Heavy Snow in Oregon, January 16, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
230 AM PST TUE JAN 16 2007

.SYNOPSIS...A PACIFIC COLD FRONT WILL BE MOVING THROUGH A COLD
AIR MASS ACROSS SOUTHWEST WASHINGTON AND NORTHWEST OREGON TODAY
WITH AREAS OF LIGHT RAIN OR SNOW. THE FRONT WILL MOVE EAST OF THE
AREA DURING THE AFTERNOON AND EVENING. HIGHER PRESSURE WILL BUILD IN
WEDNESDAY THOUGH A FEW SHOWERS MAY PERSIST OVER THE HIGHER CASCADES.
AS THE UPPER RIDGE BUILDS...A WEAK WARM FRONT MAY BRUSH THE FAR NORTH
COAST ZONES WITH A SLIGHT CHANCE OF PRECIPITATION THURSDAY AND
THURSDAY NIGHT. A WEAKENING COLD FRONT MAY BRUSH THE FAR NORTHERN
ZONES THIS WEEKEND...OTHERWISE DRY WEATHER IS EXPECTED.
&&

.SHORT TERM...MODELS ARE SHOWING THAT THE COLD FRONT JUST OFF THE
COAST WILL LIKELY HANG TOGETHER AS IT MOVES ONSHORE AND THROUGH
SOUTHWEST WASHINGTON AND NORTHWEST OREGON TODAY. NORMALLY WOULD
EXPECT MORE OF A WEAKENING TREND...BUT THE SECONDARY AREA OF COLD AIR
AND VORTICITY JUST TO THE WEST HAS MAINTAINED ITS JET STRUCTURE AND
THE CLOUD TOPS HAVE COOLED SINCE MIDNIGHT ALONG THE FRONT. THE FRONT
WAS STARTING TO MOVE ONSHORE ON THE SOUTH WASHINGTON AND NORTH OREGON
COASTS WITH SOME FREEZING RAIN AND MIXED PRECIPITATION. HAVE ISSUED
A WINTER WEATHER ADVISORY THERE FOR A COUPLE OF HOURS BEFORE IT
SHOULD MIX OVER TO RAIN. THE CENTRAL COAST LOOKS WARM/MOIST ENOUGH TO
BE JUST RAIN. BUT INLAND WILL HAVE A MIX OF SNOW OR WINTER WEATHER
ADVISORIES. MODEL SOUNDINGS INDICATE THE GORGE AND CASCADE FOOTHILLS
WILL STAY SNOW...AND ALSO POSSIBLY THE PORTLAND/VANCOUVER METRO
AREAS. THE BACK EDGE OF THE FRONT MOVES THROUGH EARLY IN THE
AFTERNOON...AND EAST OF THE CASCADES BY EARLY EVENING. SNOW AMOUNTS
IN THE CASCADES LOOK TO BE BELOW THEIR HIGHER THRESHOLDS SO NO
HIGHLIGHTS THERE.

THE SHOWERS BEHIND THE FRONT LATER TODAY AND TONIGHT SHOULD NOT BE
VERY WIDESPREAD AS THE MAIN COLD AIR AND VORTICITY BEHIND THE FRONT
DIGS SOUTH TOWARD CALIFORNIA. DID BRUSH THE SOUTHERN COASTAL WATERS
WITH HIGH POPS AND A SLIGHT CHANCE OF THUNDERSTORMS AS THIS FEATURE
PASSES BY.

