Winter Storm in Oregon, December 24, 2012

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
245 AM PST MON DEC 24 2012

.SHORT TERM...TODAY THROUGH TUESDAY NIGHT. SURFACE LOW THAT MOVED
ACROSS THE REGION YESTERDAY IS NOW LOCATED OVER EASTERN WASHINGTON.
CLOUDS WRAPPING AROUND THE LOW ARE STILL PRODUCING RAIN AND SNOW
SHOWERS FROM THE WASHINGTON CASCADES ACROSS THE COLUMBIA BASIN INTO
THE BLUES. EXPECT SNOW TO LINGER OVER THE BLUES WITH AN UPSLOPE
NORTHWEST FLOW INTO THE AFTERNOON. MOST OTHER LOCATIONS SHOULD SEE
DRY CONDITIONS WITH DECREASING CLOUDS IN THE AFTERNOON AS HIGH
PRESSURE BUILDS IN. HIGH PRESSURE WILL MAINTAIN FAIR WEATHER THROUGH
THE EVENING AND INTO TONIGHT. MID AND HIGH LEVEL CLOUDS WILL BE
INCREASING LATE AS A WARM FRONT APPROACHES THE REGION. THIS FRONT
IS ASSOCIATED WITH A LARGE UPPER LOW MOVING TOWARD THE PACIFIC
NORTHWEST. WATER VAPOR SATELLITE IMAGERY SHOWS THIS SYSTEM TO BE
STRONG AT THIS TIME LOCATED BETWEEN 140-150W. THE WARM FRONT WILL
MOVE THROUGH TUESDAY BRINGING SNOW AND SOME LOW ELEVATION RAIN.
PORTIONS OF CENTRAL AND NORTHEAST OREGON AS WELL AS THE BLUE
MOUNTAIN FOOTHILLS COULD SEE BREEZY SOUTHEAST WINDS DURING THE DAY
WITH A SURFACE LOW PRESSURE LOCATED OFF THE COAST. PRECIPITATION
WILL CONTINUE TUESDAY NIGHT AS THE UPPER LEVEL LOW REMAINS OFFSHORE.
TEMPERATURES WILL STAY FAIRLY CLOSE TO SEASONAL LEVELS THE NEXT FEW
DAYS.   94

.LONG TERM...WEDNESDAY THROUGH MONDAY...MAINLY SNOW...EXCEPT FOR
MAINLY RAIN OVER THE BLUE MOUNTAIN FOOTHILLS WILL CONTINUE INTO
WEDNESDAY AS THE WEATHER SYSTEM MAKES ITS WAY EASTWARD. THE SURFACE
LOW WILL TRACK TO THE SOUTHEAST WITH AN UPPER LEVEL NORTHERLY FLOW
DEVELOPING. THIS WILL BRING IN COLDER AIR WHICH MAY CAUSE ANY LEFT
OVER RAIN SHOWERS ALONG THE FOOTHILLS OF THE BLUES TO CHANGE OVER TO
SNOW SHOWERS. ELSEWHERE THIS EVENT WILL MAINLY BE A SNOW EVENT AND
SNOW SHOWERS WILL CONTINUE THROUGH AT LEAST WEDNESDAY MORNING. THE
PRECIPITATION WILL DECREASE IN ALL AREAS WEDNESDAY AFTERNOON THOUGH
UP SLOPE SNOW SHOWERS WILL PERSIST OVER THE EASTERN AND CENTRAL
MOUNTAINS THROUGH SATURDAY EVENING WHILE THE PRECIPITATION DECREASES
OVER THE LOWER COLUMBIA BASIN AND ADJACENT YAKIMA AND KITTITAS
VALLEYS. THERE WILL ALSO CONTINUE TO BE SPILL OVER SNOW SHOWERS OVER
THE CASCADES EAST SLOPES...ESPECIALLY NEAR THE CREST THROUGH
WEDNESDAY EVENING. HIGH PRESSURE ALOFT WILL BUILD OVER THE REGION ON
THURSDAY INTO FRIDAY. AT THIS TIME FRIDAY LOOKS TO BE A FAIRLY
DECENT DAY EXCEPT PERHAPS A FEW LINGERING SNOW SHOWERS OVER THE
NORTHEAST MOUNTAINS AND THE OREGON AND SOUTHERN WASHINGTON CASCADE
EAST SLOPES. A WEAK DISTURBANCE WILL MOVE INTO THE RIDGE FRIDAY
NIGHT AND EARLY SATURDAY BUT THE MAIN ENERGY WITH IT IS EXPECTED TO
GO WELL TO THE SOUTH OF THE FORECAST AREA IN A SPLIT FLOW. THIS WILL
LEAVE THE FORECAST AREA MOSTLY DRY EXCEPT POSSIBLE SNOW SHOWERS OVER
THE EASTERN AND NORTHEAST MOUNTAINS FRIDAY NIGHT AND SATURDAY. AFTER
THAT A DRY AND COLDER NORTHERLY FLOW WILL DEVELOP OVER THE REGION
SATURDAY NIGHT INTO SUNDAY WHICH WILL PERSIST INTO MONDAY UNDER A
LARGER AND STRONGER HIGH PRESSURE RIDGE. LONG RANGE MODELS SOLUTIONS
DO DIVERGE FROM EACH OTHER QUITE A BIT BY THAT TIME AND SO NO
CHANGES TO THE FORECAST WILL BE MADE THAT FAR OUT INTO THE FUTURE
DUE TO THE FORECAST UNCERTAINTY. HOWEVER THE EXTENDED MODELS ARE IN
AGREEMENT THAT THERE WILL BE A STRONG RIDGE SOMEWHERE ALONG THE WEST
COAST KEEPING THE FORECAST AREA MAINLY DRY AND COOLER THAN NORMAL
THROUGH MONDAY. 88

