Area Forecast Discussion
Issued by NWS Portland, OR

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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 012126
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
225 PM PDT MON SEP  1 2014

.SYNOPSIS...A WEAKENING FRONT WILL KEEP SOME CLOUDS ALONG THE NORTH
COAST THIS EVENING...OTHERWISE IT WILL BE MOSTLY CLEAR.  AN UPPER
LEVEL TROUGH WILL MOVE ACROSS THE REGION TUESDAY INTO EARLY
WEDNESDAY BRINING COOLER AND CLOUDY WEATHER. THIS SYSTEM WILL ALSO
BRING SOME LIGHT RAIN TO SOUTHWEST WASHINGTON AND THE FAR NORTHERN
PART OF NORTHWEST OREGON TUESDAY AFTERNOON AND TUESDAY NIGHT. AN
UPPER LEVEL RIDGE COMBINED WITH LOW-LEVEL EASTERLY WINDS WILL RESULT
IN SUNNIER AND WARMER WEATHER FOR THE LATTER PART OF THE WEEK.
ONSHORE FLOW WILL RETURN NEXT SUNDAY.

&&

.SHORT TERM...TONIGHT THROUGH THURSDAY...A WEAKENING FRONT JUST OFF
THE WA/OR COAST THIS AFTERNOON KEEPING A PERSISTENT AREA OF CLOUDS
OVER THE NORTH COASTAL AREA...MAINLY FROM ABOUT TILLAMOOK NORTHWARD
THIS AFTERNOON. WEBCAM IMAGERY AT ASTORIA THIS AFTERNOON ALSO SHOWED
SOME SPOTTY LIGHT DRIZZLE OCCURRING FROM TIME TO TIME. ELSEWHERE...
LOTS OF SUNSHINE GIVING WAY TO A SPLENDID LABOR DAY.

AN UPPER LEVEL TROUGH OFF THE BRITISH COLUMBIA COAST WILL DROP SOUTH
TOWARDS THE PACIFIC NW LATER TONIGHT. THE MARINE LAYER SHOULD DEEPEN
TONIGHT AND WITH INCREASED ONSHORE FLOW TONIGHT. THUS...EXPECT
MARINE CLOUDS TO PUSH FARTHER INLAND TUESDAY MORNING.  A WEAK FRONT
ASSOCIATED WITH THE UPPER LEVEL TROUGH WILL MOVE ACROSS THE NORTHERN
PART OF THE REGION TUESDAY AFTERNOON/EVENING.  THE FRONT WILL
PRODUCE SOME LIGHT RAIN ALONG THE NORTH COAST/COAST RANGE AND PART
OF THE INLAND AREA. BEST CHANCES OF MEASURABLE RAIN WILL BE IN
SOUTHWEST WA...BUT THE NORTHERN WILLAMETTE VALLEY AND ADJACENT
FOOTHILLS AND NORTH CASCADES WILL BE ON THE SOUTHERN END OF THE
FRONT AND COULD GET ALITTLE RAIN TUES EVE/NIGHT.  THERE WILL BE
ANOTHER DEEP MARINE PUSH TUESDAY NIGHT WITH A CLOUDY START TO THE
DAY ON WEDNESDAY. THE UPPER TROUGH AND INCREASE IN CLOUDS WILL KEEP
THE TEMPERATURES BELOW NORMAL TUESDAY AND WEDNESDAY.

HIGH PRESSURE WILL REBUILD OVER THE REGION THURSDAY. A FAIRLY STRONG
THERMAL TROUGH WILL ALSO BUILD NORTHWARD ALONG THE COAST. THIS WILL
RESULT IN OFFSHORE FLOW...CLEAR SKIES...AND WARMER TEMPERATURES
THE LATTER PART OF THE WORK WEEK. TW

.LONG TERM...FRIDAY THROUGH MONDAY...A WEAK...POSITIVELY-TILTED
TROUGH WILL MOVE THROUGH OUR AREA LATE THIS WEEK.  NOT ONLY IS
MOISTURE LIMITED FOR THE PASSAGE OF THIS SYSTEM...BUT ANY
PRECIPITATION THAT DOES DEVELOP SHOULD BE EAST OF THE CASCADE
RIDGE...OUTSIDE OF OUR AREA.  LATE THIS WEEKEND THE
GFS...ECMWF...AND DGEX ALL ARE SUGGESTING A LONGWAVE TROUGH WILL
MOVE ONSHORE BRINGING A CHANCE FOR SOME RAINFALL SUNDAY NIGHT OR
MONDAY. DISAGREEMENT BETWEEN MODELS ON TIMING AND BECAUSE OF HOW FAR
OUT THIS SYSTEM IS IN THE FORECAST PERIOD...THERE IS A LOT OF
UNCERTAINTY WITH THIS SYSTEM. KEPT POPS THE SAME AS THEY CAPTURE
THIS UNCERTAINTY WELL. -MCCOY
&&

