Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 110456
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
855 PM PST WED FEB 10 2016

.SYNOPSIS...MILD AIR MASS TO REMAIN OVER THE REGION THROUGH FRI.
WEAK FRONTS OFFSHORE WILL BRUSH THE NW TODAY AND THU...WITH VARIABLE
CLOUDINESS ACROSS THE REGION...ALONG WITH SOME SPOTTY LIGHT RAIN
ALONG THE COAST AND POSSIBLY INLAND. THAT CHANGES BY FRI...AS FIRST
IN A SERIES OF FRONTS PUSH INTO THE PAC NW. SHOWERY ON SATURDAY...BUT
MORE RAIN ARRIVES ON SUNDAY.

&&

.SHORT TERM...A WEAK BAROCLINIC ZONE WAS STRETCHED ACROSS THE NW
PART OF THE FORECAST THIS EVENING. LOW LEVEL MOISTURE REMAINED DEEP
ENOUGH...PRIMARILY ALONG THE COAST AND COAST RANGE...FOR SOME AREAS
OF DRIZZLE AND LIGHT RAIN THIS EVENING. THE FRONT IS LIKELY TO MOVE
LITTLE TONIGHT...BEFORE BEGINNING TO SHIFT N AGAIN THU AS A WARM
FRONT. RADAR TRENDS IN THE PAST HOUR OR SO HAVE SHOWN AN INCREASE IN
COVERAGE OF ECHOES ALONG THE CENTRAL OREGON COAST...WHICH WAS
LIFTING NE. AN INFLUX OF MID LEVEL MOISTURE LATER TONIGHT WITH
MODEST MID LEVEL ISENTROPIC LIFT SEEN AROUND THE 300K ISENTROPE WILL
BRING AN INCREASING CHANCE FOR SOME LIGHT RAIN...MAINLY TO THE N PART
OF THE FORECAST AREA LATE TONIGHT AND THU MORNING.

REMAINDER OF SHORT TERM DISCUSSION UNCHANGED...A LOW PRESSURE SYSTEM
IS STILL ON TRACK TO DEEPEN AS IT MOVES NORTHWARD ALONG 140W ON
THURSDAY. A WARM FRONT WILL SPREAD NORTHWARD IN RESPONSE AND
INCREASE RAIN CHANCES ACROSS THE AREA ON THURSDAY. AT THIS
POINT...THE DEEPEST MOISTURE AND BEST DYNAMICS WILL PRIMARILY
STAY OFFSHORE...BUT NONETHELESS...THERE SHOULD BE ENOUGH MOISTURE AND
LIFT TO PRODUCE PERIODS OF RAIN...PARTICULARLY NEAR THE COAST AND
ACROSS OUR MORE NORTHERN ZONES THURSDAY AFTERNOON.

THERE IS STILL SOME MODEST DISAGREEMENT IN REGARDS TO THE TIMING OF
WHEN A TRAILING COLD FRONT WILL PUSH THROUGH THE REGION THURSDAY
NIGHT AND/OR FRIDAY MORNING. WHILE TIMING IS STILL
UNCERTAIN...CONFIDENCE IS HIGH THAT THE AREA WILL RECEIVE A SOLID
ROUND OF RAIN AT SOME POINT DURING THIS TIME. 12Z MODEL GUIDANCE
SUGGESTED THERE MAY BE ENOUGH INSTABILITY ALOFT TO PRODUCE A FEW
ELEVATED THUNDERSTORMS AHEAD OF THE FRONT...BUT WILL HOLD OFF ON
ADDING THUNDER TO THE FORECAST UNTIL MODELS DISPLAY BETTER
CONSISTENCY.