&&

.AVIATION...12Z TAFS...THERE ARE SOME WRAP AROUND RAIN AND SNOW
SHOWERS MOVING ACROSS THE LOWER COLUMBIA BASIN AND BLUE MOUNTAIN
FOOTHILLS AT THIS TIME BUT PRECIP AMOUNTS ARE VERY LIGHT AND
CEILINGS ARE ABOVE VFR MINIMUMS. THE SHOWERS WILL DECREASE THROUGH
TODAY RESULTING IN VFR CONDITIONS PREVAILING THROUGH THE DAY...
ESPECIALLY IN THE AFTERNOON AND TONIGHT. THERE COULD BE SOME FOG
DEVELOPMENT IN THE USUAL AREAS AROUND THE LOWER COLUMBIA BASIN AND
THE ADJACENT VALLEYS/BLUE MOUNTAIN FOOTHILLS WHICH MAY CAUSE PERIODS
OF MVFR OR IFR CONDITIONS BY LATE TONIGHT. THE MOSTLY LIKELY PLACES
FOR FOG TO FORM WILL BE AT KYKM...KPSC AND KDLS. WINDS WILL BE BREEZY
THIS MORNING WITH SPEEDS GENERALLY FROM 15 TO 25 KTS BUT THEY WILL
DIMINISH THROUGH THE DAY AND TONIGHT AND WILL BECOME LIGHT...UNDER
15 KTS BY DARK THIS EVENING. 88

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  41  27  41  29 /  30  10  70  70
ALW  42  29  41  29 /  30  10  60  70
PSC  42  26  37  26 /  20  10  80  70
YKM  38  23  31  22 /  20  10  80  60
HRI  42  24  37  28 /  20  10  80  70
ELN  37  21  31  20 /  20  10  90  70
RDM  36  21  37  23 /  10  10  80  60
LGD  37  20  34  26 /  60  10  70  70
GCD  35  19  34  21 /  20  10  70  70
DLS  40  26  35  26 /  20  10  90  60

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...WINTER STORM WATCH FROM TUESDAY MORNING THROUGH LATE TUESDAY
     NIGHT ORZ042-506.

     WINTER WEATHER ADVISORY UNTIL NOON PST TODAY ORZ050-502-503.

     WINTER STORM WATCH FROM TUESDAY MORNING THROUGH LATE TUESDAY
     NIGHT ORZ041.

     WINTER STORM WATCH FROM TUESDAY MORNING THROUGH LATE TUESDAY
     NIGHT ORZ509.

WA...WINTER WEATHER ADVISORY UNTIL NOON PST TODAY WAZ030.

