER PRESSURE
INLAND THROUGH THE WEEK. SMALL CRAFT ADVISORY STRENGTH WEST WINDS OF
15 TO 25 KT WILL DEVELOP IN THE STRAIT OF JUAN DE FUCA LATE THIS
AFTERNOON OR EVENING.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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












000
FXUS66 KSEW 261533
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
830 AM PDT TUE MAY 26 2015

.SYNOPSIS...LOW LEVEL ONSHORE FLOW WILL WEAKEN THIS WEEK WITH WARMER
AND SUNNIER WEATHER AS THE WEEK PROGRESSES. A WEAK UPPER LOW COULD
BRING SOME SHOWERS AND COOLING EARLY NEXT WEEK.

&&

.SHORT TERM...AN UPPER LOW OVER EASTERN WASHINGTON WILL SHIFT INLAND
OVER THE NEXT FEW DAYS WITH WEAK HIGH PRESSURE ALOFT BUILDING OVER
WESTERN WASHINGTON. THERE IS A THREAT OF AFTERNOON AND EVENING
SHOWERS OVER THE CASCADES THROUGH THURSDAY WHERE THE AIR IS MOST
UNSTABLE AND WITH POSSIBLE WRAP AROUND MOISTURE FROM THE UPPER LOW.

ELSEWHERE...LOW LEVEL ONSHORE FLOW WILL CONTINUE...BUT IT WILL
WEAKEN A LITTLE EACH DAY. SKIES ARE CURRENTLY FAIRLY CLOUDY ALTHOUGH
THERE IS A GOOD HOLE IN THE CLOUDS OVER THE SOUTHWEST INTERIOR.
LOOKING OUT THE WINDOW...THERE IS ALREADY SOME BLUE POKING THROUGH
THE CLOUDS. THE NEWEST GFS CROSS SECTION FORECAST SUGGESTS CLOUDS
WILL THIN AND BREAK UP THIS AFTERNOON. THE FORECAST HAS ALREADY BEEN
UPDATED TO REFLECT A LITTLE MORE SUNSHINE TODAY.

IT LOOK LIKE A GOOD BET THAT WEDNESDAY AND THURSDAY WILL SEE
SUNSHINE AFTER SOME MORNING LOW CLOUDS AS LOW LEVEL ONSHORE FLOW
WEAKENS AND THE LOW LEVELS DRY. HIGHS SHOULD WARM INTO THE 70S BOTH
DAYS. SCHNEIDER

.LONG TERM...PREVIOUS DISCUSSION...EXTENDED MODELS IN GOOD AGREEMENT
ON FRIDAY WITH AN UPPER LEVEL LOW MOVING SOUTH DOWN THE BRITISH
COLUMBIA COAST BUT STILL FAR ENOUGH NORTH TO NOT BRING ANY WEATHER
TO WESTERN WASHINGTON. LIGHT ONSHORE FLOW CONTINUING AT THE LOWER
LEVELS WITH THE TEMPERATURES ALOFT CONTINUING TO WARM SLIGHTLY.
FRIDAY LOOKS TO BE THE WARMEST DAY IN THE FORECAST PERIOD WITH HIGHS
IN THE 70S TO LOWER 80S. MODELS CONTINUE TO BE IN GOOD AGREEMENT ON
SATURDAY WITH THE ECMWF NOW MORE IN LINE WITH THE GFS SOLUTION OF
MOVING THE LOW OFF TO THE EAST OVER CENTRAL BRITISH COLUMBIA.
ANOTHER SUNNY DAY FORECAST BUT WITH A LITTLE INCREASE IN THE LOW
LEVEL ONSHORE FLOW MAX TEMPERATURES A COUPLE OF DEGREES COOLER THAN
FRIDAY. ONSHORE FLOW CONTINUES TO INCREASE ON SUNDAY WITH AN UPPER
LEVEL TROUGH DIGGING OFFSHORE AND THE UPPER LEVEL LOW CONTINUING TO
MOVE EAST. TEMPERATURES ALOFT BEGIN TO COOL AS THE UPPER LEVEL
TROUGH OFFSHORE APPROACHES WITH 500 MB HEIGHTS LOWERING FROM THE MID
TO UPPER 570 DMS DOWN TO NEAR 570 DMS. THIS WILL KEEP THE COOLING
TREND GOING OVER WESTERN WASHINGTON WITH HIGHS IN THE UPPER 60S TO
MID 70S. TROUGH SWINGING INLAND ON MONDAY CONTINUING THE COOLING
TREND AND ADDING A CHANCE OF SHOWERS TO THE FORECAST. FELTON

&&

.AVIATION...AN UPPER LEVEL LOW WILL REMAIN OVER EASTERN WASHINGTON
TODAY WITH NORTHERLY FLOW ALOFT OVER WESTERN WASHINGTON. THERE ARE
AREAS OF LOW CLOUDS THAT SHOULD BURN OFF FOR THE AFTERNOON. SOME MID
LEVEL MOISTURE WILL PROBABLY COME DOWN FROM B.C. IN THE NLY FLOW
LATER THIS AFTERNOON AND EVENING. AREAS OF LOW CLOUDS WILL DEVELOP
AGAIN OVERNIGHT.

KSEA...THE LOW CLOUDS SHOULD BURN OFF AND THEN LATER TODAY SOME MID
LEVEL CLOUDS OUGHT TO DRIFT DOWN FROM B.C...THEN LOW CLOUDS AGAIN
LATE TONIGHT.

&&

.MARINE...HIGH PRESSURE WILL REMAIN OFFSHORE WITH LOWER PRESSURE
INLAND THROUGH THE WEEK. SMALL CRAFT ADVISORY STRENGTH WEST WINDS OF
15 TO 25 KT WILL DEVELOP IN THE STRAIT OF JUAN DE FUCA LATE THIS
AFTERNOON OR EVENING.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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













000
FXUS66 KSEW 261057
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
355 AM PDT TUE MAY 26 2015

.SYNOPSIS...A SURFACE RIDGE OFFSHORE WILL MAINTAIN LOW LEVEL ONSHORE
FLOW ACROSS WESTERN WASHINGTON THIS WEEK. MODERATE ONSHORE FLOW WILL
KEEP SKIES CLOUDY TODAY BUT WEAKER ONSHORE FLOW FROM MID WEEK ONWARD
ALONG WITH HIGHER PRESSURE ALOFT BUILDING OVER THE REGION WILL ALLOW
MORE AFTERNOON SUNSHINE AND A WARMING TREND. THE AIR MASS OVER THE
CASCADES WILL CONTINUE TO BECOME SLIGHTLY UNSTABLE LATE IN THE DAY
FOR A CHANCE OF SHOWERS NEAR THE CREST.

&&

.SHORT TERM...SATELLITE IMAGERY SHOWS UPPER LEVEL LOW HAS REMAINED
OVER NORTHEAST WASHINGTON EARLY THIS MORNING. OVER WESTERN
WASHINGTON SKIES WERE ONCE AGAIN CLOUDY THIS MORNING. TEMPERATURES
AT 3 AM WERE IN THE LOWER TO MID 50S.

UPPER LEVEL LOW DRIFTING SOUTH TODAY BUT REMAINING OVER EASTERN
WASHINGTON. RETURN FLOW AROUND THE LOW WILL KEEP A CHANCE OF SHOWERS
IN THE CASCADES. ONSHORE FLOW CONTINUING OVER WESTERN WASHINGTON
TODAY BUT STARTING TO SEE SIGNS THE MARINE LAYER IS BEGINNING TO
THIN OUT OVER THE AREA. CEILINGS OVER THE NORTH INTERIOR HAVE NOT
LOWERED DOWN TO LESS THAN 1000 FEET THIS MORNING. INSTEAD CEILINGS
ARE ABOVE 5000 FEET MAKING THE MARINE LAYER FAIRLY SHALLOW AND
EASIER TO BURN OFF. WITH SOME BREAKS IN THE NORTH INTERIOR THIS
AFTERNOON THIS WILL HELP ERODE THE MARINE LAYER OVER THE NORTH
CENTRAL PORTION OF THE PUGET SOUND. EVEN WITH THIS THE WINDS AT THE
LOWER LEVELS ARE LIGHT SO THERE WILL NOT BE A LOT OF MIXING. WILL GO
WITH CLOUDY WORDING ONCE AGAIN FOR MOST OF THE INTERIOR TODAY WITH
SOME AFTERNOON SUNSHINE OVER THE NORTH INTERIOR. WITH THE CLOUD
COVER WILL UNDERCUT THE MOS TEMPS BY A FEW DEGREES PUTTING HIGHS IN
THE UPPER 50S TO MID 60S.

UPPER LEVEL LOW SLOWLY MOVING SOUTHEAST TONIGHT INTO WEDNESDAY. THE
LOW WILL BE FAR ENOUGH TO THE EAST TO RETURN THE CASCADES TO THE
AFTERNOON AND EVENING CHANCE OF SHOWERS FORECAST. FOR THE LOWLANDS
LIGHT ONSHORE FLOW CONTINUING. MODEL CROSS SECTIONS SHOW THE MARINE
LAYER REALLY THINNING OUT OVER WESTERN WASHINGTON WEDNESDAY
AFTERNOON ALONG WITH SOME WARMING ALOFT...850 MB TEMPERATURES GO
FROM AROUND PLUS 8 TO PLUS 12C BY 00Z THURSDAY. ON THE OTHER SIDE OF
THE STORY WINDS REMAIN LIGHT IN THE LOWER LEVELS AND THE FLOW
REMAINS LIGHT ONSHORE. WILL STAY WITH THE IDEA OF A LITTLE SUNSHINE
WEDNESDAY AFTERNOON FOR THE INTERIOR BUT WILL CONTINUE TO UNDERCUT
MOS MAX TEMPS BY A COUPLE OF DEGREES PUTTING HIGHS IN THE 60S AND
LOWER 70S.

UPPER LEVEL RIDGE OFFSHORE BUILDING INTO THE AREA WEDNESDAY NIGHT
AND THURSDAY. AT THE LOWER LEVEL LIGHT ONSHORE FLOW CONTINUES. WITH
THE THINNING OF THE MARINE LAYER WEDNESDAY AND SOME SUBSIDENCE FROM
THE RIDGING EXPECT THE MARINE LAYER TO BURN BACK TO THE COAST BY
THURSDAY AFTERNOON LEAVING THE INTERIOR WITH SUNNY SKIES. MODELS
CONTINUING THE WARMING TREND ALOFT WITH 850 MB TEMPERATURES AROUND
PLUS 14C. HIGHS IN THE 70S WILL BE COMMON FOR THE INTERIOR WITH THE
WARMEST LOCATIONS PUSH 80 DEGREES.

.LONG TERM...EXTENDED MODELS IN GOOD AGREEMENT ON FRIDAY WITH AN
UPPER LEVEL LOW MOVING SOUTH DOWN THE BRITISH COLUMBIA COAST BUT
STILL FAR ENOUGH NORTH TO NOT BRING ANY WEATHER TO WESTERN
WASHINGTON. LIGHT ONSHORE FLOW CONTINUING AT THE LOWER LEVELS WITH
THE TEMPERATURES ALOFT CONTINUING TO WARM SLIGHTLY. FRIDAY LOOKS TO
BE THE WARMEST DAY IN THE FORECAST PERIOD WITH HIGHS IN THE 70S TO
LOWER 80S. MODELS CONTINUE TO BE IN GOOD AGREEMENT ON SATURDAY WITH
THE ECMWF NOW MORE IN LINE WITH THE GFS SOLUTION OF MOVING THE LOW
OFF TO THE EAST OVER CENTRAL BRITISH COLUMBIA. ANOTHER SUNNY DAY
FORECAST BUT WITH A LITTLE INCREASE IN THE LOW LEVEL ONSHORE FLOW
MAX TEMPERATURES A COUPLE OF DEGREES COOLER THAN FRIDAY. ONSHORE
FLOW CONTINUES TO INCREASE ON SUNDAY WITH AN UPPER LEVEL TROUGH
DIGGING OFFSHORE AND THE UPPER LEVEL LOW CONTINUING TO MOVE EAST.
TEMPERATURES ALOFT BEGIN TO COOL AS THE UPPER LEVEL TROUGH OFFSHORE
APPROACHES WITH 500 MB HEIGHTS LOWERING FROM THE MID TO UPPER 570
DMS DOWN TO NEAR 570 DMS. THIS WILL KEEP THE COOLING TREND GOING
OVER WESTERN WASHINGTON WITH HIGHS IN THE UPPER 60S TO MID 70S.
TROUGH SWINGING INLAND ON MONDAY CONTINUING THE COOLING TREND AND
ADDING A CHANCE OF SHOWERS TO THE FORECAST. FELTON

&&

.AVIATION...AN UPPER LEVEL LOW WILL REMAIN OVER EASTERN WASHINGTON
TODAY WITH NORTHERLY FLOW ALOFT OVER WESTERN WASHINGTON. MODERATE
ONSHORE FLOW AT THE SURFACE WILL KEEP THE AIR MASS MOIST IN THE
LOWER LEVELS. AIR MASS IS STABLE EXCEPT SLIGHTLY UNSTABLE OVER THE
CASCADES. MVFR CEILINGS THIS MORNING WILL LIFT INTO VFR THIS
AFTERNOON WITH SOME SUN BREAKS POSSIBLE.

