Area Forecast Discussion
Issued by NWS Pendleton, OR

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000
FXUS66 KPDT 270553
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
955 PM PST THU FEB 26 2015

.SHORT TERM...RADAR SHOWING SCATTERED SHOWERS OVER THE AREA WITH
NORTHWEST FLOW ALOFT. UPPER LOW CURRENTLY LOCATED NEAR VANCOUVER
ISLAND SHOWING GOOD ENHANCEMENT ON IR SATELLITE THE PAST FEW HOURS.
AS THIS LOW MOVES CLOSER TO THE FORECAST AREA TONIGHT EXPECT CLOUDS
AND PRECIPITATION TO INCREASE. THE LOW WILL THEN MOVE ACROSS WESTERN
WASHINGTON AND OREGON ON FRIDAY. THIS WILL RESULT IN RAIN AND
MOUNTAIN SNOW...ESPECIALLY FROM THE CASCADES INTO CENTRAL OREGON.
MODELS CONTINUE TO INDICATE A SNOW LEVEL AROUND 4000 FEET TONIGHT
THROUGH FRIDAY...THEN LOWERING FRIDAY NIGHT AS COLDER AIR MOVES IN
FROM THE NORTH. MUCH COLDER SATURDAY WITH PARTLY CLOUDY SKIES AS THE
UPPER RIDGE BUILDS BACK INTO THE REGION. BREEZY NORTH WINDS FRIDAY
NIGHT AND SATURDAY AS THE LOW MOVES INTO CALIFORNIA AND NEVADA. 94

.AVIATION...06Z TAFS. RAIN WILL OVERSPREAD YKM DLS RDM BDN TONIGHT
WITH CEILINGS LOWERING TO 030-060. THE RAIN MAY SPREAD FAR ENOUGH
EAST BY FRIDAY MORNING TO INCLUDE PSC PDT ALW. LOWERING SNOW LEVELS
COULD BRING A PERIOD OF SNOW TO RDM BDN FRIDAY EVENING. WINDS LESS
THAN 10KT TONIGHT THEN INCREASING FROM THE NORTH AT 10-20KT LATER
FRIDAY. 94

&&

.PREV DISC... /ISSUED 344 PM PST THU FEB 26 2015/

SHORT TERM...TONIGHT THROUGH SUNDAY...WINTER WEATHER CAN BE
EXPECTED OVER THE NEXT SEVERAL DAYS. AN AREA OF LOW PRESSURE OFF THE
COAST OF BRITISH COLUMBIA WILL TRAVEL SOUTH TONIGHT AND FRIDAY...AND
THEN CROSS THROUGH CENTRAL OREGON ON FRIDAY NIGHT. SIGNIFICANT
PRECIPITATION WILL ACCOMPANY THIS SYSTEM. THE HEAVIEST RAIN AND SNOW
IS LIKELY ON FRIDAY MORNING AS A DEFORMATION BAND SETS UP ON THE
NORTHEAST SIDE OF THE LOW...EXTENDING FROM THE SOUTHERN WASHINGTON
CASCADES...OVER THE SIMCOE HIGHLANDS...INTO NORTH CENTRAL OREGON AND
THE SOUTHERN BLUE MOUNTAINS...AND THEN DOWN THROUGH GRANT COUNTY.
SNOW LEVELS WILL INITIALLY BE ABOVE 4500 FEET...AND FALL TO AROUND
3000 FEET FRIDAY MORNING. ALONG THE EAST SLOPES OF THE WASHINGTON
CASCADES AND IN THE SIMCOE HIGHLANDS...HEAVY RAIN AND SNOW CAN BE
EXPECTED...BUT WITH THE HEAVIEST SNOW ABOVE 3000 FEET AND PASS
LEVELS...WINTER WEATHER HIGHLIGHTS WILL NOT BE ISSUED. HOWEVER...IN
THE MOUNTAINS AND HIGHLANDS OF CENTRAL OREGON...AND ALSO EASTERN
PORTIONS OF THE JOHN DAY BASIN...HEAVY SNOW WILL AFFECT POPULATION
CENTERS AND TRAVEL...SO WINTER WEATHER ADVISORIES ARE IN EFFECT...AS
WELL AS A WINTER STORM WARNING FOR THE OCHOCO-JOHN DAY HIGHLANDS.
RAIN SHOWERS WILL ALSO BE POSSIBLE IN AND AROUND THE LOWER COLUMBIA
BASIN...AND SNOW SHOWERS OVER THE NORTHERN BLUE MOUNTAINS AND IN
WALLOWA COUNTY...BUT PRECIPITATION AMOUNTS WILL BE MINIMAL.

