Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 040343
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
843 PM PDT FRI JUL  3 2015

.SYNOPSIS...LITTLE CHANGE IN THE OVERALL WEATHER PATTERN IS EXPECTED
THROUGH THE HOLIDAY WEEKEND AND INTO EARLY NEXT WEEK. A STRONG UPPER
LEVEL RIDGE WILL REMAIN OVER THE REGION TO KEEP INLAND TEMPS WELL
ABOVE NORMAL WITH CONTINUED DRY CONDITIONS. EARLY NEXT WEEK AN UPPER
LEVEL LOW CUTTING OFF NEAR THE CENTRAL CALIFORNIA COAST MAY SPIN
SOME MOISTURE UP TOWARD THE LANE COUNTY CASCADES FOR A CHANCE OF
THUNDERSTORMS. SOME COOLING LOOKS POSSIBLE LATE IN THE WEEK AS THE
UPPER LEVEL RIDGE GIVES WAY TO A WEAK LOW PRES CENTER ALOFT.

&&

.UPDATE...NO SIGNIFICANT CHANGES THIS EVENING. AST-DLS AND AST-PDT
GRADIENTS ARE STRONGER THAN LAST NIGHT WHICH SHOULD MEAN THAT
TEMPERATURES COOL A BIT MORE QUICKLY THIS EVENING THAN LAST.
TYPICALLY IT WOULD ALSO MEAN MARINE STRATUS WOULD PUSH FARTHER
INLAND...BUT THERE IS NO MARINE STRATUS TO SPEAK OF YET...SO THE
EXTENT OF THE INLAND PUSH WILL LIKELY DEPEND ON WHEN IT ACTUALLY
FORMS. THE DEWPOINT DEPRESSION AT NEWPORT IS ONLY ABOUT 3.5
DEGREES...SO STRATUS MAY BEGIN TO DEVELOP IN THAT AREA WITHIN THE
NEXT FEW HOURS AND LIKELY PUSH UP THE COAST AND THEN INLAND. ADDED
SOME SCATTERED CLOUD COVER TO THE PORTLAND AREA FOR SUNDAY MORNING
BUT ANY CLOUDS SHOULD BURN OFF QUICKLY. BOWEN

.SHORT TERM...A RIDGE OF HIGH PRES ALOFT FRI AFTERNOON EXTENDED FROM
THE SW U.S. TO OFF THE COAST OF THE PACIFIC NW. THE RIDGE...RUNNING
ACROSS SW OREGON...WILL REMAIN IN PLACE THROUGH MON. MODELS CONTINUE
TO SHOW THE RIDGE WEAKENING SOME OVER THE NEXT FEW DAYS RESULTING
THE DEVELOPMENT OF A COL OVER WESTERN OREGON THIS WEEKEND. UNDER THE
RIDGE NW ONSHORE PRES GRADIENTS HAVE STRENGTHENED SOME...WHICH
COUPLED WITH DECREASING HEIGHTS ALOFT WILL TAKE A LITTLE OF THE EDGE
OFF DAYTIME TEMPS FOR SAT BY CUTTING THEM DOWN A FEW DEGREES. MODELS
SHOW NOT A WHOLE LOT OF CHANGE TO THE AIR MASS AGAIN SUN...EXCEPT H8
TEMPS CREEP BACK UP TO AROUND 22 DEG C WHICH SHOULD PUT HIGH TEMPS
BACK CLOSE TO THU HIGHS. WITH THE ONSHORE FLOW MARINE CLOUDS SHOULD
FILL BACK IN ALONG THE COAST WITH A LIMITED PUSH OF MARINE CLOUDS UP
THE LOWER COLUMBIA. A WIND FLOW REVERSAL ALONG THE COAST INDICATED
BY BOTH THE NAM AND GFS SHOULD HELP SOME CLOUDS PUSH INTO THE OREGON
COAST RANGE SUN NIGHT AND EARLY MON...BUT OVERALL AIR MASS EXPECTED
TO CHANGE LITTLE SO WILL STILL SEE INLAND TEMPS TOPPING OUT IN THE
90S. WILL LEAVE A SLIGHT CHANCE FOR SOME THUNDER IN THE LANE COUNTY
CASCADES MON AFTERNOON AS GFS AND NAM SHOW SOME INSTABILITY COMING
UP FROM THE S OUT OF THE LOW OFF THE CA COAST.

