Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 121713
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
910 AM PST FRI FEB 12 2016

.SYNOPSIS...A COLD FRONT WILL BRING RAIN TO THE AREA TODAY AND
EVENTUALLY ALLOW SNOW LEVELS TO LOWER BELOW CASCADE PASSES TONIGHT
AND SATURDAY. A STRONG WARM FRONT WILL THEN SPREAD STEADY RAIN INTO
NORTHWEST OREGON AND SOUTHWEST WASHINGTON SATURDAY AFTERNOON AND
EVENING WITH A PERIOD OF HEAVY SNOW FOR THE CASCADES. HOWEVER...SNOW
LEVELS WILL RISE TO WELL ABOVE THE CASCADE PASSES AS PERIODS OF
LIGHTER RAIN FALL ON SUNDAY. ADDITIONAL UNSETTLED WEATHER WILL
PRODUCE MORE VALLEY RAIN AND MOUNTAIN SNOW NEXT WEEK.

&&

.SHORT TERM...TODAY THROUGH MONDAY...A LARGELY SOUTH TO NORTH
ORIENTED COLD FRONT IS CURRENTLY PUSHING EASTWARD INTO WESTERN
OREGON. BETWEEN 0.05 AND 0.15 INCHES OF RAIN PER HOUR HAVE BEEN
OBSERVED ALONG THE COAST SO FAR. THE STEADIER RAIN SHOULD COME TO END
BY 10 AM ALONG THE COAST. RAIN IS CURRENTLY ON THE DOORSTEP OF THE
WILLAMETTE VALLEY WITH THE BULK OF THE WET WEATHER LIKELY TO FALL
DURING THE LATE MORNING HOURS. THERE IS PLENTY OF SUNSHINE BEHIND THE
FRONT SO EXPECT SOME BREAKS IN THE CLOUDS DURING THE AFTERNOON HOURS.
THIS SHOULD ALLOW THE LOWER ATMOSPHERE TO DESTABILIZE ENOUGH TO ALLOW
SCATTERED SHOWERS TO POP IN THE WILLAMETTE VALLEY LATER THIS
AFTERNOON WITH BRIEF HEAVY RAIN THE MAIN THREAT. SNOW LEVELS WILL BE
SLOW TO COME DOWN TODAY...LIKELY ONLY DROPPING TO 4500 FT OR SO BY
LATE THIS AFTERNOON.

THE MAIN UPPER LEVEL SHORTWAVE TROUGH WILL SKIRT OUR NORTHERN ZONES
THIS EVENING AND OVERNIGHT. THIS SHOULD RESULT IN SHOWERS INCREASING
ACROSS OUR NORTHERN COASTAL ZONES AND IN THE SOUTH WASHINGTON AND
VERY NORTH OREGON CASCADES DURING THE EVENING AND OVERNIGHT HOURS.
SNOW LEVELS WILL LIKELY LOWER INTO THE 3500 FT RANGE OVERNIGHT WITH 1
TO 4 INCHES OF SNOW LIKELY. LESSER AMOUNTS WILL FALL FARTHER SOUTH
TOWARDS THE CENTRAL OREGON CASCADES OVERNIGHT.

A STRONG WARM FRONT WILL PRODUCE AN EXTENDED PERIOD OF STEADY RAIN
LATE SATURDAY AFTERNOON THROUGH SUNDAY. RAINFALL AMOUNTS OF 1 TO 3
INCHES IN THE COAST RANGE APPEAR LIKELY WITH 0.5 TO 1.0 INCH AMOUNTS
IN THE WILLAMETTE VALLEY. SNOW LEVELS WILL LIKELY START OFF AROUND
4000 FT...PARTICULARLY ACROSS THE SOUTH WASHINGTON CASCADES AND THE
NORTH OREGON CASCADES NEAR MOUNT HOOD. CURRENT THINKING IS THAT THE
COLD AIR WILL BE SLOW TO SCOUR OUT SO IT STILL APPEARS THAT AT LEAST
4 TO 8 INCHES OF SNOW WILL FALL BEFORE SNOW LEVELS ROCKET UP TO 7000
FT OR HIGHER ON SUNDAY. WHILE PRECIPITATION WILL LIKELY CONTINUE FOR
MUCH OF THE DAY ON SUNDAY IN THE COAST RANGE AND CASCADES...THE
WILLAMETTE VALLEY MAY SEE ENOUGH SHADOWING FROM THE COAST RANGE THAT
IT MAY NOT BE ALL THAT WET OF A DAY.

