FXUS66 KPQR 091032
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
231 AM PST WED DEC 9 2009
.SYNOPSIS...AN ARCTIC AIR MASS WILL CONTINUE THROUGH THE END OF THE
WEEK. THE BRUNT OF A PACIFIC SYSTEM IS EXPECTED TO MOVE INTO
CALIFORNIA LATE FRIDAY...WITH SOME PRECIPITATION LIKELY MOVING UP
INTO THE REGION FRIDAY NIGHT AND SATURDAY. THIS PRECIPITATION MAY
START OUT AS A LIGHT WINTRY MIX OVER INLAND AREAS...WITH A WINTRY MIX
POSSIBLY LINGERING INTO SATURDAY NIGHT NEAR THE COLUMBIA GORGE. A
LARGER WARMER SYSTEM IS EXPECTED FOR EARLY NEXT WEEK.
&&
.SHORT TERM...GENERALLY A CLEAR AND COLD FORECAST FOR THIS WEEK. EAST
WINDS SHOULD BE CONFINED TO THE WESTERN GORGE AND WILL BE FAIRLY
LIGHT BY GORGE STANDARDS. MAXIMUM TEMPS WILL AGAIN BE COLD TODAY AND
THU WITH ONLY BRIEF WARMING NEAR OR SLIGHTLY ABOVE FREEZING INLAND
AREAS. THE LACK OF WIND WILL ALLOW FOR SOME GOOD COOLING AGAIN
TONIGHT.
THE COLD N-NW FLOW ALOFT OVER THE NW US WILL RETREAT TO THE NE THU
NIGHT AND FRI ALLOWING THE AIR MASS ALOFT TO BEGIN SOME WARMING.
HOWEVER THE VALLEYS WILL BE SLOW TO SCOUR OUT. THE SOUTHERN JET
STREAM PUSHING SYSTEMS INTO CA WILL BEGIN TO LIFT N A BIT ON FRI FOR
THE POSSIBILITY OF SOME MOISTURE WITH A WARMER AIR MASS LIFTING INTO
OREGON. HOWEVER THE MAIN INFLUENCE WILL REMAIN TO THE S WITH THE
FORECAST AREA JUST GETTING SOME FRINGE EFFECTS INITIALLY. RW
.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...A LOT OF
UNCERTAINTY IS THE UNDERLYING THEME IN THE EXTENDED. MODELS HAVE
MAINTAINED SOME KEY DIFFERENCES IN HANDLING THE LINGERING COLD AIR
AND SOUTHERN STREAM ENERGY UNDERCUTTING THE OFFSHORE UPPER RIDGE THIS
WEEKEND. A LOT OF THE UNCERTAINTY LIES IN THE TRACK OF THE THE SYSTEM
EXPECTED TO ARRIVE ALONG THE WEST COAST...WITH THE ECMWF MAINTAINING
A SOUTHERLY TRACK HEADED INTO CA THAT WOULD MAINTAIN A COLD OFFSHORE
FLOW THROUGHOUT WHILE SEVERELY LIMITING PRECIPITATION POTENTIAL. THIS
TENDS TO BE SUPPORTED BY THE CANADIAN. GFS CONTINUES TO LIFT A SFC
LOW A LITTLE FURTHER N HEADED TOWARDS OREGON...WHICH IS A LITTLE
FURTHER S THAN YESTERDAYS RUNS. THIS YIELDS A BETTER CHANCE FOR
PRECIPITATION. ACTUAL TEMPS DURING THE EVENT STILL UNCERTAIN AS THERE
WILL BE SOME MODIFICATION TO THE AIRMASS DURING THE WEEK.
HOWEVER...WITH A LITTLE MORE CONFIDENCE IN MAINTAINING AN OFFSHORE
FLOW...WILL LEAN TOWARDS COOLER TEMPS. THIS LEANS PRECIP TYPE IN THE
INLAND VALLEYS...MAINLY IN THE N...A LITTLE MORE TOWARDS FREEZING
PRECIP...AND WILL NEED TO INTRODUCE SOME THREAT OF SNOW IN THE FAR N.
THE CHANCES FOR PRECIPITATION REMAIN MIDDLE OF THE ROAD THOUGH GIVEN
THE CONTINUED SIGNIFICANT MODELS DIFFERENCES.
GETTING INTO SUN AND BEYOND...MODELS ALSO EXHIBITING RUN TO RUN
ISSUES. WITH A LARGE SELECTION OF POSSIBILITIES BEING PRESENTED...
WILL TREND TOWARDS CLIMATOLOGY.
&&
.AVIATION...VFR CONDITIONS THROUGH THURSDAY. AIRMASS STILL VERY DRY
SO DO NOT SEE MUCH THREAT OF CLOUDS OR FOG. HOWEVER WIND SHELTERED
AREAS IN THE SOUTH VALLEY COULD SEE SOME BRIEF...PATCHY...AND
SHALLOW FREEZING FOG AROUND DAYBREAK THIS MORNING AND POSSIBLY AGAIN
THU MORNING.
KPDX AND APPROACHES...VFR CONDITIONS AND LIGHT EAST WINDS EXPECTED
THROUGH THURSDAY. DALTON
&&
.MARINE...SPURTS OF +10FT SWELLS EXPECTED TO CONTINUE TODAY...SO
WILL CONTINUE SCA FOR HAZARDOUS SEAS WITH THIS PACKAGE. PERIODS WILL
REMAIN 15-18 SECONDS TODAY AND THIS WILL GIVE ROUGH BAR CONDITIONS
TODAY...ESPECIALLY NEAR THE EBBS AROUND 1045 AM THIS MORNING AND 11
PM TONIGHT. SWELLS SUBSIDE TO 8-9FT BY MIDNIGHT TONIGHT. WINDS
REMAIN LIGHT TO LOCALLY MODERATE OFFSHORE THROUGH FRI. PREVIOUS
MODEL RUNS HAD SHOWN A LOW PRESSURE SYSTEM MOVING INTO THE SOUTHERN
WATERS BY FRI EVENING FOR SOUTHERLY SMALL CRAFT WINDS. MOST GUIDANCE
NOW FAVORING THIS SYSTEM MOVING INTO SRN OREGON/NRN CALIFORNIA.
TRENDED THE FORECAST IN THAT DIRECTION...KEEPING 10-15KT ENE WINDS
OVER THE WATERS THROUGH SATURDAY. DALTON
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR/WA...SCA FOR HAZARDOUS SEAS CAPE SHOALWATER TO FLORENCE OUT 60 NM
THROUGH LATE THIS AFTERNOON.
SCA FOR ROUGH COLUMBIA RIVER BAR THROUGH LATE TONIGHT.
&&
$$
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.
