Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 010925
AFDPQR

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

.SYNOPSIS...UPPER LEVEL RIDGING WILL PUSH INTO THE REGION TODAY AND
STRENGTHEN THROUGH THE REST OF THE WEEK. 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...WATER VAPOR PICTURES EARLY THIS MORNING SHOWED A NW
FLOW OVER THE PACIFIC NW WITH A RIDGE OF HIGH PRES OFFSHORE SHIFTING
E ACROSS 140W. RADAR AND SURFACE OBSERVATIONS INDICATE SHOWERS
PRETTY MUCH HAVE NEDED OVER THE REGION. SURFACE OBSERVATIONS ALSO
INDICATED SOME FOG AND LOW CLOUDS HAD JUST BEGIN TO FORM AT LOW
ELEVATIONS. WITH DEW POINT DEPRESSIONS ALREADY SMALL ACROSS MOST OF
THE REGION AND WINDS NEAR CALM...CONDITIONS FAVOR FOG AND LOW CLOUDS
FILLING IN MUCH OF THE VALLEYS THIS MORNING. WITH A STRONG RIDGE
MOVING IN ALOFT...SUBSIDENCE INVERSION WILL SLOW THE MIXING OUT OF
THE BOUNDARY LAYER TODAY. THIS MAY MAKE FOG AND LOW CLOUDS A BIT
MORE RELUCTANT TO BREAK OUT...WHILE ALSO LIMITING HIGH TEMPS TO
LOWER THAN WHAT THE H8 TEMPS MIGHT OTHERWISE SUGGEST. MODEL
SOUNDINGS HOWEVER SEEM INTENT IN BREAKING UP THE LOW CLOUDS BY
MIDDAY...AND WITHOUT A RECENT TRACK RECORD INDICATING OTHERWISE WILL
CONTINUE TO INDICATE SOME SUN FOR THE AFTERNOON.

THE NEXT COUPLE OF DAYS LOOK SIMILAR WITH A SUBSIDENCE INVERSION
ALOFT...EXCEPT A THERMAL INDUCED TROUGH IS EXPECTED TO BUILD UP THE
COAST TURNING THE LOW LEVEL FLOW MORE DEFINITIVELY OFFSHORE. THIS
WILL TEND TO DRY THE AIR A BIT MORE MAKING CONDITIONS FOR MORNING
CLOUDS AND FOG LESS PROGRESSIVELY LESS FAVORABLE...ESP DOWNWIND OF
THE GORGE AND ALONG THE CENTRAL OREGON COAST BY FRI MORNING. WITH
DRIER AIR MOVING IN...WIND PROTECTED VALLEYS MAY SEE TEMPS DIP AS
LOW AS THE UPPER 30S BY THU MORNING BEFORE FOG DEVELOPMENT OCCURS.
DAYTIME TEMPS EXPECTED TO GRADUALLY WARM NEXT FEW DAYS AS MODEL
SOUNDINGS INDICATE AIR MASS MIXING OUT MORE EACH DAY.

.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...VFR CONDITIONS PREVAIL ACROSS MUCH OF THE REGION EARLY
THIS MORNING WITH JUST A FEW STRAY SHOWERS REMAINING ALONG THE
COAST. GIVEN CALMING WINDS AND CLEARING SKIES...STILL ANTICIPATE
LOW MVFR TO IFR FOG OR STRATUS DEVELOPING ACROSS MOST LOCATIONS.
WHILE SOME INDICATION THAT THIS HAS BEGUN TO FORM NEAR KTTD...KUAO
AND KMMV...EXPECT BETTER CHANCES FOR MORE WIDESPREAD DEVELOPMENT AFT
12Z. THESE CONDITIONS SHOULD CLEAR OUT WED MORNING WITH VFR
CONDITIONS WED AFTERNOON AND EVENING...BEFORE CHANCES FOR PATCHY
FOG DEVELOPMENT AGAIN AFT 06Z THU.

KPDX AND APPROACHES...VFR CONDITIONS EARLY THIS MORNING. EXPECT A
PERIOD OF MVFR TO IFR CONDITIONS BETWEEN 12Z AND 16Z AS FOG/LOW
STRATUS DEVELOPS. THEN...VFR CONDITIONS UNDER CLEAR SKIES AFT 18Z
WED THROUGH 09Z THU.  CULLEN

&&

.MARINE...MODEST NORTHWEST WINDS CONTINUE OVER THE WATERS AS HIGH
PRESSURE BUILDS...AND SEAS REMAIN IN THE 7 TO 9 FT RANGE. LITTLE
CHANGE EXPECTED TODAY AS HIGH PRES CONTINUES TO BUILD WITH SEAS
SUBSIDING TO 4 TO 5 FT TONIGHT. A THERMAL TROUGH WILL BUILD N UP
THE OREGON COAST ON THU...TURNING WINDS NE...AND SLIGHTLY STRONGER
WINDS ESPECIALLY S OF CASCADE HEAD. WEAKER WINDS FRIDAY AND
SATURDAY AS THE SURFACE PRES GRADIENT WEAKENS AHEAD OF A FRONT
APPROACHING FROM THE NW.AS A FRONT APPROACHES FROM THE NW. THE
FRONT WILL DECAY AS IT MOVES FROM NORTH TO SOUTH ACROSS THE WATERS
LATE IN THE WEEKEND. CULLEN

&&

.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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