Heavy Snow in Oregon, December 19, 2015

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
653 AM PST SAT DEC 19 2015

UPDATED SHORT TERM DISCUSSION AND WATCHES/WARNINGS/ADVISORIES SECTION

.SHORT TERM...TODAY THROUGH SUNDAY NIGHT...THE COLD FRONT WITH
YESTERDAY'S SYSTEM CONTINUES TO MOVE SLOWLY EAST ACROSS UNION, GRANT
AND WALLOWA COUNTIES EARLY THIS MORNING. EXPECT VARYING AMOUNTS OF
SNOW WITH THIS FRONT AS IT MOVES EAST THIS MORNING. THE JOSEPH SNOW
CAMERA SHOWS THE JOSEPH AREA HAVING RECEIVED AROUND 2-3 INCHES OF
SNOW SINCE LATE FRIDAY EVENING. THERE IS A GOOD POTENTIAL FOR
ANOTHER 1 OR 2 INCHES THROUGH THIS MORNING. OTHER AREAS IN THE
COUNTY SHOULD BE DOING AS WELL ON THE SNOW ACCUMULATION FRONT AND
HAVE ISSUED A SNOW ADVISORY FOR A FURTHER 1-2 INCHES WITH A TOTAL OF
2-5 INCHES BY LATE MORNING. ELSEWHERE, VARYING COVERAGES OF SHOWERS
ARE EXPECTED WITH LIGHT PRECIP AMOUNTS TODAY. SNOW LEVELS BY
AFTERNOON WILL RUN FROM 1300 TO 3300 FEET AREAWIDE. ANOTHER PACIFIC
SYSTEM IS STILL EXPECTED TO SWEEP ACROSS THE REGION SUNDAY. SNOW
LEVELS WILL BE QUITE LOW IN THE MORNING. THERE REMAINS A CHANCE OF A
MIX OF FREEZING RAIN, RAIN AND SNOW AT THE LOWEST ELEVATION SUNDAY
MORNING, WITH ALL OTHER LOCATIONS SEEING SOME SNOW. WINDS WILL
INCREASE IN CENTRAL OREGON, ALONG THE BLUE MOUNTAIN FOOTHILLS AND IN
THE GRANDE RONDE VALLEY AHEAD OF THIS SYSTEM LATE TONIGHT INTO
SUNDAY MORNING. WILL SEE DECREASING RAIN AND SNOW SHOWERS SUNDAY
NIGHT.

FREEZING FOG HAS INCREASED IN COVERAGE ACROSS THE LOWER COLUMBIA
BASIN OF OREGON AND KITTITAS VALLEY IN WASHINGTON. THIS HAVE ISSUE
FREEZING FOG ADVISORIES FOR THESE AREAS. 90

.LONG TERM...MONDAY THROUGH CHRISTMAS DAY...A VERY PROGRESSIVE FLOW
ALOFT ASSOCIATED WITH A VIGOROUS UPPER LEVEL JET STREAM WILL STEER A
SERIES OF DISTURBANCES ACROSS THE INTERIOR PACIFIC NORTHWEST DURING
THE PERIOD. THE FIRST SYSTEM BRINGS A WARM FRONT INTO THE FORECAST
AREA ON MONDAY FOR RAIN AT LOWER ELEVATIONS AND SNOW IN THE
MOUNTAINS. MONDAY NIGHT THE LEFT EXIT REGION OF THE JET INTRODUCES
STRONG DYNAMIC LIFT, WHICH KEEPS SNOW LIKELY IN THE BLUE MOUNTAINS
AND ALONG THE EAST SLOPES OF THE CASCADES AS WELL AS IN THE OCHOCO
MOUNTAINS. TUESDAY A FAST MOVING COLD FRONT BARRELS THROUGH THE
REGION FOR VALLEY AND BASIN RAIN AND SNOW IN THE MOUNTAINS WITH THE
SNOW LEVEL 3000 TO 5000 FEET. THE UPPER LEVEL JET REMAINS OVER THE
PACIFIC NORTHWEST THUS KEEPING SNOW IN THE MOUNTAINS AND RAIN AT
LOWER ELEVATIONS WITH THE SNOW LEVEL 1500-2500 FEET TUESDAY NIGHT
AND WEDNESDAY. WEDNESDAY NIGHT AN AMPLIFYING MID/UPPER LEVEL TROUGH
MOVES SOUTHEAST OUT OF THE GULF OF ALASKA AND MAKES LANDFALL
OVERNIGHT, THEN MOVES ACROSS PACIFIC NORTHWEST ON THURSDAY AND
LOWERS SNOW LEVELS TO THE SURFACE FOR A CHANCE OF SNOW THROUGH THE
DAY ON THURSDAY AND ON THURSDAY NIGHT WITH THE TROUGH EXITING THE
REGION OVERNIGHT. THEN ON CHRISTMAS DAY A DRIER AND COLDER AIR MASS
MOVES INTO THE INTERIOR PACIFIC NORTHWEST FOR DRY CONDITIONS, BUT
WITH A CHANCE OF OROGRAPHIC SNOW SHOWERS IN THE NORTHERN BLUE
MOUNTAINS AND IN THE WALLOWA MOUNTAINS. POLAN

&&

.AVIATION...12Z TAFS...AREAS OF LIFR AND IFR CONDITIONS ARE
OCCURRING AT KYKM, KPSC AND KALW EARLY THIS MORNING DUE TO
INCREASING FOG AND LOW CLOUDS. KDLS WILL HAVE VLIFR CONDITIONS UNTIL
AROUND 15Z WHEN CONDITIONS SHOULD START IMPROVING. CONDITIONS AT THE
OTHER TAF SITES WILL IMPROVE TO MOSTLY VFR AFTER ABOUT 18Z TODAY.
THERE WILL BE SCATTERED RAIN AND SNOW SHOWERS TODAY AT KDLS, KRDM
AND KBDN. WINDS WILL REMAIN LIGHT THROUGH THE NEXT 24 HOURS. POLAN

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  40  31  40  34 /  30  10  70  20
ALW  39  32  41  36 /  30  10  70  30
PSC  36  30  42  34 /  10  10  60  10
YKM  35  25  38  27 /  10  20  60  10
HRI  36  29  43  34 /  20  10  60  10
ELN  32  23  35  25 /  20  20  60  20
RDM  39  25  41  29 /  30  20  70  10
LGD  37  25  36  28 /  50  20  80  40
GCD  38  24  36  28 /  40  10  80  20
DLS  39  32  42  34 /  20  30  80  30

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...FREEZING FOG ADVISORY UNTIL 11 AM PST THIS MORNING FOR ORZ044.

     WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR ORZ050.

WA...FREEZING FOG ADVISORY UNTIL 11 AM PST THIS MORNING FOR WAZ026.

&&

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

90/99/99