.LONG TERM...GFS AND ECMWF SHOW THE UPPER COL REMAINING OVER OREGON
TUE AND WED FOR CONTINUED HOT WEATHER. THIS ALSO LEAVES THE S
CASCADES OPEN INSTABILITY AND MOISTURE ALOFT SNEAKING UP FROM THE
S...SO WILL KEEP A SLIGHT CHANCE FOR DIURNAL THUNDERSTORMS OVER THE
LANE COUNTY CASCADES BOTH TUE AND WED. MODELS AT THIS POINT ARE
SUGGESTING SOME RELIEF TO THE EXTENDED HEAT WAVE COMING AROUND THU
AS THE UPPER LOW CUTOFF OFF THE CA COAST MOVES INLAND OVER CA GIVING
POTENTIALLY BRINGING A SW PUSH OF MARINE AIR INLAND. MODELS INDICATE
THE TROUGHINESS OVER THE WESTERN STATES IS THEN REINFORCED FRI AS
ANOTHER TROUGH MOVES IN OFF THE N PACIFIC FOR EVEN COOLER AIR. WILL
TREND TEMPS DOWNWARD A LITTLE MORE FOR THU AND FRI GIVEN DECENT
AGREEMENT IN MODELS WITH THIS TYPE OF SOLUTION...BUT STILL HOLD SOME
RESERVATIONS IN BUYING COMPLETELY INTO THE CHANGE AS MODELS TEND TO
STRUGGLE WITH CUTOFF LOWS ESP THIS FAR INTO THE EXTENDED PERIOD.

&&

.AVIATION...VFR NEXT 24 HRS UNDER STABLE WESTERLY FLOW ALOFT.
EXPECT THE IFR STRATUS TO REFORM ALONG THE COAST LATER THIS
EVENING...THEN PUSH INTO THE COASTAL GAPS AND UP THE COLUMBIA
RIVER AS FAR AS KELSO OVERNIGHT. INLAND TAF SITES SHOULD REMAIN
VFR THROUGH SAT. BREEZY NW WINDS RETURN AGAIN SATURDAY AFTERNOON
AND EVENING.

KPDX AND APPROACHES...VFR WILL PERSIST NEXT 24 HRS. NW WINDS WILL
BE BREEZY AGAIN AT TIMES SATURDAY AFTERNOON AND EVENING. PYLE/27

&&

.MARINE...HIGH PRES OVER THE NE PAC AND THERMAL LOW PRES INLAND
WILL CONTINUE TO PRODUCE BREEZY NORTHERLY WINDS OVER THE COASTAL
WATERS INTO SAT. THE BEST WINDS ARE FURTHER OFFSHORE...WHERE A
SMALL CRAFT ADVISORY REMAINS IN EFFECT THROUGH TONIGHT. WINDS ARE
LIGHTER NEAR SHORE...WITH GUSTS AROUND 20 KT. THE THERMAL LOW
PRES WILL MOVE WESTWARD THIS WEEKEND...WEAKENING THE PRES GRADIENT
OVER THE WATERS. THIS SHOULD ALLOW WINDS ACROSS ALL WATERS TO DROP
BELOW 20 KT LATE IN THE WEEKEND AND INTO NEXT WEEK. THE FCST
MODELS ARE INDICATING THAT A SOUTHERLY WIND REVERSAL WILL OCCUR
SOMETIME SUN.

EXPECT PERIODS OF STEEP AND CHOPPY SEAS OVER THE OUTER WATERS TO
CONTINUE OVERNIGHT WITH COMBINED SEAS OF 7 TO 8 FT AND A DOMINANT
PERIOD
AROUND 8 SECONDS. SEAS SHOULD GRADUALLY SUBSIDE LATER THIS WEEKEND
AS WINDS SLACKEN...REACHING AROUND 4 TO 5 FT BY EARLY NEXT WEEK.
PYLE

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...HEAT ADVISORY UNTIL 6 PM PDT SUNDAY FOR CASCADE FOOTHILLS IN
     LANE COUNTY-CENTRAL COAST RANGE OF WESTERN OREGON-CENTRAL
     COLUMBIA RIVER GORGE-CENTRAL WILLAMETTE VALLEY-GREATER
     PORTLAND METRO AREA- LOWER COLUMBIA-NORTHERN OREGON CASCADE
     FOOTHILLS-SOUTH WILLAMETTE VALLEY-UPPER HOOD RIVER VALLEY-
     WESTERN COLUMBIA RIVER GORGE.

WA...HEAT ADVISORY UNTIL 6 PM PDT SUNDAY FOR CENTRAL COLUMBIA RIVER
     GORGE-GREATER VANCOUVER AREA-I-5 CORRIDOR IN COWLITZ COUNTY-
     SOUTH WASHINGTON CASCADE FOOTHILLS-WESTERN COLUMBIA RIVER
     GORGE.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 7 AM PDT SATURDAY FOR
     WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR FROM 10 TO 60
     NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 7 AM PDT
     SATURDAY FOR WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR
     FROM 10 TO 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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