Heavy Snow in Washington, March 26 to 27, 2008

AREA FORECAST DISCUSSION...RETRANSMITTED
NATIONAL WEATHER SERVICE PENDLETON OR
355 PM PDT WED MAR 26 2008

UPDATED AVIATION AND LONG TERM DISCUSSIONS

.SHORT TERM...TONIGHT THROUGH THURSDAY NIGHT...STRONG SHORT WAVE
MOVING ACROSS THE PACIFIC NORTHWEST ASSOCIATED WITH 140 KT JET.
BASED ON SATELLITE ENHANCEMENT WOULD EXPECT A PERIOD OF STEADY
PRECIPITATION EARLY THIS EVENING THEN CHANGING OVER TO A SHOWERS
TYPE PATTERN FOR TONIGHT. THIS SYSTEM IS FAIRLY COLD AND WILL SEE
SNOW OR MIXED RAIN AND SNOW DOWN INTO THE LOWER ELEVATIONS.
MOUNTAINS WILL SEE DECENT SNOW ACCUMULATIONS ESPECIALLY THE
WASHINGTON CASCADES AND BLUES. AMOUNTS APPEAR TO BE A LITTLE BELOW
ADVISORY CRITERIA. SURFACE GRADIENTS ARE INCREASING FROM THE
SOUTHWEST AND COLD ADVECTION WILL BE OCCURRING OVERNIGHT SO SHOULD
SEE BREEZY CONDITIONS FOR MUCH OF THE FORECAST AREA. COOL UNSTABLE
WESTERLY FLOW ALOFT ON THURSDAY WILL PRODUCE PARTLY TO MOSTLY CLOUDY
SKIES WITH SHOWERS...ESPECIALLY OVER THE MOUNTAINS. LOCALLY BREEZY
CONDITIONS WILL CONTINUE. UPPER LEVEL LOW AND ASSOCIATED SURFACE LOW
PRESSURE SYSTEM WILL BE APPROACHING THE PACIFIC NORTHWEST THURSDAY
NIGHT. GOOD WARM AIR ADVECTION PATTERN WITH THIS STORM. CLOUDS WILL
BE INCREASING WITH PRECIPITATION SPREADING IN FROM THE WEST
OVERNIGHT. INCREASING SURFACE GRADIENTS AND 850MB WINDS WILL PRODUCE
BREEZY CONDITIONS. TEMPERATURES THROUGH THIS PERIOD WILL CONTINUE
BELOW NORMAL AS AIRMASS REMAINS COLD.  94

.LONG TERM...FRIDAY THROUGH WEDNESDAY:

.FRIDAY THROUGH SUNDAY NIGHT...A VERY STRONG UPPER LEVEL LOW
PRESSURE SYSTEM WILL PUSH A COLD FRONT ACROSS THE FORECAST AREA ON
FRIDAY. PRESSURE GRADIENTS ASSOCIATED WITH THE LOW WILL PRODUCE
SOUTHERLY WINDS VERY WINDY CONDITIONS IN THE OREGON PORTION OF THE
FORECAST AREA AND LOCALLY BREEZY SOUTHERLY WINDS IN THE WASHINGTON
PORTION. WINDS IN EASTERN OREGON WILL VEER TO THE WEST FRIDAY
AFTERNOON AS THE COLD FRONT PUSHES EAST OF THE OREGON CASCADES AND
THROUGH THE EASTERN COLUMBIA RIVER GORGE. SNOW ACCUMULATIONS OF 1 TO
6 INCHES WILL BE POSSIBLE DURING THE DAY ON FRIDAY ALONG THE EAST
SLOPES OF THE CENTRAL AND SOUTHERN WASHINGTON CASCADES. A SNOW
ADVISORY MAY BE NEEDED FOR THESE AREAS ON FRIDAY. OTHERWISE...THIS
SYSTEM WILL LOWER SNOW LEVELS FRIDAY NIGHT FOR SNOW SHOWERS OVER
MOST OF THE REGION...EXCEPT IN THE LOWER COLUMBIA BASIN AND THE
FOOTHILLS OF THE BLUE MOUNTAINS WHERE A MIX OF RAIN SHOWERS AND SNOW
SHOWERS WILL OCCUR. THE BLUE MOUNTAINS WILL HAVE SNOW ACCUMULATIONS
OF 3 TO 6 INCHES FROM FRIDAY AFTERNOON THROUGH FRIDAY NIGHT. THE LOW
WILL THEN OPEN UP TO AN UPPER LEVEL  TROUGH AS IT MOVES THROUGH THE
PACIFIC NORTHWEST FRIDAY NIGHT AND SATURDAY. THEN AN UPPER LEVEL
RIDGE OFF THE COAST WILL KEEP THE REGION IN A WESTNORTHWEST FLOW
ALOFT FOR A CHANCE OF SNOW SHOWERS IN THE MOUNTAINS EACH DAY.  POLAN

