Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 261758
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1000 AM PST WED NOV 26 2014

.SYNOPSIS...A WARM FRONT ACROSS WA THIS MORNING WILL SLOWLY LIFT
FURTHER N THROUGH TONIGHT...LEAVING THE FORECAST AREA IN A MILD AIR
MASS. A WEAK COLD FRONT WILL MOVE E ACROSS THE AREA TONIGHT BRINGING
BACK CHANCES FOR RAIN. A STRONGER COLD FRONT DROPPING DOWN FROM THE
N WILL MOVE THROUGH FRI NIGHT BRINGING COLDER WEATHER FOR THE
WEEKEND...WITH WINDS TURNING OFFSHORE SUN. SUN NIGHT AND MON A
SYSTEM COMING UP FROM THE S WILL ATTEMPT TO SPREAD SOME
PRECIPITATION UP OVER THE COLD AIR MASS LEFT OVER FROM THE WEEKEND.
&&

.SHORT TERM...RADAR AND SURFACE OBSERVATIONS SUGGEST MOST OF THE
RAIN ASSOCIATED WITH THE WARM FRONT ACROSS WA THIS MORNING WAS N OF
THE FORECAST AREA...SO WILL LEAVE JUST A LOW POP IN FOR TODAY N OF
THE COLUMBIA RIVER WHILE THE REST OF THE FORECAST AREA REMAINS DRY
AND IN THE WARM SECTOR TODAY. WITH THE REGION REMAINING IN THE WARM
SECTOR TODAY...EXPECT PERSISTENCE TYPE TEMPS TODAY TO BE THE BEST
BET...MEANING SOME MORE TEMPERATURE RECORDS MAY AGAIN BE IN JEOPARDY
TODAY.

REMAINDER OF SHORT TERM DISCUSSION UNCHANGED...THE ASSOCIATED COLD
FRONT APPROACHING 130W EARLY THIS MORNING WILL REACH THE COAST AND
BEGIN SPREADING ONSHORE TONIGHT FOR MORE RAIN AND SOME BRISK COASTAL
WINDS...BUT LIKELY STAYING BELOW HIGH WIND CRITERIA. THE FRONT WILL
CONTINUE MOVING THROUGH THE FORECAST AREA ON THANKSGIVING FOR MORE
RAIN AND LOCALLY BREEZY CONDITIONS. SNOW LEVELS WILL REMAIN QUITE
HIGH IN THE CASCADES.

THE FRONTAL BOUNDARY WILL STALL OVER THE AREA THURSDAY NIGHT BENEATH
CONFLUENT FLOW ALOFT AS THE SOUTHERN BRANCH OF THE JET MERGES WITH AN
INCREASING NORTHERN BRANCH OF THE JET. THIS WILL KEEP SOME RAIN GOING
OVER MUCH OF THE AREA THURSDAY NIGHT.

A SECONDARY COLDER COLD FRONT WILL BEGIN SAGGING INTO OUR AREA FROM
THE NORTH ON FRIDAY...MERGING WITH THE STALLED SOUTHERN COLD
FRONT...AND KEEPING THE RAIN GOING...PERHAPS A LITTLE HEAVIER THAN ON
PREVIOUS DAYS. SNOW LEVELS IN THE SOUTH WASHINGTON CASCADES MAY BEGIN
TO FALL LATE IN THE DAY AS THIS SECONDARY COLD FRONT MOVES SOUTH BUT
SNOW LEVELS WILL GENERALLY STAY ABOVE THE PASS LEVELS THROUGH FRIDAY.
TOLLESON

