Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 230355
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
855 PM PDT WED OCT 22 2014

.SYNOPSIS...A WET STRONG COLD FRONT WAS FINALLY PUSHING THROUGH
SOUTHWEST WASHINGTON AND NORTHWEST OREGON THIS EVENING AS A SURFACE
WAVE HAS MOVED INTO WESTERN WASHINGTON. THERE IS A CONSIDERABLE
AMOUNT OF COLD AIR CUMULUS OFFSHORE THAT WILL SPREAD INTO OUR
FORECAST AREA LATER TONIGHT AND ON THURSDAY FOR SHOWERS AND POSSIBLY
A FEW THUNDERSTORMS...ESPECIALLY NORTH. THE NEXT RATHER STRONG LOW
PRESSURE SYSTEM WILL APPROACH FROM THE SOUTH ON FRIDAY AS A WARM
FRONT LIFTS NORTH FRIDAY AND FRIDAY NIGHT. THE ASSOCIATED STRONG COLD
FRONT IS LIKELY TO MOVE ONSHORE SATURDAY AND SATURDAY NIGHT AS THE
LOW PRESSURE CENTER ALSO MOVES THROUGH THE PACIFIC NORTHWEST...
POSSIBLY WITH A BOUT OF FAIRLY STRONG WINDS. YET ANOTHER FRONT IS
POSSIBLE EARLY NEXT WEEK.
&&

.SHORT TERM DISCUSSION...TONIGHT THROUGH SATURDAY...THERE WAS A
DECENT SURFACE WAVE THAT MOVED ALONG OUR SLOW MOVING FRONT THAT
PRODUCED SOME MODERATELY STRONG NORTH COASTAL WINDS. THE WAVE HAS
MOVED ONSHORE AND HELPED PUSH THE FRONT SOUTH AND INLAND INTO THE
CASCADES...AND WILL THEN MOVE SOUTH OF THE AREA BY EARLY THURSDAY. AS
A RESULT...AREAS THAT HAD PERSISTENT HEAVY RAIN TODAY HAS SEEN THE
RAINFALL BREAK UP AND EASE. SOME OF THE RAINFALL AMOUNTS WERE
IMPRESSIVE...WITH 6 HOUR AMOUNTS OF 1.5 INCHES OR MORE EVEN IN THE
NORTH VALLEY. AREA RIVERS HAVE CRESTED BELOW FLOOD STAGE...AND
BELIEVE THE THREAT OF RIVER FLOODING IS OVER. HOWEVER...THERE IS A
GOOD AREA OF COLD AIR CUMULUS AND SHOWERS OFF THE COAST THAT WILL
SPREAD ONSHORE LATER TONIGHT AND ESPECIALLY ON THURSDAY FOR MORE
SHOWERS AND SOME DECENT BRIEF RAINFALL AMOUNTS. THERE IS SOME
INSTABILITY ASSOCIATED WITH THEM...SO THERE IS A THREAT OF A FEW
THUNDERSTORMS ESPECIALLY IN THE NORTH HALF OF OUR FORECAST AREA.

SOME SHOWERS WILL LINGER INTO THURSDAY NIGHT...BUT THEN ALL THE
MODELS SHOW A NEW LOW DEVELOPING AT THE BASE OF THE OFFSHORE LONG
WAVE TROUGH...THEN LIFTING NORTH TOWARD OUR AREA ON FRIDAY. WHILE
SOME DETAILS VARY AMONGST THE MODELS...THE MODELS GENERALLY SHOW A
WARM FRONT LIFTING NORTH THROUGH OUR AREA FRIDAY INTO FRIDAY NIGHT
FOR SOME MORE RAIN WHILE CAUSING EAST WINDS TO0 DEVELOP. THEN THE
ASSOCIATED STRONG COLD FRONT LIKELY MOVES ON SATURDAY FOR MORE RAIN.
THE ASSOCIATED SURFACE LOW MOVES ONSHORE AND INLAND SATURDAY AND
SATURDAY NIGHT AND COULD PRODUCE SOME STRONG SOUTHERLY WINDS AT THE
COAST AND POSSIBLY INLAND AS WELL. TOLLESON

