Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 222256
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
256 PM PST SAT NOV 22 2014

.SYNOPSIS...SHOWERS WILL GRADUALLY DECREASE THIS EVENING AND LATE
TONIGHT. THE NEXT FRONT WILL BRING RAIN AND MOUNTAIN SNOW TO SW
WASHINGTON SUNDAY MORNING. .MOVING SOUTH THROUGHOUT THE DAY. THERE
WILL BE A BREAK IN RAIN MONDAY BEFORE A WARMER SYSTEM BRINGS
ADDITIONAL RAIN FOR TUESDAY AND TUESDAY NIGHT.THE NEXT FRONT IS
EXPECTED THANKSGIVING NIGHT.
&&

.SHORT TERM...TONIGHT THROUGH TUESDAY...A FEW UPPER SHORT WAVE
TROUGHS MOVING ACROSS THE FAR NE PACIFIC WILL MAINTAIN CONVECTIVE
SHOWERS ACROSS THE PACIFIC NW THIS EVENING. FREEZING LEVELS ARE ARE
CURRENTLY AROUND 4500 FEET. WEB CAMS SHOWS SNOW SHOWERS AT THE
WILLAMETTE...SANTIAM...AND TOMBSTONE PASSES WHICH ARE AT AROUND
5100...4800...AND 4200 FEET RESPECTIVELY. THIS SUGGESTS THAT THE SNOW
LEVEL IS CURRENTLY BETWEEN 4000 AND 4000 FEET. THE SNOW LEVEL WILL
CHANGE VERY LITTLE TONIGHT AND SUNDAY.

THE SHOWERS ARE DECREASING THIS AFTERNOON...BUT SATELLITE IMAGERY
SHOWS MORE SHOWERS OFFSHORE APPROACHING THE AREA. LIGHTNING HAS BEEN
DETECTED WITH THESE OFFSHORE SHOWERS AND HAVE CONTINUED THE SLIGHT
CHANCE FOR THUNDERSTORMS THROUGH 7PM. SINCE THESE SHOWERS MAY NOT
MAKE IT TO THE CASCADES UNTIL AROUND 9 PM AM HESITANT TO END THE
WINTER WEATHER ADVISORY EARLIER THAN THE CURRENT MIDNIGHT END
TIME...EVEN THOUGH THERE MAY BE A CONSIDERATE BREAK IN SHOWERS
BETWEEN 4 AND 9 PM.

THE SHOWERS WILL DECREASE AFTER MIDNIGHT TONIGHT AS AN UPPER LEVEL
RIDGE TRIES TO BUILD OVER THE AREA. CLOUD BREAKS MAY LEAD TO
RADIATION COOLING AND FOG DEVELOPMENT LATE TONIGHT INTO SUNDAY
MORNING...ESPECIALLY FOR THE INTERIOR VALLEYS SOUTH OF SALEM. THE
NORTH IS LESS LIKELY TO HAVE FOG DUE TO SLIGHTLY STRONGER WINDS AND
POSSIBLY CLOUDIER SKIES. THE CLOUDIER SKIES WILL BE DUE TO THE NEXT
APPROACHING FRONT THAT WILL BE APPROACHING FROM THE NW.

DESPITE THE BUILDING UPPER RIDGE...ANOTHER SURFACE FRONT WILL SNEAK
INTO THE AREA SUNDAY. THIS FRONT DOES NOT LOOK WELL DEFINED ON
SATELLITE IMAGERY YET...BUT THE MODELS ARE IN GREAT AGREEMENT THAT
THE FRONT WILL BEGIN RAIN AT THE SW WASHINGTON SHORTLY AFTER
SUNRISE...SLIDING SOUTHWARD THROUGH THE DAY.

THE HIGHEST QPF WILL BE FOR AREAS NORTH OF THE COLUMBIA RIVER WHERE
THE SW WASHINGTON COAST AND THE WILLAPA HILLS CAN EXPECT AROUND A
HALF AN INCH OF RAIN SUNDAY AND SUNDAY NIGHT. THE SW WASHINGTON
CASCADES WILL SEE HIGHER RAINFALL TOTALS...AROUND 0.75 TO 1 INCH FOR
ELEVATIONS BELOW 4000 FEET...AND POSSIBLY 4 TO 9 INCHES OF ADDITIONAL
ADDITIONAL SNOW ABOVE 4000 FEET. HAVE THEREFORE ISSUED ANOTHER WINTER
WEATHER ADVISORY FOR THE SW WASHINGTON CASCADES FOR ELEVATIONS ABOVE
4000 FEET.

PRECIPITATION WILL BE LESS FOR NW OREGON AND EXPECT AMOUNTS TO
BECOME GRADUALLY LESS FROM NORTH TO SOUTH...WITH TOTALS FROM 0.40
INCH JUST NEAR THE COLUMBIA RIVER TO 0.10 INCHES ACROSS LANE COUNTY.

SHOWERS WILL DRAMATICALLY DECREASE SUNDAY NIGHT AND MONDAY AND EXPECT
MORE VALLEY FOG MONDAY MORNING. MONDAY WILL BE MOSTLY DRY...BUT NW
OREGON WILL BE BETWEEN TWO WEATHER SYSTEMS...ONE TO THE SW AND ONE TO
THE NW. MODELS ARE LEANING TOWARDS KEEPING THESE STORMS OFFSHORE
MONDAY AND HAVE REDUCED POPS QUITE A BIT. HOWEVER THE PRESENCE OF
THESE TWO STORMS WARRANT AT LEAST A SLIGHT CHANCE FOR THE COAST AND
CASCADES.

