Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 290407
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
906 PM PDT TUE JUL 28 2015

.SYNOPSIS...STRONG UPPER LEVEL HIGH PRESSURE CONTINUES TO BUILD OVER
THE REGION TONIGHT AND TOMORROW. THIS WILL BRING CONSIDERABLY WARMER
TEMPERATURES TO THE REGION. THE HOTTEST TEMPERATURES WILL OCCUR
WEDNESDAY THROUGH FRIDAY...BUT TEMPERATURES MAY REMAIN AROUND 90
DEGREES IN THE WILLAMETTE VALLEY THROUGH THE WEEKEND AND PERHAPS INTO
EARLY NEXT WEEK.

&&

.UPDATE...WITH A STRENGTHENING THERMAL LOW OVER NORTHERN
CALIFORNIA...WINDS HAVE PICKED UP ALONG THE COAST AND IN THE
WILLAMETTE VALLEY THIS EVENING. EXPECT WINDS TO DROP OFF SOME TONIGHT
BUT NOT CALM COMPLETELY BEFORE INCREASING AGAIN TOMORROW. OTHERWISE
THE IMMEDIATE TERM IS RATHER UNEVENTFUL WITH NOT EVEN ANY CLOUDS IN
THE LOCAL FORECAST AREA. CLEAR SKIES SHOULD DOMINATE OVERNIGHT BUT
COULD SEE SOME MORNING STRATUS ALONG THE NW OR AND SW WA COASTS
WEDNESDAY.

THE BIG NEWS STARTING TOMORROW WILL BE THE HEAT. NO DOUBT
TEMPERATURES WILL BE HOT BUT IT REMAINS TO BE SEEN JUST HOW HOT.
THERE IS SOME SUGGESTION IN A NUMBER OF MODELS THAT WEAK ONSHORE FLOW
MAY DEVELOP IN THE LOWER COLUMBIA AND NORTH WILLAMETTE VALLEY
AREA...WHICH COULD LIMIT HEATING SOME FOR THE NEXT COUPLE OF DAYS IN
THOSE AREAS. HAVE NOT MADE ANY CHANGES THIS EVENING TO TEMPERATURES
BUT WILL BE INTERESTED TO SEE THE TRENDS WITH THE 00Z MODELS. BOWEN

.SHORT TERM (PREVIOUS DISCUSSION)...TONIGHT THROUGH FRIDAY. A
PLEASANT LATE JULY DAY...ESPECIALLY FOR THOSE WHO ENJOY CLEAR SKIES
AND A BIT OF WARMTH...HAS DEVELOPED OVER THE REGION THIS AFTERNOON AS
TEMPERATURES HAVE WARMED INTO THE 80S AT MOST INLAND STATIONS WITH
TEMPERATURES AS OF 2 PM RUNNING 5 TO 10 DEGREES WARMER THAN THIS TIME
YESTERDAY. MEANWHILE...SOME BREEZY WINDS WITH GUSTS AROUND 25 MPH
HAVE BEGUN IN THE CENTRAL AND SOUTHERN WILLAMETTE VALLEY AS WELL AS
THE CENTRAL OREGON COAST AS THE THERMAL TROUGH OVER N CALIFORNIA AND
S OREGON COAST BUILDS NORTHWARD.

