Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 281753
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
953 AM PST WED JAN 28 2015

.SYNOPSIS...A WEAK FRONTAL BOUNDARY REMAINS DRAPED OVER NORTHWEST
OREGON WITH SOME SPOTTY LIGHT PRECIPITATION. THE FRONT WILL MOVE
LITTLE TODAY AND TONIGHT AS ONE MORE WEAK UPPER SHORT WAVE ALONG THE
COAST MOVES ONSHORE TODAY...LINGERS TONIGHT...THEN DRIFTS SOUTH OF
THE AREA LATER THURSDAY AND THURSDAY NIGHT. ANOTHER UPPER LEVEL
RIDGE IS EXPECTED TO DEVELOP OVER THE PACIFIC NORTHWEST THURSDAY
NIGHT AND FRIDAY FOR MORE DRY AND RATHER MILD WEATHER...AND A BIT OF
EASTERLY WINDS THROUGH THE GORGE...BUT WITH AREAS OF FOG AND STABLE
CONDITIONS BELOW TEMPERATURE INVERSIONS IN MOST OF THE VALLEY AREAS.
THE NEXT CHANCE FOR RAIN IS PROBABLY NOT UNTIL SUNDAY AND MONDAY.
&&

.SHORT TERM...THE LIGHT RAIN AND DRIZZLE FROM OVERNIGHT HAS EASED
THIS MORNING...BUT THE NATIONAL WEATHER SERVICE DOPPLER RADAR STILL
SHOWS SOME ECHOES ACROSS THE CENTRAL PART OF NORTHWEST OREGON THAT
COULD BE A LITTLE DRIZZLE ALONG OUR STALLED WEAK FRONTAL BOUNDARY.
WILL KEEP SOME LOW POPS TODAY FOR THIS. THERE ARE STILL A LOT OF
CLOUDS AND AREAS OF FOG OVER THE AREA...AND EXPECT THE FOG AND LOW
CLOUDS TO SLOWLY LIFT BUT SKIES TO REMAIN CLOUDY TODAY.

THERE IS STILL ONE MORE WEAK UPPER SHORT WAVE ASSOCIATED WITH THE
CLOUD MASS ALONG THE COAST AND PARTIALLY INLAND OVER WESTERN OREGON
THAT WILL CONTINUE MOVING SLOWLY ONSHORE TODAY AND TONIGHT...THEN
DRIFT SOUTHEAST ON THURSDAY AND AWAY FROM THE AREA THURSDAY NIGHT.
WILL KEEP A SMALL CHANCE OF SHOWERS INTO THURSDAY MORNING AS THIS
FEATURE MOVES THROUGH...AND KEEP CLOUDS OVER THE AREA FROM IT AS
WELL.

THE CLOUDS WILL FINALLY COLLAPSE AND CLEAR THURSDAY NIGHT AS THE
UPPER SHORT WAVE MOVES AWAY AND AN UPPER RIDGE STARTS TO MOVE IN.
EXPECT AREAS OF FOG TO REDEVELOP THURSDAY NIGHT AND CONTINUE THROUGH
AT LEAST FRIDAY MORNING ESPECIALLY IN THE VALLEYS. WILL SEE SOME
MODEST EAST WINDS THROUGH THE GORGE AS WELL...THAT MAY BRING SOME
CLEARING TO AT LEAST THE NORTH VALLEY AREAS FRIDAY AFTERNOON.
TOLLESON

