FXUS66 KPQR 251047
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
232 AM PST FRI DEC 25 2009
.SYNOPSIS...COOL DRY OFFSHORE FLOW FOR REST OF THE WEEK...AS STORMS
HOLD UP OVER THE N PAC. FOG WILL LINGER IN THE INLAND VALLEYS EXCEPT
AREAS SURROUNDING THE WESTERN PART OF THE COLUMBIA GORGE AS EAST
WINDS WILL BE PERSISTENT THROUGH THE WEEKEND. GUSTY EAST WINDS WILL
BE THE STRONGEST TODAY ON THE WEST END OF THE GORGE WITH GUSTS
APPROACHING 60 MPH POSSIBLE IN EXPOSED AREAS. ON SUN A WEAKENING
PACIFIC FRONT APPROACHES AND MAY GIVE SOME LIGHT PRECIPITATION IF
ANY.
&&
.SHORT TERM...EAST WINDS EATING AWAY AT THE FOG IN THE PORTLAND AND
VANCOUVER AREA. BUT LOCALLY DENSE FOG PERSISTS IN THE LOWER COLUMBIA
AND SOUTH OF AURORA TO EUGENE. THE DRIER EAST WINDS WILL CONTINUE TO
EAT AWAY AT THE FOG...BUT THE SOUTH WILLAMETTE VALLEY LIKELY REMAIN
IN THE SOUP NEXT DAY OR TWO. STRATUS DEEPENING EAST OF THE CASCADES
IS PUSHING ACROSS EASTERN PARTS OF SOUTH WASHINGTON CASCADES AND TO
NEAR MOUNT HOOD. DUE TO INVERSIONS AND LIGHTER WINDS BENEATH
THEM...WILL HAVE SOME PROBLEM MIXING OUT AIR MASS IN LOWER ELEVATIONS
TO THE N OF VANCOUVER AND S OF SALEM THROUGH SATURDAY. WILL CONTINUE
AIR STAGNATION ADVISORIES IN THOSE AREAS...FOR ELEVATIONS BELOW ABOUT
1500 FEET.
THE STRONG SURFACE HIGH PRES E OF THE CASCADES COUPLED WITH THE LOW
LEVEL INVERSION HAS CREATED A STRONG E TO W PRESSURE GRADIENT
THROUGH THE GORGE...TTD TO DLS UP TO 7.1 MB AT 2 AM. MODELS SUGGEST
THE PEAK GRADIENTS AROUND 10 MB OCCUR FROM FRI MORNING THROUGH SAT.
AT THIS TIME THE STRONGEST WINDS APPEAR CONFINED TO THE FAR W PART OF
THE GORGE...AND WEAKEN SOME AS THEY SPILL OUT FURTHER W. WITH LITTLE
CHANGE IN THE PLACEMENT OF THE STRONGEST GRADIENTS EXPECTED IN THE
NEXT 24 HOURS...AT THIS TIME PREFER TO NOT GO WITH ANY WIND
HEADLINES...ALTHOUGH WILL NEED TO MONITOR FOR A POSSIBLE WIND
ADVISORY IN THE EASTERN SECTIONS OF THE N WILLAMETTE VALLEY AND
CLARK COUNTY.
SATURDAY BEGINS TRANSITION PERIOD...AS A FRONT NOW ABOUT 600 MILES
OFFSHORE APPROACHES THE WEST COAST. CHANCES FOR PRECIPITATION
INCREASE SAT NIGHT INTO SUN. CONFIDENCE IS NOT VERY HIGH AT THIS TIME
IF MEASURABLE PRECIPITATION WILL FALL.NAM...ECMWF...AND CANADIAN
SPLIT THE INCOMING FRONT WITH PRECIPITATION HEADED TO THE SOUTH WHERE
MORE OF THE JET ENERGY GOES. GFS BRINGS A WEAKENING FRONT INLAND WITH
SOME LIGHT PRECIPITATION. PRECIPITATION TYPE IS ANOTHER
CONCERN...CURRENT CONDITIONS ARE MARGINAL FOR FREEZING RAIN
INLAND...BUT THE COLUMBIA GORGE WOULD BE THE BEST CANDIDATE FOR
FREEZING RAIN AND SNOW...IF...THE GFS SOLUTION WORKS OUT. MAY HAVE
BETTER FEEL FOR THIS SCENARIO LATER TODAY AND SATURDAY SHOULD MODELS
NARROW ON POSSIBLE OUTCOMES.
.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS.
