Area Forecast Discussion
Issued by NWS Portland, OR

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS66 KPQR 301551
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
852 AM PDT TUE JUN 30 2015

.SYNOPSIS...HIGH PRESSURE WILL DOMINATE THE WEATHER THE NEXT SEVERAL
DAYS. MARINE STRATUS WILL KEEP THE COASTAL TEMPERATURES IN THE 60S TO
LOW 70S...BUT HOT WEATHER WILL CONTINUE INLAND WITH AFTERNOON
TEMPERATURES MOSTLY IN THE 90S. AM UPPER LOW NORTH OF THE AREA THIS
WEEKEND WILL FLATTEN THE UPPER RIDGE AND PREVENT TEMPERATURES FROM
WARMING ABOVE THE 90S.

&&

.SHORT TERM...SATELLITE PICTURES THIS MORNING SHOWED MARINE CLOUDS
ALONG THE COAST...INTO COAST RANGE VALLEYS AND UP THE LOWER COLUMBIA
AS FAR AS PORTLAND AREA. PIREPS ALONG COAST SUGGEST MARINE MOISTURE
ON THE SHALLOW SIDE...SO EXPECT CLOUDS TO RECED BACK TO THE COAST
FAIRLY QUICKLY TODAY. 12Z SLE SOUNDING INDICATED SOME COOLING TO
LOWER AIR MASS IN THE PAST 24 HOURS...BUT WITH H8 TEMPS STILL AROUND
17 DEG C AND PLENTY OF SUN EXPECT TO SEE HIGHS THIS AFTERNOON CLOSE
TO MONDAYS HIGHS.

REMAINDER OF SHORT TERM DISCUSSION UNCHANGED...WATER VAPOR IMAGERY
SHOWS ANOTHER UPPER LEVEL SHORTWAVE CURRENTLY NEAR 40N 141W. THE
FORECAST MODELS DO NOT FORECAST THIS FEATURE...EXCEPT THE GFS HAS A
WEAK VORT MAX NEAR ITS LOCATION. SINCE THIS WAVE IS STRONGER THAN
THE MODELS...SUSPECT THAT THEY ARE UNDER FORECASTING THE POTENTIAL
FOR MARINE CLOUDS TONIGHT INTO WED MORNING. THIS WAVE LOOKS WEAKER
THAN THE FIRST ONE...AND SHOULD ALSO TAKE A NORTHERN TRACK AS THE
UPPER RIDGE BUILDS. EXPECT THAT IT WILL MAINTAIN WEAK W-NW LOW LEVEL
WINDS AND PREVENT THE RIDGE FROM TOTALLY SQUASHING THE MARINE LAYER.
THEREFORE...I HAVE ADDED A RETURN OF LOW CLOUDS TO THE IMMEDIATE
COAST TONIGHT...PUSHING INTO THE COLUMBIA RIVER VALLEY WED
MORNING...BUT NOT TO THE PORTLAND METRO AREA.

THE MODELS HAVE BACKED OFF ON THE RIDGE AMPLIFYING WEDNESDAY AND
THURSDAY...POSSIBLY DUE TO THE SHORT WAVES RIDING OVER THE RIDGE. THE
UPPER HEIGHTS WILL RAISE ENOUGH THOUGH FOR THE AFTERNOON TEMPERATURES
TO CONTINUE TO WARM INLAND EACH DAY...PUSHING INTO THE MID TO UPPER
90S. ALSO THINK THAT THE MARINE CLOUDS WILL BECOME LESS OF AN
INFLUENCE WED NIGHT.

AN UPPER LOW WILL MOVE INTO WESTERN CANADA THURSDAY NIGHT AND FRIDAY
RESULTING IN THE RIDGE FLATTENING AGAIN OVER THE PACIFIC NW AND
BUILDING WEST OVER THE NE PACIFIC. THESE SUBTLE DIFFERENCES OF THE
UPPER HEIGHTS WILL BE BARELY NOTICEABLE...BUT THERE MAY BE A VERY
SLIGHT INCREASE OF A MARINE PUSH THURSDAY NIGHT AND VERY SLIGHT
COOLING FRIDAY.