KSEA...DISCUSSION ABOVE APPLIES. THERE IS A REASONABLY GOOD CHANCE
THAT CEILINGS WILL RISE ABOVE 5K FT LATE THIS AFTERNOON. SOUTHERLY
WINDS 3-7 KT THIS MORNING WILL TURN NORTHWEST IN THE AFTERNOON. CHB

&&

.MARINE...HIGH PRES WILL REMAIN OFFSHORE WITH LOWER PRES INLAND ALL
WEEK LONG. SMALL CRAFT ADVISORY STRENGTH WINDS OF 15 TO 25 KT WILL
OCCUR IN THE STRAIT TONIGHT. LATEST MODEL RUNS SHOW WEAKER ONSHORE
GRADIENTS AFTER TONIGHT SO HAVE LIMITED WINDS TO 20 KT IN THE STRAIT
FROM WEDNESDAY EVENING INTO THE WEEKEND. CHB

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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










000
FXUS66 KSEW 261057
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
355 AM PDT TUE MAY 26 2015

.SYNOPSIS...A SURFACE RIDGE OFFSHORE WILL MAINTAIN LOW LEVEL ONSHORE
FLOW ACROSS WESTERN WASHINGTON THIS WEEK. MODERATE ONSHORE FLOW WILL
KEEP SKIES CLOUDY TODAY BUT WEAKER ONSHORE FLOW FROM MID WEEK ONWARD
ALONG WITH HIGHER PRESSURE ALOFT BUILDING OVER THE REGION WILL ALLOW
MORE AFTERNOON SUNSHINE AND A WARMING TREND. THE AIR MASS OVER THE
CASCADES WILL CONTINUE TO BECOME SLIGHTLY UNSTABLE LATE IN THE DAY
FOR A CHANCE OF SHOWERS NEAR THE CREST.

&&

.SHORT TERM...SATELLITE IMAGERY SHOWS UPPER LEVEL LOW HAS REMAINED
OVER NORTHEAST WASHINGTON EARLY THIS MORNING. OVER WESTERN
WASHINGTON SKIES WERE ONCE AGAIN CLOUDY THIS MORNING. TEMPERATURES
AT 3 AM WERE IN THE LOWER TO MID 50S.

UPPER LEVEL LOW DRIFTING SOUTH TODAY BUT REMAINING OVER EASTERN
WASHINGTON. RETURN FLOW AROUND THE LOW WILL KEEP A CHANCE OF SHOWERS
IN THE CASCADES. ONSHORE FLOW CONTINUING OVER WESTERN WASHINGTON
TODAY BUT STARTING TO SEE SIGNS THE MARINE LAYER IS BEGINNING TO
THIN OUT OVER THE AREA. CEILINGS OVER THE NORTH INTERIOR HAVE NOT
LOWERED DOWN TO LESS THAN 1000 FEET THIS MORNING. INSTEAD CEILINGS
ARE ABOVE 5000 FEET MAKING THE MARINE LAYER FAIRLY SHALLOW AND
EASIER TO BURN OFF. WITH SOME BREAKS IN THE NORTH INTERIOR THIS
AFTERNOON THIS WILL HELP ERODE THE MARINE LAYER OVER THE NORTH
CENTRAL PORTION OF THE PUGET SOUND. EVEN WITH THIS THE WINDS AT THE
LOWER LEVELS ARE LIGHT SO THERE WILL NOT BE A LOT OF MIXING. WILL GO
WITH CLOUDY WORDING ONCE AGAIN FOR MOST OF THE INTERIOR TODAY WITH
SOME AFTERNOON SUNSHINE OVER THE NORTH INTERIOR. WITH THE CLOUD
COVER WILL UNDERCUT THE MOS TEMPS BY A FEW DEGREES PUTTING HIGHS IN
THE UPPER 50S TO MID 60S.

UPPER LEVEL LOW SLOWLY MOVING SOUTHEAST TONIGHT INTO WEDNESDAY. THE
LOW WILL BE FAR ENOUGH TO THE EAST TO RETURN THE CASCADES TO THE
AFTERNOON AND EVENING CHANCE OF SHOWERS FORECAST. FOR THE LOWLANDS
LIGHT ONSHORE FLOW CONTINUING. MODEL CROSS SECTIONS SHOW THE MARINE
LAYER REALLY THINNING OUT OVER WESTERN WASHINGTON WEDNESDAY
AFTERNOON ALONG WITH SOME WARMING ALOFT...850 MB TEMPERATURES GO
FROM AROUND PLUS 8 TO PLUS 12C BY 00Z THURSDAY. ON THE OTHER SIDE OF
THE STORY WINDS REMAIN LIGHT IN THE LOWER LEVELS AND THE FLOW
REMAINS LIGHT ONSHORE. WILL STAY WITH THE IDEA OF A LITTLE SUNSHINE
WEDNESDAY AFTERNOON FOR THE INTERIOR BUT WILL CONTINUE TO UNDERCUT
MOS MAX TEMPS BY A COUPLE OF DEGREES PUTTING HIGHS IN THE 60S AND
LOWER 70S.

UPPER LEVEL RIDGE OFFSHORE BUILDING INTO THE AREA WEDNESDAY NIGHT
AND THURSDAY. AT THE LOWER LEVEL LIGHT ONSHORE FLOW CONTINUES. WITH
THE THINNING OF THE MARINE LAYER WEDNESDAY AND SOME SUBSIDENCE FROM
THE RIDGING EXPECT THE MARINE LAYER TO BURN BACK TO THE COAST BY
THURSDAY AFTERNOON LEAVING THE INTERIOR WITH SUNNY SKIES. MODELS
CONTINUING THE WARMING TREND ALOFT WITH 850 MB TEMPERATURES AROUND
PLUS 14C. HIGHS IN THE 70S WILL BE COMMON FOR THE INTERIOR WITH THE
WARMEST LOCATIONS PUSH 80 DEGREES.

.LONG TERM...EXTENDED MODELS IN GOOD AGREEMENT ON FRIDAY WITH AN
UPPER LEVEL LOW MOVING SOUTH DOWN THE BRITISH COLUMBIA COAST BUT
STILL FAR ENOUGH NORTH TO NOT BRING ANY WEATHER TO WESTERN
WASHINGTON. LIGHT ONSHORE FLOW CONTINUING AT THE LOWER LEVELS WITH
THE TEMPERATURES ALOFT CONTINUING TO WARM SLIGHTLY. FRIDAY LOOKS TO
BE THE WARMEST DAY IN THE FORECAST PERIOD WITH HIGHS IN THE 70S TO
LOWER 80S. MODELS CONTINUE TO BE IN GOOD AGREEMENT ON SATURDAY WITH
THE ECMWF NOW MORE IN LINE WITH THE GFS SOLUTION OF MOVING THE LOW
OFF TO THE EAST OVER CENTRAL BRITISH COLUMBIA. ANOTHER SUNNY DAY
FORECAST BUT WITH A LITTLE INCREASE IN THE LOW LEVEL ONSHORE FLOW
MAX TEMPERATURES A COUPLE OF DEGREES COOLER THAN FRIDAY. ONSHORE
FLOW CONTINUES TO INCREASE ON SUNDAY WITH AN UPPER LEVEL TROUGH
DIGGING OFFSHORE AND THE UPPER LEVEL LOW CONTINUING TO MOVE EAST.
TEMPERATURES ALOFT BEGIN TO COOL AS THE UPPER LEVEL TROUGH OFFSHORE
APPROACHES WITH 500 MB HEIGHTS LOWERING FROM THE MID TO UPPER 570
DMS DOWN TO NEAR 570 DMS. THIS WILL KEEP THE COOLING TREND GOING
OVER WESTERN WASHINGTON WITH HIGHS IN THE UPPER 60S TO MID 70S.
TROUGH SWINGING INLAND ON MONDAY CONTINUING THE COOLING TREND AND
ADDING A CHANCE OF SHOWERS TO THE FORECAST. FELTON

&&

.AVIATION...AN UPPER LEVEL LOW WILL REMAIN OVER EASTERN WASHINGTON
TODAY WITH NORTHERLY FLOW ALOFT OVER WESTERN WASHINGTON. MODERATE
ONSHORE FLOW AT THE SURFACE WILL KEEP THE AIR MASS MOIST IN THE
LOWER LEVELS. AIR MASS IS STABLE EXCEPT SLIGHTLY UNSTABLE OVER THE
CASCADES. MVFR CEILINGS THIS MORNING WILL LIFT INTO VFR THIS
AFTERNOON WITH SOME SUN BREAKS POSSIBLE.

KSEA...DISCUSSION ABOVE APPLIES. THERE IS A REASONABLY GOOD CHANCE
THAT CEILINGS WILL RISE ABOVE 5K FT LATE THIS AFTERNOON. SOUTHERLY
WINDS 3-7 KT THIS MORNING WILL TURN NORTHWEST IN THE AFTERNOON. CHB

&&

.MARINE...HIGH PRES WILL REMAIN OFFSHORE WITH LOWER PRES INLAND ALL
WEEK LONG. SMALL CRAFT ADVISORY STRENGTH WINDS OF 15 TO 25 KT WILL
OCCUR IN THE STRAIT TONIGHT. LATEST MODEL RUNS SHOW WEAKER ONSHORE
GRADIENTS AFTER TONIGHT SO HAVE LIMITED WINDS TO 20 KT IN THE STRAIT
FROM WEDNESDAY EVENING INTO THE WEEKEND. CHB

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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









000
FXUS66 KSEW 260346
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
900 PM PDT MON MAY 25 2015

.SYNOPSIS...A SURFACE RIDGE OFFSHORE WILL MAINTAIN MOIST LOW LEVEL
ONSHORE FLOW ACROSS WESTERN WASHINGTON THIS WEEK. MODERATE ONSHORE
FLOW WILL KEEP SKIES MOSTLY CLOUDY THROUGH TUESDAY...BUT WEAKER
ONSHORE FLOW FROM MID WEEK ONWARD ALONG WITH HIGHER PRESSURE
BUILDING OVER THE REGION WILL ALLOW MORE AFTERNOON SUNSHINE AND A
WARMING TREND. THE AIR MASS OVER THE CASCADES WILL CONTINUE TO
BECOME SLIGHTLY UNSTABLE LATE IN THE DAY FOR A CHANCE OF SHOWERS
NEAR THE CREST.

&&

.SHORT TERM...THE FORECAST WAS UPDATED THIS EVENING TO REMOVE
THUNDERSTORMS OVER THE CASCADES OF WHATCOM AND SKAGIT COUNTIES. THE
UPPER LEVEL LOW IS NOW SPINNING OVER EASTERN WA WITH T-STORMS
REMAINING EAST OF THE CREST TONIGHT. THE REST OF THE FORECAST IS
UNCHANGED.

THE UPPER LEVEL LOW WILL SPIN OVER THE WA/ID BORDER THROUGH TUESDAY.
SHOWERS WILL MAINLY AFFECT EASTERN WA WITH A FEW SHOWERS CLIPPING
THE CASCADES. OTHERWISE...THE LOWLANDS WILL BE DRY BUT MOSTLY CLOUDY
AS ONSHORE FLOW PERSISTS.

THE UPPER LEVEL LOW WILL WEAKEN AND EXIT EAST ON WEDNESDAY WHILE
HIGH PRESSURE BUILDS IN FROM THE WEST. WE MAY SEE A BREAK IN THE
CLOUDS WEDNESDAY AFTERNOON FOR A FEW SUNBREAKS AND WARMER WEATHER.
THERE IS STILL ENOUGH MOISTURE AND INSTABILITY FOR A CHANCE OF
SHOWERS IN THE CASCADES WEDNESDAY AFTERNOON AND EVENING...WITH
THUNDERSTORMS POSSIBLE NEAR THE CREST. 33

.LONG TERM...PREVIOUS DISCUSSION...GFS/ECMWF/CANADIAN ALL BRING
ANOTHER UPPER LEVEL LOW DOWN THE B.C. COAST WEDNESDAY THROUGH FRIDAY
MORNING...WHEN PER THE ECMWF/CANADIAN IT WILL BE CENTERED OVER THE
CENTRAL B.C. COAST. THE GFS DOES NOT BRING THE LOW AS FAR S AND IS
QUICKER IN SENDING IT EAST OVER THE WEEKEND. NONE OF THE MODELS SHOW
ANY PRECIP REACHING W WA...BUT IT WILL PROBABLY PREVENT THE UPPER
LEVEL RIDGE OVER THE PACIFIC NW FROM BUILDING ANY HIGHER THAN 5760
METERS. ONSHORE FLOW SHOULD REMAIN FAIRLY WEAK FOR PARTLY TO MOSTLY
CLOUDY MORNINGS AND AFTERNOON SUNSHINE. MAX TEMPS ARE EXPECTED TO
TOP OUT IN THE 70S EACH DAY THIS WEEKEND.

ALL THREE MODELS AGREE ON PROGRESSING THE RIDGE QUICKLY E SUNDAY
NIGHT...ALLOWING AN UPPER LEVEL TROUGH TO APPROACH THE REGION FROM
THE SW ON MONDAY. KAM

&&

.AVIATION...A WEAK CLOSED UPPER LOW WILL MOVE SOUTHEAST THROUGH
EASTERN WASHINGTON TONIGHT THROUGH TUESDAY...REACHING NORTHEAST
OREGON LATE TUESDAY NIGHT. LIGHT NORTHWEST FLOW ALOFT. MODERATE
ONSHORE FLOW AT THE SFC WILL KEEP THE AIR MASS MOIST IN THE LOWER
LEVELS AND SOMEWHAT MOIST ALOFT. AIR MASS IS STABLE EXCEPT SLIGHTLY
UNSTABLE OVER THE CASCADES.

MOSTLY HIGH END MVFR CIGS THIS EVENING WILL LOWER TO 1-2K FT
OVERNIGHT. CEILINGS WILL LIFT TUESDAY AFTERNOON TO 3-5K FT. PATCHY
MORNING DRIZZLE IS POSSIBLE OVER THE LOWLANDS AND SOMEWHAT MORE
LIKELY ALONG THE COAST.