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...
FRIDAY NIGHT THROUGH TUESDAY...COMPLICATED PATTERN EVOLVES FRIDAY
NIGHT AND SAT WITH THE COLDER AIR CONTINUING TO SLIDE S THROUGH WA
AND INTO NRN OREGON. 12Z GFS MORE IN LINE WITH THE PREVIOUS COUPLE OF
ECMWF RUNS...DEPICTING A COLD AIR WEDGE IN THE CENTRAL COLUMBIA GORGE
BY 00Z SUN. LOOK FOR THE EAST WIND TO RETURN AS WELL...BEGINNING SAT
MORNING AND CONTINUING THROUGH THE WEEKEND. BY 00Z SUN THE GFS HAS -8
TO -10C 850 MB AIR IN THE CENTRAL COLUMBIA GORGE...WHILE THE ECMWF IS
JUST A TOUCH WARMER. FORTUNATELY...THE DRIER NLY FLOW WILL SHUNT
PRECIP FURTHER TO THE S. A CLOSED LOW WELL OF THE NRN CA COAST SAT
STARTS TO DRIFT NE SAT NIGHT AND SUN. THERE IS THE POTENTIAL FOR A
DEFORMATION BAND OVER NRN CA TO DRIFT NWD LATE SUN INTO MON. THIS
COULD BE PROBLEMATIC AS THE MOISTURE OVERRUNS THE COLD
AIR....ESPECIALLY FOR THE COLUMBIA GORGE AND UPPER HOOD RIVER VALLEY.
WEISHAAR
&&

.AVIATION...GENERALLY VFR ACROSS THE AREA AS OF 17Z...EXCEPT FOR
AREAS OF IFR ALONG THE N OREGON AND S WA COAST. EXPECT VFR TO
PREVAIL THROUGH AT LEAST THE EVENING HOURS. CIGS LOWER ALONG THE
COAST AFTER 03Z THU AS A COLD FRONT APPROACHES. LOOK FOR
CONDITIONS ALONG THE COAST TO FALL INTO MVFR BETWEEN 04Z TO 06Z
WITH PRECIP INCREASING OVERNIGHT. VFR SHOULD HOLD OVER THE INLAND
AREAS THROUGH AT LEAST 12Z THU...THEN MVFR CONDITIONS
INCREASE...WITH HIGHER TERRAIN BECOMING OBSCURED.

KPDX AND APPROACHES...VFR CONDITIONS TO PREVAIL THROUGH AT LEAST
12Z THU. RAIN DEVELOPS OVER WRN APPROACHES AROUND 10Z THEN SPREADS
E THEREAFTER...WITH LOCALIZED MVFR DEVELOPING AFTER 13Z. WEISHAAR

&&

.MARINE...WIND SPEEDS HOLDING AT 15 TO 20 KT THIS MORNING WITH
GUSTS UP TO 25 KT. SPEEDS RAMP UP THIS AFTERNOON AHEAD OF AN
APPROACHING FRONTAL SYSTEM. SHOULD SEE GALE FORCE WIND GUSTS OVER
MUCH OF THE WATERS BY LATE THIS AFTERNOON...BUT MORE SO IN THE 02Z
TO 08Z TIME FRAME. ALTHOUGH NOT A CLASSIC CASE...SOME MODEL
GUIDANCE IS SUGGESTING THE POTENTIAL FOR SOME COASTAL JET
ENHANCEMENT WITHIN 20 NM. COULD SEE SOME GUSTS UP TO 40 KT IF THIS
OCCURS. HIGH-END SMALL CRAFT ADVISORY SPEEDS PERSIST THU MORNING.
LATEST MODEL RUNS SHOW 20-25 KT NW WIND DEVELOPING OVER THE N
WATERS FRI EVENING THEN SPREADING FURTHER S OVERNIGHT. WIND TURNS
OFFSHORE OVER THE WEEKEND WITH POTENTIAL GUSTS 20 TO 30 KT NEAR
GAPS IN THE COASTAL TERRAIN.

SEAS EXPECTED TO BUILD TO 10 FT LATER TODAY THEN STAY ABOVE 10 FT
THROUGH AT LEAST FRI NIGHT. WEISHAAR

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 4 PM PST THIS AFTERNOON FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     GALE WARNING FROM 4 PM THIS AFTERNOON TO 4 AM PST THURSDAY FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM 4 PM THIS
     AFTERNOON TO 10 AM 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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