Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 010352
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
845 PM PDT TUE SEP 30 2014

.SYNOPSIS...THE FEW REMAINING SHOWERS OVER THE MOUNTAINS WILL TAPER
OFF TONIGHT AS UPPER LEVEL RIDGING BEGINS TO PUSH INTO THE REGION.
THE RIDGE WILL STRENGTHEN THROUGH THE REST OF THE WEEK AND LIKELY
REMAIN IN PLACE INTO EARLY NEXT WEEK. THIS WILL BRING A RETURN TO
WARMER AND DRIER WEATHER. THE RIDGE MAY WEAKEN ENOUGH OVER THE
WEEKEND TO ALLOW SOME LIGHT PRECIPITATION OVER THE SOUTH WASHINGTON
AND NORTH OREGON COAST AND COAST RANGE.

&&

.SHORT TERM DISCUSSION...TONIGHT THROUGH FRIDAY...
A FEW HEAVY SHOWERS DEVELOPED OVER THE NORTH WILLAMETTE VALLEY AND SW
WASHINGTON THIS AFTERNOON. THE SHOWERS WERE FEW AND SPACED IN NEARLY
PARALLEL LINES STRETCHING FROM THE NW TO SE. THE SHOWERS DECREASED
AFTER SUNSET AND IS ALL BUT GONE. THERE ARE A FEW SHOWERS SEEN ON
RADAR OVER THE COAST AND CASCADES.

SKIES ARE BEGINNING TO CLEAR IN THE VALLEY AS THE ATMOSPHERE
CONTINUES TO STABILIZE. AN UPPER LEVEL RIDGE WILL SHIFT INTO THE
PACNW INCREASING SUBSIDENCE WHICH SHOULD ALSO BRING QUITE A BIT OF
CLEARING IN THE CLOUD COVER OVERNIGHT. COMBINED WITH DECOUPLING WINDS
OVERNIGHT...THIS WILL LEAD TO SIGNIFICANT RADIATIONAL COOLING AND
FOG DEVELOPMENT OVER THE COAST AND LOW LYING VALLEYS BY WEDNESDAY
MORNING.

PREVIOUS DISCUSSION FOLLOWS....A FEW ISOLATED SHOWERS MAY LINGER INTO
TOMORROW MORNING OVER THE HIGHER TERRAIN...BUT THE OVERALL TREND IS
TOWARD DRIER WEATHER TOMORROW AS THE UPPER LEVEL RIDGE CONTINUES TO
STRENGTHEN. THE AIR MASS WILL BEGIN TO WARM UP A BIT...LEADING TO
AFTERNOON HIGHS CLOSER TO SEASONAL NORMALS. HOWEVER...EVEN BETTER
RADIATIONAL COOLING IS EXPECTED TOMORROW NIGHT WITH LITTLE IN THE WAY
OF CLOUDS COVER. THIS SHOULD LEAD TO THE COOLEST NIGHT OF THE SEASON
SO FAR FOR MOST. IT IS NOT OUT OF THE QUESTION THAT A FEW OUTLYING
VALLEY LOCATIONS MAY SEE TEMPS DIP INTO THE UPPER 30S BY EARLY THU
MORNING. AGAIN...EXPECT PLENTY OF FOG DEVELOPMENT FOR THE COAST AND
LOW LYING VALLEY LOCATIONS.

THE UPPER LEVEL RIDGE AXIS MOVES OVER THE U.S. WEST COAST ON THU.
THIS IS MODELED TO CREATE A THERMALLY INDUCED SURFACE TROUGH ALONG
THE S OREGON COAST...BRINGING A PERIOD OF OFFSHORE FLOW TO MUCH OF SW
WASHINGTON AND NW OREGON ON THU AND THU NIGHT. THIS SHOULD LEAD TO A
PLEASANT SUNNY DAY WITH HIGHS NEAR OR JUST ABOVE SEASONAL NORMALS.
THE RIDGE IS FCST TO STRENGTHEN FURTHER FRI...BRINGING ANOTHER MOSTLY
SUNNY DAY WITH TEMPS OVER THE INTERIOR LOWLANDS RUNNING A GOOD 5 TO
10 DEG ABOVE NORMAL. PYLE

.LONG TERM...FEW CHANGES WERE MADE TO THE EXTENDED FORECAST
TODAY AS THE MODELS CONTINUE TO SHOW UPPER LEVEL RIDGING OVER THE
PACIFIC NORTHWEST. AS SUCH...WE CAN EXPECT TO SEE DRY CONDITIONS AND
SLIGHTLY WARMER TEMPS THROUGH MUCH OF NEXT WEEK. STILL KEEPING A
SLIGHT CHANCE OF RAIN FOR THE NORTH COAST DUE TO THE POSSIBILITY OF
WEAK SHORTWAVES MOVING THROUGH THE AREA. AS MENTIONED
PREVIOUSLY...AN ATMOSPHERIC RIVER EVENT SEEMS LIKELY AT THIS POINT.
MOST OF THE RAIN SHOULD REMAIN TO OUR NORTH. HOWEVER...IF THE RIDGE
BREAKS DOWN OR BECOMES FLATTER WE COULD SEE SOME RAIN PUSH INTO THE
REGION. THE NEXT WIDE SPREAD RAIN EVENT LOOKS TO ARRIVE TOWARDS THE
END OF NEXT WEEK AND SHOULD BRING WITH IT SLIGHTLY COOLER TEMPS. /64
&&

.AVIATION...SHOWERS ARE DWINDLING THIS EVENING...AND VFR
CONDITIONS PREVAIL. THERE IS STILL BRIEF MVFR CIGS ONCE IN A
WHILE...MAINLY ALONG THE NORTH COAST. WITH CALMING WINDS AND
CLEARING SKIES TONIGHT...THERE IS A GOOD CHANCE OF IFR STRATUS AND
VIS ACROSS THE FORECAST AREA WEDNESDAY MORNING. LIFR CIGS AND/OR
VIS ARE POSSIBLE PARTICULARLY AT KSLE AND KEUG AFTER 12Z. CLEARING
AND VFR CONDITIONS EXPECTED WEDNESDAY AFTERNOON.

KPDX AND APPROACHES...VFR CONDITIONS THIS EVENING. LOW MVFR CIGS
EXPECTED BETWEEN 10Z AND 15Z WITH...CLEARING AROUND 18Z WED. VFR
CONDITIONS EXPECTED WED AFTERNOON AND EVENING. TJ

&&

.MARINE...NORTHWEST WINDS OVER THE WATERS AS HIGH PRESSURE BUILDS.
SEAS ARE BETWEEN 7 AND 9 FEET THIS EVENING. THERE WILL BE LITTLE
CHANGE WED AS HIGH PRESSURE CONTINUES TO BUILD...AND SEAS GRADUALLY
SUBSIDE. A THERMAL TROUGH WILL MOVE NORTHWARD THROUGH THE WATERS UP
TO AROUND TILLAMOOK OREGON ON THURSDAY. THIS WILL RESULT IN NE WINDS
THROUGH FRIDAY MORNING...AND SLIGHTLY STRONGER WINDS..NEAR NEWPORT
AND FURTHER SOUTH. LIGHT WINDS FRIDAY AND SATURDAY AS A FRONT
APPROACHES FROM THE NW. THE FRONT WILL DECAY AS IT MOVES FROM NORTH
TO SOUTH ACROSS THE WATERS LATE IN THE WEEKEND. TJ

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL
     11 PM PDT THIS EVENING.

&&

$$

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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