Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 011616
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
915 AM PDT WED OCT  1 2014

.SYNOPSIS...NORTHWEST FLOW ALOFT WILL BE ACROSS THE PACIFIC NORTHWEST
TODAY IN THE WAKE OF A RECENT LOW PRESSURE SYSTEM...WITH DECREASING
CLOUDS AND MORE SUNSHINE. WEAK OFFSHORE FLOW IS EXPECTED TO DEVELOP
THURSDAY AND FRIDAY. AN UPPER RIDGE ANCHORED OUT AROUND 135W WILL
SLOWLY REACH THE COAST LATE THURSDAY AND ONSHORE THURSDAY NIGHT AND
FRIDAY. THIS WILL BRING A RETURN TO WARMER AND DRIER WEATHER. THE
RIDGE MAY WEAKEN ENOUGH OVER THE WEEKEND TO ALLOW SOME LIGHT
PRECIPITATION OVER THE SOUTH WASHINGTON AND NORTH OREGON COAST AND
COAST RANGE.
&&

.SHORT TERM...THERE ARE MULTIPLE LAYERS OF CLOUDS AROUND THIS
MORNING...WITH SOME IN THE 3000 TO 4000 FOOT RANGE ALONG THE WEST
SLOPES OF THE CASCADES AND PART OF THE VALLEY AREAS..AND BACK TOWARD
THE NORTH COAST. THERE HAS BEEN SOME LOCAL FOG WITH CEILINGS BELOW
500 FEET...AND SOME CIGS AROUND 1200 FT ALONG THE LOWER COLUMBIA AND
I5 CORRIDOR AREA. WITH NORTHWEST FLOW ALOFT IN THE WAKE OF THE LOW OF
THE PAST FEW DAYS...THIS MAY KEEP THE CLOUDS HANGING AROUND FOR A
WHILE INTO THE AFTERNOON. THE LAST REMAINING SHOWERS SEEM TO BE
MAINLY OVER THE COASTAL WATERS. OTHERWISE WE WILL SEE INCREASING
AMOUNTS OF SUNSHINE TODAY. WITH THE COOL AIR MASS OVER OUR FORECAST
AREA...TEMPS TODAY WILL LIKELY STAY A LITTLE BELOW NORMAL...IN THE 65
TO 70 RANGE INLAND.

AN UPPER RIDGE HAS ITS AXIS ANCHORED OUT NEAR 135W TODAY. THE MODELS
FORECAST A LIGHT OFFSHORE FLOW PATTERN DEVELOPING THURSDAY AND
FRIDAY...PARTLY DUE TO A SYSTEM PASSING WELL TO OUR NORTH INTO
MONTANA AND ITS TRAILING HIGHER PRESSURE...AND DUE TO GOOD
RADIATIONAL CONDITIONS THE NEXT COUPLE OF DAYS THAT WILL LEAD TO A
COOLER AIR MASS EAST OF THE CASCADES. GRADIENTS WILL REMAIN VERY
LIGHT TONIGHT AND EARLY THURSDAY...SO WITH SOMEWHAT DAMP GROUND
CONTINUING...EXPECT AREAS OF FOG AND LOW STRATUS TO DEVELOP AGAIN
TONIGHT AND EARLY THURSDAY IN COMBINATION WITH COOL TEMPS. THE MODELS
SHOW MORE OF A NORTHERLY FLOW DEVELOPING DOWN THE VALLEY WITH A LIGHT
EAST FLOW IN THE GORGE ON THURSDAY. THE GRADIENT TURNS MORE EASTERLY
THURSDAY NIGHT AND FRIDAY AND THE EAST WIND THROUGH THE GORGE WILL
INCREASE THEN...WITH GUSTS TO 35 MPH OR SO POSSIBLE AROUND CORBETT.