.AVIATION...A WEAK DISTURBANCE WILL BE PASSING BY THROUGH WESTERN
WASHINGTON AND BRUSH EXTREME NORTHWEST OREGON TODAY FOR SOME FOR
MOSTLY VFR CIGS ALONG THE SOUTH WASHINGTON AND NORTH OREGON COASTS
AND INLAND NEAR THE COLUMBIA RIVER TO KKLS OR SO. THE LOWEST CIGS
WILL BE ALONG THE NORTH COASTAL AREAS. FARTHER INLAND THERE MAY BE
A FEW CIGS NEAR THE MOUNTAINS BUT LESS CHANCE IN THE VALLEYS. THE
SURFACE PATTERN SUGGESTS THE CENTRAL OREGON COAST AND THE SOUTH
WILLAMETTE VALLEY WILL TEND TO STAY CLEAR THIS AFTERNOON AND
EVENING. WITH PLENTY OF CLOUDS UPSTREAM OVER THE NE PACIFIC...
EXPECT MVFR CIGS TO PUSH ONTO THE COAST OVERNIGHT TONIGHT AND
SPREAD INLAND TO KPDX AND POSSIBLY A BIT SOUTH BY TUESDAY MORNING.
ANOTHER MORE ORGANIZED FRONT IS EXPECTED TO SPREAD IN FROM THE
NORTHWEST TUESDAY WITH MVFR CIGS OR PERHAPS HIGH IFR AND SOME
LIGHT RAIN ON THE COAST...APPROACHING KPDX BY 00Z WEDNESDAY...
WHICH IS 5 PM TUESDAY.

KPDX AND APPROACHES...VFR CONDITIONS TODAY. MAY SEE SOME VFR CIGS
FOR A TIME LATE THIS AFTERNOON AND EVENING AROUND 5000 OR 6000
FT. THERE IS A DECENT CHANCE MVFR CONDITIONS WILL IMPACT THE
TERMINAL TOWARDS 12Z TUESDAY. SOME VFR CIGS AND POSSIBLY A SHOWER
ARE POSSIBLE LATE TUESDAY. PT
&&

.MARINE...A WEAK DISTURBANCE PASSING BY TO OUR NORTH BRIEFLY
TURNED THE WINDS IN OUR NORTHERN WATERS TO LIGHT SOUTHERLY...BUT
THEN WEAK HIGH PRES WILL BRIEFLY BUILD BACK IN TONIGHT AND EARLY
TUESDAY FOR NORTH TO NORTHWEST FLOW ALONG THE ENTIRE COAST...WHICH
MAY GIVE SMALL CRAFT ADVISORY THRESHOLD GUSTS TO OUR CENTRAL
OREGON WATERS MAINLY TONIGHT. ANOTHER SLIGHTLY STRONGER FRONTAL
BAND IS FORECAST TO MOVE INTO THE WATERS MIDDAY TUESDAY AND
ONSHORE TUESDAY EVENING...WITH THE MAIN EFFECT BEING SOME
MODERATE NW WINDS BEHIND THE FRONT THAT MAY GIVE SOME GUSTS ABOVE
20 KT AS WELL ESPECIALLY IN THE OUTER WATERS. THE THERMAL TROUGH
BEGINS REDEVELOPING IN NORTHERN CALIFORNIA WEDNESDAY...WITH SMALL
CRAFT ADVISORY THRESHOLD NORTHERLY WINDS BEGINNING TO SPREAD NORTH
ALONG THE CENTRAL OREGON COAST LATE WEDNESDAY. THE WINDS WILL THEN
SPREAD NORTHWARD THROUGH ALL THE WATERS THURSDAY AND FRIDAY AS
THE THERMAL TROUGH CONTINUES TO BUILDS FARTHER NORTH ALONG THE
COAST. WINDS THURSDAY AFTERNOON AND EVENING WILL BE ON THE HIGH
SIDE OF THE SMALL CRAFT ADVISORY RANGE.

SEAS MAY GET CLOSE TO 10 FT IN THE NORTHERN WATERS FROM THE
NORTHWESTERLIES WEDNESDAY...AND POSSIBLY AGAIN AROUND 8 TO 10 FT
LATE THURSDAY AND THURSDAY NIGHT FROM THE NORTHERLIES DUE TO THE
NORTHWARD BUILDING THERMAL TROUGH. PT
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 5 PM THIS AFTERNOON TO
     3 AM PDT TUESDAY 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.


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