Heavy Snow in Washington, November 12, 2012

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1010 PM PST SUN NOV 11 2012

.SHORT TERM...PRECIPITATION IS STARTING TO OVERSPREAD THE WESTERN
PORTION OF THE FORECAST AREA THIS EVENING. SURFACE REPORTS INDICATE
EITHER RAIN OR SNOW FROM BEND AND REDMOND NORTHWARD INTO THE DALLES
YAKIMA AND ELLENSBURG. MODELS DID A GOOD JOB TIMING THE ONSET OF
THIS AND THINK THEY SHOULD HANDLE THE INCOMING FRONT WELL. THE
INITIAL SURGE OF RAIN/SNOW IS COMING FROM A SHORT WAVE AND WARM
FRONT MOVING INTO THE PAC NW. WATER VAPOR SATELLITE IMAGERY SHOWS
ANOTHER STRONG SHORT WAVE OFF THE NORTHERN CALIFORNIA COAST AROUND
40/130. THIS SYSTEM WILL BRING ADDITIONAL PRECIPITATION LATER
TONIGHT INTO MONDAY. 00Z MODELS CONTINUE TO SHOW DECENT AMOUNTS OVER
THE NEXT 24 HOURS. BASED ON CURRENT TEMPERATURES AND DEW POINTS
APPEARS MOST LOCATIONS WILL END UP IN THE UPPER 20S TO MID 30S
TONIGHT WITH MIXED PRECIP. WARM ADVECTION WILL BOOST TEMPS INTO THE
40S MOST AREAS WITH A TRANSITION TO RAIN MONDAY. SURFACE GRADIENTS
AND WINDS ALOFT WILL RESULT IN LOCALLY BREEZY CONDITIONS. THE GRANDE
RONDE VALLEY AND THE MOUNTAINS WILL LIKELY SEE THE STRONGEST SOUTH
WINDS TONIGHT AND MONDAY.    94

.AVIATION...06Z TAFS. WEATHER SYSTEM MOVING THROUGH THE REGION WILL
BRING RAIN AND SNOW TO THE TAF SITES TONIGHT AND MONDAY. EXPECT MVFR
AND POSSIBLE IFR CONDITIONS AT TIMES. YKM IS THE LOCATION LIKELY TO
SEE THE LONGEST DURATION OF SNOW WITH MIXED PRECIPITATION OR RAIN AT
THE OTHER SITES. RDM BDN WILL HAVE SOME SOUTH WINDS AT 10-20KT. PDT
ALW COULD SEE A SOUTHEAST DOWNSLOPE WIND DEVELOP OFF THE BLUES LATE
TONIGHT INTO MONDAY. PSC DLS YKM SHOULD HAVE LIGHTER WINDS LESS THAN
10KT.   94

