Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 270322
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
821 PM PDT TUE AUG 26 2014

.SYNOPSIS...LITTLE CHANGE THROUGH WED AS WILL HAVE ONE MORE RATHER
WARM DAY. THEN ONSHORE FLOW INCREASES WED NIGHT AND THU...BRINGING A
GRADUAL COOLING TREND. HIGHS ONLY IN THE LOWER 70S INLAND THIS
WEEKEND. WILL HAVE ALSO HAVE A THREAT OF SHOWERS THIS WEEKEND BUT
APPEARS WILL LIKELY HAVE MORE DRY PERIODS THAN SHOWERS.
&&

.SHORT TERM...TONIGHT THROUGH FRIDAY...
NOT MUCH CHANGE...AS STRONG HIGH PRES REMAINS OVER THE REGION.
THERMAL LOW PRES TROUGH SITS ON THE EAST SLOPES OF THE COAST RANGE
THIS EVENING. TO THE WEST...EXTENSIVE LOW CLOUDS AND COOL CONDITIONS
ON THE COAST. TO THE EAST OF THE THERMAL TROUGH LIES WARM AND DRY
CONDITIONS. THE TROUGH WILL MOVE LITTLE TONIGHT AND EARLY WED...THEN
PUSH ACROSS THE WILLAMETTE VALLEY ON WED AND WED EVENING. AS A
RESULT...INLAND AREAS WILL SEE ANOTHER MILD NIGHT WITH ONE MORE
RATHER WARM DAY. ONCE THE TROUGH SHIFTS EAST OF THE REGION...ONSHORE
FLOW WILL INCREASE. THIS WILL BRING A DEEPENING MARINE LAYER AND
COOLER TEMPERATURES INTO THE INTERIOR FOR LATER WED NIGHT AND THU.

WESTERLY FLOW ALOFT WILL BE INCREASING ON THU AND FRI...ALLOWING THE
RIDGE TO FLATTEN. THIS WILL BRING A FEW WEAK DISTURBANCES INTO THE
PAC NW...BUT MAINLY AFFECTING WASHINGTON AND SOUTHERN BRITISH
COLUMBIA. AS MARINE LAYER DEEPENS LATE WED NIGHT AND THU AM...ONE
WEAK DISTURBANCE WILL BE CLOSE ENOUGH TO PROVIDE WEAK LIFT NORTH OF A
NEWPORT TO PORTLAND TO MT ADAMS LINE...RESULTING IN AREAS OF
DRIZZLE...ESPECIALLY OVER SW WASHINGTON AND N OREGON COAST.

EITHER WAY...ONSHORE FLOW THU AND FRI WILL COOL AIR MASS...WITH
INTERIOR HIGH STILL LOW TO MID 80S ON THU...THEN NEAR 80 ON FRI. BUT
FRI HIGHS MAY BE STILL TOO WARM IF CLOUDS PERSISTS.  WOULD NOT BE
SURPRISED IF GUIDANCE IS CORRECT AND HIGHS ARE ONLY IN THE LOWER TO
MID 70S ON FRI. WILL MAKE NO CHANGES THIS EVENING...AND WILL LET MID
SHIFT PONDER WHETHER OR NOT TO COOL FRI HIGHS FURTHER.  ROCKEY.

.LONG TERM...A TROUGH APPROACHES THE WEST COAST ON FRIDAY WHICH WILL
BRING A CHANCE OF RAIN OVER THE WEEKEND. THE 12Z ECMWF AND GFS BOTH
BRING THE SYSTEM ONSHORE LATE FRIDAY NIGHT. NORTHWESTERLY FLOW WILL
BECOME DOMINANT OVER OUR AREA BEHIND THE INITIAL COLD FRONT...WITH
MULTIPLE IMPULSES BRINGING CHANCES OF RAIN THROUGH SUNDAY EVENING.
12Z GFS SEEMS A LITTLE STRONG EARLY NEXT WEEK BRINGING RAIN AND CLOUD
COVER OVER OUR AREA AFTER TWO DAYS OF NORTHWESTERLY FLOW...SO OPTED
TO LEAN MORE TOWARDS ECMWF WITH SLIGHT CHANCE OF RAIN MAINLY ALONG
SOUTH WASHINGTON CASCADE AND COASTAL RANGES. -MCCOY
&&

.AVIATION...VFR CONDITIONS INLAND TONIGHT AND WED...EXCEPT SOME
MVFR MARINE STRATUS PUSHING INLAND TO ABOUT KELSO AND SCAPPOOSE
BY 15Z. ON THE COAST...IFR OR LIFR CIGS RETURN TONIGHT WITH
PERSISTENT IFR VSBY ALONG THE CENTRAL OREGON COAST. SOME LOCALIZED
SMOKE FROM THE FIRES NEAR OAKRIDGE IN EASTERN LANE COUNTY MAY REDUCE
VSBY IN THAT AREA.

KPDX AND APPROACHES...VFR CONDITIONS TONIGHT AND WED.
&&

.MARINE...PERSISTENT PATTERN CONTINUES WITH HIGH PRESSURE OVER
THE NE PACIFIC AND THERMAL LOW OVER NORTHERN CALIFORNIA. WINDS
WILL BE BELOW 20 KTS TONIGHT...SO HAVE CANCELLED THE SMALL CRAFT
ADVISORY ABOUT AN HOUR EARLIER THAN IT WAS SET TO EXPIRE. SEAS
REMAIN CHOPPY TONIGHT WITH SHORT PERIOD WIND WAVES DOMINATING.

HIGH PRESSURE SINKS SOUTHWARD THROUGH THE WEEK...MAKING WAY FOR
OUR NEXT LOW PRESSURE SYSTEM TO APPROACH FRIDAY NIGHT WITH INCREASING
SWELL LATE SATURDAY. WINDS TURN SOUTHERLY OVER THE NEARSHORE
WATERS ON THE BACK SIDE OF THE LOW SUNDAY WITH SOME DISAGREEMENT
AMONG MODELS AS TO TIMING OF SHIFT BACK TO N AND NW BUT WINDS
WILL REMAIN BELOW 10 KT DURING THE PERIOD OF UNCERTAINTY...SO
IMPACT SHOULD BE MINIMAL. TW
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...NONE.

&&

$$

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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