Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 312131
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
230 PM PDT FRI JUL 31 2015

.SYNOPSIS...AN UPPER LEVEL RIDGE OF HIGH PRESSURE OVER THE REGION
WILL CONTINUE TO BRING WARM TEMPERATURES TO THE INLAND AREAS THROUGH
THE WEEKEND.  THE RIDGE OF HIGH PRESSURE WILL MOVE EAST OF THE
REGION EARLY NEXT WEEK AND BRING A GRADUAL COOLING TREND. MONSOONAL
MOISTURE FROM THE SOUTH WILL BRING A SLIGHT CHANCE OF A SHOWER OR
THUNDERSTORM TO THE OREGON CASCADE CREST LATE IN THE WEEKEND AND
EARLY NEXT WEEK...BUT CONFIDENCE REMAINS LOW IN THE THUNDERSTORM
THREAT.

&&

.SHORT TERM...TODAY THROUGH TUESDAY. AS OF 230 PM...INLAND
TEMPERATURES ARE WELL INTO THE 90S ACROSS THE REGION AND REMAIN ON
TRACK TO REACH OR EXCEED THE CENTURY MARK AGAIN THIS AFTERNOON. SOME
LOCATIONS IN THE SOUTHERN WILLAMETTE VALLEY WILL MEET OR EXCEED
YESTERDAY/S HIGH TEMPERATURE READINGS. THE COASTAL STRIP REMAINS
QUITE PLEASANT WITH LIGHT ONSHORE FLOW.

SATELLITE IMAGERY SHOWS SOME MID-LEVEL MOISTURE SLOWLY DRIFTING
NORTHWARD FROM NOCAL AND THE GREAT BASIN WITH CUMULUS CLOUDS
BUILDING ALONG THE CASCADE CREST IN LANE COUNTY.  THE STEERING FLOW
REMAINS OUT OF SOUTHWEST SO ANY CLOUD BUILD UPS WILL REMAIN ON OR
EAST OF THE CASCADE CREST.AS THE UPPER LEVEL RIDGE AXIS BEGINS TO
SHIFT EAST DURING THE WEEKEND...THE MID LEVEL STEERING FLOW BECOMES
MORE SOUTHERLY. THIS WILL BRING AN INCREASE IN MID AND HIGH LEVEL
CLOUDS TO THE AREA. MODEL SOUNDINGS SHOW SOME OF THE INITIAL
MOISTURE WILL LIKELY BE TOO HIGH TO PRODUCE ELEVATED THUNDERSTORMS
ON SATURDAY...BUT THIS MAY BEGIN TO CHANGE LATE SATURDAY NIGHT OR
SUNDAY ACROSS EASTERN LANE AND LINN COUNTIES. CONFIDENCE REMAINS LOW
THOUGH...AS MODELS DO NOT REALLY SHOW MUCH IN THE WAY OF A MID LEVEL
TRIGGER.

THE INCREASE IN MID AND UPPER LEVEL CLOUDS COMBINED WITH THE
STRENGTHENING OF THE LOW LEVEL ONSHORE FLOW WILL BRING A SLOW
DOWNWARD TREND IN TEMPERATURES OVER THE NEXT SEVERAL DAYS.
TEMPERATURES WILL ONLY DECREASE A FEW DEGREES EACH DAY...BUT INLAND
DAYTIME MAX TEMPERATURES SHOULD FALL BELOW 90 DEGREES BY TUESDAY. TW

&&

.LONG TERM...A FEW MODEL DISCREPANCIES START OFF THE EXTENDED
PERIOD. BOTH THE 12Z GFS AND ECMWF SHOW AN UPPER LEVEL TROUGH
APPROACHING THE REGION FROM THE NORTHWEST LATE MONDAY...BUT THE
ECMWF DEEPENS THE LOW BY EARLY TUESDAY WHEREAS THE GFS JUST SKIMS
THE TOP OF THE PACIFIC NORTHWEST EARLY NEXT WEEK. THE MODELS THEN
HAVE TIMING ISSUES ON BRINGING A TROUGH OVER THE AREA LATE NEXT
WEEK. OVERALL...WE WILL SEE A GENERAL COOLING TREND THROUGH THE WEEK
WITH HIGH TEMPERATURES RETURNING BACK TO NORMAL. COULD SEE A THREAT
FOR CASCADE THUNDERSTORMS MONDAY EVENING AND AGAIN TUESDAY AFTERNOON
AND EVENING. WE MAY ALSO SEE SOME SHOWERS CLIP THE SW WASHINGTON AND
NW OREGON COAST BY WEDNESDAY AND THURSDAY IF THE ECMWF SOLUTION
COMES TO FRUITION. /27