KSEA...THE DEEP MARINE LAYER WILL REMAIN INTACT FOR THE NEXT 30
HOURS ALONG WITH BKN-OVC CLOUD COVERAGE. CEILINGS WILL FALL BELOW
2K FT TONIGHT AND TUESDAY MORNING...THEN LIFT NEAR 4K FT IN THE
AFTERNOON. SOUTHERLY WIND 3-7 KT. CHB

&&

.MARINE...HIGH PRES WILL REMAIN OFFSHORE WITH LOWER PRES INLAND ALL
WEEK LONG. SMALL CRAFT ADVISORY STRENGTH WINDS OF 15 TO 25 KT WILL
OCCUR THIS EVENING AND MOST EVENINGS THIS WEEK. THE LOWEST CHANCE OF
SMALL CRAFT ADVISORY STRENGTH WESTERLIES WILL BE ON THURSDAY WHEN
ONSHORE FLOW SHOULD BE WEAKEST. CHB

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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






000
FXUS66 KSEW 252225
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
325 PM PDT MON MAY 25 2015

.SYNOPSIS...A SURFACE RIDGE OFFSHORE WILL MAINTAIN MOIST LOW LEVEL
ONSHORE FLOW ACROSS WESTERN WASHINGTON THIS WEEK. MODERATE ONSHORE
FLOW WILL KEEP SKIES MOSTLY CLOUDY THROUGH TUESDAY...BUT WEAKER
ONSHORE FLOW FROM MID WEEK ONWARD ALONG WITH HIGHER PRESSURE
BUILDING OVER THE REGION WILL ALLOW MORE AFTERNOON SUNSHINE AND A
WARMING TREND. THE AIR MASS OVER THE CASCADES WILL CONTINUE TO
BECOME SLIGHTLY UNSTABLE LATE IN THE DAY FOR A CHANCE OF SHOWERS
NEAR THE CREST.

&&

.SHORT TERM...SATELLITE IMAGERY SHOWS THE UPPER LEVEL LOW IS STILL
HANGING OUT JUST ACROSS THE CENTRAL WA BORDER OVER S CENTRAL B.C.
MOISTURE CONTINUES TO ROTATE AROUND THE LOW...BUT ASIDE FROM THE
AREA OF RAIN THAT CROSSED THE N INTERIOR THIS MORNING...NOTHING HAS
REACHED W WA. ALL MODELS EXCEPT FOR THE ARW KEEP THE N INTERIOR AND
THE REST OF THE W WA LOWLANDS DRY TONIGHT. A CHANCE OF SHOWERS WILL
CONTINUE FOR THE CASCADES TONIGHT ALONG WITH A SLIGHT CHANCE OF
EVENING THUNDERSTORMS OVER THE FAR NE CORNER. HOWEVER CONFIDENCE IS
ONLY MODERATE THAT NO SHOWERS WILL CREEP S OVER THE N INTERIOR
LOWLANDS OVERNIGHT.

WEAK ONSHORE FLOW CONTINUES THIS AFTERNOON DESPITE SURFACE PRESSURE
GRADIENTS BEING SLACK EARLY THIS AFTERNOON. ONSHORE PRESSURE
GRADIENTS WILL INCREASE THIS EVENING BRINGING IN A LITTLE MORE LOW
LEVEL MOISTURE. GFS/NAM TIME-HEIGHT SECTIONS SHOW SOME THINNING OF
THE MARINE LAYER TUESDAY AFTERNOON...BUT MEAN RH VALUES IN THE
MARINE LAYER DO NOT LOWER ENOUGH TO EXPECT MORE THAN SOME AFTERNOON
SUNBREAKS. MODELS SHOW A LITTLE LOW LEVEL WARMING...ENOUGH TO NUDGE
MAX TEMPS UP INTO THE MID 60S.

THE UPPER LEVEL LOW WILL MOVE SE OVER SE WA TUESDAY AFTERNOON THEN
CEASE TO BE A FACTOR WEDNESDAY AS IT CONTINUES MOVING E. AN UPPER
LEVEL RIDGE OFFSHORE WILL BUILD SLOWLY INLAND BEHIND THE DEPARTING
LOW. THE AIR MASS OVER THE CASCADES WILL CONTINUE BECOME UNSTABLE
EACH AFTERNOON FOR A CHANCE OF SHOWERS. I WILL LEAVE THUNDERSTORMS
OUT OF THE FORECAST FOR NOW SINCE THE CHANCE IS VERY LOW.

ONSHORE FLOW SHOULD BE WEAK ENOUGH AND WESTERLY ENOUGH TO ALLOW
PARTIAL CLEARING WEDNESDAY AFTERNOON...AND PROBABLY HOPEFULLY MOSTLY
SUNNY SKIES THURSDAY AFTERNOON. CONTINUING WEAK ONSHORE FLOW WILL
STILL PRODUCE AREAS OF MORNING LOW CLOUDS. WARMING FROM THE UPPER
LEVEL RIDGE COMBINED WITH MORE SUNSHINE SHOULD ALLOW MAX TEMPS TO
REACH INTO THE LOWER 70S ON THURSDAY. 500 MB HEIGHTS WILL APPROACH
5760 METERS OVER PUGET SOUND WITH 850 MB TEMPS CLOSE TO 14C. KAM

.LONG TERM...GFS/ECMWF/CANADIAN ALL BRING ANOTHER UPPER LEVEL LOW
DOWN THE B.C. COAST WEDNESDAY THROUGH FRIDAY MORNING...WHEN PER THE
ECMWF/CANADIAN IT WILL BE CENTERED OVER THE CENTRAL B.C. COAST. THE
GFS DOES NOT BRING THE LOW AS FAR S AND IS QUICKER IN SENDING IT
EAST OVER THE WEEKEND. NONE OF THE MODELS SHOW ANY PRECIP REACHING W
WA...BUT IT WILL PROBABLY PREVENT THE UPPER LEVEL RIDGE OVER THE
PACIFIC NW FROM BUILDING ANY HIGHER THAN 5760 METERS. ONSHORE FLOW
SHOULD REMAIN FAIRLY WEAK FOR PARTLY TO MOSTLY CLOUDY MORNINGS AND
AFTERNOON SUNSHINE. MAX TEMPS ARE EXPECTED TO TOP OUT IN THE 70S
EACH DAY THIS WEEKEND.

ALL THREE MODELS AGREE ON PROGRESSING THE RIDGE QUICKLY E SUNDAY
NIGHT...ALLOWING AN UPPER LEVEL TROUGH TO APPROACH THE REGION FROM
THE SW ON MONDAY. KAM

&&

.AVIATION...A WEAK...CLOSED UPPER LOW WILL MOVE S-SE THROUGH ERN WA
FROM TONIGHT THROUGH TUE...REACHING NE ORE LATE TUE NGT. THIS WILL
BRING LIGHT N-NW FLOW ALOFT OVER WRN WA THROUGH TUE EVNG. MODERATE
ONSHORE FLOW AT THE SFC WILL KEEP THE AIR MASS MOIST IN THE LOWER
LEVELS...AND SOMEWHAT MOIST ALOFT. WEAKLY STABLE AIR MASS...EXCEPT
UNSTABLE OVER THE CASCADES DURING THE AFTN AND EARLY EVNG HOURS.

MVFR AND VFR CIGS PREVAILING THIS EVNG...THEN LOWERING TO MAINLY IFR
CIGS OVERNIGHT AND TUE MORNING. THE TREND OF LIFTING CIGS ON TUE
AFTN WILL FOLLOW CLOSELY TO TRENDS THAT ARE BEING OBSERVED TODAY.
SIGNIFICANT SCATTERING OF CLOUDS IS NOT LIKELY FOR THE REST OF
TODAY...AND IT LOOKS UNLIKELY AGAIN ON TUE. PATCHY DRIZZLE IS
POSSIBLE ON TUE MRNG OVER THE LOWLANDS BUT ESPECIALLY ALONG THE
COAST.

KSEA...THE DEEP MARINE LAYER WILL REMAIN INTACT FOR THE NEXT 30
HOURS ALONG WITH BKN-OVC CLOUD COVERAGE. VFR CIGS NEAR 040 ARE
EXPECTED THIS EVNG...FALLING TO BELOW 020 TONIGHT AND TUE MRNG. CIGS
LIFTING AGAIN ON TUE TO NEAR 040. SW WIND 6-10 KT EXPECTED TO
PERSIST NEAR THE TERMINAL...WITH THE PUGET SOUND CONVERGENCE ZONE
GETTING ABOUT AS FAR SOUTH AS ELLIOTT BAY BETWEEN 03Z AND 06Z THIS
EVNG.     HANER

&&

.MARINE...HIGH PRES WILL REMAIN OFFSHORE WITH LOWER PRES INLAND ALL
WEEK LONG. SMALL CRAFT ADVISORY STRENGTH WINDS OF 15 TO 25 KT WILL
OCCUR THIS EVENING AND MOST EVENINGS THIS WEEK...SIMPLY AS A
FUNCTION OF DIURNAL STRENGTHENING AND WEAKENING OF ONSHORE PRESSURE
GRADIENTS. THE LOWEST CHANCE OF SMALL CRAFT WESTERLIES WILL BE ON
THU...WHEN ONSHORE FLOW SHOULD BE WEAKEST.      HANER

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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
















000
FXUS66 KSEW 252225
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
325 PM PDT MON MAY 25 2015

.SYNOPSIS...A SURFACE RIDGE OFFSHORE WILL MAINTAIN MOIST LOW LEVEL
ONSHORE FLOW ACROSS WESTERN WASHINGTON THIS WEEK. MODERATE ONSHORE
FLOW WILL KEEP SKIES MOSTLY CLOUDY THROUGH TUESDAY...BUT WEAKER
ONSHORE FLOW FROM MID WEEK ONWARD ALONG WITH HIGHER PRESSURE
BUILDING OVER THE REGION WILL ALLOW MORE AFTERNOON SUNSHINE AND A
WARMING TREND. THE AIR MASS OVER THE CASCADES WILL CONTINUE TO
BECOME SLIGHTLY UNSTABLE LATE IN THE DAY FOR A CHANCE OF SHOWERS
NEAR THE CREST.

&&

.SHORT TERM...SATELLITE IMAGERY SHOWS THE UPPER LEVEL LOW IS STILL
HANGING OUT JUST ACROSS THE CENTRAL WA BORDER OVER S CENTRAL B.C.
MOISTURE CONTINUES TO ROTATE AROUND THE LOW...BUT ASIDE FROM THE
AREA OF RAIN THAT CROSSED THE N INTERIOR THIS MORNING...NOTHING HAS
REACHED W WA. ALL MODELS EXCEPT FOR THE ARW KEEP THE N INTERIOR AND
THE REST OF THE W WA LOWLANDS DRY TONIGHT. A CHANCE OF SHOWERS WILL
CONTINUE FOR THE CASCADES TONIGHT ALONG WITH A SLIGHT CHANCE OF
EVENING THUNDERSTORMS OVER THE FAR NE CORNER. HOWEVER CONFIDENCE IS
ONLY MODERATE THAT NO SHOWERS WILL CREEP S OVER THE N INTERIOR
LOWLANDS OVERNIGHT.

WEAK ONSHORE FLOW CONTINUES THIS AFTERNOON DESPITE SURFACE PRESSURE
GRADIENTS BEING SLACK EARLY THIS AFTERNOON. ONSHORE PRESSURE
GRADIENTS WILL INCREASE THIS EVENING BRINGING IN A LITTLE MORE LOW
LEVEL MOISTURE. GFS/NAM TIME-HEIGHT SECTIONS SHOW SOME THINNING OF
THE MARINE LAYER TUESDAY AFTERNOON...BUT MEAN RH VALUES IN THE
MARINE LAYER DO NOT LOWER ENOUGH TO EXPECT MORE THAN SOME AFTERNOON
SUNBREAKS. MODELS SHOW A LITTLE LOW LEVEL WARMING...ENOUGH TO NUDGE
MAX TEMPS UP INTO THE MID 60S.

THE UPPER LEVEL LOW WILL MOVE SE OVER SE WA TUESDAY AFTERNOON THEN
CEASE TO BE A FACTOR WEDNESDAY AS IT CONTINUES MOVING E. AN UPPER
LEVEL RIDGE OFFSHORE WILL BUILD SLOWLY INLAND BEHIND THE DEPARTING
LOW. THE AIR MASS OVER THE CASCADES WILL CONTINUE BECOME UNSTABLE
EACH AFTERNOON FOR A CHANCE OF SHOWERS. I WILL LEAVE THUNDERSTORMS
OUT OF THE FORECAST FOR NOW SINCE THE CHANCE IS VERY LOW.

ONSHORE FLOW SHOULD BE WEAK ENOUGH AND WESTERLY ENOUGH TO ALLOW
PARTIAL CLEARING WEDNESDAY AFTERNOON...AND PROBABLY HOPEFULLY MOSTLY
SUNNY SKIES THURSDAY AFTERNOON. CONTINUING WEAK ONSHORE FLOW WILL
STILL PRODUCE AREAS OF MORNING LOW CLOUDS. WARMING FROM THE UPPER
LEVEL RIDGE COMBINED WITH MORE SUNSHINE SHOULD ALLOW MAX TEMPS TO
REACH INTO THE LOWER 70S ON THURSDAY. 500 MB HEIGHTS WILL APPROACH
5760 METERS OVER PUGET SOUND WITH 850 MB TEMPS CLOSE TO 14C. KAM

.LONG TERM...GFS/ECMWF/CANADIAN ALL BRING ANOTHER UPPER LEVEL LOW
DOWN THE B.C. COAST WEDNESDAY THROUGH FRIDAY MORNING...WHEN PER THE
ECMWF/CANADIAN IT WILL BE CENTERED OVER THE CENTRAL B.C. COAST. THE
GFS DOES NOT BRING THE LOW AS FAR S AND IS QUICKER IN SENDING IT
EAST OVER THE WEEKEND. NONE OF THE MODELS SHOW ANY PRECIP REACHING W
WA...BUT IT WILL PROBABLY PREVENT THE UPPER LEVEL RIDGE OVER THE
PACIFIC NW FROM BUILDING ANY HIGHER THAN 5760 METERS. ONSHORE FLOW
SHOULD REMAIN FAIRLY WEAK FOR PARTLY TO MOSTLY CLOUDY MORNINGS AND
AFTERNOON SUNSHINE. MAX TEMPS ARE EXPECTED TO TOP OUT IN THE 70S
EACH DAY THIS WEEKEND.