&&

.PREV DISCUSSION... /ISSUED 343 PM PST SUN NOV 11 2012/

SHORT TERM...TONIGHT THROUGH MONDAY...THE NEXT PACIFIC SYSTEM HAS
MOVED EAST OF 130W, AND HAS PUSHED PRECIP INTO WESTERN WASHINGTON
AND OREGON. THIS PRECIP HAS REACHED THE CASCADE CREST FROM MOUNT
HOOD NORTH INTO WASHINGTON. THIS PRECIP WILL GRADUALLY SPREAD EAST
TONIGHT, FIRST ATTACHED TO A WARM FRONT THAT WILL BE QUICKLY
FOLLOWED BY A PACIFIC COOL FRONT MONDAY. EXPECT ALMOST ALL LOCATIONS
TO PICK UP SOME MEASURABLE PRECIP. HEAVIEST PRECIP LOOKS TO OCCUR
ACROSS CENTRAL AND SOUTH-CENTRAL WASHINGTON, PRIMARILY FROM MID
EVENING INTO VERY EARLY MONDAY MORNING. SNOW LEVELS WILL GENERALLY
RUN FROM 2000 FEET NEAR THE COLUMBIA RIVER GORGE TO 1000 FEET IN
YAKIMA AND KITTITAS COUNTIES. DEW POINT TEMPS ARE IN THE MID 20S IN
KITTITAS COUNTY, THUS AS PRECIP STARTS THE AIR TEMP SHOULD FALL TO
FREEZING WITH ALMOST ALL PRECIP TO BE SNOW IN THIS AREA TONIGHT.
YAKIMA VALLEY SHOULD SEE SNOW ABOVE 1000 FT WITH MOSTLY RAIN BELOW,
AS DEW POINTS ARE NEAR 30. THUS HAVE ADDED A SNOW ADVISORY TONIGHT
FOR PORTIONS OF THE YAKIMA VALLEY, WHILE CONTINUING THE WARNING AND
ADVISORIES ALREADY OUT IN SOUTH-CENTRAL WASHINGTON. SNOW LEVELS
ACROSS THE BASIN AND FOOTHILLS WILL RUN BETWEEN 1200 AND 2000 FT
TONIGHT THUS SNOW WILL BE LIMITED IN THESE ZONES. CENTRAL AND
NORTH-CENTRAL OREGON WILL START WITH SNOW LEVELS IN THE 2000 TO 3000
FOOT RANGE, AND THESE ARE EXPECTED TO RISE LATER TONIGHT. PRECIP
AMOUNTS LOOK TO BE LIGHT, AND WILL NOT GO WITH HIGHLIGHTS FOR THIS
AREA AT THIS TIME. THESE ZONES SHOULD BE MONITORED THOUGH. THE SNOW
LEVELS LOOK TO REMAIN LOWER ACROSS GRANT AND EASTERN CROOK COUNTIES.
THERE LOOKS TO BE ENOUGH PRECIP FOR 2-4 INCHES OF SNOW LATE TONIGHT
INTO MONDAY MORNING. THUS WILL RUN ADVISORIES FOR THESE AREAS. THE
NORTHERN BLUES LOOK TO SEE LESS THAN 5 INCHES, WHILE WALLOW COUNTY
AND THE GRANDE RONDE VALLEY SHOULD SEE 2 INCHES OR LESS. THE
PRESSURE GRADIENT ACROSS THE SOUTHERN GRANDE RONDE VALLEY WILL
TIGHTEN FOR SOME STRONGER WINDS LATER TONIGHT INTO MONDAY. THUS WILL
GO WITH A WIND ADVISORY IN THIS AREA. 90

LONG TERM...MONDAY NIGHT THROUGH THURSDAY...MONDAY NIGHT A COLD
FRONT WILL MOVE THROUGH EASTERN OREGON. PRECIPITATION WILL DECREASE
OVERNIGHT AND BECOME SHOWERY. THERE WILL BE ENOUGH INSTABILITY TO
KEEP A CHANCE OF PRECIPITATION OVER THE CWA. WESTERLY MID LEVEL
WINDS WILL DEVELOP BEHIND THE FRONT. UPSLOPE EFFECTS WILL KEEP
PRECIPITATION LIKELY IN THE MOUNTAINS. TUESDAY AN UPPER LEVEL TROUGH
WILL DIG OFF THE COAST. A CUTOFF LOW WILL DEVELOP IN THE BASE OF THE
TROUGH TUESDAY NIGHT...RESULTING IN WEAK RIDGING OVER WASHINGTON AND
OREGON. A DISTURBANCE WILL MOVE THROUGH THE RIDGE IN EASTERN OREGON
TUESDAY NIGHT KEEPING A CHANCE OF SHOWERS OVER OREGON. TEMPERATURES
WILL INCREASE PARTICULARLY IN THE HIGHER ELEVATIONS WITH THE
RIDGING. THURSDAY THE RIDGING WILL MOVE INTO EASTERN WASHINGTON AND
OREGON WITH DRIER CONDITIONS. A FEW SHOWERS MAY LINGER OVER THE
MOUNTAINS. COONFIELD

