Heavy Snow in Oregon, January 29, 2008

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
950 PM PST MON JAN 28 2008

.UPDATE...SATELLITE SHOWS THE NEXT FRONT APPROACHING THE COAST WITH
CLOUDS SPREADING OVER WASHINGTON AND OREGON AHEAD OF IT. A FEW
SHOWERS HAVE STARTED AT THE DALLES...BUT MOST OF THE PRECIPITATION
IS STILL WEST OF THE CASCADES. EXPECT SNOW TO SPREAD OVER EASTERN
WASHINGTON AND OREGON OVERNIGHT. TEMPERATURES DROPPED DURING BRIEF
CLEARING EARLIER TONIGHT SO I ISSUED AN UPDATE TO LOWER OVERNIGHT
LOWS IN THE COLUMBIA BASIN. WITH INCREASING CLOUDS TEMPERATURES HAVE
INCREASED AGAIN TO MID 30S IN VALLEYS WHERE WINDS MIXED OUT SURFACE
COLD AIR...INCLUDING MOST OF THE LOWER COLUMBIA BASIN EXCEPT
HANFORD...AND MAINLY 20S OTHER LOCATIONS.  AS PRECIPITATION SPREADS
EAST EXPECT MAINLY SNOW...THOUGH IT MAY BE MIXED WITH RAIN OVER THE
LOWER COLUMBIA BASIN. COLD AIR DAMMING WILL KEEP COLDER AIR IN THE
YAKIMA AND KITTITAS VALLEYS SO PRECIPITATION WILL BE SNOW. REST OF
FORECAST LOOKS GOOD...BUT MAY UPDATE AGAIN TO REMOVE EVENING
WORDING. COONFIELD

&&

.AVIATION...CEILINGS WILL GRADUALLY LOWER THROUGH THE NIGHT. SNOW
SHOWERS WILL INTERMITTENTLY REDUCE VISIBILITIES AND CEILINGS TO
MVFR/IFR LEVELS THROUGH 18Z. CLEARING WILL BEGIN AT YKM AND RDM BY
18Z AND SPREAD EAST TO PSC. UPSLOPE TERRAIN EFFECTS WILL KEEP
CEILINGS AROUND 4-5 KFT AT ALW AND PDT 18-06Z.  76

&&

.PREV DISCUSSION... /ISSUED 835 PM PST MON JAN 28 2008/

SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT.  DOPPLER RADAR
CONTINUES TO SHOW SCATTERED SHOWERS OVER THE CASCADES AND THE BLUE
MOUNTAINS WHERE BRIEF ACCUMULATIONS OF 1-3 INCHES HAVE BEEN OBSERVED
WITH MODERATE TO HEAVY SNOW.  THE PRECIPITATION COVERAGE IS TAPERING
OFF SO DO NOT ANTICIPATE ANY ADVISORIES THE REST OF THE AFTERNOON
AND EVENING.  THE NEXT SYSTEM NOW MOVING ACROSS THE GULF OF ALASKA
WILL BE THE NEXT BIG SNOW PRODUCER...ESPECIALLY ALONG THE CASCADES
AND THE BLUE MOUNTAINS.  THE EAST SLOPES OF THE CASCADES (BOTH
WASHINGTON AND OREGON) WILL SEE WIDESPREAD SNOW STARTING AROUND 10
PM AND INCREASING IN INTENSITY EARLY TUESDAY MORNING.  A MOIST
WESTERLY FLOW WILL SPILL SNOW INTO THE VALLEYS THE REMAINDER OF
TUESDAY AND TUESDAY EVENING. WILL BE UPGRADING THE WINTER STORM
WATCHES TO HEAVY SNOW WARNINGS FOR THE WASHINGTON EAST SLOPES AS
WELL AS CENTRAL OREGON.  THE EASTERN COLUMBIA RIVER GORGE...NORTH
CENTRAL OREGON...AND THE YAKIMA/KITTITAS VALLEYS SHOULD ALSO SEE
BRIEF HEAVY SNOW LATE TONIGHT AND EARLY TUESDAY MORNING...ENOUGH TO
MEET SNOW ADVISORY CRITERIA.

