000
FXUS66 KPQR 271644
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
845 AM PST MON DEC 27 2010
.SYNOPSIS...WET WEATHER TO CONTINUE...ALONG WITH SOME WINDY
CONDITIONS TONIGHT INTO TUE. THEN TURNING COLDER WED...WITH SOME
THREAT OF SNOW...EVEN DOWN TO INTERIOR VALLEY FLOORS POSSIBLY. LATER
PART OF THE WEEK WILL FOCUS ON COLDER WEATHER...AND MAYBE A BIT OF
OCCASIONAL RAIN OR SNOW...DEPENDING ON ELEVATION.
&&
.SHORT TERM...PLENTY OF CLOUDS OFFSHORE...WHICH SIGNAL A RETURN TO
VERY WET CONDITIONS TO RETURN. SATELLITE IMAGERY CLEARLY SHOWS
THE OVERRUNNING CLOUDS FROM THE NEXT SYSTEM ALREADY REACHING THE
COAST AND SPREADING INLAND. RADAR SHOWING SOLID BAND OF LIGHT RAIN
SPREADING INLAND ON THE COAST AND COAST RANGE. WILL CONTINUE TO SEE
LIGHT RAIN INCREASE ACROSS THE REGION TODAY.
WARM ADVECTION PATTERN WILL CONTINUE TODAY AND TONIGHT...FORCING SNOW
LEVELS TO CLIMB. BY LATE THIS EVENING...BOTH GFS AND NAM SHOW
1000-500 MB THICKNESS VALUES RISING TO AROUND 543 DM IN
THE CASCADES...WHICH TRANSLATES TO ABOUT A 4000 FOOT SNOW LEVEL.
THERE MAY BE A SLIGHT EAST COMPONENT TO THE LOW-LEVEL FLOW SO KEPT
SNOW LEVELS A LITTLE LOWER. BY 12Z TUE 850 MB TEMPS AND THICKNESS
VALUES SEEM TO PEAK FOR THE CASCADES...NEAR 2C AND 546 DM
RESPECTIVELY. EXPECT A GOOD SLUG OF MOISTURE TO HIT THE COAST
STARTING LATE THIS AFTERNOON...THEN SPREADING FURTHER INLAND TONIGHT.
SIGNIFICANT SNOWFALL WILL OCCUR AT THE PASSES AND SKI RESORTS TONIGHT
THROUGH TUE MORNING. WILL MAINTAIN WINTER STORM WARNING FOR LATE
TODAY AND TONIGHT DUE TO ANTICIPATED HEAVY SNOW IN THE CASCADES.
WIND MAY BECOME AN ISSUE ALONG THE COAST LATE THIS AFTERNOON AND THIS
EVENING. AS PER PREVIOUS SHIFT...HIGH WIND WATCH WAS DROPPED. NOTHING
IN THE LATEST ROUND OF MODELS SCREAMS WARNING. THE 06Z NAM SEEMS TO
BE A BIT SLOWER MOVING THE SURFACE LOW NORTH OF ASTORIA COMPARED TO
THE PREVIOUS COUPLE RUNS. IT IS ALSO A LITTLE WEAKER WITH THE SURFACE
LOW...AT 00Z TUE THE NAM AND GFS SHOW A 1006 MB LOW WITH A 6-7 MB
KAST-KOTH GRADIENT. WOULD LIKE TO SEE 8 MB OR MORE FOR MORE
CONFIDENCE. LOOKS LIKE THE PEAK WIND PERIOD WILL BE 00Z TO TO ABOUT
10Z OR SO. HOWEVER... THE 4KM WRF INDICATES 30-35 KT 10M WIND SPEEDS
AT 00Z AND 06Z. THE NAM ALSO SHOWS A SMATTERING OF 50-55 KT 950 MB
WIND BARBS ALONG THE COAST 03Z TO 09Z.ALL SAID...DECENT GRADIENTS TO
KEEP IT BREEZY ON THE COAST...WITH WINDS GUSTING 45 TO 55 MPH ON THE
COAST...WITH 25 TO 40 MPH GUSTS INLAND. STILL CANNOT RULE OUT A STRAY
60 MPH GUST SOMEWHERE...LIKELY THE YAQUINA BAY BRIDGE OR SOME
HEADLAND LOCATION.
