Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 060508
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
906 PM PST THU MAR  5 2015

.SYNOPSIS...AN UPPER LEVEL RIDGE OF HIGH PRES WILL REMAIN THROUGH
THE WEEKEND MAINTAINING A DRY...SUNNY...AND WARMER THAN AVERAGE
WEATHER PATTERN. THE UPPER RIDGE WILL WEAKEN EARLY NEXT WEEK AND A
FRONT MAY BRING RAIN TO THE REGION BY TUESDAY.
&&

.SHORT TERM...TONIGHT THROUGH SUNDAY...
TEMPERATURES AND DEWPOINTS THIS EVENING ARE RUNNING SEVERAL DEGREES
HIGHER THAN WE HAVE SEEN THE PAST COUPLE OF NIGHTS. THE LATEST IR
SATELLITE IMAGERY IS ALSO SHOWING A DECENT AMOUNT OF HIGH CLOUDS FROM
A SYSTEM WELL OFFSHORE MOVING INTO THE PAC NW. GIVEN THESE
FACTORS...THINK THE FCST OVERNIGHT LOWS LOOK REASONABLE...WITH TEMPS
REMAINING A GOOD 5 DEGREES WARMER THAN THE PAST COUPLE OF NIGHTS.
THIS WILL LIKELY PREVENT MUCH IN THE WAY OF FROST FORMATION. HOWEVER
GIVEN THE HIGHER DEWPOINTS...SOME PATCHY FOG MAY DEVELOP ALONG THE
COAST AND IN PARTS OF THE INTERIOR EARLY FRI MORNING ESPECIALLY IN
THE MORE FOG PRONE LOCATIONS. MEANWHILE...FORECAST MODELS REMAIN IN
DECENT AGREEMENT THAT A WIND REVERSAL ALONG THE COAST WILL
OCCUR...BUT ENOUGH OFFSHORE COMPONENT WILL REMAIN TO PREVENT A
STRONG PUSH OF MOISTURE INTO THE COASTAL AREAS AND INTO THE INTERIOR
ON FRI. STILL THINK THE BULK OF THE CLOUDS WILL REMAIN
OFFSHORE...BUT IT IS POSSIBLE THAT INCREASED CLOUDS WILL ALSO MAKE
THEIR WAY ALONG THE IMMEDIATE COASTLINE.

LITTLE CHANGE WILL OCCUR INTO THE WEEKEND WITH HIGH PRESSURE
CONTINUING TO DRIVE OUR WEATHER. TEMPS ON SAT AND SUN ARE EXPECTED TO
BE INTO THE MID 60S OVER THE INTERIOR LOWLANDS...WHICH IS ABOUT 10
DEG ABOVE NORMAL FOR THIS TIME OF YEAR. GRADUAL WARMING IN OVERNIGHT
LOWS WILL BRING THEM CLOSER TO NORMALS AND WELL ABOVE FREEZING FOR
MOST LOCATIONS. A RETURN TO MORE OFFSHORE LOW-LEVEL WINDS AND A DRIER
NORTHERLY FLOW ALOFT WILL DECREASE CLOUDS ONCE AGAIN AND DRIVE ANY
COASTAL CLOUDINESS MORE OFFSHORE. PYLE

&&

.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...THE UPPER RIDGE WILL
GRADUALLY BREAK DOWN EARLY NEXT WEEK AFTER STARTING WITH THE AXIS
OVER THE COAST. AS THE UPPER RIDGE EXPANDS EASTWARD MONDAY...MODELS
ARE SHOWING A SOMEWHAT AGGRESSIVE TROUGH SWING SOUTH FROM ALASKA AND
EAST ACROSS BRITISH COLUMBIA. THIS APPEARS TO OPEN THE DOOR FOR A
WARM CORE CUT OFF LOW CENTERED NEAR 150W TO DRIFT TOWARD THE PACNW.
THE NORTHERN SHORTWAVE MAY BRING VERY LIGHT RAIN TO THE FAR NORTHERN
REACHES OF THE CWA. THE FILLING UPPER LOW GETS CLOSE ENOUGH TO THE
COAST TO SPREAD RAIN WELL INLAND BY TUESDAY NIGHT. MODELS HAVE
CONSISTENTLY SHOWN SOME LOOSE VERSION OF THIS SCENARIO FOR A FEW DAYS