SNOW LEVELS WILL RISE BACK TO AROUND 4000 FEET DURING THE DAY
FRIDAY...BUT THEN FALL AGAIN FRIDAY NIGHT AND SATURDAY AS THE FLOW
SHIFTS NORTHERLY BEHIND THE LOW. THESE NORTHERLY LOW-LEVEL WINDS
WILL THEN ACT TO ENHANCE UPSLOPE PRECIPITATION IN CENTRAL
OREGON...ESPECIALLY SOUTH AND WEST OF DOWNTOWN BEND...WHERE SEVERAL
INCHES OF SNOW WILL BE POSSIBLE. SNOW SHOWERS WILL TAPER OFF
SATURDAY AFTERNOON AS THE LOW MOVES SOUTH OF THE REGION. COLD AND
DRY CONDITIONS WILL FOLLOW ON SATURDAY NIGHT. SUNDAY WILL REMAIN
COOL...BUT DRY...WITH TEMPERATURES IN THE 30S AND 40S. COBB

LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...THERE IS FAIR AGREEMENT
BETWEEN THE MID RANGE MODELS THAT A WAVE WILL DROP SOUTH OUT OF
BRITISH COLUMBIA AND THROUGH THE PACIFIC NORTHWEST MONDAY AND
TUESDAY. THIS WAVE WILL PULL MODIFIED ARCTIC AIR SOUTH INTO THE
PACNW MONDAY AND MONDAY NIGHT. AS SUCH, SNOW LEVELS WILL FALL
AREAWIDE, WITH SNOW POSSIBLE EVEN AT THE LOWEST ELEVATIONS IN THE
BASIN BY MONDAY NIGHT AND EARLY TUESDAY MORNING. AT THIS TIME SNOW
AMOUNTS LOOK LIGHT WITH NORTH FACING MOUNTAIN AND FOOTHILL SLOPES
POSSIBLY SEEING SOME LOCAL UPSLOPE INDUCED ENHANCEMENT. THE COLD AIR
MASS WILL ALSO BE ACCOMPANIED BY LOCAL BREEZY WINDS, ESPECIALLY IN
THE LOWER BASIN, THE YAKIMA VALLEY AND THE KITTITAS VALLEY.
LINGERING SNOW SHOWERS SHOULD END BY LATE AFTERNOON TUESDAY WITH THE
REGION BEING UNDER A COLD, DRY NORTH FLOW ON WEDNESDAY. CONDITIONS
LOOK TO REMAIN DRY THURSDAY, THOUGH COULD SEE SOME MODERATION OF
TEMPS AS THE UPPER RIDGE SLIDES EAST OVER THE REGION. 90

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  37  49  28  43 /  30  30  20  10
ALW  38  52  31  46 /  30  20  20  10
PSC  37  55  32  50 /  30  30  10  10
YKM  35  52  30  47 /  60  70  20  10
HRI  37  52  30  48 /  30  40  20  10
ELN  36  52  29  47 /  60  70  30  10
RDM  32  45  23  36 /  60  60  50  30
LGD  30  46  27  41 /  30  30  30  20
GCD  29  43  27  37 /  50  90  70  40
DLS  41  51  33  50 /  80  60  30  20

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...WINTER STORM WARNING FROM 10 PM THIS EVENING TO 7 AM PST
     SATURDAY ORZ506.

     WINTER WEATHER ADVISORY FROM 4 PM FRIDAY TO 4 AM PST SATURDAY
     ORZ511.

     WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 7 AM PST
     SATURDAY ORZ505.

     WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 4 AM PST
     SATURDAY ORZ503.

     WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 4 AM PST
     SATURDAY ORZ509.

WA...NONE.
&&

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

$$

94/





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