&&


.AVIATION...INLAND VFR WILL PREVAIL FOR THE NEXT 24 HOURS ALTHOUGH
THERE WILL BE AREAS OF CUMULUS AND SMOKE MAINLY ABOVE FL080 NEAR
AND ALONG THE CASCADES. COASTAL AREAS WILL SEE A SHALLOW REGION OF
LOW STRATUS BEGIN TO PUSH INLAND AS THE SEA BREEZES MATURE THIS
AFTERNOON AND EARLY EVENING. ALSO EXPECT GUSTS MAINLY 20 TO 25 KT
THERE WITH LOCALIZED 25 TO 30 KT CLOSER TO FLORENCE. PLANNING ON
THE COASTAL STRATUS/MIST WILL RETURN TONIGHT AS WINDS EASE OVERNIGHT.

KPDX AND APPROACHES...VFR CONDITIONS. /JBONK

&&

.MARINE...HIGH PRES LINGERING OVER THE OFFSHORE WATERS THROUGH
SUN WILL KEEP N WINDS BLOWING OVER THE COASTAL WATERS THROUGH THE
WEEKEND. EXPECT THE WINDS TO PICK UP SOME LATER TODAY AS THE
TROUGH OF LOW PRES OVER WESTERN OREGON MOVES FURTHER
INLAND...RESULTING IN WIND GUSTS RISING INTO THE 20 TO 25 KT RANGE
FROM LATE TODAY INTO SUN. SEAS WILL REMAIN DOMINATED BY N TO NW
WIND WAVES AND FRESH SWELL...KEEPING SEAS STEEP AND AT TIMES
NECESSITATING AN ADVISORY FOR HAZARDOUS SEAS MAINLY DURING LATE
AFTERNOON TO OVERNIGHT HOURS.

THE HIGH PRES WEAKENS BY LATE SUN AND MON...ALLOWING A WEAK COLD
FRONT TO MOVE S INTO THE WATERS LATE MON. SYSTEM LOOKS WEAK ENOUGH
TO ALLOW WINDS AND SEAS TO DROP BELOW SMALL CRAFT CRITERIA.

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...EXCESSIVE HEAT WARNING UNTIL 9 PM PDT THIS EVENING FOR CENTRAL
     COLUMBIA RIVER GORGE-CENTRAL WILLAMETTE VALLEY-GREATER
     PORTLAND METRO AREA-SOUTH WILLAMETTE VALLEY-UPPER HOOD
     RIVER VALLEY-WESTERN COLUMBIA RIVER GORGE.

     RED FLAG WARNING UNTIL 10 PM PDT SATURDAY FOR CENTRAL OREGON
     CASCADE FOOTHILLS-EAST SLOPES OF THE CENTRAL OREGON COAST
     RANGE-MT. HOOD NATIONAL FOREST WEST OF CASCADE CREST-NORTH
     OREGON CASCADE FOOTHILLS-NORTH OREGON COAST RANGE-
     WILLAMETTE NATIONAL FOREST-WILLAMETTE VALLEY.

     HEAT ADVISORY UNTIL 9 PM PDT THIS EVENING FOR CASCADE FOOTHILLS
     IN LANE COUNTY-CENTRAL COAST RANGE OF WESTERN OREGON-COAST
     RANGE OF NORTHWEST OREGON-LOWER COLUMBIA-NORTHERN OREGON
     CASCADE FOOTHILLS.

WA...EXCESSIVE HEAT WARNING UNTIL 9 PM PDT THIS EVENING FOR CENTRAL
     COLUMBIA RIVER GORGE-GREATER VANCOUVER AREA-WESTERN
     COLUMBIA RIVER GORGE.

     RED FLAG WARNING UNTIL 10 PM PDT SATURDAY FOR CLARK COUNTY
     LOWLANDS-EAST WILLAPA HILLS-EXTREME SOUTH WASHINGTON
     CASCADES AND FOOTHILLS.

     HEAT ADVISORY UNTIL 9 PM PDT THIS EVENING FOR I-5 CORRIDOR IN
     COWLITZ COUNTY.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 5 AM PDT SUNDAY FOR COASTAL

     WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 7 AM PDT SATURDAY
     FOR COASTAL WATERS FROM CASCADE HEAD OR TO FLORENCE OR OUT 60
NM.
&&

$$

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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