Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 210933
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
231 AM PDT SUN SEP 21 2014

.SYNOPSIS...INCREASING ONSHORE FLOW TODAY WILL KEEP THE COAST CLOUDY
AND COOL. FURTHER INLAND...NO CLOUDS BUT A BIT COOLER AS OCEAN AIR
SPILLS THROUGH THE COAST RANGES.  MILD DAYS FOR MON AND TUE...BUT
CLOUDS ON THE INCREASE. SHOULD SEE RAIN TUE NIGHT AND WED...WITH
SHOWERY WEATHER AFTERWARDS.
&&

.SHORT TERM...LOW STRATUS HAS RAPIDLY SPREAD UP THE OREGON COAST
OVERNIGHT...AND CONTINUES TO PUSH UP THE WASHINGTON COAST. THERMAL
TROUGH NOW LIES FROM FAR NW WASHINGTON OVER THE WILLAPA HILLS THEN
OVER THE WILLAMETTE VALLEY. THIS IS THE LINE MARKING THE SHIFT FROM
OFFSHORE TO ONSHORE WINDS.  THIS THERMAL WILL SHIFT EAST OF THE
CASCADES BY EARLY AFTERNOON. THIS WILL ALLOW ALL WINDS TO BECOMING
ONSHORE BY LATE MORNING ACROSS THE REGION. WHILE NOT ALL THAT STRONG
OVER THE INTERIOR...WILL BE ENOUGH TO HOLD TODAYS HIGHTEMPERATURES
IN THE LOWER TO MIDDLE 80S. LOW CLOUDS WILL NOT MOVE MUCH ALONG THE
COAST...KEEPING TEMPERATURES THERE IN THE LOWER TO MID 60S.

ONSHORE FLOW WILL CONTINUE TO INCREASE TONIGHT...WITH MARINE LAYER
DEEPENING AND PUSHING MARINE CLOUDS INTO THE INTERIOR. MORNING LOW
CLOUDS ON MONDAY WILL GRADUALLY BREAK UP. BUT IT WILL BE MUCH COOLER
INLAND WITH HIGHS ONLY THE 70S. AT THE SAME TIME...A FRONTAL SYSTEM
ALONG 145W WILL BE APPROACHING THE PAC NW COAST. THERE IS GOOD
AGREEMENT THAT THIS SYSTEM WILL STRETCH APART WHILE APPROACHING THE
COAST...WITH THE BULK OF LEFTOVER ENERGY HEADED TOWARD BRITISH
COLUMBIA. THE FRONT MAY HOLD TOGETHER LONG ENOUGH FOR SPOTTY LIGHT
RAIN ALONG THE WASHINGTON AND N OREGON COAST.

WILL ALSO KEEP MINOR THREAT OF SHOWERS OVER THE HIGH CASCADES OF
OREGON FOR MONDAY. THIS DUE TO MOISTURE ROTATING UP OUT OF NEVADA
INTO SOUTHERN OREGON. SINCE SO CLOSE TO THE MOISTURE POOL...CAN NOT
RULE OUT A SHOWER OR TWO.

ANOTHER FRONT WILL APPROACH LATER TUESDAY...AND WILL BE A BIT
STRONGER. SO SEEMS TUESDAY WILL BE A REPEAT OF MONDAY...BUT THREAT OF
MOISTURE PUSHES FURTHER INLAND INTO THE COAST RANGES. HAVE INCREASED
CLOUD COVER...AND PUT THREAT OF OCCASIONAL SPRINKLES OVER INTERIOR
FOR TUE.     ROCKEY.

.LONG TERM...FIRST SIGNIFICANT FRONT OF THE FALL SEASON ARRIVES LATE
TUE NIGHT AND WED. VERY WELL COULD SEE AROUND 1 INCH OF RAIN IN THE
COAST RANGES...AND WIDESPREAD 0.33 TO 0.50 INCH ACROSS INLAND AREAS.
FRONT IS ARRIVING IN A SOUTH TO NORTH ORIENTATION. AS A RESULT...IT
WILL BE SLOWING ITS EASTWARD PROGRESSION INTO THE PAC NW. SO RAINFALL
HAS POTENTIAL TO BE A BIT HEAVIER OVER THE WEST SLOPES OF THE COAST
AND CASCADES RANGES. WILL BE PLENTY OF CLOUDS AND MUCH COOLER FOR
WED. AFTER THAT FRONT CLEARS THE REGION WED EVENING... AIR MASS WILL
REMAIN UNSETTLED WITH SHOWERS AND COOL WEATHER. SUCH COOL DAMP
WEATHER WILL GO FAR IN QUIETING WILDFIRE ACTIVITY. ROCKEY.
&&

.AVIATION...VFR CONDITIONS PERSIST INLAND THROUGH THIS EVENING.
MARINE STRATUS WILL THEN FILL THE VALLEY WITH LOW MVFR CIGS BY
MONDAY MORNING. AT THE COAST...IFR TO LIFR CIGS WITH OCCASIONAL
VISIBILITY RESTRICTION IN FOG CONTINUE TODAY. CIGS ARE EXPECTED TO
RISE TONIGHT TO 1000-1500 FT RANGE AS AN UPPER TROUGH APPROACHES
THE REGION.

KPDX AND APPROACHES...VFR CONDITIONS THROUGH 09Z MON THEN
INCREASING CHANCES FOR LOW MVFR CIGS. LOW MVFR CIGS LIKELY BY 12Z
MON.
&&

.MARINE...SOUTHERLY WINDS HAVE SPREAD ACROSS THE AREA OVERNIGHT AS
THE COASTAL TROUGH SPREAD INTO WASHINGTON. LOW MARINE STRATUS HAS
SPREAD INTO THE WATERS AS WELL.  WINDS WERE EARLIER THOUGHT TO
REMAIN JUST BELOW ADVISORY CRITERIA FOR TODAY...BUT APPEARS IT
WILL MEET CRITERIA OVER THE NORTHERN ZONES. THE STRONGEST WINDS
ARE EXPECTED OUT TO ABOUT 30-40 NM THROUGH THIS AFTERNOON. WINDS
WILL EASE ACROSS ALL WATERS THIS EVENING. THE NEXT WEAKENING FRONT
FOR MONDAY AFTERNOON MAY BRING ANOTHER ROUND OF SMALL CRAFT
ADVISORY WINDS. A BETTER CHANCE FOR SMALL CRAFT ADVISORIES WILL BE
ON TUE THROUGH THU AS A FAIRLY STRONG LOW PRES ROLLS UP TOWARD THE
B.C. COAST.

WESTERLY SWELL 6 FT STARTS OUT THE DAY THEN SLOWLY SUBSIDES OVER
THE NEXT FEW DAYS...THEN RISE ABOVE 10 FT WED BUT SHOULD NOT
EXCEED 15 FT. MODEL DIFFERENCES AFTER THU INCREASE UNCERTAINTY
AND CONFIDENCE IN THE FORECAST. /MH
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 3 PM THIS AFTERNOON FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO CASCADE HEAD 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 AS THE FORECAST AREA.


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