AS THE RIDGE OF HIGH PRESSURE ALOFT CONTINUES TO STRENGTHEN THROUGH
THE NEXT FEW DAYS...FORECAST MODELS SUGGEST H5 HEIGHTS BUILDING TO
590 DAM BY LATE THURSDAY AFTERNOON. MEANWHILE H8 TEMPS AROUND 14 C
TODAY WILL INCREASE TO AROUND 22 C BY THE SAME TIME. THIS GENERALLY
TRANSLATES TO SURFACE TEMPERATURES AROUND 7 F TO 10 F WARMER FOR
WEDNESDAY...BEFORE WARMING AN ADDITIONAL FEW DEGREES FOR THURSDAY.
MODELS CONTINUE TO POINT TO THURSDAY AS THE LIKELY PEAK OF THE
STRETCH OF HOT WEATHER FOR MANY LOCATIONS AS THE THERMALLY INDUCED
SURFACE LOW PRESSURE LOOKS TO PUSH EAST OF THE CASCADES INTO THE
COLUMBIA BASIN BY LATE THURSDAY. THERE IS A LITTLE MORE SPREAD IN THE
MODEL GUIDANCE FOR TEMPERATURES THIS AFTERNOON...PARTICULARLY FROM
THE GFS BUT ALSO IN THE ECMWF...LIKELY DUE TO RESOLVING A BIT
STRONGER AND MORE WELL DEFINED THERMAL LOW STRETCHING INTO SOUTHEAST
WASHINGTON. THIS WOULD TURN THE LOW LEVEL FLOW A BIT MORE NORTHWEST
RATHER THAN NORTHEAST AND ALLOW SOME MARINE AIR TO FILTER INTO THE
WILLAMETTE VALLEY. THIS MAY ALLOW TEMPERATURES TO COOL A LITTLE ALONG
THE LOWER COLUMBIA AND NORTH WILLAMETTE VALLEY ON FRIDAY...THOUGH
WINDS IN THE SOUTH AND CENTRAL VALLEY AND OVER THE COAST RANGE
LIKELY REMAIN NORTH TO NORTHEAST SO SIMILAR CONDITIONS ARE LIKELY
FRIDAY FOR THESE LOCATIONS. ALL OF THIS SAID...WHILE CONFIDENCE IS
SLIGHTLY LOWER FOR FRIDAY FOR NORTHERN LOCATIONS...THE HEAT
ADVISORIES REMAIN ON TRACK.  CULLEN

&&

.LONG TERM...FRIDAY NIGHT THROUGH TUESDAY. FEW CHANGES NEEDED TO THE
EXTENDED PERIOD TODAY. THE BROAD UPPER RIDGE WILL REMAIN OVER THE
REGION BUT WILL FLATTEN WITH LOWERING H5 HEIGHTS OVER THE AREA WITH A
FEW WEAK DISTURBANCES PASSING INTO SOUTHERN CANADA. MEANWHILE...THERE
IS A SMALL CHANCE THAT MID LEVEL MOISTURE MAY ROTATE INTO THE REGION
FROM THE SOUTH. THIS REMAINS RATHER SMALL AT THIS POINT...SO
RESTRICTED SLIGHT CHANCE OF THUNDER PRIMARILY IN THE HIGHER CASCADES
OF LANE COUNTY. IN TERMS OF TEMPERATURES THROUGH THE FIRST PART OF
NEXT WEEK...GUIDANCE STILL SUGGESTS TEMPERATURES MODERATING A BIT
FROM THE END OF THIS WEEK...BUT STILL WELL ABOVE NORMAL ACROSS THE
REGION.   CULLEN

&&

.FIRE WEATHER...A THERMAL TROUGH HAS BUILT INTO SOUTHERN OREGON
TODAY...LEADING TO DRYING NORTHERLY TO NORTHEASTERLY WINDS
DEVELOPING OVER THE REGION. THE THERMAL TROUGH IS EXPECTED TO EXPAND
NORTHWARD INTO THE OREGON CASCADES AND OVER THE SOUTHERN WILLAMETTE
VALLEY AND ADJACENT FOOTHILLS ON WED AND THU...AND POTENTIALLY INTO
FRI AS WELL. THIS WILL BRING ENHANCED INSTABILITY AND MIXING...THAT
COMBINED WITH THE EXPECTED VERY HOT AND DRY CONDITIONS...MAY CREATE
CRITICAL FIRE WEATHER CONDITIONS. ALSO...ALTHOUGH MANY LOCATIONS
RECEIVED RAIN OVER THE WEEKEND...FUELS ARE FORECASTED TO DRY OUT
RAPIDLY DURING THE MIDWEEK PERIOD. A FIRE WEATHER WARNING HAS BEEN
ISSUED STARTING WED AFTERNOON AND CONTINUING THROUGH THU EVENING.
THE THERMAL TROUGH IS CURRENTLY EXPECTED TO PUSH EAST OF THE
CASCADES OVER THE WEEKEND. PYLE

&&

.AVIATION...VFR CONDITIONS SHOULD CONTINUE OVERNIGHT TONIGHT
ACROSS THE AREA THROUGH THE DAY TOMORROW...EXCEPT KAST MAY SEE
SOME PATCHY MVFR STRATUS BETWEEN 10Z-14Z. NORTHERLY WINDS GUSTING
TO 20 KTS THIS EVENING SHOULD DECREASE AROUND 05Z-06Z. LIGHTER
NORTHERLY WINDS THROUGH EARLY WEDNESDAY WILL INCREASE AGAIN
WEDNESDAY AFTERNOON AROUND 18Z-19Z WITH GUSTS TO 20 KTS POSSIBLE
WEDNESDAY EVENING.