AS COLDER AIR SPREADS INTO THE REGION FRIDAY...EXPECT SNOW LEVELS TO
LOWER INTO THE 4000-4500 FT RANGE AND PERHAPS ANOTHER 500-1000 FT
LOWER FRIDAY NIGHT INTO EARLY SATURDAY. QPF SHOULD BE SUFFICIENT TO
BRING SOME ACCUMULATING SNOW TO THE CASCADES AND CREATE A PERIOD OF
HAZARDOUS TRAVEL CONDITIONS...BUT NOT SURE IT WILL BE ENOUGH TO
WARRANT A WINTER WX ADVISORY. /NEUMAN

.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...THE PROGRESSIVE
WEATHER PATTERN WILL PERSIST INTO NEXT WEEK. MODELS CONTINUE TO SHOW
A FRONT MOVING ACROSS THE PAC NW LATE SATURDAY/EARLY SUNDAY. HAVE
INCREASED POPS ACROSS MUCH OF THE REGION SATURDAY EVENING TO ACCOUNT
FOR THE FASTER TIMING OF THE ECMWF. NOT EXPECTING TO SEE A LOT OF
CASCADE SNOW WITH THIS FRONT AS SNOW LEVELS QUICKLY RISE ABOVE 7000
FT EARLY SUNDAY. WE COULD SEE A BRIEF BREAK FROM THE RAIN MONDAY AS
A TRANSIENT UPPER LEVEL RIDGE MOVES ACROSS THE REGION...BUT WILL
MAINTAIN CHANCE POPS DUE TO SOME LINGERING INSTABILITY. A WEAK
SHORTWAVE COULD BRING SOME LIGHT SHOWERS TUESDAY. ANOTHER FRONT
ARRIVES LATE TUESDAY AND SHOULD BRING MORE RAIN AND CASCADE SNOW TO
THE REGION...WITH SNOW LEVELS LOWERING TO AROUND 3500 FT WEDNESDAY
AFTERNOON. TEMPS LOOK TO REMAIN SLIGHTLY ABOVE NORMAL THROUGH THE
FORECAST...BUT WILL TREND COOLER AFTER MONDAY. /64
&&

.AVIATION...MOSTLY VFR INLAND THIS EVENING WITH A MIX OF MVFR AND
IFR ALONG THE COAST. CONDITIONS WILL NOT IMPROVE MUCH ALONG THE
COAST INTO THU MORNING AS A WARM FRONT APPROACHES. THE WARM FRONT
WILL BRING A MIX OF VFR AND MVFR CONDITIONS ACROSS THE AREA
THURSDAY.

KPDX AND APPROACHES...VFR CONDITIONS TONIGHT AND THURSDAY MORNING.
MVFR CIGS POSSIBLE LATE THURSDAY MORNING THROUGH THURSDAY
AFTERNOON. BOWEN/TJ

&&

.MARINE...WINDS HAVE DECREASED TO NEAR CALM THIS EVENING. HOWEVER A
FRONTAL SYSTEM WILL SUPPORT ANOTHER ROUND OF SMALL CRAFT WINDS OUT
OF THE SOUTH THURSDAY AND FRIDAY. A SERIES OF LOWS OFFSHORE WILL
RESULT IN CONFUSED SEAS THURSDAY AND THURSDAY NIGHT...WITH A LONG-
PERIOD SW SWELL AND A SHORTER PERIOD NW SWELL MOVING THROUGH THE
WATERS. THE COMBINED SEAS WILL RANGE BETWEEN 10 AND 14 FEET.
BOWEN/TJ

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 10 AM THURSDAY TO 4 AM PST
     FRIDAY FOR WATERS FROM CAPE SHOALWATER WA TO CASCADE HEAD
     OR FROM 10 TO 60 NM-WATERS FROM CASCADE HEAD TO FLORENCE OR
     FROM 10 TO 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 3 AM THURSDAY TO 4
     AM PST SATURDAY FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO
     FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR WINDS FROM 4 PM THURSDAY TO 4 AM PST
     FRIDAY FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO
     CASCADE HEAD OR OUT 10 NM-COASTAL WATERS FROM CASCADE HEAD
     TO FLORENCE OR OUT 10 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM 4 AM TO
     9 AM PST THURSDAY.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM 4 PM TO
     11 PM PST 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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