THURSDAY NIGHT THROUGH SUNDAY...MODELS SHOW WEAK RIDGING BEING
DISPLACED BY A WEAK TROUGH THURSDAY NIGHT AND FRIDAY. MODELS
DISAGREE IN THEIR HANDLING OF THIS SYSTEM AS THE GFS PUTS MOST OF
THE PRECIPITATION INTO THE WASHINGTON CASCADES WHILE THE ECMWF SENDS
MOST OF IT INTO CENTRAL OREGON AND THE EASTERN MOUNTAINS.
COMPROMISED WITH A CHANCE OF MAINLY RAIN IN THE MOUNTAINS AND A
SLIGHT CHANCE IN THE LOWER ELEVATIONS. THE RAIN WILL TAPER OFF TO
SHOWERS IN THE MOUNTAINS AND CENTRAL OREGON FRIDAY NIGHT. SNOW
LEVELS WILL REMAIN ABOVE 5000 FEET WITH THIS SYSTEM. SATURDAY
THROUGH SUNDAY, A STRENGTHENING RIDGE WILL BE OVER THE ROCKIES WHILE
A DEEP TROUGH OUT IN THE EASTERN PACIFIC WILL SEND A SOUTHWEST FLOW
OVER THE AREA. THE TROUGH WILL HAVE A FAIRLY STRONG FRONT BUT IT
WILL HAVE A TOUGH TIME MOVING ASHORE WITH THE RIDGE OVER THE
ROCKIES. MODELS ARE IN AGREEMENT IN KEEPING THE FRONT OUT OF THE
AREA SATURDAY AND SATURDAY NIGHT. THE ECMWF BRINGS THE SYSTEM TO THE
CASCADE CREST SUNDAY AFTERNOON WITH SHOWERS MAINLY ALONG THE CREST
BUT INTO CENTRAL OREGON AS WELL. THE GFS KEEPS IT OFFSHORE ON
SUNDAY. KEPT THE AREA MAINLY DRY ASIDE FROM RAIN SHOWERS IN THE
CASCADES SATURDAY AND SATURDAY NIGHT THEN BROUGHT IN A SLIGHT CHANCE
OF RAIN SHOWERS SUNDAY IN CENTRAL OREGON AND THE MOUNTAINS. HIGH
TEMPERATURES WILL BE IN THE MID 40S TO LOWER 50S WITH LOWER TO MID
40S IN THE MOUNTAINS. NIGHT TIME LOWS WILL BE IN THE LOWER TO MID
30S WITH MAINLY 20S IN THE MOUNTAINS THURSDAY AND FRIDAY NIGHTS THEN
WARM TO THE MID TO UPPER 30S WITH MID 20S TO MID 30S IN THE
MOUNTAINS SATURDAY NIGHT. PERRY

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  33  47  36  46 /  60  80  50  20
ALW  36  48  37  47 /  60  80  50  30
PSC  33  46  36  49 /  70  80  30  10
YKM  33  46  31  48 /  80  60  30  20
HRI  34  48  35  48 /  70  80  30  20
ELN  31  43  32  46 /  80  80  40  30
RDM  32  49  32  51 /  70  60  40  30
LGD  33  42  32  45 /  40  80  40  40
GCD  30  46  33  49 /  60  80  40  40
DLS  38  52  39  51 /  80  60  30  30

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...WINTER WEATHER ADVISORY UNTIL NOON PST MONDAY ABOVE 3500 FEET
     FOR THE ORZ503-506.

     WINTER WEATHER ADVISORY UNTIL NOON PST MONDAY ABOVE 2500 FEET
     FOR THE ORZ505.

     WIND ADVISORY FROM 1 AM TO 1 PM PST MONDAY FOR LADD AND PYLES
     CANYONS IN THE ORZ049.

WA...WINTER STORM WARNING UNTIL NOON PST MONDAY WAZ520.

     WINTER WEATHER ADVISORY UNTIL 5 AM PST MONDAY ABOVE 1000 FEET
     FOR THE WAZ027.

     WINTER WEATHER ADVISORY UNTIL NOON PST MONDAY WAZ026.

