Heavy Snow in Washington, March 10 to 11, 2006

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
917 PM PST FRI MAR 10 2006

UPDATED AVIATION DISCUSSION

.UPDATE...AN UPPER LOW PRESSURE SYSTEM OFF THE WASHINGTON AND
OREGON COAST CONTINUES TO KEEP COOL AND UNSETTLED WEATHER OVER
THE AREA. SCATTERED SHOWERS HAVE GRADUALLY DECREASED AFTER SUNSET
FOR MOST OF THE REGION...HOWEVER SOME SNOW SHOWERS REMAIN IN
CENTRAL OREGON AND SOUTH CENTRAL WASHINGTON NEAR THE CASCADES.
THE UNSETTLED WEATHER WILL CONTINUE FOR THE NEXT FEW DAYS AS AN
UPPER LOW PRESSURE SYSTEM REMAINS ALONG THE COAST. THE CURRENT
FORECAST LOOKS GOOD...AND WILL ONLY NEED TO UPDATE TO REMOVE
EVENING WORDING.

&&

.AVIATION...VFR CONDITIONS WILL PERSIST FOR ALL TAF SITES AND ALONG
ALL TWEB ROUTES. SCATTERED SHOWERS WILL AGAIN DEVELOP TOMORROW
AFTERNOON IN UNSTABLE AIR WITH POSSIBLE BRIEF MVFR CONDITIONS
OCCURRING WITH THE HEAVIER SHOWERS.

&&

.PREV DISCUSSION... (ISSUED 221 PM PST FRI MAR 10 2006)

SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT...THE REGION WILL REMAIN
UNDER A COLD UPPER TROUGH THROUGH THIS PERIOD. THEREFORE EXPECT
ISOLATED TO SCATTERED SHOWERS TO CONTINUE THROUGH MOST OF THE
PERIOD. SHOWER COVERAGE WILL FAVOR A DIURNAL DISTRIBUTION WITH THE
BEST COVERAGE IN THE AFTERNOONS AND EVENINGS. THE MAIN UPPER LOW
CENTER IS CURRENTLY STRETCHED OUT ALONG THE BRITISH COLUMBIA AND
WASHINGTON COASTS. THIS UPPER LOW CENTER WILL SLOWLY SHIFT SOUTH TO
A POSITION OFF THE OREGON COAST BY SATURDAY. THUS EXPECT COLDEST AIR
ALOFT AND THE GREATEST INSTABILITIES TO BE WEST OF THE CASCADES. DO
HOWEVER EXPECT THIS AREA OF HIGHER INSTABILITY TO BLEED OVER INTO
THE EAST SLOPES OF THE CASCADES...ESPECIALLY IN CENTRAL OREGON. WILL
CONTINUE A MENTION OF ISOLATED THUNDER OVER NORTH-CENTRAL AND
CENTRAL OREGON EARLY THIS EVENING...THEN AGAIN SATURDAY AFTERNOON.
ELSEWHERE JUST LOOKING FOR ISOLATED TO SCATTERED RAIN OR SNOW
SHOWERS. SMALL HAIL IS POSSIBLE AS WELL...BOTH FROM THE SHOWERS AND
ANY THUNDERSTORMS. SNOW ACCUMULATIONS WILL BE SPOTTY AND LIMITED
THOUGH HEAVY SHOWERS COULD PUT DOWN A QUICK INCH AT A FEW LOCATIONS
ACROSS THE AREA. TEMPS WILL REMAIN BELOW SEASONAL THROUGH SUNDAY
NIGHT. THE UPPER TROUGH LOOKS TO BEGIN EXITING THE WESTERN U.S.
SUNDAY NIGHT AS AN UPPER RIDGE AHEAD OF YET ANOTHER PACIFIC SYSTEM
MOVES ONSHORE. EXPECT SHOWER ACTIVITY TO DROP OFF IN THE MOUNTAINS
AND END IN THE VALLEYS SUNDAY NIGHT AS THIS RIDGE APPROACHES. 90

LONG TERM...MONDAY THROUGH WEDNESDAY...ACTIVE WEATHER PATTERN IN
STORE FOR NEXT WEEK WITH 2 MAJOR TROUGHS TO IMPACT THE REGION...WITH
INTERVENING MOIST WESTERLY FLOW. THE FIRST TROUGH WILL AFFECT THE
AREA ON MONDAY AFTERNOON AND NIGHT BRINGING A GOOD CHANCE OF RAIN
AND MOUNTAIN SNOW. ON TUESDAY THE GFS DEPICTS A STRONG LOW LEVEL JET
AND TIGHT SURFACE PRESSURE GRADIENT OVER THE AREA SO THERE IS SOME
POTENTIAL FOR WINDY CONDITIONS. AT LEAST SLIGHT CHANCES FOR RAIN AND
MOUNTAIN SNOW WILL CONTINUE INTO THURSDAY...BEFORE THE NEXT MAJOR
TROUGH MOVES THROUGH AT THE END OF THE WEEK WITH A GOOD CHANCE FOR
PRECIPITATION. TEMPERATURES WILL BE RUNNING BELOW NORMAL ON AVERAGE
WHICH WILL KEEP DAYTIME SNOW LEVELS IN THE 3000-3500 FOOT RANGE. SO
THERE IS SOME CONCERN FOR ACCUMULATING SNOW IN THE MOUNTAINS THROUGH
THE FORECAST PERIOD. 78

&&

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

TI:GGG
FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT...
WWW.WEATHER.GOV/PENDLETON
84/78/84

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
259 PM PST FRI MAR 10 2006

WAZ024-501-502-026>030-ORZ041>044-049-050-501>506-111315-
EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON-
EAST SLOPES OF THE SOUTHERN CASCADES OF WASHINGTON-
KITTITAS VALLEY-YAKIMA VALLEY-LOWER COLUMBIA BASIN OF WASHINGTON-
FOOTHILLS OF THE BLUE MOUNTAINS OF WASHINGTON-
NORTHWEST BLUE MOUNTAINS-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-
259 PM PST FRI MAR 10 2006

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

.DAY ONE...

THUNDERSTORMS
     NORTH CENTRAL OREGON, CENTRAL OREGON

INSTABILITY DUE TO A COLD UPPER LEVEL LOW PRESSURE SYSTEM MAY CAUSE
THE DEVELOPMENT OF ISOLATED THUNDERSTORMS OVER CENTRAL AND NORTH
CENTRAL OREGON THROUGH EARLY EVENING. OTHERWISE ISOLATED TO
SCATTERED AFTERNOON AND EVENING SHOWERS CAN BE EXPECTED ACROSS THE
REGION. SMALL HAIL MAY ALSO BE PRODUCED BY THESE THUNDERSTORMS AND
SHOWERS.

.DAYS TWO THROUGH SEVEN...

THUNDERSTORMS SATURDAY
     NORTH CENTRAL OREGON, CENTRAL OREGON, OCHOCO-JOHN DAY
     HIGHLANDS

THE COLD UPPER LOW WILL REMAIN OVER THE PACIFIC NORTHWEST THROUGH
THE WEEKEND RESULTING IN ISOLATED TO SCATTERED SHOWERS. ISOLATED
AFTERNOON AND EVENING THUNDERSTORMS MAY ALSO OCCUR OVER PORTIONS OF
CENTRAL OREGON.

COOL AND UNSETTLED CONDITIONS WILL PERSIST ACROSS THE REGION THROUGH
THE MIDDLE OF NEXT WEEK.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED.

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/PENDLETON/CURRENTHAZARDS/HWO.HTML

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