THE TWO WEAK STORMS MAY MERGE OFFSHORE MONDAY EVENING AND PUSH
ONSHORE MONDAY NIGHT INTO TUESDAY. THE MODELS ARE NOT IN GREAT
AGREEMENT ON THIS BUT HAVE INCREASED POPS. THE SOUTHERN SYSTEM SHOULD
BRING WARMER AIR TO THE REGION AND RAISE SNOW LEVELS WELL ABOVE THE
PASSES MONDAY AND TUESDAY. TJ

.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY...THE MODELS ARE
CURRENTLY SHOWING THE UPPER LEVEL RIDGE FLATTENING OUT ON TUESDAY.
THEY TEND TO KEEP MOST OF THE MOISTURE TO OUR NORTH WHICH JUSTIFIED
LOWERING THE POPS THROUGH WEDNESDAY AFTERNOON...BUT KEEPING A SLIGHT
CHANCE OF RAIN FOR THE NORTHERN PORTIONS OF THE FORECAST AREA AND
ALONG THE COAST. THE RIDGE BUILDS SLIGHTLY ON THURSDAY...BUT A WEAK
SHORTWAVE COULD BRING ANOTHER ROUND OF RAIN THROUGH FRIDAY. A MUCH
STRONGER AND WETTER SYSTEM LOOKS TO MOVE IN OVER THE WEEKEND WHICH
COULD POSE A THREAT TO TRAVELERS RETURNING AFTER THE THANKSGIVING
HOLIDAY. DETAILS AT THIS POINT ARE STILL UNKNOWN AND WILL BE REFINED
WITH FUTURE UPDATES. THE GOOD NEWS IS THAT TEMPERATURES IN THE
EXTENDED WILL BE AT OR ABOVE SEASONAL NORMALS. /64
&&

.AVIATION...MAINLY VFR CONDITIONS BEING OBSERVED THIS AFTERNOON IN
A SHOWERY AND UNSTABLE AIR MASS. EXPECT LITTLE CHANGE THROUGH THIS
EVENING...ALTHOUGH SHOWERS SHOULD BEGIN TO DECREASE IN COVERAGE
AFTER SUNSET. EXPECT SOME PATCHY MVFR/IFR FOG OR LOW STRATUS WILL
FORM OVERNIGHT...ESPECIALLY FURTHER SOUTH INCLUDING KEUG AND KSLE.
THINK IT WILL STAY WELL MIXED ENOUGH TO KEEP VFR IN CONTROL AT THE
COAST AND OVER THE NORTHERN INTERIOR SITES. ANOTHER FRONT WILL
WORK IN FROM NORTH TO SOUTH SUN MORNING...BRINGING INCREASING RAIN
AND LIKELY MVFR CIGS TO THE NORTHERNMOST TAF SITES BETWEEN 15Z AND
18Z. THE FRONT WILL SAG SLOWLY FURTHER SOUTH THROUGH THE DAY...BUT
THE MAIN IMPACTS WILL CONTINUE TO BE FOR LOCATIONS FURTHER NORTH.

KPDX AND APPROACHES...A POST FRONTAL SHOWERY AIR MASS WILL LEAD
TO PREDOMINANTLY VFR CONDITIONS INTO SUN MORNING. A FRONT MOVING
IN FROM THE NORTH WILL SPREAD LIGHT RAIN AND POSSIBLY MVFR CIGS IN
BY AROUND 18Z SUN. PYLE
&&

.MARINE...GUSTY WESTERLY WINDS EARLIER TODAY HAVE EASED SOMEWHAT
THIS AFTERNOON...AND ARE NOW AROUND 15 KT. DECIDED TO GO AHEAD AND
CANCEL THE SMALL CRAFT ADVISORY FOR WINDS THAT WAS IN EFFECT
THROUGH THIS AFTERNOON. THE LULL IN THE WINDS SHOULD LAST THROUGH
THIS EVENING...BUT ANOTHER FRONT WILL MOVE INTO THE WATERS FROM
NORTH TO SOUTH OVERNIGHT. THIS FRONT SHOULD BRING ANOTHER ROUND OF
SOLID SMALL CRAFT ADVISORY WINDS...MAINLY OVER THE NORTHERN WATERS.
WINDS WILL SUBSIDE AGAIN SUN AFTERNOON AND EVENING...BEFORE YET
ANOTHER FRONT BRINGS MORE SMALL CRAFT WINDS ON MON.

SEAS REMAIN AROUND 12 TO 13 FT AND SHOULD CHANGE VERY LITTLE
THROUGH TONIGHT. SEAS MAY THEN INCREASE A BIT MORE INTO THE MID
TEENS ON SUN. THE NEXT FRONT ON MON AND SEVERAL SYSTEMS MOVING
THROUGH TO OUR NORTH EARLY NEXT WEEK...EXPECT SEAS TO REMAIN ABOVE
10 FT UNTIL MIDWEEK. THE LATEST ENP WAVE GUIDANCE THEN SUGGESTS
THEY FALL BELOW 10 FT TUE OR WED.
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER WEATHER ADVISORY UNTIL MIDNIGHT PST TONIGHT FOR CASCADES
     IN LANE COUNTY-NORTHERN OREGON CASCADES.

WA...WINTER WEATHER ADVISORY UNTIL MIDNIGHT PST TONIGHT FOR SOUTH
     WASHINGTON CASCADES.

     WINTER WEATHER ADVISORY FROM 7 AM TO 10 PM PST SUNDAY FOR SOUTH
     WASHINGTON CASCADES.

PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 1 AM TO 2 PM PST SUNDAY FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO CASCADE HEAD OR OUT 60
     NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 PM PST SUNDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60
     NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM PST
     SUNDAY.
&&

$$

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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