ALL THREE MODELS AGREE ON PROGRESSING THE RIDGE QUICKLY E SUNDAY
NIGHT...ALLOWING AN UPPER LEVEL TROUGH TO APPROACH THE REGION FROM
THE SW ON MONDAY. KAM

&&

.AVIATION...A WEAK...CLOSED UPPER LOW WILL MOVE S-SE THROUGH ERN WA
FROM TONIGHT THROUGH TUE...REACHING NE ORE LATE TUE NGT. THIS WILL
BRING LIGHT N-NW FLOW ALOFT OVER WRN WA THROUGH TUE EVNG. MODERATE
ONSHORE FLOW AT THE SFC WILL KEEP THE AIR MASS MOIST IN THE LOWER
LEVELS...AND SOMEWHAT MOIST ALOFT. WEAKLY STABLE AIR MASS...EXCEPT
UNSTABLE OVER THE CASCADES DURING THE AFTN AND EARLY EVNG HOURS.

MVFR AND VFR CIGS PREVAILING THIS EVNG...THEN LOWERING TO MAINLY IFR
CIGS OVERNIGHT AND TUE MORNING. THE TREND OF LIFTING CIGS ON TUE
AFTN WILL FOLLOW CLOSELY TO TRENDS THAT ARE BEING OBSERVED TODAY.
SIGNIFICANT SCATTERING OF CLOUDS IS NOT LIKELY FOR THE REST OF
TODAY...AND IT LOOKS UNLIKELY AGAIN ON TUE. PATCHY DRIZZLE IS
POSSIBLE ON TUE MRNG OVER THE LOWLANDS BUT ESPECIALLY ALONG THE
COAST.

KSEA...THE DEEP MARINE LAYER WILL REMAIN INTACT FOR THE NEXT 30
HOURS ALONG WITH BKN-OVC CLOUD COVERAGE. VFR CIGS NEAR 040 ARE
EXPECTED THIS EVNG...FALLING TO BELOW 020 TONIGHT AND TUE MRNG. CIGS
LIFTING AGAIN ON TUE TO NEAR 040. SW WIND 6-10 KT EXPECTED TO
PERSIST NEAR THE TERMINAL...WITH THE PUGET SOUND CONVERGENCE ZONE
GETTING ABOUT AS FAR SOUTH AS ELLIOTT BAY BETWEEN 03Z AND 06Z THIS
EVNG.     HANER

&&

.MARINE...HIGH PRES WILL REMAIN OFFSHORE WITH LOWER PRES INLAND ALL
WEEK LONG. SMALL CRAFT ADVISORY STRENGTH WINDS OF 15 TO 25 KT WILL
OCCUR THIS EVENING AND MOST EVENINGS THIS WEEK...SIMPLY AS A
FUNCTION OF DIURNAL STRENGTHENING AND WEAKENING OF ONSHORE PRESSURE
GRADIENTS. THE LOWEST CHANCE OF SMALL CRAFT WESTERLIES WILL BE ON
THU...WHEN ONSHORE FLOW SHOULD BE WEAKEST.      HANER

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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
















000
FXUS66 KSEW 252225
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
325 PM PDT MON MAY 25 2015

.SYNOPSIS...A SURFACE RIDGE OFFSHORE WILL MAINTAIN MOIST LOW LEVEL
ONSHORE FLOW ACROSS WESTERN WASHINGTON THIS WEEK. MODERATE ONSHORE
FLOW WILL KEEP SKIES MOSTLY CLOUDY THROUGH TUESDAY...BUT WEAKER
ONSHORE FLOW FROM MID WEEK ONWARD ALONG WITH HIGHER PRESSURE
BUILDING OVER THE REGION WILL ALLOW MORE AFTERNOON SUNSHINE AND A
WARMING TREND. THE AIR MASS OVER THE CASCADES WILL CONTINUE TO
BECOME SLIGHTLY UNSTABLE LATE IN THE DAY FOR A CHANCE OF SHOWERS
NEAR THE CREST.

&&

.SHORT TERM...SATELLITE IMAGERY SHOWS THE UPPER LEVEL LOW IS STILL
HANGING OUT JUST ACROSS THE CENTRAL WA BORDER OVER S CENTRAL B.C.
MOISTURE CONTINUES TO ROTATE AROUND THE LOW...BUT ASIDE FROM THE
AREA OF RAIN THAT CROSSED THE N INTERIOR THIS MORNING...NOTHING HAS
REACHED W WA. ALL MODELS EXCEPT FOR THE ARW KEEP THE N INTERIOR AND
THE REST OF THE W WA LOWLANDS DRY TONIGHT. A CHANCE OF SHOWERS WILL
CONTINUE FOR THE CASCADES TONIGHT ALONG WITH A SLIGHT CHANCE OF
EVENING THUNDERSTORMS OVER THE FAR NE CORNER. HOWEVER CONFIDENCE IS
ONLY MODERATE THAT NO SHOWERS WILL CREEP S OVER THE N INTERIOR
LOWLANDS OVERNIGHT.

WEAK ONSHORE FLOW CONTINUES THIS AFTERNOON DESPITE SURFACE PRESSURE
GRADIENTS BEING SLACK EARLY THIS AFTERNOON. ONSHORE PRESSURE
GRADIENTS WILL INCREASE THIS EVENING BRINGING IN A LITTLE MORE LOW
LEVEL MOISTURE. GFS/NAM TIME-HEIGHT SECTIONS SHOW SOME THINNING OF
THE MARINE LAYER TUESDAY AFTERNOON...BUT MEAN RH VALUES IN THE
MARINE LAYER DO NOT LOWER ENOUGH TO EXPECT MORE THAN SOME AFTERNOON
SUNBREAKS. MODELS SHOW A LITTLE LOW LEVEL WARMING...ENOUGH TO NUDGE
MAX TEMPS UP INTO THE MID 60S.

THE UPPER LEVEL LOW WILL MOVE SE OVER SE WA TUESDAY AFTERNOON THEN
CEASE TO BE A FACTOR WEDNESDAY AS IT CONTINUES MOVING E. AN UPPER
LEVEL RIDGE OFFSHORE WILL BUILD SLOWLY INLAND BEHIND THE DEPARTING
LOW. THE AIR MASS OVER THE CASCADES WILL CONTINUE BECOME UNSTABLE
EACH AFTERNOON FOR A CHANCE OF SHOWERS. I WILL LEAVE THUNDERSTORMS
OUT OF THE FORECAST FOR NOW SINCE THE CHANCE IS VERY LOW.

ONSHORE FLOW SHOULD BE WEAK ENOUGH AND WESTERLY ENOUGH TO ALLOW
PARTIAL CLEARING WEDNESDAY AFTERNOON...AND PROBABLY HOPEFULLY MOSTLY
SUNNY SKIES THURSDAY AFTERNOON. CONTINUING WEAK ONSHORE FLOW WILL
STILL PRODUCE AREAS OF MORNING LOW CLOUDS. WARMING FROM THE UPPER
LEVEL RIDGE COMBINED WITH MORE SUNSHINE SHOULD ALLOW MAX TEMPS TO
REACH INTO THE LOWER 70S ON THURSDAY. 500 MB HEIGHTS WILL APPROACH
5760 METERS OVER PUGET SOUND WITH 850 MB TEMPS CLOSE TO 14C. KAM

.LONG TERM...GFS/ECMWF/CANADIAN ALL BRING ANOTHER UPPER LEVEL LOW
DOWN THE B.C. COAST WEDNESDAY THROUGH FRIDAY MORNING...WHEN PER THE
ECMWF/CANADIAN IT WILL BE CENTERED OVER THE CENTRAL B.C. COAST. THE
GFS DOES NOT BRING THE LOW AS FAR S AND IS QUICKER IN SENDING IT
EAST OVER THE WEEKEND. NONE OF THE MODELS SHOW ANY PRECIP REACHING W
WA...BUT IT WILL PROBABLY PREVENT THE UPPER LEVEL RIDGE OVER THE
PACIFIC NW FROM BUILDING ANY HIGHER THAN 5760 METERS. ONSHORE FLOW
SHOULD REMAIN FAIRLY WEAK FOR PARTLY TO MOSTLY CLOUDY MORNINGS AND
AFTERNOON SUNSHINE. MAX TEMPS ARE EXPECTED TO TOP OUT IN THE 70S
EACH DAY THIS WEEKEND.

ALL THREE MODELS AGREE ON PROGRESSING THE RIDGE QUICKLY E SUNDAY
NIGHT...ALLOWING AN UPPER LEVEL TROUGH TO APPROACH THE REGION FROM
THE SW ON MONDAY. KAM

&&

.AVIATION...A WEAK...CLOSED UPPER LOW WILL MOVE S-SE THROUGH ERN WA
FROM TONIGHT THROUGH TUE...REACHING NE ORE LATE TUE NGT. THIS WILL
BRING LIGHT N-NW FLOW ALOFT OVER WRN WA THROUGH TUE EVNG. MODERATE
ONSHORE FLOW AT THE SFC WILL KEEP THE AIR MASS MOIST IN THE LOWER
LEVELS...AND SOMEWHAT MOIST ALOFT. WEAKLY STABLE AIR MASS...EXCEPT
UNSTABLE OVER THE CASCADES DURING THE AFTN AND EARLY EVNG HOURS.

MVFR AND VFR CIGS PREVAILING THIS EVNG...THEN LOWERING TO MAINLY IFR
CIGS OVERNIGHT AND TUE MORNING. THE TREND OF LIFTING CIGS ON TUE
AFTN WILL FOLLOW CLOSELY TO TRENDS THAT ARE BEING OBSERVED TODAY.
SIGNIFICANT SCATTERING OF CLOUDS IS NOT LIKELY FOR THE REST OF
TODAY...AND IT LOOKS UNLIKELY AGAIN ON TUE. PATCHY DRIZZLE IS
POSSIBLE ON TUE MRNG OVER THE LOWLANDS BUT ESPECIALLY ALONG THE
COAST.

KSEA...THE DEEP MARINE LAYER WILL REMAIN INTACT FOR THE NEXT 30
HOURS ALONG WITH BKN-OVC CLOUD COVERAGE. VFR CIGS NEAR 040 ARE
EXPECTED THIS EVNG...FALLING TO BELOW 020 TONIGHT AND TUE MRNG. CIGS
LIFTING AGAIN ON TUE TO NEAR 040. SW WIND 6-10 KT EXPECTED TO
PERSIST NEAR THE TERMINAL...WITH THE PUGET SOUND CONVERGENCE ZONE
GETTING ABOUT AS FAR SOUTH AS ELLIOTT BAY BETWEEN 03Z AND 06Z THIS
EVNG.     HANER

&&

.MARINE...HIGH PRES WILL REMAIN OFFSHORE WITH LOWER PRES INLAND ALL
WEEK LONG. SMALL CRAFT ADVISORY STRENGTH WINDS OF 15 TO 25 KT WILL
OCCUR THIS EVENING AND MOST EVENINGS THIS WEEK...SIMPLY AS A
FUNCTION OF DIURNAL STRENGTHENING AND WEAKENING OF ONSHORE PRESSURE
GRADIENTS. THE LOWEST CHANCE OF SMALL CRAFT WESTERLIES WILL BE ON
THU...WHEN ONSHORE FLOW SHOULD BE WEAKEST.      HANER

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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















000
FXUS66 KSEW 252225
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
325 PM PDT MON MAY 25 2015

.SYNOPSIS...A SURFACE RIDGE OFFSHORE WILL MAINTAIN MOIST LOW LEVEL
ONSHORE FLOW ACROSS WESTERN WASHINGTON THIS WEEK. MODERATE ONSHORE
FLOW WILL KEEP SKIES MOSTLY CLOUDY THROUGH TUESDAY...BUT WEAKER
ONSHORE FLOW FROM MID WEEK ONWARD ALONG WITH HIGHER PRESSURE
BUILDING OVER THE REGION WILL ALLOW MORE AFTERNOON SUNSHINE AND A
WARMING TREND. THE AIR MASS OVER THE CASCADES WILL CONTINUE TO
BECOME SLIGHTLY UNSTABLE LATE IN THE DAY FOR A CHANCE OF SHOWERS
NEAR THE CREST.

&&

.SHORT TERM...SATELLITE IMAGERY SHOWS THE UPPER LEVEL LOW IS STILL
HANGING OUT JUST ACROSS THE CENTRAL WA BORDER OVER S CENTRAL B.C.
MOISTURE CONTINUES TO ROTATE AROUND THE LOW...BUT ASIDE FROM THE
AREA OF RAIN THAT CROSSED THE N INTERIOR THIS MORNING...NOTHING HAS
REACHED W WA. ALL MODELS EXCEPT FOR THE ARW KEEP THE N INTERIOR AND
THE REST OF THE W WA LOWLANDS DRY TONIGHT. A CHANCE OF SHOWERS WILL
CONTINUE FOR THE CASCADES TONIGHT ALONG WITH A SLIGHT CHANCE OF
EVENING THUNDERSTORMS OVER THE FAR NE CORNER. HOWEVER CONFIDENCE IS
ONLY MODERATE THAT NO SHOWERS WILL CREEP S OVER THE N INTERIOR
LOWLANDS OVERNIGHT.