     WINTER STORM WATCH FROM TUESDAY MORNING THROUGH LATE TUESDAY
     NIGHT WAZ024.

&&

THREAT INDEX
TODAY : YELLOW
TUESDAY : YELLOW
WEDNESDAY : GREEN

GREEN: NONE OR LIMITED NEED FOR WATCHES, WARNINGS, OR ADVISORIES.
YELLOW: A FEW WATCHES, WARNINGS, OR ADVISORIES POSSIBLE OR IN EFFECT.
RED: NUMEROUS WATCHES, WARNINGS, OR ADVISORIES POSSIBLE OR IN EFFECT.

FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT...
WWW.WEATHER.GOV/PENDLETON

94/88/88

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
800 PM PST SUN DEC 23 2012

UPDATED THE DAYS TWO THROUGH SEVEN DISCUSSION FOR A WINTER STORM
WATCH ON CHRISTMAS DAY AND TUESDAY NIGHT. UPDATED THE DAY ONE
DISCUSSION TO REMOVE MENTION OF WINTER STORM WARNING, WHICH EXPIRED
AT 6 PM PST TODAY.

ORZ041-042-044-049-050-502-503-505>509-WAZ024-026>030-520-521-
241415-
EASTERN COLUMBIA RIVER GORGE OF OREGON-NORTH CENTRAL OREGON-
LOWER COLUMBIA BASIN OF OREGON-GRANDE RONDE VALLEY-WALLOWA COUNTY-
NORTHERN BLUE MOUNTAINS OF OREGON-
SOUTHERN BLUE MOUNTAINS OF OREGON-JOHN DAY BASIN-OCHOCO-
JOHN DAY HIGHLANDS-
FOOTHILLS OF THE NORTHERN BLUE MOUNTAINS OF OREGON-
FOOTHILLS OF THE SOUTHERN BLUE MOUNTAINS OF OREGON-
EAST SLOPES OF THE OREGON CASCADES-
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 OF WASHINGTON-
EAST SLOPES OF THE WASHINGTON CASCADES-SIMCOE HIGHLANDS-
800 PM PST SUN DEC 23 2012

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

A LOW PRESSURE SYSTEM MOVING ACROSS THE REGION WILL BRING NUMEROUS
RAIN SHOWERS TO THE LOWER COLUMBIA BASIN AND SNOW TO THE MOUNTAINS
OF NORTHEAST OREGON FOR THE REST OF TONIGHT. WINTER WEATHER
ADVISORIES FOR SNOW REMAIN IN EFFECT FOR MANY LOCATIONS. DETAILS CAN
BE FOUND IN THE NWS PRODUCT PDXWSWPDT.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

SNOW MONDAY
     EAST SLOPES OF THE WASHINGTON CASCADES, NORTHWEST BLUE
     MOUNTAINS OF WASHINGTON, WALLOWA COUNTY, NORTHERN BLUE
     MOUNTAINS OF OREGON, SOUTHERN BLUE MOUNTAINS OF OREGON

SNOW CHRISTMAS DAY
	EASTERN COLUMBIA RIVER GORGE OF WASHINGTON, EASTERN COLUMBIA
        RIVER GORGE OF OREGON, NORTH CENTRAL OREGON, EAST SLOPES OF
        THE OREGON CASCADES, OCHOCO-JOHN DAY HIGHLANDS

ANOTHER STORM WILL MOVE ACROSS THE PACIFIC NORTHWEST TUESDAY AND
WEDNESDAY. THIS WILL BRING ADDITIONAL RAIN AND SNOW. THERE IS A
GOOD POSSIBILITY OF HEAVY SNOW IN THE EASTERN COLUMBIA RIVER
GORGE, THE EAST SLOPES OF THE OREGON CASCADES, NORTH CENTRAL
OREGON, AND THE OCHOCO-JOHN DAY HIGHLANDS ON CHRISTMAS DAY. A WINTER
STORM WATCH IS IN EFFECT FOR THESE AREAS. FOR DETAILS, REFER TO THE
NWS PRODUCT PDXWSWPDT.

.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/PDT/CURRENTHAZARDS/HWO.HTML

ALL LETTERS IN THE ABOVE URL ARE LOWER CASE.