A STRONG COLD SHORT WAVE WILL DROP DOWN FROM THE NORTHWEST TUESDAY
NIGHT AND WEDNESDAY...BRINGING INCREASING SHOWERS AND MUCH COLDER AND
LOWER SNOW LEVELS WITH IT. 1000 TO 500 MB THICKNESS DROP BELOW 522 DM
WEDNESDAY AND THIS COULD THREATEN SOME SNOW NEAR THE VALLEY FLOOR ON
WEDNESDAY.ROCKEY/WEISHAAR
.LONG TERM...MAIN STORY FOR THE BEGINNING OF THE EXTENDED PERIOD IS
THE REMAINDER OF THE COLD UPPER TROUGH IMPACTING THE REGION EARLY
THURSDAY. HIGH PRESSURE BEGINS SPREADING INTO THE PACIFIC NORTHWEST
BY THURSDAY AFTERNOON. AS SUCH...AND IN AGREEMENT WITH NEIGHBORS
DECIDED TO CUT POPS THU. NEED TO WATCH FOR LITTLE SHORT-WAVES DIVING
DOWN IN THE NORTH FLOW...BUT THE OVERLAND TRAJECTORY WOULD LIMIT ANY
PRECIP. THE ECMWF AND GFS SHOW OFFSHORE FLOW RETURNING THU NIGHT AND
STRENGTHENING FRIDAY. THE CURRENT GRIDS APPEAR TO BE TOO WET IN THAT
TIME FRAME. THE EAST FLOW WILL KEEP THINGS RATHER COOL. MEDIUM RANGE
MODELS DIVERGE QUITE A BIT STARTING 12Z SAT. GFS WANTS TO SEND A
CLOSED UPPER LOW DOWN THE COASTLINE WHILE THE ECMWF KEEPS IT MUCH
FURTHER OFFSHORE...AND OF COURSE THE CANADIAN IS SOMEWHERE IN THE
MIDDLE. ONCE THAT SYSTEM DEPARTS...WHEREVER IT ENDS UP GOING...MODELS
SEEM TO AGREE THAT SUNDAY WILL BE DRY . OF COURSE...WITH THE
PROLONGED OFFSHORE FLOW ALL EYES WILL BE FOCUSED ON WHAT HAPPENS WHEN
THE NEXT WEATHER SYSTEM ENCOUNTERS THE COLDER ENVIRONMENT. WILL JUST
HAVE TO SEE HOW THINGS PLAY OUT. WEISHAAR
&&
.AVIATION...MIXTURE OF MVFR AND VFR THIS MORNING FROM DEPARTING
SHOWERS LOWERING TO MOSTLY MVFR THROUGH THE DAY AND TONIGHT AS A
WARM FRONT SPREADS IN. MAY SEE SOME IFR IN HEAVIER RAIN ESPECIALLY
AT THE COAST LATER THIS AFTERNOON AND TONIGHT BUT ALSO LOCALLY
INLAND THIS EVENING. A STRONG COLD FRONT MOVING THROUGH LATER
TONIGHT AND EARLY TUESDAY WILL KEEP AT LEAST MVFR CONDITIONS
CONTINUING. STRONG GUSTY SOUTH WINDS ARE EXPECTED ALONG THE COAST
LATER TODAY AND TONIGHT.
KPDX AND APPROACHES...MOSTLY VFR EARLY TODAY THEN MVFR DEVELOPING
DURING THE AFTERNOON AND CONTINUING TONIGHT. PT
&&
.MARINE...A DEVELOPING SURFACE LOW IS EXPECTED TO PASS JUST TO
THE NORTH OF THE COASTAL WATERS LATE TODAY AND TONIGHT AT AROUND
1005 MB. THE ASSOCIATED WARM FRONT WILL PRODUCE GALE FORCE WINDS.
THESE WINDS ARE NOT EXPECTED TO DROP UNTIL THE COLD FRONT MOVES
ACROSS THE WATERS AND INLAND LATE TONIGHT IN THE NORTH AND AROUND
SUNRISE TUESDAY IN THE SOUTH. WINDS WILL EASE SOME TUESDAY BEFORE
INCREASING TO SMALL CRAFT LEVELS BY WEDNESDAY AS A COLDER SYSTEM
DROPS IN FROM THE NORTH. SEAS ARE A COUPLE OF FEET BELOW THE
MODELS THIS MORNING BUT WILL RISE TO MID TEENS LATER TODAY AND
TONIGHT AS WINDS INCREASE...BRIEFLY DROPPING TO CLOSE TO 10 FT
LATE TUESDAY AND EARLY TUESDAY NIGHT. SEAS WILL INCREASE WITH
INCREASING NORTHERLY WINDS WEDNESDAY. PT
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO 10 PM PST
TUESDAY FOR CASCADES IN LANE COUNTY-NORTHERN OREGON
CASCADES.
WA...WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO 10 PM PST
TUESDAY FOR SOUTH WASHINGTON CASCADES.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL NOON PST TODAY FOR COASTAL
WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT TO 60 NM.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL NOON PST TODAY FOR
COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT TO 60
NM.
GALE WARNING FROM NOON TODAY TO 2 AM PST TUESDAY FOR COASTAL
WATERS FROM CAPE SHOALWATER WA TO CASCADE HEAD OR OUT TO 60 NM.
GALE WARNING FROM NOON TODAY TO 6 AM PST TUESDAY FOR COASTAL
WATERS FROM CASCADE HEAD TO FLORENCE OR OUT TO 60 NM.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA BAR UNTIL 6 AM 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.