.MONDAY THROUGH WEDNESDAY...A RIDGE WILL MOVE OVER THE PACIFIC
NORTHWEST MONDAY AND MONDAY NIGHT WITH PREDOMINATELY DRY AND WARMER
CONDITIONS. MODELS DIVERGE ON TUESDAY AND WEDNESDAY. GFS HAS A MOIST
SOUTHERLY FLOW OF WRAPAROUND MOISTURE FROM A CUTOFF LOW MOVING INTO
OREGON AND WASHINGTON TUESDAY...THEN THE LOW OPENING UP AND A TROUGH
OVER OREGON AND WASHINGTON WEDNESDAY. THE ECMWF KEEPS THE CUTOFF LOW
MUCH FARTHER SOUTH TUESDAY WITH ZONAL FLOW IN OREGON AND
WASHINGTON...THEN SOUTHWEST FLOW AHEAD OF A FRONT WEDNESDAY. WITH
LOW CONFIDENCE DUE TO LACK OF CONSISTENCY IN MODEL SOLUTIONS WITH
EACH OTHER OR YESTERDAYS SOLUTIONS OPTED TO INCREASE SKY COVER AND
POPS IN MOUNTAINS A LITTLE RATHER THAN MAKE DRASTIC CHANGES.
COONFIELD

&&

.AVIATION...00Z TAFS...AN UPPER LEVEL SHORT WAVE NOW CROSSING THE
NORTHERN OREGON COAST JUST SOUTH OF KAST WILL MOVE EASTWARD TONIGHT
AND PUSH A COLD FRONT EAST OF THE CASCADES AND THROUGH THE FORECAST
AREA. LOOK FOR CLOUD CEILINGS TO LOWER THROUGH THE REMAINDER OF THIS
AFTERNOON AND THIS EVENING AS LIFT ASSOCIATED WITH THE SHORT WAVE
MOVES EAST OF THE CASCADES. WINDS WILL INCREASE BY LATE THIS
AFTERNOON AND THIS EVENING AT TAF SITES WITH SUSTAINED WINDS FROM
THE SOUTHWEST AND WEST OF 10-20 KNOTS. THERE IS A POTENTIAL FOR MVFR
CONDITIONS TONIGHT WITH RAIN SHOWERS AT KALW. IFR CONDITIONS WILL
OCCUR TONIGHT ALONG FLIGHT ROUTES OVER THE BLUE MOUNTAINS DUE TO LOW
CEILINGS AND REDUCED VISIBILITIES IN NUMEROUS SNOW SHOWERS.  POLAN

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  32  50  31  45 /  50  20  10  60
ALW  33  50  33  47 /  50  20  10  60
PSC  31  55  31  49 /  40  20  10  50
YKM  24  53  28  47 /  40  20  20  60
HRI  31  51  31  49 /  40  20  10  60
ELN  24  48  25  44 /  50  20  30  70
RDM  18  43  24  41 /  60  20  30  70
LGD  28  42  30  40 /  60  30  20  60
GCD  28  44  25  41 /  70  30  20  60
DLS  32  52  32  47 /  60  20  30  70

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
&&

TI:GYG
FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT...
WWW.WEATHER.GOV/PENDLETON
94/99/99

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
500 PM PDT WED MAR 26 2008

ORZ041>044-049-050-501>506-WAZ024-026>030-501-502-271415-
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-
500 PM PDT WED MAR 26 2008

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

.DAY ONE...TONIGHT

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

A STORM SYSTEM WILL SPREAD SHOWERS ACROSS THE AREA WITH SNOW
ACCUMULATION OF 2 TO 5 INCHES LIKELY IN THE BLUE MOUNTAINS TONIGHT.
SOME SHOWERS MAY PRODUCE SMALL HAIL THIS AFTERNOON AND EARLY THIS
EVENING. BREEZY CONDITIONS ARE POSSIBLE AS WELL FOR THE REMAINDER OF
THIS AFTERNOON AND TONIGHT...MAINLY IN THE EASTERN COLUMBIA RIVER
GORGE...THE KITTITAS VALLEY...THE LOWER COLUMBIA BASIN AND THE
FOOTHILLS OF THE BLUE MOUNTAINS.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

SNOW FRIDAY
     EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON, EAST SLOPES
     OF THE SOUTHERN CASCADES OF WASHINGTON

ANOTHER STORM SYSTEM WILL AFFECT THE AREA ON FRIDAY AND FRIDAY NIGHT
WITH RAIN AND SNOW EXPECTED. SNOW ACCUMULATIONS OF 1 TO 6 INCHES ARE
POSSIBLE FRIDAY ALONG THE EAST SLOPES OF THE CENTRAL AND SOUTHERN
WASHINGTON CASCADES AND A SNOW ADVISORY MAY BE NEEDED FOR THESE
AREAS ON FRIDAY. THIS STORM SYSTEM WILL PUSH A VIGOROUS COLD FRONT
THROUGH THE FORECAST AREA FRIDAY AFTERNOON. TIGHT PRESSURE GRADIENTS
ASSOCIATED WITH THE FRONT AND AFTER THE FRONTAL PASSAGE THROUGH THE
AREA WILL PRODUCE BREEZY TO WINDY CONDITIONS FRIDAY AFTERNOON AND
FRIDAY NIGHT IN THE EASTERN COLUMBIA RIVER GORGE...CENTRAL AND NORTH
CENTRAL OREGON...THE LOWER COLUMBIA BASIN...THE FOOTHILLS OF THE
BLUE MOUNTAINS...THE GRANDE RONDE VALLEY AND IN WALLOWA COUNTY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED FRIDAY FOR SNOW ALONG THE EAST
SLOPES OF THE CENTRAL AND SOUTHERN WASHINGTON CASCADES.

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.