Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 230918
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
220 AM PDT WED APR 23 2014

.SYNOPSIS...A WARM FRONT WILL APPROACH THE COAST TODAY THEN LIFT N
INTO WA TONIGHT. A COLD FRONT WILL FOLLOW CLOSELY BEHIND...MOVING
INLAND THU MORNING. THIS WILL USHER IN ANOTHER COOL SHOWERY PATTERN
THAT WILL LAST UNTIL THE END OF THE WEEK AS AN UPPER TROUGH SLOWLY
MOVES ACROSS. AN ACTIVE WEATHER PATTERN IS EXPECTED TO CONTINUE THIS
WEEKEND.

&&

.SHORT TERM...MODELS ALL INDICATE DEEP MOIST ISENTROPIC LIFT TODAY
ON LAYERS FROM 285K THROUGH 300K...SPELLING A WET DAY TODAY. THE
ISENTROPIC LIFT CONTINUES UNTIL A WARM FRONT LIFTS THROUGH NW OREGON
THIS EVENING. LATER TONIGHT INTO THU MORNING LIFT RELIES MORE ON THE
COLD FRONT AND SHORTWAVE MODELS DEPICT MOVING THROUGH AS AN UPPER
TROUGH BGINS TO DIG IN ALONG THE COAST. THIS WILL KEEP POPS
CATEGORICAL FOR THE ENTIRE REGION TODAY THROUGH THU MORNING...
ALTHOUGH THERE MAY BE A SHORT DOWN TIME ON PRECIPITATION AFTER THE
WARM FRONT MOVES THROUGH AND BEFORE THE DYNAMIC LIFTING KICKS IN.
SURFACE OBSERVATIONS OVER THE CASCADES EARLY WED MORNING SHOWED SNOW
LEVELS ON THE ORDER OF 3500 FT...AND ARE LIKELY TO LIFT ONLY SLOWLY
UNTIL THE WARM FRONT MOVES IN THIS EVENING. AT THAT POINT MODELS
SUGGEST SNOW LEVELS POP UP ABOVE THE CASCADE PASSES...BRINGING AN
END TO THE ACCUMULATING SNOW. WILL CONTINUE WITH THE WINTER WEATHER
ADVISORY THROUGH 5 PM.

INITIALLY BEHIND THE COLD FRONT THU AFTERNOON ONSHORE FLOW WILL HELP
TO SUSTAIN CHANCES FOR SHOWERS...PARTICULARLY FOR OROGRAPHICALLY
FAVORED MOUNTAINS. THE ONSHORE FLOW HOWEVER WEAKENS CONSIDERABLY THE
NIGHT...SO SHOWERS WILL BECOME INCREASINGLY RELIANT ON INSTABILITY
CREATED BY THE COOL AIR ALOFT WITH THE DIGGING TROUGH FRI.

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...FRIDAY NIGHT
THROUGH TUESDAY...EXPECT COOL AND SHOWERY CONDITIONS FOR MOST OF THE
LONG TERM FCST PERIOD. POST FRONTAL SHOWERS LINGERING THU NIGHT AND
FRI AS THE UPPER LEVEL TROF AND ASSOCIATED INSTABILITY PASS OVER THE
REGION. THERE MAY BE A BIT OF A BREAK TO START THE WEEKEND...BUT
ANOTHER FRONT IS PUSH ONSHORE LATE SAT OR SUN WHICH SHOULD BRING
ANOTHER ROUND OF MORE ORGANIZED PRECIPITATION. THE LATEST MODEL TREND
IS NOW TOWARD BUILDING AN UPPER LEVEL RIDGE OVER THE PAC NW TO START
NEXT WEEK. IT IS STILL QUITE A WAY OUT...BUT RECENT TRENDS IN MODELS
GIVE HIGHER CONFIDENCE EARLY NEXT WEEK WILL BE WARMER AND DRIER.

&&

.AVIATION...EXPECT MAINLY VFR CONDITIONS WITH ONLY OCCASIONAL MVFR
CONDITIONS EXPECTED TODAY AS MOIST AND RELATIVELY UNSTABLE ONSHORE
FLOW CONTINUES. THE LOWER ATMOSPHERE WILL STABILIZE THIS EVENING
AS THE HEART OF A WARM FRONT SPREADS OVER THE REGION...WHICH SHOULD
ALLOW CONDITIONS TO BECOME MORE SOLIDLY MVFR. IFR CONDITIONS WILL
CERTAINLY BE POSSIBLE ALONG THE COAST AND AT KHIO. HOWEVER...GUSTY
SOUTH WINDS SHOULD KEEP THE CORE WILLAMETTE VALLEY TAF SITES FROM
FALLING INTO IFR. OTHERWISE...EXPECT CONDITIONS TO IMPROVE ONCE A
COLD FRONT PASSES THROUGH AROUND OR SHORTLY AFTER 12Z THURSDAY.

KPDX AND APPROACHES...EXPECT MAINLY VFR CONDITIONS WITH OCCASIONAL
MVFR CONDITIONS MIXED IN TODAY. CONDITIONS SHOULD TREND MORE
SOLIDLY INTO MVFR THIS EVENING AS A WARM FRONT SPREADS INTO THE
REGION. EXPECT CONDITIONS TO IMPROVE WITH A COLD FRONTAL PASSAGE
AROUND OR SHORTLY AFTER 12Z THURSDAY. /NEUMAN

&&

.MARINE...A DEVELOPING 990 MB LOW PRESSURE WILL SLOWLY MOVE TOWARDS
VANCOUVER ISLAND OVER THE NEXT 36 HOURS. THIS WILL RESULT IN A
WARM FRONT SPREAD NORTHEASTWARD ACROSS THE WATERS TODAY...WHICH
SHOULD RESULT IN WIND GUSTS OF 30 TO 35 KT SPREADING OVER THE
WATERS...PARTICULARLY SOUTH OF TILLAMOOK. A TRAILING COLD FRONT
WILL THEN PUSH TOWARDS THE COAST THIS EVENING...CAUSING A COASTAL
JET TO INTENSIFY WITH SOLID 35 TO 40 KT WIND GUSTS LIKELY WITHIN
20 NM OF THE COAST. GALE FORCE WINDS SHOULD END AROUND DAYBREAK...
BUT WILL KEEP THE KEEP THE CURRENT TIMING ASSOCIATED WITH THE GALE
HEADLINE AS IS...IN CASE THIS SYSTEM SLOWS DOWN A FEW HOURS.
ANOTHER APPROACHING FRONT SATURDAY AFTERNOON AND EVENING WILL
LIKELY CAUSE SOUTH WIND GUSTS TO INCREASE INTO THE 30 TO 35 KT
RANGE.

EXPECT SEAS TO FLUCTUATE BETWEEN 8 AND 12 FT THROUGH THE WEEKEND.
SEAS SHOULD TOP OUT IN THE 12 TO 14 FT RANGE WEDNESDAY NIGHT WHEN
THE MOST SUSTAINED GALE FORCE WIND GUSTS WILL LIKELY OCCUR. /NEUMAN



&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER WEATHER ADVISORY UNTIL 5 PM PDT THIS AFTERNOON FOR
     NORTHERN OREGON CASCADES.

WA...WINTER WEATHER ADVISORY UNTIL 5 PM PDT THIS AFTERNOON FOR SOUTH
     WASHINGTON CASCADES.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 10 AM PDT THIS MORNING FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     GALE WARNING FROM 10 AM THIS MORNING TO 11 AM PDT THURSDAY FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 AM PDT THIS
     MORNING FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR
     OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 11 AM PDT
     THURSDAY.

&&

$$

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..


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