FXUS66 KPQR 141628
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
826 AM PST MON DEC 14 2009

.SYNOPSIS...SHOWERS WILL TAPER OFF THIS MORNING FOR A BRIEF MIDDAY
BREAK BEFORE RAIN ACCOMPANYING A STRONG FRONTAL SYSTEM SPREADS
INLAND. WINDS WILL INCREASE ALONG THE COAST AND IN THE MOUNTAINS THIS
AFTERNOON AND EVENING. HEAVY SNOW WILL DEVELOP IN THE CASCADES WITH A
MIX OF RAIN...FREEZING RAIN AND SNOW POSSIBLE IN THE GORGE TONIGHT.
ADDITIONAL STRONG AND RATHER WET FRONTAL SYSTEMS TRACK INLAND THIS
WEEK BRINGING WINDY CONDITIONS TO THE COAST. TEMPERATURES WILL
INCREASE THROUGH THE WEEK WITH SNOW LEVELS RETREATING HIGHER INTO THE
CASCADES.

&&

.SHORT TERM...NATIONAL WEATHER SERVICE DOPPLER RADAR SHOWS SHOWERS
RAPIDLY LIFTING NORTH INTO WASHINGTON THIS MORNING. MAY SEE A FEW 
SHOWERS LINGERING ALONG THE NORTHERN OREGON COAST OR COAST RANGE 
THROUGH 18Z. HOWEVER...MOST SHOWERS WILL BE CONFINED TO THE SOUTH 
WASHINGTON CASCADES THROUGH LATER THIS MORNING. WILL LIKELY SEE A 
BREAK IN THE SHOWER ACTIVITY LATE THIS MORNING INTO EARLY AFTERNOON. 
INFRARED SATELLITE IMAGERY SHOWS RAPID CLEARING IN THE CASCADES AND 
CASCADE FOOTHILLS SOUTH OF MT HOOD THIS MORNING...AS WELL AS AT 
LEAST THE EASTERN ESCARPMENT OF THE WILLAMETTE VALLEY. LOWERED CLOUD 
COVER IN THESE AREAS AS THE LOW LEVEL CLOUD DECKS SHOULD BREAK UP 
ENOUGH BY MID-MORNING FOR PARTLY CLOUDY SKIES THERE. SUN WILL BE 
SHORT LIVED AS CIRRUS SHIELD FROM APPROACHING FRONT WILL SPREAD 
OVERHEAD BY EARLY AFTERNOON.

NO OTHER CHANGES FOR THE MORNING UPDATE. PREVIOUS DISCUSSION FOLLOWS.
THE RADAR HAS BEEN SHOWING SHOWERS GRADUALLY WEAKENING
OVERNIGHT AND WITH THE INFLUENCE OF THE APPROACHING FRONT...THE LAST
OF THE SHOWERS SHOULD GONE BY MID MORNING. THE BREAK BETWEEN SYSTEMS
HOWEVER WILL BE SHORT LIVED AS RAIN FROM THE INCOMING FRONT WILL
REACH THE COAST BY EARLY AFTERNOON AND SPREAD QUICKLY INLAND.
PRECIPITATION WILL REACH THE CASCADES BETWEEN 4 AND 6 PM THEN
INCREASE RAPIDLY IN INTENSITY OVERNIGHT...THEREFORE HAVE ISSUED A
WINTER STORM WARNING FOR THE SOUTH WASHINGTON AND NORTH OREGON
CASCADES FOR 12 TO 18 INCHES TONIGHT AND AN ADVISORY FOR THE CENTRAL
OREGON CASCADES WHERE QPF AMOUNTS WILL BE A BIT LESS. SNOW LEVELS
WILL START OFF FAIRLY LOW IN THE EVENING...1500 FEET NORTH AND 3000
FEET SOUTH THEN INCREASE OVERNIGHT REACHING 4000 FT NORTH AND 5000
FEET SOUTH BY TUESDAY MORNING. OTHER CONCERNS INCLUDE INCREASING
WINDS ALONG THE COAST AND LOWER ELEVATION WINTER PRECIPITATION IN THE
GORGE AND UPPER HOOD RIVER VALLEY.  

AS FOR THE WINDS...A HIGH WIND WARNING HAS BEEN ISSUED FOR THE
CENTRAL AND NORTH OREGON COAST...LOOKS LIKE A FAIRLY LOW END EVENT ON
THE SUSTAINED WIND SIDE OF THINGS BUT GUSTS TO 60 OR 70 MPH ARE
POSSIBLE ON THE TYPICALLY WINDY HEADLANDS AND EXPOSED BEACHES. WINDY
CONDITIONS ARE ALSO LIKELY IN THE CASCADES WHERE RIDGE LEVEL WINDS
WILL INCREASE TO 30 TO 40 MPH WITH GUSTS TO 50 OR 60 MPH. WILL ALSO
NEED TO WATCH THE LOW ROLLING UP THE COAST ON TUESDAY AS IT HAS QUITE
A BIT OF POTENTIAL AS WELL AND A LARGER SOUTHERLY COMPONENT TO THE
WINDS...WHICH COULD MAKE IT A MORE WIDESPREAD COASTAL EVENT.  