THE NORTHERN BLUE MOUNTAINS WILL SEE THE HEAVIEST SNOW TUESDAY AND
TUESDAY NIGHT.  THE ACCUMULATIONS CURRENTLY IN FORECAST SHOW 10-20
INCHES WHICH LOOK REASONABLE.  BELIEVE PRECIPITATION WILL LIKELY
SPILL OVER INTO THE GRANDE RONDE VALLEY WHERE SNOW ADVISORY AMOUNTS
WILL BE MET...ESPECIALLY AREAS NORTH OF LA GRANDE. IT WILL BE TOUGH
TO MEET WARNING CRITERIA IN THE SOUTHERN BLUES SO WILL ONLY GO
ADVISORY FOR EARLY TUESDAY MORNING THROUGH EARLY WEDNESDAY MORNING.
WINDS AND BLOWING AND DRIFTING WILL ALSO BE A CONCERN IN THESE
AREAS.  THE WINDS IN THE GRANDE RONDE VALLEY MAY BRIEFLY REACH WIND
ADVISORY CRITERIA LATE TONIGHT AND EARLY TUESDAY.  FOR NOW...WILL
KEEP WINDS SUSTAINED AT 25-35 MPH...JUST BELOW ADVISORY CRITERIA.

THE UPPER LEVEL TROUGH WILL MOVE INTO IDAHO WEDNESDAY FOLLOWED BY A
WEAK SHORTWAVE RIDGE.  THE BLUE MOUNTAINS WILL CONTINUE TO SEE
SCATTERED-NUMEROUS OROGRAPHIC SHOWERS WEDNESDAY MORNING.
OTHERWISE...PRECIPITATION WILL TAPER OFF ACROSS THE AREA.  JOHNSON

LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY NIGHT...ACTIVE WEATHER IS
EXPECTED TO CONTINUE THROUGH THE END OF THE WEEK. PROGRESSIVE
WESTERLY FLOW WILL BRING A FRONTAL SYSTEM INTO THE NORTHWEST ON
WEDNESDAY NIGHT WITH A REINFORCING SURGE OF MOISTURE ON THURSDAY.
ALTHOUGH THE MODELS INDICATE A WARMING TREND DUE TO SOUTHERLY
FLOW...HAVE CHOSEN TO LEAN TOWARDS THE COOLER SIDE OF GUIDANCE.
GIVEN MODEL PERFORMANCE SO FAR THIS WINTER...IT IS EVIDENT THAT THEY
DO NOT HANDLE COLD AIR DAMMING IN THE LOWER COLUMBIA BASIN WELL AS
THEY TEND TO HAVE A WARM BIAS. THEREFORE...HAVE GONE WITH A MOSTLY
SNOW FORECAST FOR THURSDAY. HOWEVER...CANNOT RULE OUT THE
POSSIBILITY THAT THE LOWER LEVELS WILL WARM SUFFICIENTLY TO ALLOW
RAIN TO MIX IN. SCATTERED RAIN AND SNOW SHOWERS WILL TAPER ON FRIDAY
BEFORE MORE WIDESPREAD PRECIPITATION MOVES INTO THE AREA ON SATURDAY
IN ASSOCIATION WITH ANOTHER PACIFIC STORM SYSTEM. SNOW SHOWERS WILL
THEN CONTINUE THROUGH THE WEEKEND WHILE RAIN OR A RAIN/SNOW/SLEET
MIX WILL BE POSSIBLE IN THE LOWER COLUMBIA BASIN DURING THE DAYTIME
HOURS. DUE TO THE STRONG WESTERLY FLOW...THE MOST SIGNIFICANT SNOW
AMOUNTS ARE LIKELY ALONG THE CASCADE CRESTS AND EASTERN SLOPES WITH
LESSER AMOUNTS ACROSS THE REMAINDER OF THE AREA. TEMPERATURES SHOULD
REMAIN FAIRLY CONSISTENT WITH HIGHS IN THE 20S AND 30S AND LOWS IN
THE TEENS AND 20S.  CALDER