MODELS CONTINUE TO BREAK DOWN A PERSISTENT UPPER LEVEL RIDGE THROUGH
SUN AFTERNOON. PREVIOUSLY THOUGHT TO TRAVEL DIRECTLY TOWARDS THE PAC
NW...A SYSTEM TRACKS TOWARDS NORTHERN CALIF. NOT LIKELY THE CWA WILL
SEE ANY PRECIP WITH THIS PARTICULAR SYSTEM. GFS AND ECMWF DISAGREE
ON A SECOND SYSTEM BY TUE. ECMWF IS FASTER...HAVING THE ASSOCIATED
COLD FRONT ARRIVE EARLY TUE. GFS HAS A RIDGE RETURN...PUSHING THIS
UPPER LOW INTO THE REGION BY LATE WED. NEVERTHELESS...EXPECT WET
WEATHER FOR THE REMAINDER OF NEXT WEEK. 500MB TEMPS BY FRI LOOK A
FEW DEGREES WARMER THAN THE PREVIOUS WEEK. RIGHT NOW...ANY PRECIP
FOR LATE NEXT WEEK WILL PROBABLY BE RAIN. RAMIREZ
&&
.AVIATION...IT IS LOOKING LIKE SANTA WILL NEED RUDOLPH AND HIS
NOSE...DOPPLER RADAR...AND PERHAPS A GPS TO NAVIGATE THE FOG THIS
MORNING. CONDITIONS ARE MOSTLY IFR OR LIFR EARLY THIS MORNING
INLAND THOUGH VISIBILITIES ARE NOT TOTALLY ON THE DECK. WE ARE
SEEING SOME IMPROVEMENT DOWNSTREAM FROM THE GORGE DUE TO THE EAST
WINDS WITH A CLEARER CORRIDOR FROM KPDX TO KHIO. MAY SEE A BIT
MORE CLEARING TODAY DOWN THE VALLEY AND UP TOWARD KELSO BUT EXPECT
SOME STUBBORN AREAS FROM AROUND SALEM SOUTHWARD AND UP IN COWLITZ
COUNTY. EXPECT THE IFR AND LIFR TO EXPAND TONIGHT IN THE INTERIOR
BUT SOME AREAS NEAR PORTLAND MAY STAY CLEAR. THE COAST SHOULD STAY
VFR TODAY AND TONIGHT.
KPDX AND APPROACHES...KPDX IS ON THE EDGE OF THE FOG EARLY THIS
MORNING...ALONG A CORRIDOR OF CLEARING THAT EXTENDS FROM THE GORGE
TO NEAR KHIO. CANNOT RULE OUT A LITTLE IFR OR LIFR BUT AS THE
NEARLY 8 MB GRADIENT THROUGH THE GORGE CONTINUES...THE FOG MAY BE
JUST HELD AT BAY. EXPECT LESS FOG TONIGHT. TOLLESON
&&
.MARINE...BORDERLINE ADVISORY SITUATION WITH REGARD TO WIND AND
SEAS. HAVE DECIDED TO DROP THE SMALL CRAFT ADVISORY DUE TO
HAZARDOUS SEAS AS IT LOOKS TO STAY JUST BELOW 10 FT TODAY.
HOWEVER...SOME LONG PERIOD SWELL OUT NEAR 18 SECONDS WILL COME IN
TONIGHT AND CONTINUE THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK
WITH SEAS IN THE MID TEENS OR SO...AND WILL HAVE A SMALL CRAFT
ADVISORY FOR THAT BEGINNING TONIGHT. WINDS ARE LARGELY GAP WINDS
FROM THE OFFSHORE FLOW...AND WILL HAVE THAT THROUGH AT LEAST
SATURDAY. THE STRONGEST WINDS LOOK TO BE IN THE NORTH AND IN THE
INNER WATERS. THE GFS MODEL IS STILL TRYING TO BRING UP SMALL
CRAFT WINDS SATURDAY FROM A STRETCHING FRONT...WHILE THE ECMWF
WEAKENS THE FRONT MORE DUE TO THE SPLITTING. HAVE GONE WITH AN
AVERAGE OF THE WINDS...BUT THE ECMWF MAY END UP BEING BETTER. THE
NEXT BETTER SHOT AT WIND WILL BE WITH A FRONT IN THE TUESDAY TO
WEDNESDAY TIME FRAME. TOLLESON
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...AIR STAGNATION ADVISORY UNTIL 6 PM PST SATURDAY FOR CENTRAL
WILLAMETTE VALLEY-SOUTH WILLAMETTE VALLEY.
WA...AIR STAGNATION ADVISORY UNTIL 6 PM PST SATURDAY FOR GREATER
VANCOUVER AREA-I-5 CORRIDOR IN COWLITZ COUNTY.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 10 PM PST SATURDAY
FOR COASTAL COASTAL WATERS FROM CAPE SHOALWATER WA TO
FLORENCE OR.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM THIS EVENING
THROUGH SUNDAY EVENING FOR COASTAL COASTAL WATERS FROM
CAPE SHOALWATER WA TO FLORENCE OR.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR TODAY
AND 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.