SHORTWAVE RIDGING SHOULD THEN BEGIN TO PUSH INTO THE REGION SUNDAY
NIGHT AND MONDAY SO EXPECT A GENERAL DRYING TREND DURING THIS PERIOD
WITH MILD TEMPERATURES RETURNING AS THE JET STREAM SHIFTS NORTH INTO
CANADA. /NEUMAN



.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...
SUNDAY NIGHT THROUGH THURSDAY...THE PROGRESSIVE WEATHER PATTERN WILL
PERSIST INTO NEXT WEEK. MODELS CONTINUE TO SHOW A FLAT UPPER LEVEL
RIDGE MOVING OVER THE PAC NW EARLY NEXT WEEK. THIS COULD BRING A
BRIEF BREAK FROM THE RAIN MONDAY...BUT WILL MAINTAIN SOME CHANCE POPS
IN THE FORECAST DUE TO LINGERING INSTABILITY. A WEAK SHORTWAVE
DISTURBANCE LOOKS TO RIDE OVER THE TOP OF THE RIDGE ON TUESDAY AND
WILL LIKELY PUSH ANOTHER FRONT ACROSS THE REGION LATE TUESDAY/EARLY
WEDNESDAY BRINGING MORE RAIN. CASCADE SNOW LOOKS TO RETURN WEDNESDAY
AFTERNOON WITH SNOW LEVELS LOWERING TO AROUND 3500 FT. UNSETTLED
WEATHER AND LOWERING SNOW LEVELS CONTINUE INTO THURSDAY AS THE BASE
OF THE TROUGH MOVES ACROSS THE FORECAST AREA. MONDAY WILL LIKELY BE
THE WARMEST DAY...WITH TEMPS TRENDING COOLER EARLY NEXT WEEK. /64


&&

.AVIATION...AS OF 830 AM...A WEAK FRONT IS OVER THE COAST RANGE.
EXPECT MOSTLY MVFR CONDITIONS AHEAD OF AND WITH THE FRONT PASSAGE
TODAY...WITH LOCALIZED IFR CONDITIONS. MOST AREAS WILL SEE A WINDS
SHIFT FROM SE TO S OR S TO SW THIS AFTERNOON. EAST WINDS
SURPRISINGLY STILL GUSTING NEAR KTTD AROUND 25KT. THESE WINDS
SHOULD EASE LATE THIS AFTERNOON BEHIND THE FRONT. EXPECT
CONDITIONS TO IMPROVE VFR IN MOST AREAS LATE THIS AFTERNOON AND
EARLY THIS EVENING. A TROUGH WILL PRODUCE SHOWERS TONIGHT AND
LIKELY A RETURN OF MVFR. THERE SHOULD BE ENOUGH MIXING TO PREVENT
WIDESPREAD IFR CONDITIONS BUT COULD SEE LOCALIZED IFR AGAIN
SATURDAY MORNING...ESPECIALLY ALONG THE COAST.

KPDX AND APPROACHES...WEAK FRONT WILL BRING RAIN AND A CHANCE OF MVFR
CONDITIONS BETWEEN 18 AND 22Z. SE WINDS WILL BECOME SOUTH AND
WEAKEN AFT 23Z. VFR CONDITIONS EXPECTED TONIGHT WITH OCCASIONAL RAIN.
TJ

&&

.MARINE...BUOY OBSERVATIONS SHOW THAT WIND GUSTS HAVE EASED BELOW
25KT THIS MORNING AND HAVE LET THE SMALL CRAFT ADVISORY FOR WINDS
EXPIRE. SEAS ARE RUNNING 12 TO 14 FT WITH 17 SECOND PERIODS AND
WILL SLOWLY SUBSIDE THROUGH THE WEEKEND. SEAS SHOULD DROP BELOW 10
FT MONDAY OR TUESDAY.

A SURFACE TROUGH WILL MOVE ACROSS THE WATERS TONIGHT AND MAY
PRODUCE BRIEF AND INFREQUENT GUSTS AROUND 25 KT TONIGHT. THESE
GUSTS WILL NOT BE WIDESPREAD ENOUGH TO WARRANT AN ADVISORY. THE
NEXT CHANCE FOR STRONGER WINDS IS SATURDAY AND SATURDAY NIGHT WHEN
A FRONT MOVES ACROSS THE WATERS. THIS WILL EITHER BE A SOLID SMALL
CRAFT WIND EVENT OR A LOW-END GALE EVENT. TJ

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 AM PST SUNDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
    60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 AM
    PST SATURDAY.

&&



$$

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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