WEAK ONSHORE FLOW CONTINUES THIS AFTERNOON DESPITE SURFACE PRESSURE
GRADIENTS BEING SLACK EARLY THIS AFTERNOON. ONSHORE PRESSURE
GRADIENTS WILL INCREASE THIS EVENING BRINGING IN A LITTLE MORE LOW
LEVEL MOISTURE. GFS/NAM TIME-HEIGHT SECTIONS SHOW SOME THINNING OF
THE MARINE LAYER TUESDAY AFTERNOON...BUT MEAN RH VALUES IN THE
MARINE LAYER DO NOT LOWER ENOUGH TO EXPECT MORE THAN SOME AFTERNOON
SUNBREAKS. MODELS SHOW A LITTLE LOW LEVEL WARMING...ENOUGH TO NUDGE
MAX TEMPS UP INTO THE MID 60S.

THE UPPER LEVEL LOW WILL MOVE SE OVER SE WA TUESDAY AFTERNOON THEN
CEASE TO BE A FACTOR WEDNESDAY AS IT CONTINUES MOVING E. AN UPPER
LEVEL RIDGE OFFSHORE WILL BUILD SLOWLY INLAND BEHIND THE DEPARTING
LOW. THE AIR MASS OVER THE CASCADES WILL CONTINUE BECOME UNSTABLE
EACH AFTERNOON FOR A CHANCE OF SHOWERS. I WILL LEAVE THUNDERSTORMS
OUT OF THE FORECAST FOR NOW SINCE THE CHANCE IS VERY LOW.

ONSHORE FLOW SHOULD BE WEAK ENOUGH AND WESTERLY ENOUGH TO ALLOW
PARTIAL CLEARING WEDNESDAY AFTERNOON...AND PROBABLY HOPEFULLY MOSTLY
SUNNY SKIES THURSDAY AFTERNOON. CONTINUING WEAK ONSHORE FLOW WILL
STILL PRODUCE AREAS OF MORNING LOW CLOUDS. WARMING FROM THE UPPER
LEVEL RIDGE COMBINED WITH MORE SUNSHINE SHOULD ALLOW MAX TEMPS TO
REACH INTO THE LOWER 70S ON THURSDAY. 500 MB HEIGHTS WILL APPROACH
5760 METERS OVER PUGET SOUND WITH 850 MB TEMPS CLOSE TO 14C. KAM

.LONG TERM...GFS/ECMWF/CANADIAN ALL BRING ANOTHER UPPER LEVEL LOW
DOWN THE B.C. COAST WEDNESDAY THROUGH FRIDAY MORNING...WHEN PER THE
ECMWF/CANADIAN IT WILL BE CENTERED OVER THE CENTRAL B.C. COAST. THE
GFS DOES NOT BRING THE LOW AS FAR S AND IS QUICKER IN SENDING IT
EAST OVER THE WEEKEND. NONE OF THE MODELS SHOW ANY PRECIP REACHING W
WA...BUT IT WILL PROBABLY PREVENT THE UPPER LEVEL RIDGE OVER THE
PACIFIC NW FROM BUILDING ANY HIGHER THAN 5760 METERS. ONSHORE FLOW
SHOULD REMAIN FAIRLY WEAK FOR PARTLY TO MOSTLY CLOUDY MORNINGS AND
AFTERNOON SUNSHINE. MAX TEMPS ARE EXPECTED TO TOP OUT IN THE 70S
EACH DAY THIS WEEKEND.

ALL THREE MODELS AGREE ON PROGRESSING THE RIDGE QUICKLY E SUNDAY
NIGHT...ALLOWING AN UPPER LEVEL TROUGH TO APPROACH THE REGION FROM
THE SW ON MONDAY. KAM

&&

.AVIATION...A WEAK...CLOSED UPPER LOW WILL MOVE S-SE THROUGH ERN WA
FROM TONIGHT THROUGH TUE...REACHING NE ORE LATE TUE NGT. THIS WILL
BRING LIGHT N-NW FLOW ALOFT OVER WRN WA THROUGH TUE EVNG. MODERATE
ONSHORE FLOW AT THE SFC WILL KEEP THE AIR MASS MOIST IN THE LOWER
LEVELS...AND SOMEWHAT MOIST ALOFT. WEAKLY STABLE AIR MASS...EXCEPT
UNSTABLE OVER THE CASCADES DURING THE AFTN AND EARLY EVNG HOURS.

MVFR AND VFR CIGS PREVAILING THIS EVNG...THEN LOWERING TO MAINLY IFR
CIGS OVERNIGHT AND TUE MORNING. THE TREND OF LIFTING CIGS ON TUE
AFTN WILL FOLLOW CLOSELY TO TRENDS THAT ARE BEING OBSERVED TODAY.
SIGNIFICANT SCATTERING OF CLOUDS IS NOT LIKELY FOR THE REST OF
TODAY...AND IT LOOKS UNLIKELY AGAIN ON TUE. PATCHY DRIZZLE IS
POSSIBLE ON TUE MRNG OVER THE LOWLANDS BUT ESPECIALLY ALONG THE
COAST.

KSEA...THE DEEP MARINE LAYER WILL REMAIN INTACT FOR THE NEXT 30
HOURS ALONG WITH BKN-OVC CLOUD COVERAGE. VFR CIGS NEAR 040 ARE
EXPECTED THIS EVNG...FALLING TO BELOW 020 TONIGHT AND TUE MRNG. CIGS
LIFTING AGAIN ON TUE TO NEAR 040. SW WIND 6-10 KT EXPECTED TO
PERSIST NEAR THE TERMINAL...WITH THE PUGET SOUND CONVERGENCE ZONE
GETTING ABOUT AS FAR SOUTH AS ELLIOTT BAY BETWEEN 03Z AND 06Z THIS
EVNG.     HANER

&&

.MARINE...HIGH PRES WILL REMAIN OFFSHORE WITH LOWER PRES INLAND ALL
WEEK LONG. SMALL CRAFT ADVISORY STRENGTH WINDS OF 15 TO 25 KT WILL
OCCUR THIS EVENING AND MOST EVENINGS THIS WEEK...SIMPLY AS A
FUNCTION OF DIURNAL STRENGTHENING AND WEAKENING OF ONSHORE PRESSURE
GRADIENTS. THE LOWEST CHANCE OF SMALL CRAFT WESTERLIES WILL BE ON
THU...WHEN ONSHORE FLOW SHOULD BE WEAKEST.      HANER

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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















000
FXUS66 KSEW 251626
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
926 AM PDT MON MAY 25 2015

.SYNOPSIS...A SURFACE RIDGE OFFSHORE WILL MAINTAIN MOIST LOW LEVEL
ONSHORE FLOW ACROSS WESTERN WASHINGTON THIS WEEK. MODERATE ONSHORE
FLOW WILL KEEP SKIES MOSTLY CLOUDY THROUGH TUESDAY...BUT WEAKER
ONSHORE FLOW FROM MID WEEK ONWARD ALONG WITH HIGHER PRESSURE
BUILDING OVER THE REGION WILL ALLOW MORE AFTERNOON SUNSHINE AND A
WARMING TREND. THE AIR MASS OVER THE CASCADES WILL CONTINUE TO
BECOME SLIGHTLY UNSTABLE LATE IN THE DAY FOR A CHANCE OF SHOWERS
NEAR THE CREST.

&&

.SHORT TERM...WATER VAPOR IMAGERY SHOWS THE UPPER LEVEL LOW HAS
MOVED OVER SOUTH CENTRAL BRITISH COLUMBIA THIS MORNING JUST N OF THE
WA CASCADES. AN AREA OF RETURN FLOW RAIN COMING S ON THE W SIDE OF
THE LOW HAS MOVED OVER THE FAR N INTERIOR OF W WA THIS MORNING. THIS
APPEARS TO BE ASSOCIATED WITH A SMALL UPPER LEVEL SHORTWAVE TROUGH
THAT SHOWS UP IN BOTH THE NAM AND GFS. THE MODELS MOVE THE SHORTWAVE
OVER THE N CASCADES BY 18Z SO THE AREA OF RAIN SHOULD BE MOVING E
AWAY FROM BELLINGHAM LATE THIS MORNING. BASED ON MODEL VORTICITY...
IT LOOKS LIKE A WEAKER TROUGH COULD SLIDE S OVER THE N INTERIOR
LATER THIS AFTERNOON...AND PER THE HIRES-ARW ANOTHER MIGHT REACH THE
AREA LATER TONIGHT. CONFIDENCE IS NOT ALL THAT HIGH WHEN DEALING
WITH THESE SMALL FEATURES.

THE UPPER LEVEL LOW WILL HELP DESTABILIZE THE AIR MASS OVER THE
CASCADES AGAIN THIS AFTERNOON...BUT LIFTED INDICES ONLY DROP TO -2
OVER THE FAR NE CORNER. A CHANCE OF AFTERNOON/EVENING THUNDERSTORMS
STILL LOOKS FINE FOR THIS AREA...WITH JUST A CHANCE OF SHOWERS FOR
THE REST OF THE CASCADES NEAR THE CREST. N STEERING FLOW MAY ALSO
ALLOW CELLS OVER INTERIOR B.C. TO DRIFT S OVER THE N CASCADES.

RESIDUAL WEAK ONSHORE FLOW WILL KEEP THE MARINE LAYER MOIST TODAY.
THE HQM-SEA AND AST-SEA PRESSURE GRADIENTS WERE FLAT AT 8 AM...BUT
SURFACE WINDS OVER SW WA REMAINED WEAK W-SW. VISIBLE SATELLITE
IMAGERY SHOWED CLOUD TOP MOTIONS MOVING INLAND FROM THE COAST...
CONFIRMING THE CONTINUING ONSHORE TENDENCY IN THE MARINE LAYER. SO
WITH WEAK ONSHORE FLOW CONTINUING IN THE MARINE LAYER OVER SW WA AND
AND HIGHER CLOUD LAYERS WRAPPING AROUND THE UPPER LEVEL LOW AND
MOVING S OVER THE N INTERIOR...IT DOES NOT LOOK ALL THAT PROMISING
FOR ANY CLEARING THIS AFTERNOON. LOOKS LIKE ONLY SOME BRIEF
AFTERNOON SUNBREAKS AT BEST.

ONSHORE FLOW WILL CONTINUE THE REST OF THIS WEEK BUT THE MODELS
CONTINUE THE TREND OF WEAKENING THE FLOW AND THE MARINE LAYER A
LITTLE EACH DAY. THERE SHOULD BE MORE BREAKS OR EVEN PARTIAL
CLEARING TUESDAY AFTERNOON...AND PERHAPS PARTLY SUNNY IN THE
AFTERNOON ON WEDNESDAY. THE AIR MASS WILL WARM GRADUALLY THE NEXT
COUPLE OF DAYS AS SUNSHINE INCREASES...AND AS THE UPPER LEVEL LOW
HEADS E AND AN OFFSHORE RIDGE BUILDS INLAND. MAX TEMPS MAY REACH THE
LOWER 70S IN SPOTS WEDNESDAY AFTERNOON.

THE AIR MASS OVER THE CASCADES WILL CONTINUE TO BECOME UNSTABLE EACH
AFTERNOON FOR A CHANCE OF SHOWERS NEAR THE CREST. THE CHANCE OF A
THUNDERSTORM IS LOW BUT NOT OUT OF THE QUESTION. KAM

.LONG TERM...PREVIOUS DISCUSSION FROM THE 335 PM AFD...EXTENDED
MODELS WHICH HAVE BEEN IN GOOD AGREEMENT THE LAST COUPLE OF NIGHTS
HAVE LOST A BIT OF CONSISTENCY BOTH AMONG THE INDIVIDUAL MODELS AND
RUN TO RUN. GFS SHOWING UPPER LEVEL RIDGE MOVING INTO WESTERN
WASHINGTON ON THURSDAY. THE ECMWF IS WEAKER WITH THIS FEATURE
BECAUSE OF YET ANOTHER UPPER LEVEL LOW MOVING INTO CENTRAL BRITISH
COLUMBIA. THE GFS IS WEAKER AND FURTHER NORTH WITH THIS FEATURE.
BOTH MODELS STILL HAVE DECENT 500 MB HEIGHTS OVER WESTERN
WASHINGTON...MID 570 DMS AND WEAK LOW LEVEL ONSHORE FLOW. WILL STAY
WITH THE IDEA OF CONTINUING THE WARMING TREND ON THURSDAY WITH
PLENTY OF HIGHS IN THE 70S OVER THE INTERIOR. ECMWF CONTINUES TO
DROP THE LOW SOUTH ON FRIDAY INDUCING A STRONGER ONSHORE PATTERN
VERSUS THE GFS WHICH HAS THE LOW MUCH FURTHER NORTH. THE ECMWF DOES
KEEP THE PRECIPITATION WITH THE LOW NORTH OF THE BORDER. ON SATURDAY
THE ECMWF MOVES THE LOW BACK TO THE NORTHEAST WHILE THE GFS SOLUTION
CONTINUES TO PUT THE LOW FURTHER TO THE NORTH AND EAST. MODELS ARE
IN GENERAL AGREEMENT WITH ANOTHER WEAK UPPER LEVEL LOW DEVELOPING
NEAR HAIDA GWAII ON SUNDAY. CURRENT FORECAST FOLLOWS THE WARMER...BY
ABOUT 5 DEGREES...GFS SOLUTION FOR FRIDAY THROUGH SUNDAY WITH HIGHS
IN THE LOWER TO MID 60S ON THE COAST AND MID 60S TO MID 70S OVER THE
INTERIOR WITH THE WARMEST DAY BEING FRIDAY. WITH THE NEWER SOLUTIONS
IN THE EXTENDED RUNS THIS MORNING WILL LET THE CURRENT FORECAST RIDE
FOR ANOTHER FORECAST PACKAGE. FELTON

&&

.AVIATION...A WEAK...CLOSED UPPER LOW WILL MOVE S-SE THROUGH ERN WA
TODAY AND TUE...REACHING NE ORE LATE TUE NGT. THIS WILL BRING LIGHT
N-NW FLOW ALOFT THROUGH TUE. MODERATE ONSHORE FLOW AT THE SFC WILL
KEEP THE AIR MASS MOIST IN THE LOWER LEVELS...AND SOMEWHAT MOIST
ALOFT. WEAKLY STABLE AIR MASS...EXCEPT UNSTABLE OVER THE CASCADES
DURING THE AFTN AND EARLY EVNG HOURS.