THE PRECIPITATION TYPE IN THE COLUMBIA RIVER GORGE AND THE UPPER HOOD
RIVER VALLEY REMAIN THE TRICKIEST AND MOST UNCERTAIN PART OF THE
FORECAST.  EASTERLIES AHEAD OF THE FRONT WILL DRAW COLD AIR OUT OF
THE COLUMBIA BASIN BUT TEMPERATURES AT THE DALLES HAVE ONLY FALLEN 30
DEGREES SO FAR.  ALSO THE FRONT WILL BRING QUITE A BIT OF WARM MOIST
AIR IN ALOFT WITH IT SO IT DOES HAVE THE POTENTIAL TO RAIN OUT THE
COLD AIR BEING OVERRUN IN THE GORGE EVEN WITH THE EASTERLY FLOW
PERSISTING.  THEREFORE HAVE OPTED FOR A WINTER WEATHER ADVISORY WITH
A MIX OF PRECIP TYPES...MOSTLY SNOW NEAR HOOD RIVER AND MORE FREEZING
RAIN FURTHER EAST BUT NOT LASTING ALL THAT LONG.  FOR THE UPPER HOOD
RIVER VALLEY ALSO WENT WITH AN ADVISORY BUT FOR SNOW.  A LITTLE
FREEZING RAIN MIXING IN IS POSSIBLE BUT THE PRIMARY CONCERN SHOULD BE
SNOW. DALTON/RUTHFORD

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...EXPECT A
WARMER AND WETTER PATTERN THROUGH THE EXTENDED PERIOD. BY WED
AFTERNOON...AN UPPER LEVEL TROUGH PUSHES ONSHORE. MODELS SHOW PRECIP
THROUGHOUT THE CWA...AND A RIDGE BUILDING BEHIND THE ASSOCIATED COLD
FRONT AS IT MOVES FURTHER EAST AROUND THU. A BRIEF BREAK IS POSSIBLE
BY THU NIGHT AS THIS RIDGE AMPLIFIES. IT IS SQUEEZED OUT BY THE FIRST
OF A SERIES OF FRONTAL SYSTEMS BEGINNING FRI. THESE SLOW MOVING
SYSTEMS MAY STALL AS THEY TRY TO CROSS THE CASCADES...WINDY
CONDITIONS AND HEAVY RAIN FALL ARE POSSIBLE DURING THIS TIME. EXPECT
SNOW LEVELS TO RISE TO NEAR 8000 FT THROUGH THE WEEKEND. LRAMIREZ
&&

.AVIATION...MVFR CEILINGS ACROSS THE NORTHERN HALF OF THE REGION 
THIS MORNING...WITH MOSTLY VFR CONDITIONS OVER THE SOUTHERN HALF.  
MOST AREAS WILL IMPROVE TO VFR LATER THIS MORNING. APPROACHING FRONT 
WILL SPREAD HIGH END MVFR CIGS BACK TO COAST AFTER 21Z...ALONG WITH 
INCREASING S WINDS. AFTER 00Z EXPECT THESE MVFR CONDITIONS WITH RAIN 
TO SPREAD INLAND AS FRONT PUSHES TOWARDS COAST.

.KPDX AND APPROACHES...MIX OF HIGH END MVFR AND LOW VFR...WILL 
GRADUALLY IMPROVE TO VFR BY 19Z. SHOULD REMAIN VFR FOR REST OF 
DAY...THEN RETURN OF MVFR AFTER 01Z AS RAIN INCREASES. &&

.MARINE...STRONG FRONT WILL ARRIVE ON THE OUTER WATERS LATER THIS 
AFTERNOON...WITH INCREASING S GALES OVER THE COASTAL WATERS THIS 
AFTERNOON. STRONGEST WINDS LIKELY TO HAVE GUSTS APPROACHING STORM 
FORCE OVER THE OREGON COASTAL WATERS THIS EVENING. FRONT PUSHES 
INLAND AFTER 08Z...WITH DECREASING WINDS. S GALES WILL DEVELOP AGAIN 
ON TUE. COMBINED SEAS WILL CLIMB BACK TO NEAR 15 FT TONIGHT...WITH 
CLOSER TO 20 FT POSSIBLE LATER TUE AND TUE NIGHT. SHOULD SEE WINDS 
AND SEAS REMAIN ON THE ACTIVE SIDE THROUGH AT LEAST THU. 
&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR/WA...GALE WARNING ON COASTAL WATERS FROM CAPE SHOALWATER TO 
     FLORENCE FROM THIS AFTERNOON THROUGH TONIGHT.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA BAR CONDITIONS 
     FOR THIS AFTERNOON...AND LATER TONIGHT THROUGH TUE.

OR...WINTER STORM WARNING THIS AFTERNOON THROUGH TUESDAY  
MORNING FOR NORTHERN OREGON CASCADES.
     WINTER WEATHER ADVISORY FOR THE WESTERN COLUMBIA RIVER 
GORGE THIS AFTERNOON THROUGH 6 AM TUESDAY.
     WINTER WEATHER ADVISORY FOR THE UPPER HOOD RIVER VALLEY
THIS AFTERNOON THROUGH TUESDAY MORNING.
     HIGH WIND WARNING FOR THE NORTH AND CENTRAL OREGON 
COAST THIS AFTERNOON THROUGH MIDNIGHT.
WA...WINTER STORM WARNING THIS AFTERNOON THROUGH TUESDAY 
MORNING FOR SOUTH WASHINGTON CASCADES.
     WINTER WEATHER ADVISORY FOR THE WESTERN COLUMBIA RIVER 
GORGE THIS AFTERNOON THROUGH 6 AM TUESDAY.
PZ...GALE WARNING ON COASTAL WATERS FROM CAPE SHOALWATER TO 
FLORENCE FROM THIS AFTERNOON THROUGH TONIGHT.
     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA BAR CONDITIONS 
FOR THIS AFTERNOON...AND LATER TONIGHT THROUGH TUE.

&&

$$

MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND

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.