&&

THREAT INDEX
MONDAY : YELLOW
TUESDAY : GREEN
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/

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
330 PM PST SUN NOV 11 2012

ORZ041-042-044-049-050-502-503-505>509-WAZ024-026>030-520-521-
121415-
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-
330 PM PST SUN NOV 11 2012

UPDATED FOR SNOW ADVISORIES IN THE YAKIMA VALLEY, SOUTHERN BLUE
MOUNTAINS OF OREGON, OCHOCO-JOHN DAY HIGHLANDS AND WIND ADVISORY IN
THE SOUTHERN GRANDE RONDE VALLEY

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, KITTITAS VALLEY,
     YAKIMA VALLEY, SOUTHERN BLUE MOUNTAINS OF OREGON, OCHOCO-JOHN
     DAY HIGHLANDS

STRONG WIND
     GRANDE RONDE VALLEY

A PACIFIC STORM WILL MOVE INTO THE REGION THIS EVENING BRINGING A
VARIETY OF WEATHER. PRECIPITATION WILL BEGIN AS SNOW IN MOST AREAS
AND CHANGE TO RAIN AS SNOW LEVELS RISE FROM SOUTH TO NORTH. THE
KITTITAS VALLEY AND THE SOUTH CENTRAL WASHINGTON CASCADE EAST SLOPES
WILL SEE MAINLY SNOW FROM THIS SYSTEM. THERE WILL BE ENOUGH SNOW
ALONG THE CASCADE EAST SLOPES FOR A WINTER STORM WARNING. IN THE
KITTITAS VALLEY THERE WILL BE ENOUGH SNOW FOR A WINTER WEATHER
ADVISORY. IN THE YAKIMA VALLEY SNOW WILL ACCUMULATE MAINLY ABOVE
1000 FEET TONIGHT BEFORE CHANGING TO RAIN EARLY MONDAY MORNING. IN
THE JOHN DAY BASIN SNOW WILL ACCUMULATE MAINLY ABOVE 2500 FEET. IN
THE SOUTHERN BLUE MOUNTAINS AND OCHOCO-JOHN DAY HIGHLANDS WILL
ACCUMULATE MAINLY ABOVE 3500 FEET. PLEASE REFER TO NWS HAZARD
PRODUCT ID PDXWSWPDT FOR MORE DETAILS. ELSEWHERE THE PRECIPITATION
MAY BEGIN AS A BRIEF PERIOD OF SNOW BEFORE QUICKLY CHANGING OVER TO
RAIN. THE EXCEPTION WILL BE THE NORTHEAST MOUNTAINS WHERE THE
PRECIPITATION WILL FALL AS SNOW FOR A LONGER PERIOD OF TIME AND MAY
ACCUMULATE SEVERAL INCHES BEFORE CHANGING TO RAIN.

STRONG SOUTHERLY WINDS WILL DEVELOP TONIGHT AHEAD OF THE STORM IN
THE SOUTHERN GRANDE RONDE VALLEY. A WIND ADVISORY HAS BEEN ISSUED
FOR LADD AND PYLES CANYON FROM 1 AM TO 1 PM MONDAY. PLEASE REFER TO
NWS HAZARD PRODUCT ID PDXNPWPDT FOR MORE DETAILS.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

SNOW MONDAY
     EAST SLOPES OF THE WASHINGTON CASCADES, KITTITAS VALLEY,
     YAKIMA VALLEY, SOUTHERN BLUE MOUNTAINS OF OREGON, OCHOCO-JOHN
     DAY HIGHLANDS

STRONG WIND MONDAY
     GRANDE RONDE VALLEY

THE SNOW WILL CONTINUE ON MONDAY MORNING AND WILL EITHER END OR
CHANGE TO RAIN BEFORE ENDING IN THE KITTITAS VALLEY AND THE SOUTH
CENTRAL WASHINGTON CASCADE EAST SLOPES. IN THE JOHN DAY BASIN, THE
SOUTHERN BLUE MOUNTAINS, AND OCHOCO-JOHN DAY HIGHLANDS THE SNOW WILL
CHANGE TO RAIN LATE MONDAY MORNING. THE WINTER WEATHER ADVISORIES
AND WINTER STORM WARNING WILL CONTINUE UNTIL NOON MONDAY FOR THESE
AREAS. ELSEWHERE THE RAIN AND SNOW WILL DECREASE TO RAIN AND SNOW
SHOWERS BY MONDAY AFTERNOON. UNSETTLED WEATHER IS THEN EXPECTED TO
PERSIST THROUGH THE REST OF THE WEEK WITH FREQUENT...BUT WARMER...
WEATHER SYSTEMS WITH HIGHER SNOW LEVELS.

.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.