THE MODELS GENERALLY SHOW AN UPPER RIDGE BUILDING IN TONIGHT AND
WEDNESDAY OVER THE PACIFIC NORTHWEST. THE MODELS DO SHOW A WEAK SHORT
WAVE DIGGING SOUTH ON WEDNESDAY INTO EASTERN WASHINGTON AND OREGON.
THE MODELS SHOW A TOUCH OF PRECIPITATION IN OUR AREA FROM THIS...AND
FOR NOW JUST PUT A SLIGHT CHANCE OF SHOWERS IN THE NORTHERN CASCADE
ZONES. THE MODELS THEN SHOW THE TAIL END OF A WARM FRONT POSSIBLY
BRUSHING THE NORTH COAST ZONES THURSDAY AND PUT A SLIGHT CHANCE THERE
FOR NOW. TOLLESON

.LONG TERM...MODELS HAVING SOME DIFFICULTY IN SETTLING ON DETAILS IN
EXTENDED PERIOD. WE MAY GET BRUSHED BY A WEAK SYSTEM THIS WEEKEND.
WILL NOT MAKE ANY CHANGES FOR NOW. TOLLESON
&&

.AVIATION...VFR AT INLAND TERMINALS AT 1030Z...BUT CONDITIONS WILL
NOT LAST LONG. -FZRA AND POSSIBLY -SN AT KAST EARLIER AND EXPECT THIS
TO CONTINUE THROUGH ABOUT 12Z. WILL NEED TO WATCH THIS CLOSE FOR THE
12Z PACKAGE. EXPECT MVFR AT KAST AND KONP FOR THE FIRST FEW HOURS OF
THE 12Z FORECAST. INLAND SITES WILL SEE -SN AROUND 12Z OR SHORTLY
THEREAFTER...WITH MVFR IN -SN AND CIGS THROUGH ABOUT 18Z. FRONT FALLS
APART THIS AFTERNOON AND WOULD EXPECT A RETURN TO VFR AT ALL SITES BY
21Z. FZFG IN THE UMPQUA VLY AT THE MOMENT AND THIS SHOULD CONTINUE
FOR THE NEXT FEW HOURS. ANOTHER PROBLEM AREA IS IN THE GORGE EAST OF
K4S2 WITH SOME MVFR CIGS.
&&

.MARINE...LOW END SMALL CRAFT WINDS ALREADY OCCURRING IN THE NRN
WATERS. BUOY 050 RIGHT ON THE CUSP OF SMALL CRAFT WIND AT 10Z SO
EXPANDED THE ADVISORY TO COVER ALL WATERS THROUGH 15Z. ALSO...SWELL
STARTING TO CREEP UP SO ADDED A ROUGH BAR THIS AFTERNOON. NO OTHER
CONCERNS UNTIL AFTER 12Z WED WHEN SWELL IS EXPECTED TO BE AROUND 10
FT. DID NOT INCLUDE THE HAZARD JUST YET SINCE IT IS JUST BEYOND 24
HOURS OUT.  WEISHAAR
&&

.PQR WATCHES/WARNINGS/ADVISORIES
.OR/WA...SMALL CRAFT ADVISORY FOR WINDS CAPE SHOALWATER TO FLORENCE
          THIS MORNING.
         SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR THIS
          AFTERNOON.
         SNOW ADVISORY THIS MORNING AND EARLY AFTERNOON FOR THE
          GREATER PORTLAND/VANCOUVER METRO AREA AND THE CENTRAL
          WILLAMETTE VALLEY.
         SNOW ADVISORY FOR THE WESTERN COLUMBIA RIVER GORGE AND THE
          CASCADE FOOTHILLS OF SOUTHWEST WASHINGTON AND NORTHWEST
          OREGON TODAY.
         WINTER WEATHER ADVISORY EARLY THIS MORNING FOR THE SOUTH
          WASHINGTON AND NORTH OREGON COASTS.
         WINTER WEATHER ADVISORY LATER THIS MORNING AND EARLY
          AFTERNOON FOR THE SOUTHERN WILLAMETTE VALLEY.
         WINTER WEATHER ADVISORY THIS MORNING AND EARLY AFTERNOON FOR
          THE COASTAL MOUNTAINS AND FOR THE LOWER COLUMBIA AREA AND
          INTERSTATE 5 CORRIDOR OF SOUTHWEST WASHINGTON AND EXTREME
          NORTHWEST OREGON.
&&

.PRELIMINARY POINT POPS...
AST 92122   PDX 8211-   SLE 8211-   EUG 82110

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.