NOW SO BUMPED POPS UP TO LOW END LIKELY FROM TUESDAY NIGHT ONWARD.
THE VARIOUS MEDIUM RANGE MODELS DO CONTINUE TO STRUGGLE WITH THE
TRACK OF THE UPPER LOW SO CONFIDENCE IN ACTUAL PRECIPITATION AMOUNTS
REMAINS VERY LOW BUT FIND IT DIFFICULT TO EXPECT ANY AREA GETTING
MORE THAN AN INCH DURING THE TUESDAY THROUGH THURSDAY TIME FRAME.
TEMPERATURES WILL BE MODESTLY WARM WITH SNOW LEVELS FAIRLY HIGH SO
EXPECT NO SIGNIFICANT ADDITION TO THE CASCADE SNOW PACK. /JBONK
GRADUALLY BREAK DOWN EARLY NEXT WEEK AFTER STARTING WITH THE AXIS
OVER THE COAST. AS THE UPPER RIDGE EXPANDS EASTWARD MONDAY.
&&

.AVIATION...VFR THROUGH FRI. THERE MAY BE SOME PATCHY FOG 10Z-
18Z FRI...PRIMARILY ALONG THE S WA AND N OREGON COAST NEAR THE
BAYS...THE NEHALEM RIVER VALLEY AS WELL AND THE WILLAMETTE VALLEY
AND LOWER COLUMBIA RIVER.

KPDX AND APPROACHES...VFR PREVAILING NEXT 24 HOURS. THERE MAY BE
SOME FOG PATCHES IN THE AREA 14Z-17Z FRI. /MH

&&

.MARINE...QUIET WEATHER PATTERN OVER THE WATERS FOR THE NEXT
SEVERAL DAYS. HIGH PRES OVER WESTERN WA WITH LOWER PRES OFFSHORE
GIVING LIGHT NE WIND OVER MOST OF THE WATER. HOWEVER THERE IS A
WEAK TROUGH OFF THE SOUTH OREGON COAST BRINGING MORE E-SE WIND TO
THE CENTRAL OREGON COAST. WINDS WILL TRANSITION TO NORTHERLY FOR
THE WEEKEND WITH 15 TO 20 KT GUSTS OVER THE FAR SRN WATERS SAT
NIGHT AND SUN. LONGER RANGE MODELS STARTING TO SHOW A LITTLE MORE
AGREEMENT. CLOSED UPPER LOW OVER THE CENTRAL PAC MON DRIFTS CLOSER
TO THE CALIFORNIA AND S OREGON COAST TUE AND WED. GFS HAS GONE
AWAY FROM ITS COOL AND WET NWLY UPPER FLOW PATTERN TO THE MORE
MILD AND SOMEWHAT DRIER SWLY PATTERN OF THE ECMWF AND GEM.

SEAS HOLDING IN THE 3 TO 5 FOOT RANGE FOR FOR THE NEXT FEW DAYS.
SPECTRAL ANALYSIS SUGGESTS THERE WILL BE MULTIPLE 2 OR 3 FOOT
COMPONENTS THROUGH AT LEAST FRI...PRIMARILY FROM THE WNW AND SSW.
ENP GUIDANCE SHOWS 12 TO 14 FT WAVE HEIGHTS NEXT WED NIGHT AND
THU. BELIEVE THIS TO BE OVERDONE AS THE CLOSED SURFACE LOW IS NOT
ALL THAT STRONG IN THE MODELS. THE MODELS ALSO DO NOT SHOW ANY
SIGNIFICANT FETCH REGION TO DEVELOP WAVES THAT HIGH. BROUGHT SEAS
UP TO 10 FT FOR NOW. WEISHAAR

&&

.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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