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...
FRIDAY NIGHT THROUGH TUESDAY...THE UPPER RIDGE CONTINUES THROUGH
SATURDAY OFF THE PACNW COAST AS A HIGH AMPLITUDE PATTERN IN THE NORTH
PACIFIC CONTINUES. THIS WILL MEAN DRY WEATHER WITH FOG IN THE
INTERIOR VALLEYS WHILE THE MOUNTAINS WILL BE MILD NEARLY CLOUD FREE.
MODELS ARE CONTINUE TO SHOW THE RIDGE SHIFTING INLAND AS A MORE
CONSOLIDATED JETSTREAM APPROACHES THE WEST COAST. ECMWF...GFS AND GFS
ENSEMBLE MEAN ARE IN GOOD AGREEMENT IN BRINGING A WARM FRONT THROUGH
THE AREA LATE SUNDAY INTO MONDAY. THE ECMWF FLATTENS THE RIDGE MORE
SO SNOW LEVELS WILL BE LOWER BUT STILL ABOVE MOST CASCADE PASSES.
WITH THE WEAKER RIDGE AND STRONGER JET STREAM POINTED INTO THE REGION
WE CAN EXPECT MORE CLOUDS AND HIGHER CHANCES FOR RAIN FOR THE
REMAINDER OF THE LONG TERM.  OVERALL HAVE INCREASED POPS SUN NIGHT
THROUGH TUE WITH EMPHASIS ON SUN NIGHT AND MONDAY.  THERE MAY BE
ANOTHER FRONT TUE BUT MODEL SOLUTIONS DIVERGE REGARDING THIS FEATURE.
/26
&&

.AVIATION...A PREVIOUSLY STALLED FRONTAL BOUNDARY IS NOW LIFTING
SLOWLY NORTH ACROSS NW OREGON AND SW WASHINGTON AS A WEAK WARM FRONT.
THIS IS RESULTING IN PATCHY DRIZZLE AND WIDESPREAD IFR OR LOWER CIGS
AND VSBYS THIS MORNING FOR THE INTERIOR LOWLANDS AND NORTHERN COASTAL
LOCATIONS. THE FOG AND LOW CIGS WILL LIKELY PERSIST THROUGH THE
MORNING...AND POTENTIALLY IN THE EARLY AFTERNOON FOR SOME SPOTS.
HOWEVER...EXPECT CONDITIONS SHOULD GRADUALLY IMPROVE TO VFR THIS
AFTERNOON AS THE FRONT CONTINUES TO LIFT NORTHWARD AND WEAKEN.
ADDITIONAL LIFR AND IFR CONDITIONS WILL THEN LIKELY REDEVELOP AFTER
03Z THURSDAY AT MANY TAF SITES. INCREASING EASTERLY WINDS NEAR THE
COLUMBIA RIVER GORGE MAY KEEP CONDITIONS FROM DETERIORATING AT KTTD
AND KPDX THOUGH.

KPDX AND APPROACHES...PATCHY DRIZZLE AND LIFR CONDITIONS WILL
CONTINUE THROUGH AT LEAST 18Z. CONDITIONS SHOULD GRADUALLY IMPROVE TO
IFR AND THEN FINALLY VFR BETWEEN 18Z AND 21Z. STRENGTHENING EASTERLY
WINDS TONIGHT MAY ALLOW VFR CONDITIONS TO PERSIST THROUGH 12Z
THURSDAY...BUT THERE IS A CHANCE CONDITIONS COULD DETERIORATE INTO
MVFR OR IFR TOWARDS THAT PERIOD IF THE WINDS DO NOT MATERIALIZE.
PYLE/NEUMAN
&&

.MARINE...A WEAK LOW PRESSURE IS PUSHING NORTHEASTWARD TODAY...
LIFTING A PREVIOUSLY STALLED FRONT AS A WARM FRONT OVER THE WATERS.
EXPECT THIS FRONT TO HAVE FEW IMPACTS ON MARINE INTERESTS. HIGH
PRESSURE WILL THEN STRENGTHEN OVER THE NORTHEAST PACIFIC AS THERMAL
LOW PRESSURE STRENGTHENS OVER NORTHERN CALIFORNIA. THIS SHOULD SET
THE STAGE FOR A MORE SUMMER LIKE PATTERN OF NORTHERLY WINDS ACROSS
THE WATERS THURSDAY THROUGH SATURDAY. A WEAKENING FRONTAL STORM
SYSTEM WILL THEN LIKELY IMPACT THE WATERS ON SUNDAY. A MORE ACTIVE
STORM PATTERN CERTAINLY APPEARS POSSIBLE NEXT WEEK...BUT UNCERTAINTY
IN DETAILS REMAINS HIGH. PYLE/NEUMAN
&&

.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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