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  22  32  26  31 /  50  80  60  30
ALW  22  34  27  33 /  50  80  60  30
PSC  13  34  26  34 /  40  70  40  20
YKM  18  34  19  33 /  60  70  30  20
HRI  22  33  25  34 /  40  80  40  20
ELN  17  30  18  30 /  60  80  40  20
RDM  20  35  20  33 /  60  70  60  30
LGD  21  31  21  31 /  60  80  70  40
GCD  18  32  18  31 /  60  70  50  30
DLS  25  35  28  34 /  60  80  60  30

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...HEAVY SNOW WARNING UNTIL 10 PM PST TUESDAY FOR ORZ043.

     SNOW ADVISORY UNTIL 10 PM PST TUESDAY FOR ORZ042.

     WINTER STORM WARNING FROM 2 AM TUESDAY TO 4 AM PST WEDNESDAY FOR
     ORZ502.

     SNOW AND BLOWING SNOW ADVISORY FROM 2 AM TUESDAY TO 4 AM PST
     WEDNESDAY FOR ORZ049-503.

     SNOW ADVISORY UNTIL 10 AM PST TUESDAY FOR ORZ041.

WA...HEAVY SNOW WARNING UNTIL 10 PM PST TUESDAY FOR WAZ501-502.

     WINTER STORM WARNING FROM 2 AM TUESDAY TO 4 AM PST WEDNESDAY FOR
     WAZ030.

     SNOW ADVISORY UNTIL 10 AM PST TUESDAY FOR WAZ024-026-027.

&&

TI:GYG
FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT...
WWW.WEATHER.GOV/PENDLETON
76/76/76

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
335 PM PST MON JAN 28 2008

UPDATED FOR WINTER WEATHER STATEMENTS

ORZ041>044-049-050-501>506-WAZ024-026>030-501-502-291415-
EASTERN COLUMBIA RIVER GORGE OF OREGON-NORTH CENTRAL OREGON-
CENTRAL OREGON-LOWER COLUMBIA BASIN OF OREGON-GRANDE RONDE VALLEY-
WALLOWA COUNTY-FOOTHILLS OF THE BLUE MOUNTAINS OF OREGON-
NORTHERN BLUE MOUNTAINS OF OREGON-
SOUTHERN BLUE MOUNTAINS OF OREGON-
NORTHERN WHEELER AND SOUTHERN GILLIAM COUNTIES-JOHN DAY BASIN-
OCHOCO-JOHN DAY HIGHLANDS-
EASTERN COLUMBIA RIVER GORGE OF WASHINGTON-KITTITAS VALLEY-
YAKIMA VALLEY-LOWER COLUMBIA BASIN OF WASHINGTON-
FOOTHILLS OF THE BLUE MOUNTAINS OF WASHINGTON-
NORTHWEST BLUE MOUNTAINS-
EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON-
EAST SLOPES OF THE SOUTHERN CASCADES OF WASHINGTON-
328 PM PST MON JAN 28 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL AND NORTHEAST OREGON
AS WELL AS SOUTH CENTRAL AND SOUTHEAST WASHINGTON.

