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000
FXUS66 KPQR 101350 AAA
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
646 AM PDT MON MAR 10 2014

.SYNOPSIS...AIR MASS REMAINS UNSTABLE AND MOIST AS AN UPPER TROUGH
MOVES THROUGH THE REGION. EXPECT SHOWERS THROUGH TODAY. SHOWERS WILL
GRADUALLY DECREASE LATER MON AS HIGH PRES BEGINS BUILDING INTO THE
REGION.  HIGH PRES WILL BRING MILD AND DRY WEATHER FOR TUE THROUGH
EARLY THU...THEN SOME THREAT OF SHOWERS RETURNS ON FRIDAY BEFORE HIGH
PRESSURE RETURNS FOR THE WEEKEND.
&&

.UPDATE...SOME RAIN SHADOWING GOING ON IN THE VALLEY...BUT AS THE
BACK EDGE OF THE UPPER TROUGH MOVES IN EXPECT SHOWERS TO FILL INTO
THE VALLEY A BIT MORE IN THE COMING HOURS. OCCASIONAL MODERATE TO
BRIEFLY HEAVY DOWNPOURS WILL BE THE MAIN HAZARD. ISOLATED THUNDER
CHANCE STILL EXISTS. WE ALSO ADDED A SMALL CRAFT ADVISORY FOR WINDS
FOR THE WATERS AS THE GRADIENT IS A BIT TIGHTER THAN INITIALLY
EXPECTED. RAP/HRRR SHOW WINDS COMING DOWN LATE THIS MORNING/EARLY
AFTERNOON. KMD/CULLEN

&&

.SHORT TERM...TPW PLOTS SHOW THE MAIN MOISTURE PLUME IS NOW OFF TO
OUR SOUTH AND EAST. THE MAIN SURFACE FRONT HAS SHIFTED EAST OF THE
CASCADES BUT AN ELEVATED FRONTAL BOUNDARY LINGERS OVER THE CASCADES
WHERE STEADY BUT LIGHTER PRECIPITATION CONTINUES. ROAD REPORTS FROM
ODOT SUGGEST SLUSH/SNOW AT SANTIAM PASS AND THUS SNOW LEVELS ARE
GETTING DOWN INTO THE 4500-5000 FOOT RANGE OR SO. MEANWHILE...THE
TRAILING UPPER TROUGH IS JUST OFFSHORE...WITH SLIGHTLY DEEPER
MOISTURE ALONG AND NORTH OF THE COLUMBIA RIVER. AT THE SURFACE...WE
ARE STARTING TO ADVECT IN COOLER AND DRIER AIR SEEN IN DEWPOINT
READING NOT DROPPING BACK INTO THE MID 40S.

THE UPPER TROUGH AXIS WILL REACH THE COAST SOON..AND PUSH INTO THE
VALLEY THIS MORNING. THERE HAVE ALREADY BEEN QUITE A FEW SHOWERS
AHEAD OF THIS WAVE INLAND WITH A LONE LIGHTNING STRIKE OR TWO NEAR
GRESHAM JUST BEFORE MIDNIGHT. THE MOST ORGANIZED BATCH IS AT THE
MOUTH OF THE COLUMBIA RIVER UNDER THE COLD POOL. AS THE COLD CORE
MOVES OVERHEAD EXPECT INSTABILITY TO INCREASE AND GIVE A BIT MORE
KICK TO THE SHOWERS THIS MORNING. IN THE AFTERNOON THE CORE OF THE
UPPER TROUGH HAS PUSHED INTO THE CASCADES...SO EXPECT THINGS TO WIND
DOWN FARTHER WEST. ISOLATED THUNDER IS POSSIBLE JUST ABOUT ANYWHERE
WITH A BETTER CHANCE IN THE NORTH. MORE COMMON WILL BE HEAVIER
SHOWERS WITH BRIEF DOWNPOURS AND POSSIBLY SOME SMALL HAIL. SINCE THE
LAST FEW DAYS HAVE BEEN FAIRLY MILD...IT WILL FEEL SOMEWHAT COOLER
TODAY...AND TO SOME DEGREE THAT WILL HOLD TUESDAY...ESPECIALLY IN
THE MORNING...AS OVERNIGHT LOWS TONIGHT WILL BE QUITE A BIT COLDER
THAN THE LAST FEW NIGHTS. OUTLYING AREAS WILL BE PUSHING THE
FREEZING MARK POSSIBLY TONIGHT AND AGAIN ON TUESDAY NIGHT.

SNOW LEVELS IN THE CASCADES WILL HOLD NEAR THE PASS ELEVATIONS TODAY.
CURRENT WINTER WEATHER ADVISORY IS IN PLACE AND WILL LEAVE IT ALONE
AS IT HAS NOT SNOWED AT THE PASSES IN A LITTLE WHILE. EXPECT
GENERALLY 2 TO 3 INCHES AT PASS LEVELS. THE BETTER VORTICITY
ADVECTION ASSOCIATED WITH THE BASE OF THE TROUGH MOVES THROUGH THE
SOUTH...THUS MAYBE 5-6 INCHES AT THE HIGHEST CASCADE ELEVATIONS OF
LANE COUNTY WHERE THE FRONT IS HUNG UP WITH BETTER MOISTURE. EXPECT
MORE SHOWERY ACCUMULATIONS CLOSER TO MOUNT HOOD.