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...
SATURDAY NIGHT THROUGH WEDNESDAY...AN ACTIVE WEATHER PATTERN WILL
PERSIST THROUGH THE LONG TERM FORECAST WITH FRONTAL SYSTEMS MOVING
ACROSS THE REGION EVERY 24 TO 48 HOURS. MODELS ARE IN GOOD AGREEMENT
THAT A FRONT WILL BRING RAIN AND GUSTY WINDS SATURDAY NIGHT INTO
SUNDAY MORNING...WITH SHOWERS DWINDLING SUNDAY AFTERNOON. SNOW LEVELS
MAY DROP DOWN TO NEAR OR JUST BELOW THE CASCADE PASSES WITH THE
SHOWERS SUNDAY AFTERNOON. A WARM FRONT AHEAD OF THE NEXT SYSTEM
SHOULD GENERATE LIGHT PRECIPITATION SUNDAY NIGHT AND MONDAY BEFORE A
COLD FRONT MOVES THROUGH TUESDAY. THE MODELS ARE IN LESS AGREEMENT
WITH THE STRENGTH AND POSITION OF THE LOW WITH THIS STORM...BUT ARE
IN FAIR AGREEMENT ON THE TIMING OF RAIN. SHOWERS WILL CONTINUE
TUESDAY NIGHT INTO WEDNESDAY...THEN ANOTHER FRONT IS EXPECTED
WEDNESDAY AFTERNOON OR EVENING...WITH GREATER UNCERTAINTY ON THE
TIMING AND STRENGTH TJ.
&&

.AVIATION...THE STEADY RAINS HAVE MOVED EAST OF THE TAF LOCATIONS
WITH SHOWERS NOW MOVING INTO THE AREA. GENERALLY VFR CONDITIONS OVER
THE INTERIOR WITH SPLIT BETWEEN VFR AND MVFR ON THE COAST. SOME OF
THE HEAVIER SHOWERS MAY PRODUCE ISOLATED IFR CIGS AND VIS TONIGHT AND
THURSDAY. ANOTHER DEVELOPING WEAK LOW PRESSURE SYSTEM COULD
TEMPORARILY REDUCE FLIGHT CONDITIONS THURSDAY MORNING INTO MIDDAY
THURSDAY. IN ADDITION THERE IS A SLIGHT CHANCE FOR THUNDERSTORMS
OVERNIGHT INTO THURSDAY FOR THE NORTH OREGON AND SOUTH WASHINGTON
COASTAL AREAS.

KPDX AND APPROACHES...EXPECT VFR CONDITIONS TO PREVAIL BUT THERE
SHOULD BE OCCASIONAL MVFR CIGS WITH HEAVIER SHOWERS. A MORE ORGANIZED
SHOWERS MAY BRING INCREASED MVFR CONDITIONS THURSDAY MORNING...BUT
VFR IS EXPECTED TO PREVAIL FOR THE AFTERNOON. /26
&&

.MARINE...THE LAST LOW THAT MODELS HANDLED SOMEWHAT POORLY MOVED
THROUGH THE NORTHERN WATERS THIS AFTERNOON AND EARLY EVENING BRINGING
DECENT GALES THERE. WINDS ARE ON THE DECREASE THIS EVENING AND SHOULD
DROP BELOW SMALL CRAFT ADVISORY CRITERIA OVERNIGHT. HOWEVER MODELS
ARE SHOWING ANOTHER TROUGH SWINGING THROUGH THURSDAY MORNING AND
SHOULD BRING MARGINAL SMALL CRAFT ADVISORY WINDS. WILL HAVE TO WATCH
THIS AS THERE IS STILL THE STRONG ZONAL JET IN ABOUT THE SAME
POSITION AND CONCERN IS FOR MORE DEVELOPMENT THAN WHAT MODELS ARE
DEPICTING RIGHT NOW. SEAS WILL IN GENERAL BE ON THE DECREASE AND
SHOULD BE SUBSIDING BELOW 10 FT LATER THURSDAY. FRIDAY STILL LOOKS
RELATIVELY QUIET ACROSS THE WATERS AS SEAS WILL LIKELY DROP BELOW 10
FT.

THE BIG STORY WILL BE THIS WEEKENDS LOW PRESSURE SYSTEM. MODELS
CONTINUE TO VARY ON THE DETAILS...BUT GENERALLY AGREE A DEVELOPING
LOW PRESSURE SYSTEM...AROUND 985MB...WILL MOVE NORTHWARD INSIDE 130 W
AND POSSIBLY MAKE LANDFALL SOMEWHERE BETWEEN VANCOUVER ISLAND AND THE
NORTH OREGON COAST. THIS WILL ALMOST CERTAINLY PRODUCE GALE FORCE
WINDS ACROSS THE WATERS ON SATURDAY...WITH A STRONG POSSIBILITY OF
LOW END STORM FORCE GUSTS OF 50 KT. SEAS TO 20 FT SEEM MORE THAN
POSSIBLE LATE SATURDAY.

AFTER A BREAK LATE IN THE WEEKEND INTO EARLY NEXT WEEK...MODELS
SUGGEST ANOTHER LOW PRESSURE WILL MAKE LANDFALL ON THE WEST COAST
NEXT TUESDAY. GALE FORCE TO STORM FORCE WINDS CERTAINLY APPEAR
POSSIBLE WITH THIS STORM SYSTEM AS WELL. /NEUMAN /26
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 2 PM PDT THURSDAY FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 11 PM PDT
     THURSDAY FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO
     FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL
     9 PM PDT THURSDAY.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.
&&



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