.DAY ONE...TONIGHT

SNOW
     EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON, EAST SLOPES
     OF THE SOUTHERN CASCADES OF WASHINGTON, EASTERN COLUMBIA RIVER
     GORGE OF WASHINGTON, KITTITAS VALLEY, YAKIMA VALLEY, EASTERN
     COLUMBIA RIVER GORGE OF OREGON, NORTH CENTRAL OREGON, CENTRAL
     OREGON

A STRONG PACIFIC STORM SYSTEM WILL BRING ANOTHER ROUND OF MODERATE
TO HEAVY SNOW ACROSS SOUTH CENTRAL AND SOUTHEAST WASHINGTON AND
CENTRAL AND NORTHEAST OREGON TONIGHT AND TUESDAY.  THE FRONT WILL
INITIALLY BRING HEAVY SNOW TO THE EAST SLOPES OF THE WASHINGTON AND
OREGON CASCADES BETWEEN 10 PM AND MIDNIGHT. MODERATE TO HEAVY SNOW
IS ALSO POSSIBLE IN THE EASTERN COLUMBIA RIVER GORGE...THE KITTITAS
AND YAKIMA VALLEYS...AND NORTH CENTRAL OREGON.  HEAVY SNOW WARNINGS
AND SNOW ADVISORIES HAVE BEEN POSTED FOR THESE AREAS BEGINNING 10 PM
THIS EVENING.  FOR DETAILS...PLEASE REFER TO THE PRODUCT PDXWSPDT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH MONDAY

SNOW TUESDAY
     EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON, EAST SLOPES
     OF THE SOUTHERN CASCADES OF WASHINGTON, EASTERN COLUMBIA RIVER
     GORGE OF WASHINGTON, KITTITAS VALLEY, YAKIMA VALLEY, NORTHWEST
     BLUE MOUNTAINS, EASTERN COLUMBIA RIVER GORGE OF OREGON, NORTH
     CENTRAL OREGON, CENTRAL OREGON, GRANDE RONDE VALLEY, NORTHERN
     BLUE MOUNTAINS OF OREGON, SOUTHERN BLUE MOUNTAINS OF OREGON

SNOW THURSDAY
     EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON, EAST SLOPES
     OF THE SOUTHERN CASCADES OF WASHINGTON, EASTERN COLUMBIA RIVER
     GORGE OF WASHINGTON, NORTHWEST BLUE MOUNTAINS, EASTERN
     COLUMBIA RIVER GORGE OF OREGON, NORTH CENTRAL OREGON, CENTRAL
     OREGON, GRANDE RONDE VALLEY, WALLOWA COUNTY, NORTHERN BLUE
     MOUNTAINS OF OREGON, SOUTHERN BLUE MOUNTAINS OF OREGON, JOHN
     DAY BASIN, OCHOCO-JOHN DAY HIGHLANDS

THE STORM SYSTEM WILL SPREAD SNOW TO THE BLUE MOUNTAINS OF OREGON
AND WASHINGTON AS WELL AS THE GRANDE RONDE VALLEY EARLY TUESDAY
MORNING.  HEAVY SNOW WARNINGS AND SNOW AND BLOWING SNOW ADVISORIES
HAVE BEEN POSTED.  MORE INFORMATION CAN BE FOUND IN THE WINTER
STATEMENT...PDXWSWPDT.  WINDS WILL CAUSE BLOWING AND DRIFTING SNOW
WITH POOR VISIBILITIES.  IN THE SOUTHERN PORTION OF THE GRANDE RONDE
VALLEY...THE VISIBILITY COULD BE NEAR ZERO AT TIMES ON TUESDAY.  THE
WINTER STORM WILL MOVE INTO IDAHO WEDNESDAY.  ANOTHER PACIFIC STORM
SYSTEM WILL ARRIVE FOR MORE MOUNTAIN SNOW ON THURSDAY.  FORECAST
MODELS ARE ADVERTISING ANOTHER STORM SYSTEM ON SATURDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL BE LIKELY TONIGHT THROUGH TUESDAY NIGHT.

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

GRAPHICAL FORECASTS OF WEATHER HAZARDS OUT TO SEVEN DAYS
ARE DISPLAYED ON THE WORLD WIDE WEB AT:

WWW.WRH.NOAA.GOV/PDT/CURRENTHAZARDS/HWO.HTML

ALL LETTERS IN THE ABOVE URL ARE LOWER CASE...EXCEPT THE H IN
CURRENTHAZARDS.