AN UPPER RIDGE WILL BUILD IN TONIGHT AND MOVE ONSHORE TUESDAY
FOR DRYING...WITH SOME LOCAL FOG AND LOW CLOUDS IN THE NIGHT AND
MORNING HOURS. IT LOOKS LIKE WE SHOULD GET A FAIR AMOUNT OF SUNSHINE
TUESDAY AFTERNOON AS A THERMAL TROUGH DEVELOPS IN WESTERN OREGON
TUESDAY AFTERNOON...THEN SHIFTS TO THE COAST TUESDAY NIGHT AND
WEDNESDAY. THIS SHOULD BRING A MODEST NORTH TO NORTHEAST LOW LEVEL
WIND FLOW TO OUR AREA TUESDAY AFTERNOON THAT TURNS EASTERLY AND
INCREASES MODESTLY TUESDAY NIGHT IN WEDNESDAY.  /KMD

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...WEDNESDAY
NIGHT THROUGH SUNDAY...MODELS CONTINUE TO SHOW
HIGH PRESSURE PREVAILING OVER THE REGION LATE WEDNESDAY...BUT NOW
BOTH THE GFS AND ECMWF HAVE COME ON BOARD WITH A WEAK SHORTWAVE
RIDING OVER THE RIDGE BY THURSDAY. THIS WILL STRENGTHEN ONSHORE FLOW
AND BRING A THREAT FOR LIGHT SHOWERS AND INCREASED CLOUD COVER
THROUGH LATE THIS WEEK...MAINLY OVER THE FAR NW CORNER OF OUR
FORECAST AREA. THE UPPER LEVEL RIDGE AMPLIFIES ONCE AGAIN BY THIS
UPCOMING WEEKEND...BRINGING DRY AND SEASONAL CONDITIONS. /27
&&

.AVIATION...GENERALLY VFR INLAND AND IFR ALONG THE COAST AT THIS
HOUR. UNSTABLE AIR MASS REMAINS OVER THE COAST TODAY FOR MOSTLY
MVFR...THOUGH CHANCE OF SOME IMPROVEMENT TO VFR. HEAVIER SHOWERS
LIKELY TO RESULT IN BRIEF PERIODS OF 2-3 SM VSBY AND SMALL HAIL.
INSTABILITY SUFFICIENT TO NOT RULE OUT TSTMS ALONG THE COAST UNTIL
18Z...AND INLAND THROUGH ABOUT 02Z. INLAND AREAS LIKELY
PREDOMINATELY VFR...EXCEPT FOR BRIEF ROUNDS OF MVFR IN HEAVIER
SHOWERS. COAST RANGE...CASCADES AND OTHER HIGHER TERRAIN TO BE
FREQUENTLY OBSCURED.

KPDX AND APPROACHES...EXPECT PREDOMINANTLY VFR CONDITIONS TODAY
WITH ROUNDS OF RAIN SHOWERS. HOWEVER...HEAVIER SHOWERS WILL LIKELY
PRODUCE BRIEF PERIODS OF MVFR. ENOUGH INSTABILITY WILL BE PRESENT
FOR A 10 TO 20 PERCENT CHANCE OF A TSTM AT THE TERMINAL AND
VICINITY THROUGH ABOUT 02Z. SHOWERS SHOULD END IN THE
EVENING WITH THE POTENTIAL FOR MVFR PATCHY FOG AFTER 09Z. CULLEN

&&

.MARINE...WINDS REMAIN QUITE LIGHT TONIGHT WITH GUSTS TOPPING OUT
AT 15 KT. HIGH PRESSURE WILL KEEP THINGS QUIET TODAY AS HIGH PRES
CONTINUES TO BUILD OVER THE WATERS. HOWEVER...A THERMALLY-INDUCED
AREA OF LOW PRES IS EXPECTED TO FORM ALONG THE S OREGON COAST
EARLY TUE AND THEN EXPAND N TUE AFTERNOON. THIS WILL CREATE THE
OPPORTUNITY FOR SOME N GUSTS 20 TO 25 KT...PARTICULARLY S OF
NEWPORT.

SEAS HAVE BEEN TRACKING QUITE CLOSE TO ENP GUIDANCE AND HAVE BEEN
HOVERING NEAR 10 FT SINCE LATE LAST EVENING. BUOY OBS CURRENTLY
SHOW SEAS REMAINING AT OR JUST BELOW A ROUNDED 10 FT...SO ELECTED
TO KEEP THE SCA FOR HAZARDOUS SEAS IN EFFECT UNTIL CURRENT
EXPIRATION TIME OF 4 AM. SEAS WILL CONTINUE TO GRADUALLY DECREASE
TODAY...TO NEAR 7 FT BY LATE THIS AFTERNOON. AN INCOMING WEST
SWELL AROUND 10 TO 12 FT STILL LOOKS ON TAP FOR WEDNESDAY WITH
SEAS QUIETING DOWN ONCE AGAIN LATE IN THE WEEK...UNTIL THE NEXT
SYSTEM MOVES INTO THE WATERS ON SAT. CULLEN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER WEATHER ADVISORY UNTIL 4 PM PDT THIS AFTERNOON FOR
     CASCADES IN LANE COUNTY-NORTHERN OREGON CASCADES.

WA...NONE.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL  2PM FOR COASTAL WATERS
     FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM 11 AM
     THIS MORNING TO 3 PM PDT THIS AFTERNOON.

&&


$$

MORE WEATHER INFORMATION ONLINE AT..
    HTTP://WEATHER.GOV/PORTLAND

INTERACT WITH US VIA SOCIAL MEDIA
    WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
    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.