THE COOL AIR MASS AND GOOD RADIATIONAL CONDITIONS WILL LEAD TO COOL
NIGHTTIME TEMPS THE NEXT FEW NIGHTS. THE MODELS FORECAST DEWPOINTS
STAYING IN THE LOWER 40S SO THIS MAY LIMIT HOW COOL WE DO GET...BUT
SOME UPPER 30S ARE POSSIBLE TONIGHT AND MID TO UPPER 30S THURSDAY
NIGHT. TOLLESON

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS. FEW CHANGES
WERE MADE TO THE EXTENDED FORECAST TODAY AS THE MODELS CONTINUE TO
SHOW UPPER LEVEL RIDGING OVER THE PACIFIC NORTHWEST. AS SUCH...WE
CAN EXPECT TO SEE DRY CONDITIONS AND SLIGHTLY WARMER TEMPS THROUGH
MUCH OF NEXT WEEK. STILL KEEPING A SLIGHT CHANCE OF RAIN FOR THE
NORTH COAST DUE TO THE POSSIBILITY OF WEAK SHORTWAVES MOVING THROUGH
THE AREA. AS MENTIONED PREVIOUSLY...AN ATMOSPHERIC RIVER EVENT SEEMS
LIKELY AT THIS POINT. MOST OF THE RAIN SHOULD REMAIN TO OUR NORTH.
HOWEVER...IF THE RIDGE BREAKS DOWN OR BECOMES FLATTER WE COULD SEE
SOME RAIN PUSH INTO THE REGION. THE NEXT WIDE SPREAD RAIN EVENT
LOOKS TO ARRIVE TOWARDS THE END OF NEXT WEEK AND SHOULD BRING WITH
IT SLIGHTLY COOLER TEMPS. /64 &&

.AVIATION...PATCHY FOG AND IFR CONDITIONS FOR THE SOUTH AND CENTRAL
WILLAMETTE VALLEY AND AREAS ALONG THE LOWER COLUMBIA RIVER THIS
MORNING...IMPACTING KEUG AND KSPB. OTHERWISE...MOSTLY VFR CONDITIONS.
THE FOG SHOULD CLEAR FOR THE LOWER COLUMBIA RIVER VALLEY AROUND 1630Z
AND NEAR KEUG AROUND 18Z. WIDESPREAD VFR CONDITIONS THIS AFTERNOON
AND EVENING. OFFSHORE WINDS WILL DEVELOP TONIGHT... BUT WILL BE TOO
WEAK TO PREVENT FOG FORMATION OVERNIGHT. THE CENTRAL OREGON COAST
NEAR KONP HAS THE BEST CHANCE FOR OVERNIGHT VFR CONDITIONS.

KPDX AND APPROACHES...MVFR CIGS WILL LIFT BY 17Z WITH VFR CONDITIONS
THROUGH THIS EVENING. RADIATION FOG IS LIKELY LATE TONIGHT WITH
POSSIBLY IFR CONDITIONS AFTER 9Z. TJ
&&

.MARINE...HIGH PRESSURE OVER THE WATERS TODAY WITH A THERMAL TROUGH
OVER THE SOUTHERN OREGON WATERS WILL MAINTAIN N WINDS OVER THE
NORTHERN OREGON WATERS...AND NE WINDS SOUTH OF CASCADE HEAD.  THE
WINDS TODAY WILL GENERALLY BE AROUND 10 KT WITH AN OCCASIONAL GUST TO
15 KT SOUTH OF NEWPORT. THE THERMAL TROUGH WILL SHIFT NORTHWARD
THURSDAY AND THE WINDS WILL BECOME MORE OFFSHORE...AND SLIGHTLY
STRONGER SOUTH OF CASCADE HEAD. THERE WILL BE LITTLE CHANGE IN THE
PRESSURE PATTERN FRIDAY. THE PRESSURE GRADIENT WILL REMAIN CONSTANT
SOUTH OF CASCADE HEAD THROUGH THE WEEKEND WITH GUSTS FLIRTING WITH
SMALL CRAFT ADVISORY. WINDS NORTH OF CASCADE HEAD WILL BE MUCH WEAKER
AS A FRONT DECAYS OVER THE NORTHERN WATERS. HIGH PRESSURE WILL
REBUILD MONDAY TO THE NORTH WITH A THERMAL TROUGH HANGING ON ACROSS
THE SOUTHERN WATERS.

SEAS WILL GRADUALLY SUBSIDE TODAY AND SATURDAY THEN BUILD AGAIN
SATURDAY NIGHT...BUT WILL GENERALLY REMAIN BETWEEN 5 AND 7 FEET. TJ
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...NONE.
&&

$$

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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