RADAR SHOWS AN AREA OF RAIN SPREADING SOUTH OF THE CANADIAN
BORDER...AFFECTING THE NORTH CASCADES AND BRUSHING KBLI FROM NOW
INTO THIS AFTERNOON. OTHERWISE...IFR AND MVFR CIGS OVER THE LOWLANDS
WILL LIFT TO MVFR AND VFR THIS AFTN...BUT SIGNIFICANT SCATTERING
IS UNLIKELY.

KSEA...CIGS WILL RISE TO 4K FT THIS AFTERNOON. THIS OCCURRED AROUND
22Z YESTERDAY...AND TIMING TREND WILL BE SIMILAR TODAY. THE DEEP
MARINE LAYER WILL REMAIN INTACT ALONG WITH BKN-OVC CLOUD COVERAGE.
SW WIND 6-10 KT.     HANER

&&

.MARINE...HIGH PRES WILL REMAIN OFFSHORE WITH LOWER PRES INLAND.
SMALL CRAFT ADVISORY STRENGTH WINDS OF 15 TO 25 KT WILL OCCUR AGAIN
THIS EVNG AND TUE EVNG...SIMPLY AS A FUNCTION OF DIURNAL
STRENGTHENING AND WEAKENING OF ONSHORE PRESSURE GRADIENTS.
LARGER-SCALE ONSHORE FLOW WILL BE WEAKER FROM WED THROUGH FRI.
HANER

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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












000
FXUS66 KSEW 251626
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
926 AM PDT MON MAY 25 2015

.SYNOPSIS...A SURFACE RIDGE OFFSHORE WILL MAINTAIN MOIST LOW LEVEL
ONSHORE FLOW ACROSS WESTERN WASHINGTON THIS WEEK. MODERATE ONSHORE
FLOW WILL KEEP SKIES MOSTLY CLOUDY THROUGH TUESDAY...BUT WEAKER
ONSHORE FLOW FROM MID WEEK ONWARD ALONG WITH HIGHER PRESSURE
BUILDING OVER THE REGION WILL ALLOW MORE AFTERNOON SUNSHINE AND A
WARMING TREND. THE AIR MASS OVER THE CASCADES WILL CONTINUE TO
BECOME SLIGHTLY UNSTABLE LATE IN THE DAY FOR A CHANCE OF SHOWERS
NEAR THE CREST.

&&

.SHORT TERM...WATER VAPOR IMAGERY SHOWS THE UPPER LEVEL LOW HAS
MOVED OVER SOUTH CENTRAL BRITISH COLUMBIA THIS MORNING JUST N OF THE
WA CASCADES. AN AREA OF RETURN FLOW RAIN COMING S ON THE W SIDE OF
THE LOW HAS MOVED OVER THE FAR N INTERIOR OF W WA THIS MORNING. THIS
APPEARS TO BE ASSOCIATED WITH A SMALL UPPER LEVEL SHORTWAVE TROUGH
THAT SHOWS UP IN BOTH THE NAM AND GFS. THE MODELS MOVE THE SHORTWAVE
OVER THE N CASCADES BY 18Z SO THE AREA OF RAIN SHOULD BE MOVING E
AWAY FROM BELLINGHAM LATE THIS MORNING. BASED ON MODEL VORTICITY...
IT LOOKS LIKE A WEAKER TROUGH COULD SLIDE S OVER THE N INTERIOR
LATER THIS AFTERNOON...AND PER THE HIRES-ARW ANOTHER MIGHT REACH THE
AREA LATER TONIGHT. CONFIDENCE IS NOT ALL THAT HIGH WHEN DEALING
WITH THESE SMALL FEATURES.

THE UPPER LEVEL LOW WILL HELP DESTABILIZE THE AIR MASS OVER THE
CASCADES AGAIN THIS AFTERNOON...BUT LIFTED INDICES ONLY DROP TO -2
OVER THE FAR NE CORNER. A CHANCE OF AFTERNOON/EVENING THUNDERSTORMS
STILL LOOKS FINE FOR THIS AREA...WITH JUST A CHANCE OF SHOWERS FOR
THE REST OF THE CASCADES NEAR THE CREST. N STEERING FLOW MAY ALSO
ALLOW CELLS OVER INTERIOR B.C. TO DRIFT S OVER THE N CASCADES.

RESIDUAL WEAK ONSHORE FLOW WILL KEEP THE MARINE LAYER MOIST TODAY.
THE HQM-SEA AND AST-SEA PRESSURE GRADIENTS WERE FLAT AT 8 AM...BUT
SURFACE WINDS OVER SW WA REMAINED WEAK W-SW. VISIBLE SATELLITE
IMAGERY SHOWED CLOUD TOP MOTIONS MOVING INLAND FROM THE COAST...
CONFIRMING THE CONTINUING ONSHORE TENDENCY IN THE MARINE LAYER. SO
WITH WEAK ONSHORE FLOW CONTINUING IN THE MARINE LAYER OVER SW WA AND
AND HIGHER CLOUD LAYERS WRAPPING AROUND THE UPPER LEVEL LOW AND
MOVING S OVER THE N INTERIOR...IT DOES NOT LOOK ALL THAT PROMISING
FOR ANY CLEARING THIS AFTERNOON. LOOKS LIKE ONLY SOME BRIEF
AFTERNOON SUNBREAKS AT BEST.

ONSHORE FLOW WILL CONTINUE THE REST OF THIS WEEK BUT THE MODELS
CONTINUE THE TREND OF WEAKENING THE FLOW AND THE MARINE LAYER A
LITTLE EACH DAY. THERE SHOULD BE MORE BREAKS OR EVEN PARTIAL
CLEARING TUESDAY AFTERNOON...AND PERHAPS PARTLY SUNNY IN THE
AFTERNOON ON WEDNESDAY. THE AIR MASS WILL WARM GRADUALLY THE NEXT
COUPLE OF DAYS AS SUNSHINE INCREASES...AND AS THE UPPER LEVEL LOW
HEADS E AND AN OFFSHORE RIDGE BUILDS INLAND. MAX TEMPS MAY REACH THE
LOWER 70S IN SPOTS WEDNESDAY AFTERNOON.

THE AIR MASS OVER THE CASCADES WILL CONTINUE TO BECOME UNSTABLE EACH
AFTERNOON FOR A CHANCE OF SHOWERS NEAR THE CREST. THE CHANCE OF A
THUNDERSTORM IS LOW BUT NOT OUT OF THE QUESTION. KAM

.LONG TERM...PREVIOUS DISCUSSION FROM THE 335 PM AFD...EXTENDED
MODELS WHICH HAVE BEEN IN GOOD AGREEMENT THE LAST COUPLE OF NIGHTS
HAVE LOST A BIT OF CONSISTENCY BOTH AMONG THE INDIVIDUAL MODELS AND
RUN TO RUN. GFS SHOWING UPPER LEVEL RIDGE MOVING INTO WESTERN
WASHINGTON ON THURSDAY. THE ECMWF IS WEAKER WITH THIS FEATURE
BECAUSE OF YET ANOTHER UPPER LEVEL LOW MOVING INTO CENTRAL BRITISH
COLUMBIA. THE GFS IS WEAKER AND FURTHER NORTH WITH THIS FEATURE.
BOTH MODELS STILL HAVE DECENT 500 MB HEIGHTS OVER WESTERN
WASHINGTON...MID 570 DMS AND WEAK LOW LEVEL ONSHORE FLOW. WILL STAY
WITH THE IDEA OF CONTINUING THE WARMING TREND ON THURSDAY WITH
PLENTY OF HIGHS IN THE 70S OVER THE INTERIOR. ECMWF CONTINUES TO
DROP THE LOW SOUTH ON FRIDAY INDUCING A STRONGER ONSHORE PATTERN
VERSUS THE GFS WHICH HAS THE LOW MUCH FURTHER NORTH. THE ECMWF DOES
KEEP THE PRECIPITATION WITH THE LOW NORTH OF THE BORDER. ON SATURDAY
THE ECMWF MOVES THE LOW BACK TO THE NORTHEAST WHILE THE GFS SOLUTION
CONTINUES TO PUT THE LOW FURTHER TO THE NORTH AND EAST. MODELS ARE
IN GENERAL AGREEMENT WITH ANOTHER WEAK UPPER LEVEL LOW DEVELOPING
NEAR HAIDA GWAII ON SUNDAY. CURRENT FORECAST FOLLOWS THE WARMER...BY
ABOUT 5 DEGREES...GFS SOLUTION FOR FRIDAY THROUGH SUNDAY WITH HIGHS
IN THE LOWER TO MID 60S ON THE COAST AND MID 60S TO MID 70S OVER THE
INTERIOR WITH THE WARMEST DAY BEING FRIDAY. WITH THE NEWER SOLUTIONS
IN THE EXTENDED RUNS THIS MORNING WILL LET THE CURRENT FORECAST RIDE
FOR ANOTHER FORECAST PACKAGE. FELTON

&&

.AVIATION...A WEAK...CLOSED UPPER LOW WILL MOVE S-SE THROUGH ERN WA
TODAY AND TUE...REACHING NE ORE LATE TUE NGT. THIS WILL BRING LIGHT
N-NW FLOW ALOFT THROUGH TUE. MODERATE ONSHORE FLOW AT THE SFC WILL
KEEP THE AIR MASS MOIST IN THE LOWER LEVELS...AND SOMEWHAT MOIST
ALOFT. WEAKLY STABLE AIR MASS...EXCEPT UNSTABLE OVER THE CASCADES
DURING THE AFTN AND EARLY EVNG HOURS.

RADAR SHOWS AN AREA OF RAIN SPREADING SOUTH OF THE CANADIAN
BORDER...AFFECTING THE NORTH CASCADES AND BRUSHING KBLI FROM NOW
INTO THIS AFTERNOON. OTHERWISE...IFR AND MVFR CIGS OVER THE LOWLANDS
WILL LIFT TO MVFR AND VFR THIS AFTN...BUT SIGNIFICANT SCATTERING
IS UNLIKELY.

KSEA...CIGS WILL RISE TO 4K FT THIS AFTERNOON. THIS OCCURRED AROUND
22Z YESTERDAY...AND TIMING TREND WILL BE SIMILAR TODAY. THE DEEP
MARINE LAYER WILL REMAIN INTACT ALONG WITH BKN-OVC CLOUD COVERAGE.
SW WIND 6-10 KT.     HANER

&&

.MARINE...HIGH PRES WILL REMAIN OFFSHORE WITH LOWER PRES INLAND.
SMALL CRAFT ADVISORY STRENGTH WINDS OF 15 TO 25 KT WILL OCCUR AGAIN
THIS EVNG AND TUE EVNG...SIMPLY AS A FUNCTION OF DIURNAL
STRENGTHENING AND WEAKENING OF ONSHORE PRESSURE GRADIENTS.
LARGER-SCALE ONSHORE FLOW WILL BE WEAKER FROM WED THROUGH FRI.
HANER

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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













000
FXUS66 KSEW 251035
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
335 AM PDT MON MAY 25 2015

.SYNOPSIS...A RIDGE OFFSHORE WILL MAINTAIN LOW LEVEL ONSHORE FLOW
ACROSS WESTERN WASHINGTON THROUGH TUESDAY...KEEPING SKIES MOSTLY
CLOUDY. WEAKER ONSHORE FLOW FROM MID WEEK ONWARD ALONG WITH HIGHER
PRESSURE BUILDING OVER THE REGION WILL ALLOW MORE AFTERNOON SUNSHINE
AND A WARMING TREND. THE AIR MASS OVER THE CASCADES WILL CONTINUE TO
BECOME SLIGHTLY UNSTABLE LATE IN THE DAY FOR A CHANCE OF SHOWERS
NEAR THE CREST.

&&

.SHORT TERM...SATELLITE IMAGERY SHOWS UPPER LEVEL LOW HAS MOVED INTO
SOUTH CENTRAL BRITISH COLUMBIA EARLY THIS MORNING. OVER WESTERN
WASHINGTON MORE OF THE SAME WITH CLOUDY SKIES ACROSS THE AREA.
TEMPERATURES AT 3 AM WERE IN THE UPPER 40S TO MID 50S.