KPDX AND APPROACHES...VFR THE NEXT 24 HOURS. GUSTY NORTHERLY WINDS
DECREASE AFTER 05Z WED. NORTHERLY WINDS EXPECTED TO INCREASE AGAIN
AFTER 19Z WEDNESDAY. -MCCOY

&&

.MARINE...TYPICAL SUMMERTIME PATTERN THROUGH THE END OF THE WEEK
INTO THIS WEEKEND. WINDS AT BUOY 50 ARE GUSTING TO 25 KTS THIS
EVENING...BUT DO NOT SEEM AS STRONG AS THE MODELS FORECAST...AT
LEAST ACCORDING TO BUOY 50 AND WAVE HEIGHTS AT BUOY 89 AND 29. STILL
THINKING WE COULD SEE A FEW GUSTS TO 30 KTS IN THE SOUTHERN
WATERS...WITH SEAS BECOMING STEEP AND CHOPPY AROUND 7 FT WITH WAVE
PERIODS AROUND 6 TO 7 SECONDS. HAVE DROPPED THE SMALL CRAFT
ADVISORY FOR HAZARDOUS SEAS IN THE NORTHERN WATERS FOR THIS
EVENING AS SEAS LOOK LIKE THEY WON`T GET QUITE TO 7 FT TO MEET
ADVISORY CRITERIA UNTIL LATE WEDNESDAY MORNING.

STRONGEST WINDS STILL APPEAR TO BE WEDNESDAY AFTERNOON/EVENING WITH
A FEW GUSTS TO 35 KTS POSSIBLE OVER THE CENTRAL OREGON WATERS.
WILL KEEP A HIGH END SMALL CRAFT ADVISORY FOR WINDS AS GUSTS ABOVE
33 KTS WILL BE VERY INFREQUENT. WIND-DRIVEN SEAS WILL BECOME STEEP
UP TO AROUND 6 TO 8 FT WITH DOMINANT WAVE PERIODS AROUND 7 TO 8
SECONDS...WARRANTING A SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS AS
WELL.

GUSTY AFTERNOON NORTHERLY WINDS UP TO AROUND 25 KTS LIKELY TO
CONTINUE THROUGH THE WEEKEND...WITH PERIODS OF SUB-ADVISORY WINDS
POSSIBLE DURING THE MORNING HOURS FRIDAY THROUGH SUNDAY. WAVE
HEIGHTS LOOK TO STAY AROUND 5 TO 7 FT THROUGH THE WEEKEND AS WELL.
-MCCOY

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING FROM NOON WEDNESDAY TO 11 PM PDT THURSDAY FOR
     ZONE 604-ZONE 605-ZONE 606-ZONE 607-ZONE 608.

     HEAT ADVISORY FROM 11 AM WEDNESDAY TO 9 PM PDT FRIDAY FOR
     CENTRAL COAST RANGE OF WESTERN OREGON-CENTRAL COLUMBIA
     RIVER GORGE-CENTRAL WILLAMETTE VALLEY-COAST RANGE OF
     NORTHWEST OREGON-GREATER PORTLAND METRO AREA-SOUTH
     WILLAMETTE VALLEY-UPPER HOOD RIVER VALLEY-WESTERN COLUMBIA
     RIVER GORGE.

     HEAT ADVISORY FROM 11 AM WEDNESDAY TO 9 PM PDT THURSDAY FOR
     LOWER COLUMBIA.

WA...HEAT ADVISORY FROM 11 AM WEDNESDAY TO 9 PM PDT FRIDAY FOR
     CENTRAL COLUMBIA RIVER GORGE-GREATER VANCOUVER AREA-WESTERN
     COLUMBIA RIVER GORGE.

     HEAT ADVISORY FROM 11 AM WEDNESDAY TO 9 PM PDT THURSDAY FOR I-5
     CORRIDOR IN COWLITZ COUNTY.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 5 AM PDT THURSDAY FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 11 AM WEDNESDAY TO
     5 AM PDT THURSDAY FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO
     CASCADE HEAD OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 AM PDT THURSDAY
     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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