195
FXUS66 KPQR 232251 CCA
AFDPQR
AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE PORTLAND OR
250 PM PST MON NOV 23 2009
SYNOPSIS
A WEAK COLD FRONT WILL SAG SE INTO NW OREGON TONIGHT.
THE FRONT WILL STALL LATE TONIGHT...THEN LIFT NE AS A WARM FRONT ON
TUE. THE NEXT FRONTAL SYSTEM IS NOT EXPECTED TO MOVE IN UNTIL LATE
THURSDAY.
SHORT TERM
NOT MUCH TO TALK ABOUT THROUGH WEDNESDAY. A WEAK FRONT
OFFSHORE WILL BE THE MAIN THREAT FOR RAIN TONIGHT MAINLY OVER
THE NW PART OF THE FORECAST AREA...WHERE ISENTROPIC LIFT IS BEST
AHEAD OF THE WARM FRONT OFFSHORE.
MODELS INDICATE A COLD FRONT SAGGING DOWN INTO THE REGION TONIGHT.
WILL NEED TO INCLUDE POPS MOST NORTHERN AREAS TONIGHT AND
EARLY TUE WITH BAROCLINIC ZONE OVER THE AREA...BUT WITH WEAK DYNAMICS
POPS WILL BE LIMITED TO CHANCE. FRONT LIFTS BACK TO THE N LATE TUE
AND TUE NIGHT WITH THE UPPER RIDGE REBOUNDING...RESULTING IN
DIMINISHING POPS BY TUE NIGHT...AND A DRY DAY WED. WHICH WILL SET THE
STAGE FOR SOME FOG IN THE VALLEYS WEDNESDAY MORNING. WOLFE
LONG TERM
THE MODELS SHOW A SYSTEM MOVING THROUGH THURSDAY NIGHT
AND FRIDAY THAT SHOWS SOME SIGNS OF SPLITTING WITH SOME OF THE
ENERGY DIGGING INTO NORTHERN CALIFORNIA...SO AM NOT GOING QUITE AS
CONSOLIDATED AS THE LATEST 12Z GFS MODEL. A TRAILING SHORT WAVE FROM
THE NORTHWEST KEEPS A BIT OF PRECIPITATION GOING FRIDAY NIGHT INTO
SATURDAY. THEN THE MODELS SHOW SOME RIDGING OVER THE PACIFIC
NORTHWEST DUE TO A DIGGING/DEVELOPING SYSTEM OUT 140W. THIS SHOULD
BRING DRYING WITH THE INCREASED POSSIBILITY OF VALLEY FOG. THE
MODELS DIVERGE FOR EARLY NEXT WEEK WITH THE LAST COUPLE OF ECMWF
RUNS WHILE THE GFS IS DRY STILL. HOWEVER...THE GFS ENSEMBLES HAVE A
VERY LARGE SPREAD AT THAT POINT. FOR NOW HAVE GONE WITH SOME POP FOR
MONDAY BUT BELOW CLIMO TO ACCOUNT FOR THE ECMWF AND THE ENSEMBLE
SPREAD. TOLLESON
AVIATION
A SLOW MOVING WARM FRONT ARRIVES AT THE PACIFIC NW COAST
THIS AFTERNOON...BRINGING MVFR CONDITIONS AND AREAS OF LIGHT RAIN TO
THE COAST THROUGH THE EVENING. INLAND VISIBILITIES REMAIN AT VFR
EXCEPT SOME AREAS MAY FLIRT WITH MVFR THIS EVENING AS AREAS OF LIGHT
RAIN MOVE INLAND...POSSIBLY AS EARLY AS 06Z. MVFR CIGS/VSBYS MAY
LINGER WELL INTO THE DAY TUE...DUE TO ABUNDANT LOW LEVEL MOISTURE
AND THE LACK OF SIGNIFICANT WIND TO MIX THE LOWER LAYERS.
KPDX AND APPROACHES...VFR CONDITIONS TO REMAIN THROUGH 06Z TONIGHT.
SOME LOCAL MVFR DEVELOPING LATER THIS EVENING AS AREAS OF LIGHT RAIN
DEVELOP. AREAS MVFR MAY LINGER WELL INTO THE DAY TUE...BUT MAINLY
OUTSIDE OF THE CITY. WEAGLE/LRAMIREZ
MARINE...LOW PRESSURE IS MOVING INTO BRITISH COLUMBIA TODAY
PUSHING A WARM FRONT INTO WASHINGTON AND OREGON. ASSOCIATED COLD
FRONT EXTENDS SW FROM LOW AND WILL NOT DIRECTLY MOVE THROUGH WATERS
UNTIL MIDWEEK. WINDS THUS FAR ASSOCIATED WITH THE FRONTAL SYSTEM
HAVE REMAINED BELOW GALE...WITH MOST GUSTS AROUND 25 KNOTS. AS THE
MAIN LOW TRAVELS FURTHER INLAND INTO CANADA...WINDS ASSOCIATED WITH
THE FRONT WILL EASE BELOW SCA CRITERIA OVERNIGHT. SEAS APPEAR TO BE
BRIEFLY FALLING BELOW 10 FT THIS AFTERNOON AT SOME LOCATIONS...BUT
EXPECT WEST SWELL ASSOCIATED WITH THE LOW PRESSURE SYSTEM TO PUSH
SEAS BACK UP ABOVE 10 FT THIS EVENING. THUS WILL LEAVE SCA FOR HAZ
SEAS IN EFFECT THROUGH TUE. THE RATHER LONG PERIOD SWELL IMPACTING
THE BAR WILL CONTINUE ROUGH BAR CONDITIONS THROUGH TUE DESPITE THE
WEAK EBBS. GENERALLY TRANQUIL WEATHER THEN EXPECTED INTO WED...THEN
THE COLD FRONT WILL FINALLY SLIDE ACROSS THE COASTAL WATERS WED
NIGHT/THU. SOME MODELS SHOW THE POSSIBILITY OF A STRONG LOW
DEVELOPING ALONG THIS FRONT OFF THE OREGON COAST WED NIGHT OR EARLY
THU...WILL NEED TO MONITOR THIS FOR POTENTIAL GALES DURING THAT TIME
PERIOD. WEAGLE
PQR WATCHES/WARNINGS/ADVISORIES
WA/OR...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS CAPE SHOALWATER TO
FLORENCE OUT 0-60 NM THROUGH TUE.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR THROUGH
TUE AFTERNOON.
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.
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