MONSOONAL MOISTURE SHOULD REMAIN SOUTH OF THE AREA THROUGH THE SHORT
TERM. SOME CUMULUS MAY DEVELOP OVER THE CASCADES IN THE AFTERNOONS
BUT EXPECT SUBSIDENCE FROM THE HIGH TO PREVENT THE CUMULUS FROM
GROWING TALL ENOUGH TO GENERATE SHOWERS OR THUNDERSTORMS. TJ

.LONG TERM...FRIDAY NIGHT THROUGH MONDAY...THE UPPER LOW OVER WESTERN
CANADA WILL DEEPEN AS IT SHIFTS EASTWARD NEXT WEEKEND RESULTING IN
UPPER HEIGHTS DECREASING SOME OVER THE PACIFIC NW. THIS WILL HELP
MODERATE THE TEMPERATURES SOME...BUT STILL EXPECT DAYTIME HIGHS TO BE
WELL ABOVE NORMAL...AND LIKELY IN THE 90S INLAND. COASTAL CLOUDS
SHOULD CONTINUE TO KEEP THE COASTAL TEMPERATURES CLOSER TO THE
SEASONAL NORMALS. THE UPPER TROUGH WILL DESTABILIZE THE ATMOSPHERE IN
THE CENTRAL OREGON CASCADES FOR POSSIBLY ISOLATED THUNDERSTORMS IN
THE AFTERNOONS AND EVENINGS...MAINLY NEAR THE CREST OF THE CASCADES
IN LANE COUNTY. THE MODELS VARY CONSIDERABLY FOR MONDAY WITH THE
ECMWF REBUILDING THE RIDGE OVER US...AND THE GFS DROPPING AN UPPER
LOW SOUTHWARD ALONG THE WESTERN CANADA COAST. LEFT THE MONDAY
FORECAST UNCHANGED DUE TO THESE DIFFERENCES. TJ
&&


.AVIATION...MILD DRY SW FLOW ALOFT WILL KEEP REGION UNDER MOSTLY
CLEAR SKIES THROUGH TONIGHT. STRATUS WITH CIGS 1000 TO 1200 FT
INLAND OVER SW WASH AND ALONG COLUMBIA RIVER WILL BURN OFF BY
19Z. HOWEVER...IFR STRATUS AND PATCHY FOG ALONG THE COAST WILL
TAKE A BIT LONGER TO BREAK UP...BUT SHOULD BURN BACK TO BEACHES
THIS AFTERNOON...THEN PUSH BACK ONSHORE AFTER 03Z.

KPDX AND APPROACHES...VFR TODAY AND TONIGHT. WILL HAVE CIGS AROUND
1200 FT UNTIL 17Z...WITH STATUS MOST EXTENSIVE TO N OF OPS AREA.
ROCKEY. &&

.MARINE...WIND SPEEDS UNDER 10 KT EARLY THIS MORNING...BUT WILL
INCREASE LATER THIS MORNING AND INTO THE AFTERNOON. EXPECT SMALL
CRAFT ADVISORY WIND SPEEDS ACROSS THE MAJORITY OF THE WATERS BY
19Z TUE. HAVE ADJUSTED THE TIMING OF THE SMALL CRAFT ADVISORY TO
START IT A BIT LATER AND EXTEND IT THROUGH WED AFTERNOON.
STRONGEST WIND SPEEDS WILL BE OVER THE SRN WATERS...GENERALLY S OF
HECETA HEAD WHERE AFTERNOON AND EARLY-EVENING GUSTS TO 30 KT CAN
BE EXPECTED. MODELS SHOW WIND SPEEDS GRADUALLY DECREASING LATE IN
THE WEEK AND OVER THE WEEKEND.

GENERALLY WIND-WAVE DRIVEN SEAS FOR THE NEXT FEW DAYS. SPECTRAL
ANALYSIS MAINTAINS A RESIDUAL BACKGROUND LONG-PERIOD SW SWELL FOR
THE NEXT COUPLE OF DAYS AND HAVE INDICATED THIS IN THE GRIDS.
OTHERWISE...STEEP AND CHOPPY CONDITIONS WILL PREVAIL DUE TO THE
LARGE WIND-WAVE COMPONENT. A BUILDING NW SWELL LOOKS TO ARRIVE
OVER THE WEEKEND AND COULD REACH 10 FT. WEISHAAR

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS THROUGH WED ON ALL WATERS.

&&

$$

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.


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.