LITTLE CHANGE IN THE FORECAST THIS MORNING. LOW LEVEL ONSHORE FLOW
CONTINUING TODAY KEEPING SKIES CLOUDY ACROSS THE AREA. TOPS OF THE
MARINE LAYER BETWEEN 5000 AND 6000 FEET SO ONCE AGAIN NO REAL
BREAKOUT EXPECTED THIS AFTERNOON. MODELS HAVE THE LOW DRIFTING SOUTH
THIS MORNING AND GIVEN THE DEEP MARINE LAYER A LITTLE EXTRA LIFT
COULD RESULT IN SOME LOCAL DRIZZLE. BY 00Z TUESDAY UPPER LEVEL LOW
OVER THE NORTHERN PORTION OF EASTERN WASHINGTON. AIR MASS OVER THE
CASCADES BECOMING SLIGHTLY UNSTABLE THIS AFTERNOON. THIS ADDED ON TO
SOME WRAP AROUND MOISTURE FROM THE LOW WILL KEEP A CHANCE OF SHOWERS
IN THE FORECAST. HIGHS IN THE LOWLANDS WILL CONTINUE TO BE A LITTLE
BELOW NORMAL...UPPER 50S TO MID 60S.

UPPER LEVEL LOW NOT MOVING MUCH TONIGHT AND TUESDAY WITH THE LOW
CENTER MODELED TO BE NEAR PASCO BY 00Z WEDNESDAY. WITH THE LOW IN
THE VICINITY THIS WILL KEEP THE THREAT OF SHOWERS GOING IN THE
CASCADES. FOR THE LOWLANDS ONSHORE FLOW CONTINUES TONIGHT AND
TUESDAY BUT BEGINS TO WEAKEN A TOUCH TUESDAY AFTERNOON INCREASING
THE CHANCES FOR A LITTLE SUN LATE IN THE DAY ON TUESDAY. WITH PLENTY
OF CLOUD COVER TONIGHT LOW TUESDAY MORNING WILL BE IN THE UPPER 40S
TO MID 50S. LOW LEVEL ONSHORE FLOW TUESDAY WILL KEEP HIGHS IN THE
UPPER 50S TO MID 60S.

UPPER LEVEL LOW KICKS OUT SLOWLY TO THE SOUTHEAST TUESDAY NIGHT AND
WEDNESDAY WITH AN UPPER LEVEL RIDGE BUILDING OFFSHORE. THE SLOW
TREND OF WEAKENING ONSHORE FLOW WILL CONTINUE ON WEDNESDAY RESULTING
IN A LITTLE SUNSHINE IN THE AFTERNOON. TEMPERATURES ALOFT DO NOT
WARM MUCH WITH THE 850 MB TEMPERATURES ONLY RISING FROM AROUND PLUS
8 ON TUESDAY TO PLUS 10 ON WEDNESDAY. ONSHORE FLOW STILL STRONG
ENOUGH FOR PLENTY OF CLOUD COVER TUESDAY NIGHT INTO AT LEAST EARLY
WEDNESDAY AFTERNOON FOR THE INTERIOR WITH THE CLOUDS HANGING TOUGH
ALONG THE COAST WEDNESDAY AFTERNOON. MOS SEEMS A LITTLE OVER
AGGRESSIVE WITH THE WARM UP WITH THE ONSHORE FLOW STILL PRESENT
WEDNESDAY AFTERNOON. WILL UNDERCUT THE GUIDANCE BY A COUPLE OF
DEGREES GOING FOR 60S AND LOWER 70S INLAND WHILE KEEPING HIGHS IN
THE LOWER 60S ALONG THE COAST. EVEN WITH THE RIDGE BUILDING OFFSHORE
THE AIR MASS OVER THE CASCADES WILL ONCE AGAIN BECOMING SLIGHTLY
UNSTABLE LATE IN THE DAY FOR A CHANCE OF SHOWERS...MAINLY NEAR THE
CREST.

.LONG TERM...EXTENDED MODELS WHICH HAVE BEEN IN GOOD AGREEMENT THE
LAST COUPLE OF NIGHTS HAVE LOST A BIT OF CONSISTENCY BOTH AMONG THE
INDIVIDUAL MODELS AND RUN TO RUN. GFS SHOWING UPPER LEVEL RIDGE
MOVING INTO WESTERN WASHINGTON ON THURSDAY. THE ECMWF IS WEAKER WITH
THIS FEATURE BECAUSE OF YET ANOTHER UPPER LEVEL LOW MOVING INTO
CENTRAL BRITISH COLUMBIA. THE GFS IS WEAKER AND FURTHER NORTH WITH
THIS FEATURE. BOTH MODELS STILL HAVE DECENT 500 MB HEIGHTS OVER
WESTERN WASHINGTON...MID 570 DMS AND WEAK LOW LEVEL ONSHORE FLOW.
WILL STAY WITH THE IDEA OF CONTINUING THE WARMING TREND ON THURSDAY
WITH PLENTY OF HIGHS IN THE 70S OVER THE INTERIOR. ECMWF CONTINUES
TO DROP THE LOW SOUTH ON FRIDAY INDUCING A STRONGER ONSHORE PATTERN
VERSUS THE GFS WHICH HAS THE LOW MUCH FURTHER NORTH. THE ECMWF DOES
KEEP THE PRECIPITATION WITH THE LOW NORTH OF THE BORDER. ON SATURDAY
THE ECMWF MOVES THE LOW BACK TO THE NORTHEAST WHILE THE GFS SOLUTION
CONTINUES TO PUT THE LOW FURTHER TO THE NORTH AND EAST. MODELS ARE
IN GENERAL AGREEMENT WITH ANOTHER WEAK UPPER LEVEL LOW DEVELOPING
NEAR HAIDA GWAII ON SUNDAY. CURRENT FORECAST FOLLOWS THE WARMER...BY
ABOUT 5 DEGREES...GFS SOLUTION FOR FRIDAY THROUGH SUNDAY WITH HIGHS
IN THE LOWER TO MID 60S ON THE COAST AND MID 60S TO MID 70S OVER THE
INTERIOR WITH THE WARMEST DAY BEING FRIDAY. WITH THE NEWER SOLUTIONS
IN THE EXTENDED RUNS THIS MORNING WILL LET THE CURRENT FORECAST RIDE
FOR ANOTHER FORECAST PACKAGE. FELTON

&&

.AVIATION...A WEAK UPPER LEVEL LOW WILL SLOWLY MOVE SOUTHEAST
ACROSS MAINLY EASTERN WASHINGTON THROUGH TUESDAY. LIGHT NW FLOW
ALOFT. AIR MASS IS MOIST IN THE LOWER LEVELS AND SOMEWHAT MOIST
ALOFT. STABLE CONDITIONS EXCEPT SLIGHTLY UNSTABLE ALONG THE CASCADE
CREST.

THE UPPER LOW WILL DEEPEN THE MARINE LAYER AND WEAK LIFT MAY PRODUCE
PATCHY DRIZZLE THIS MORNING. WIDESPREAD MVFR IS LIKELY THIS MORNING
WITH PATCHY IFR CONDITIONS WHERE DRIZZLE DEVELOPS. MVFR CEILINGS
WILL BRIEFLY SCATTER THIS AFTERNOON AND EVENING BUT SHOULD FILL BACK
IN OVERNIGHT.

 KSEA...CEILING AROUND 1-3K FT WILL RISE TO 4K FT IN THE AFTERNOON.
DRIZZLE IS POSSIBLE THIS MORNING. THE DEEP MARINE LAYER WILL REMAIN
INTACT. SW WIND 6-10 KT. CHB

&&

.MARINE...HIGH PRES WILL REMAIN OFFSHORE WITH LOWER PRES INLAND.
SMALL CRAFT ADVISORY STRENGTH WINDS OF 15 TO 25 KT WILL EACH EVENING
THROUGH TUESDAY NIGHT AS ONSHORE FLOW INCREASES. ONSHORE FLOW WILL
WEAKEN WEDNESDAY THROUGH FRIDAY. CHB

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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









000
FXUS66 KSEW 251035
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
335 AM PDT MON MAY 25 2015

.SYNOPSIS...A RIDGE OFFSHORE WILL MAINTAIN LOW LEVEL ONSHORE FLOW
ACROSS WESTERN WASHINGTON THROUGH TUESDAY...KEEPING SKIES MOSTLY
CLOUDY. WEAKER ONSHORE FLOW FROM MID WEEK ONWARD ALONG WITH HIGHER
PRESSURE BUILDING OVER THE REGION WILL ALLOW MORE AFTERNOON SUNSHINE
AND A WARMING TREND. THE AIR MASS OVER THE CASCADES WILL CONTINUE TO
BECOME SLIGHTLY UNSTABLE LATE IN THE DAY FOR A CHANCE OF SHOWERS
NEAR THE CREST.

&&

.SHORT TERM...SATELLITE IMAGERY SHOWS UPPER LEVEL LOW HAS MOVED INTO
SOUTH CENTRAL BRITISH COLUMBIA EARLY THIS MORNING. OVER WESTERN
WASHINGTON MORE OF THE SAME WITH CLOUDY SKIES ACROSS THE AREA.
TEMPERATURES AT 3 AM WERE IN THE UPPER 40S TO MID 50S.

LITTLE CHANGE IN THE FORECAST THIS MORNING. LOW LEVEL ONSHORE FLOW
CONTINUING TODAY KEEPING SKIES CLOUDY ACROSS THE AREA. TOPS OF THE
MARINE LAYER BETWEEN 5000 AND 6000 FEET SO ONCE AGAIN NO REAL
BREAKOUT EXPECTED THIS AFTERNOON. MODELS HAVE THE LOW DRIFTING SOUTH
THIS MORNING AND GIVEN THE DEEP MARINE LAYER A LITTLE EXTRA LIFT
COULD RESULT IN SOME LOCAL DRIZZLE. BY 00Z TUESDAY UPPER LEVEL LOW
OVER THE NORTHERN PORTION OF EASTERN WASHINGTON. AIR MASS OVER THE
CASCADES BECOMING SLIGHTLY UNSTABLE THIS AFTERNOON. THIS ADDED ON TO
SOME WRAP AROUND MOISTURE FROM THE LOW WILL KEEP A CHANCE OF SHOWERS
IN THE FORECAST. HIGHS IN THE LOWLANDS WILL CONTINUE TO BE A LITTLE
BELOW NORMAL...UPPER 50S TO MID 60S.

UPPER LEVEL LOW NOT MOVING MUCH TONIGHT AND TUESDAY WITH THE LOW
CENTER MODELED TO BE NEAR PASCO BY 00Z WEDNESDAY. WITH THE LOW IN
THE VICINITY THIS WILL KEEP THE THREAT OF SHOWERS GOING IN THE
CASCADES. FOR THE LOWLANDS ONSHORE FLOW CONTINUES TONIGHT AND
TUESDAY BUT BEGINS TO WEAKEN A TOUCH TUESDAY AFTERNOON INCREASING
THE CHANCES FOR A LITTLE SUN LATE IN THE DAY ON TUESDAY. WITH PLENTY
OF CLOUD COVER TONIGHT LOW TUESDAY MORNING WILL BE IN THE UPPER 40S
TO MID 50S. LOW LEVEL ONSHORE FLOW TUESDAY WILL KEEP HIGHS IN THE
UPPER 50S TO MID 60S.

UPPER LEVEL LOW KICKS OUT SLOWLY TO THE SOUTHEAST TUESDAY NIGHT AND
WEDNESDAY WITH AN UPPER LEVEL RIDGE BUILDING OFFSHORE. THE SLOW
TREND OF WEAKENING ONSHORE FLOW WILL CONTINUE ON WEDNESDAY RESULTING
IN A LITTLE SUNSHINE IN THE AFTERNOON. TEMPERATURES ALOFT DO NOT
WARM MUCH WITH THE 850 MB TEMPERATURES ONLY RISING FROM AROUND PLUS
8 ON TUESDAY TO PLUS 10 ON WEDNESDAY. ONSHORE FLOW STILL STRONG
ENOUGH FOR PLENTY OF CLOUD COVER TUESDAY NIGHT INTO AT LEAST EARLY
WEDNESDAY AFTERNOON FOR THE INTERIOR WITH THE CLOUDS HANGING TOUGH
ALONG THE COAST WEDNESDAY AFTERNOON. MOS SEEMS A LITTLE OVER
AGGRESSIVE WITH THE WARM UP WITH THE ONSHORE FLOW STILL PRESENT
WEDNESDAY AFTERNOON. WILL UNDERCUT THE GUIDANCE BY A COUPLE OF
DEGREES GOING FOR 60S AND LOWER 70S INLAND WHILE KEEPING HIGHS IN
THE LOWER 60S ALONG THE COAST. EVEN WITH THE RIDGE BUILDING OFFSHORE
THE AIR MASS OVER THE CASCADES WILL ONCE AGAIN BECOMING SLIGHTLY
UNSTABLE LATE IN THE DAY FOR A CHANCE OF SHOWERS...MAINLY NEAR THE
CREST.

.LONG TERM...EXTENDED MODELS WHICH HAVE BEEN IN GOOD AGREEMENT THE
LAST COUPLE OF NIGHTS HAVE LOST A BIT OF CONSISTENCY BOTH AMONG THE
INDIVIDUAL MODELS AND RUN TO RUN. GFS SHOWING UPPER LEVEL RIDGE
MOVING INTO WESTERN WASHINGTON ON THURSDAY. THE ECMWF IS WEAKER WITH
THIS FEATURE BECAUSE OF YET ANOTHER UPPER LEVEL LOW MOVING INTO
CENTRAL BRITISH COLUMBIA. THE GFS IS WEAKER AND FURTHER NORTH WITH
THIS FEATURE. BOTH MODELS STILL HAVE DECENT 500 MB HEIGHTS OVER
WESTERN WASHINGTON...MID 570 DMS AND WEAK LOW LEVEL ONSHORE FLOW.
WILL STAY WITH THE IDEA OF CONTINUING THE WARMING TREND ON THURSDAY
WITH PLENTY OF HIGHS IN THE 70S OVER THE INTERIOR. ECMWF CONTINUES
TO DROP THE LOW SOUTH ON FRIDAY INDUCING A STRONGER ONSHORE PATTERN
VERSUS THE GFS WHICH HAS THE LOW MUCH FURTHER NORTH. THE ECMWF DOES
KEEP THE PRECIPITATION WITH THE LOW NORTH OF THE BORDER. ON SATURDAY
THE ECMWF MOVES THE LOW BACK TO THE NORTHEAST WHILE THE GFS SOLUTION
CONTINUES TO PUT THE LOW FURTHER TO THE NORTH AND EAST. MODELS ARE
IN GENERAL AGREEMENT WITH ANOTHER WEAK UPPER LEVEL LOW DEVELOPING
NEAR HAIDA GWAII ON SUNDAY. CURRENT FORECAST FOLLOWS THE WARMER...BY
ABOUT 5 DEGREES...GFS SOLUTION FOR FRIDAY THROUGH SUNDAY WITH HIGHS
IN THE LOWER TO MID 60S ON THE COAST AND MID 60S TO MID 70S OVER THE
INTERIOR WITH THE WARMEST DAY BEING FRIDAY. WITH THE NEWER SOLUTIONS
IN THE EXTENDED RUNS THIS MORNING WILL LET THE CURRENT FORECAST RIDE
FOR ANOTHER FORECAST PACKAGE. FELTON

&&

.AVIATION...A WEAK UPPER LEVEL LOW WILL SLOWLY MOVE SOUTHEAST
ACROSS MAINLY EASTERN WASHINGTON THROUGH TUESDAY. LIGHT NW FLOW
ALOFT. AIR MASS IS MOIST IN THE LOWER LEVELS AND SOMEWHAT MOIST
ALOFT. STABLE CONDITIONS EXCEPT SLIGHTLY UNSTABLE ALONG THE CASCADE
CREST.

THE UPPER LOW WILL DEEPEN THE MARINE LAYER AND WEAK LIFT MAY PRODUCE
PATCHY DRIZZLE THIS MORNING. WIDESPREAD MVFR IS LIKELY THIS MORNING
WITH PATCHY IFR CONDITIONS WHERE DRIZZLE DEVELOPS. MVFR CEILINGS
WILL BRIEFLY SCATTER THIS AFTERNOON AND EVENING BUT SHOULD FILL BACK
IN OVERNIGHT.

 KSEA...CEILING AROUND 1-3K FT WILL RISE TO 4K FT IN THE AFTERNOON.
DRIZZLE IS POSSIBLE THIS MORNING. THE DEEP MARINE LAYER WILL REMAIN
INTACT. SW WIND 6-10 KT. CHB

&&

.MARINE...HIGH PRES WILL REMAIN OFFSHORE WITH LOWER PRES INLAND.
SMALL CRAFT ADVISORY STRENGTH WINDS OF 15 TO 25 KT WILL EACH EVENING
THROUGH TUESDAY NIGHT AS ONSHORE FLOW INCREASES. ONSHORE FLOW WILL
WEAKEN WEDNESDAY THROUGH FRIDAY. CHB

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.

&&

$$

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000
FXUS66 KSEW 250402
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
902 PM PDT SUN MAY 24 2015

.SYNOPSIS...A RIDGE OFFSHORE WILL MAINTAIN LOW LEVEL ONSHORE FLOW
ACROSS WESTERN WASHINGTON THROUGH TUESDAY...KEEPING SKIES MOSTLY
CLOUDY. WEAKER ONSHORE FLOW FROM MID WEEK ONWARD ALONG WITH HIGHER
PRESSURE BUILDING OVER THE REGION WILL ALLOW MORE AFTERNOON SUNSHINE
AND A WARMING TREND. THE AIR MASS OVER THE CASCADES WILL CONTINUE TO
BECOME SLIGHTLY UNSTABLE LATE IN THE DAY FOR A CHANCE OF SHOWERS
NEAR THE CREST.

&&

.SHORT TERM...AN UPPER LEVEL LOW OVER SOUTHERN B.C. WILL SPIN OVER
WASHINGTON MONDAY AND TUESDAY FOR ISOLATED TO SCATTERED SHOWERS IN
THE CASCADES. THERE IS ALSO A CHANCE OF THUNDERSTORMS IN THE NORTH
CASCADES MONDAY AFTERNOON AND EVENING AS THE COLD POOL MOVES
OVERHEAD...HOWEVER MOST OF THE ACTIVITY WILL LIKELY BE EAST OF THE
CREST. MEANWHILE...LOW LEVEL ONSHORE FLOW WILL CONTINUE FOR MOSTLY
CLOUDY SKIES ACROSS THE LOWLANDS.

THE UPPER LOW WILL WEAKEN AS IT EXITS EAST ON WEDNESDAY WHILE A
RIDGE MOVES IN FROM THE WEST. THERE IS STILL ENOUGH MOISTURE AND
INSTABILITY FOR A CHANCE OF SHOWERS ALONG THE WEST SLOPES OF THE
CASCADES...WITH ISOLATED THUNDERSTORMS POSSIBLE. THE LOWLANDS WILL
REMAIN DRY WITH A FEW SUNBREAKS POSSIBLE IN THE AFTERNOON. 33

.LONG TERM...PREVIOUS DISCUSSION...THE OFFSHORE UPPER LEVEL RIDGE
AXIS WILL MOVE INLAND OVER W WA ON THURSDAY THEN SHIFT E OVER MT ON
FRIDAY. HOWEVER THE RIDGE WILL BE BROADENING AT THE SAME TIME SO
THAT W WA WILL REMAIN UNDER ITS INFLUENCE. A SURFACE RIDGE WILL
REMAIN ABOUT 500 NM OFFSHORE ALONG ROUGHLY 135W...BUT THE ONSHORE
PRESSURE GRADIENTS OVER W WA WILL BE WEAK AND PREDOMINANTLY
WESTERLY. THIS WILL LIMIT THE AMOUNT OF MARINE MOISTURE SPREADING
INLAND OVER W WA EACH EVENING...RESULTING IN AFTERNOON CLEARING
AFTER AREAS OF MORNING LOW CLOUDS. ADDITIONAL WARMING FROM THE RIDGE
WITH AFTERNOON SUNSHINE SHOULD KICK MAX TEMPS INTO THE 70S OVER THE
INTERIOR. ONSHORE FLOW WILL KEEP THE COAST IN THE 60S. KAM

&&

.AVIATION...A WEAK UPPER LEVEL LOW WILL SLOWLY MOVE SOUTHEAST
ACROSS MAINLY EASTERN WASHINGTON TONIGHT THROUGH TUESDAY. LIGHT NW
FLOW ALOFT. AIR MASS IS MOIST IN THE LOWER LEVELS AND SOMEWHAT MOIST
ALOFT. STABLE CONDITIONS EXCEPT SLIGHTLY UNSTABLE ALONG THE CASCADE
CREST. THE UPPER LOW WILL DEEPEN THE MARINE LAYER AND WEAK LIFT MAY
PRODUCE PATCHY DRIZZLE MONDAY MORNING. MVFR CEILINGS WILL BRIEFLY
SCATTER THIS EVENING BUT SHOULD FILL BACK IN OVERNIGHT. WIDESPREAD
MVFR IS EXPECTED MONDAY MORNING WITH PATCHY IFR CONDITIONS WHERE
DRIZZLE DEVELOPS.

KSEA...CEILING AROUND 3K FT WILL LOWER TO 1-2K FT OVERNIGHT. DRIZZLE
IS POSSIBLE MONDAY MORNING. CEILINGS WILL LIFT LATE MONDAY AFTERNOON
BUT ANY SCATTERING WILL BE SHORT LIVED AS THE DEEP MARINE LAYER
REMAINS INTACT. CHB

&&

.MARINE...HIGH PRES WILL REMAIN OFFSHORE WITH LOWER PRES INLAND.
WINDS OF 15 TO 25 KT WILL INCREASE TO 20 TO 30 KT DURING THE EVENING
THROUGH EARLY MONDAY MORNING AS ONSHORE FLOW INCREASES. SMALL CRAFT
ADVISORY STRENGTH WESTERLY WINDS ARE LIKELY EACH EVENING IN THE
STRAIT TONIGHT THROUGH AT LEAST TUESDAY NIGHT. ONSHORE FLOW WILL
WEAKEN WEDNESDAY THROUGH FRIDAY. CHB

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.

&&

$$

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000
FXUS66 KSEW 250402
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
902 PM PDT SUN MAY 24 2015

.SYNOPSIS...A RIDGE OFFSHORE WILL MAINTAIN LOW LEVEL ONSHORE FLOW
ACROSS WESTERN WASHINGTON THROUGH TUESDAY...KEEPING SKIES MOSTLY
CLOUDY. WEAKER ONSHORE FLOW FROM MID WEEK ONWARD ALONG WITH HIGHER
PRESSURE BUILDING OVER THE REGION WILL ALLOW MORE AFTERNOON SUNSHINE
AND A WARMING TREND. THE AIR MASS OVER THE CASCADES WILL CONTINUE TO
BECOME SLIGHTLY UNSTABLE LATE IN THE DAY FOR A CHANCE OF SHOWERS
NEAR THE CREST.

&&

.SHORT TERM...AN UPPER LEVEL LOW OVER SOUTHERN B.C. WILL SPIN OVER
WASHINGTON MONDAY AND TUESDAY FOR ISOLATED TO SCATTERED SHOWERS IN
THE CASCADES. THERE IS ALSO A CHANCE OF THUNDERSTORMS IN THE NORTH
CASCADES MONDAY AFTERNOON AND EVENING AS THE COLD POOL MOVES
OVERHEAD...HOWEVER MOST OF THE ACTIVITY WILL LIKELY BE EAST OF THE
CREST. MEANWHILE...LOW LEVEL ONSHORE FLOW WILL CONTINUE FOR MOSTLY
CLOUDY SKIES ACROSS THE LOWLANDS.

THE UPPER LOW WILL WEAKEN AS IT EXITS EAST ON WEDNESDAY WHILE A
RIDGE MOVES IN FROM THE WEST. THERE IS STILL ENOUGH MOISTURE AND
INSTABILITY FOR A CHANCE OF SHOWERS ALONG THE WEST SLOPES OF THE
CASCADES...WITH ISOLATED THUNDERSTORMS POSSIBLE. THE LOWLANDS WILL
REMAIN DRY WITH A FEW SUNBREAKS POSSIBLE IN THE AFTERNOON. 33

.LONG TERM...PREVIOUS DISCUSSION...THE OFFSHORE UPPER LEVEL RIDGE
AXIS WILL MOVE INLAND OVER W WA ON THURSDAY THEN SHIFT E OVER MT ON
FRIDAY. HOWEVER THE RIDGE WILL BE BROADENING AT THE SAME TIME SO
THAT W WA WILL REMAIN UNDER ITS INFLUENCE. A SURFACE RIDGE WILL
REMAIN ABOUT 500 NM OFFSHORE ALONG ROUGHLY 135W...BUT THE ONSHORE
PRESSURE GRADIENTS OVER W WA WILL BE WEAK AND PREDOMINANTLY
WESTERLY. THIS WILL LIMIT THE AMOUNT OF MARINE MOISTURE SPREADING
INLAND OVER W WA EACH EVENING...RESULTING IN AFTERNOON CLEARING
AFTER AREAS OF MORNING LOW CLOUDS. ADDITIONAL WARMING FROM THE RIDGE
WITH AFTERNOON SUNSHINE SHOULD KICK MAX TEMPS INTO THE 70S OVER THE
INTERIOR. ONSHORE FLOW WILL KEEP THE COAST IN THE 60S. KAM

&&

.AVIATION...A WEAK UPPER LEVEL LOW WILL SLOWLY MOVE SOUTHEAST
ACROSS MAINLY EASTERN WASHINGTON TONIGHT THROUGH TUESDAY. LIGHT NW
FLOW ALOFT. AIR MASS IS MOIST IN THE LOWER LEVELS AND SOMEWHAT MOIST
ALOFT. STABLE CONDITIONS EXCEPT SLIGHTLY UNSTABLE ALONG THE CASCADE
CREST. THE UPPER LOW WILL DEEPEN THE MARINE LAYER AND WEAK LIFT MAY
PRODUCE PATCHY DRIZZLE MONDAY MORNING. MVFR CEILINGS WILL BRIEFLY
SCATTER THIS EVENING BUT SHOULD FILL BACK IN OVERNIGHT. WIDESPREAD
MVFR IS EXPECTED MONDAY MORNING WITH PATCHY IFR CONDITIONS WHERE
DRIZZLE DEVELOPS.

KSEA...CEILING AROUND 3K FT WILL LOWER TO 1-2K FT OVERNIGHT. DRIZZLE
IS POSSIBLE MONDAY MORNING. CEILINGS WILL LIFT LATE MONDAY AFTERNOON
BUT ANY SCATTERING WILL BE SHORT LIVED AS THE DEEP MARINE LAYER
REMAINS INTACT. CHB

&&

.MARINE...HIGH PRES WILL REMAIN OFFSHORE WITH LOWER PRES INLAND.
WINDS OF 15 TO 25 KT WILL INCREASE TO 20 TO 30 KT DURING THE EVENING
THROUGH EARLY MONDAY MORNING AS ONSHORE FLOW INCREASES. SMALL CRAFT
ADVISORY STRENGTH WESTERLY WINDS ARE LIKELY EACH EVENING IN THE
STRAIT TONIGHT THROUGH AT LEAST TUESDAY NIGHT. ONSHORE FLOW WILL
WEAKEN WEDNESDAY THROUGH FRIDAY. CHB

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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







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