FXUS66 KPDT 070546 AAA
AFDPDT
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
946 PM PST SUN DEC 6 2009
UPDATED AVIATION DISCUSSION.
.UPDATE...COLD DRY AIR CONTINUES TO WORK ITS WAY INTO THE AREA
TONIGHT ON A GENERALLY NORTHERLY FLOW. OBSERVATIONS SHOW SOMEWHAT
MORE MOISTURE REMAINING IN THE SOUTHERN THIRD OF THE AREA SO WILL
KEEP A SLIGHT CHANCE OF SNOW DOWN THERE DESPITE NOT SEEING MUCH
ACTIVITY ON WEBCAMS...AT LEAST ON THE WEBCAMS WITH ENOUGH CLARITY TO
SHOW SNOW AT NIGHT. CERTAINLY AM NOT SEEING ACCUMULATING SNOW
ANYWHERE AT THIS POINT. WINTER WEATHER ADVISORY FOR CENTRAL OREGON
WILL LIKELY BE ALLOWED TO EXPIRE AT 10 PM PST. WIND HAS BEEN
DECREASING SLOWLY AND HAVE ALREADY LET WIND ADVISORY FOR THE LOWER
COLUMBIA BASIN OF WASHINGTON AND THE YAKIMA VALLEY EXPIRE. WINDS
CONTINUE AT 10 TO 20 MPH THERE. HAVE LOWERED WINDS IN GENERAL A FEW
MPH THROUGH TOMORROW MORNING. TEMPERATURES ARE STAYING UP WHERE
WINDS CONTINUE TO BE OVER 10 MPH. HAVE RAISED LOW TEMPS IN A FEW
PLACES LIKE THE TRI-CITIES AND HERMISTON WHERE WINDS WILL STAY UP
LONGEST. HAVE LOWERED TEMPS IN PLACES WHERE TEMPS HAVE DROPPED THE
FASTEST OR WHERE THERE IS APPRECIABLE SNOW ON THE GROUND...MAINLY
THE MOUNTAINS AND AROUND BEND. UPDATE OUT SOON. PERRY
&&
.AVIATION...06Z TAFS...VFR CONDITIONS WILL BE PREVALENT FOR THE NEXT
24 HOURS WITH THE MAIN EXCEPTION BEING POSSIBLE LOW STRATUS ABOVE
SURFACE SNOW COVER CREATING MVFR CEILINGS IN THE VICINITY OF KRDM
THROUGH 07/18Z. SKIES WILL GRADUALLY CLEAR FROM NORTH TO SOUTH
THROUGH TOMORROW AFTERNOON WITH JUST FEW TO SCT CIRRUS ABOVE 20000
FT AGL AFTER 08/00Z. KDLS...KPSC...KYKM AND KRDM WILL HAVE 10 TO 20
KT WINDS THROUGH 07/12Z...OTHERWISE ALL TAF LOCATIONS WILL BE UNDER
15 KTS THROUGH TOMORROW EVENING. PERRY
WINDS WILL DIMINISH AND SKIES WILL CLEAR
OVERNIGHT THROUGH MONDAY MORNING WITH THE EXCEPTION AT KRDM. THERE
WILL BE LOW LEVEL UPSLOPE THAT COULD BRING STRATOCUMULUS CLOUDS IN
CENTRAL OREGON WHERE THERE IS A BLANKET OF SNOW THAT FELL EARLIER
TODAY. WILL INDICATE BKN015 FROM 10Z-20Z AT KRDM. JOHNSON
&&
.PREV DISCUSSION... /ISSUED 345 PM PST SUN DEC 6 2009/
SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT...MOISTURE CONTINUES TO
BANK UP AGAINST THE NORTH AND NORTHEAST SIDE OF THE OCHOCO MOUNTAINS
AND ALONG THE HIGHER TERRAIN FROM LAVA BUTTE NORTHWEST TO THE
CASCADE CREST WEST OF SISTERS. THE MOST SIGNIFICANT SNOW TO FALL
TODAY HAS BEEN ALONG AND NEAR THE HIGHER TERRAIN SOUTH AND WEST OF
BEND. NORTHEAST UPSLOPE FLOW LOOKS TO KEEP SNOW SHOWERS PERSISTING
INTO THE EVENING IN THIS AREA AND WILL EXTEND THE CURRENT ADVISORY
UNTIL 10 PM. SNOW IN THE MITCHELL AREA LOOKS TO BE ABOUT 1-3 INCHES
ON CAMERAS. AT THIS TIME DO NOT EXPECT MUCH ADDITIONAL SNOW SO WILL
NOT GO WITH ANY HIGHLIGHTS THERE. MAY SEE A FEW SNOW SHOWERS LINGER
OVER THE WASHINGTON CASCADE EAST SLOPES THIS EVENING...BUT THEY
SHOULD END BY MIDNIGHT. SHOULD SEE ISOLATED TO SCATTERED SNOW
SHOWERS ACROSS CROOK...GRANT AND SOUTHERN UMATILLA COUNTIES
TONIGHT...WITH DRY CONDITIONS ELSEWHERE. WINDS REMAIN RELATIVELY
STRONG OUT OF THE NORTHEAST ACROSS CENTRAL WASHINGTON AND INTO THE
COLUMBIA RIVER GORGE. THE STRONGEST WINDS HAVE BE OVER THE LOWER
COLUMBIA BASIN OF WASHINGTON AND IN THE YAKIMA VALLEY...WHERE SOME
PATCHY BLOWING DUST HAS OCCURRED. THESE TWO AREAS ARE CURRENTLY
UNDER A WIND ADVISORY...AND WILL EXTEND THIS ADVISORY INTO THE EARLY
EVENING AS THE WIND SPEEDS HAVE NOT YET BEGUN TO TREND DOWNWARD. THE
UPPER LOW...WHICH IS CURRENTLY NEAR THE SOUTHWEST OREGON/NORTHEAST
CALIFORNIA BORDER...WILL GRADUALLY FILL AND SWING THE LARGER SCALE
UPPER TROUGH AXIS EASTWARD THROUGH MONDAY. AS A RESULT WILL SEE THE
SNOW SHOWERS CONTINUE TO DECREASE IN COVERAGE WHILE SHIFTING
SOUTHEAST OUT OF THE AREA LATE TONIGHT THROUGH MONDAY. SKIES WILL
ALSO BECOME MOSTLY CLEAR TO PARTLY CLOUDY TONIGHT THROUGH MONDAY.
THE REGION WILL THEN BE UNDER A COLD...MOSTLY DRY UPPER LEVEL AND
SURFACE FLOW DURING THIS PERIOD. THIS COLD AND DRY AIR OVER THE
REGION WILL LEAD TO TEMPS (HIGHS AND LOWS) THAT WILL BE WELL BELOW
SEASONAL. 90
LONG TERM...WEDNESDAY THROUGH SUNDAY. A COLD AND DRY NORTHERLY
FLOW ALOFT WILL REMAIN EAST OF THE CASCADES FROM WEDNESDAY THROUGH
THURSDAY NIGHT WITH AFTERNOON TEMPERATURES IN THE TEENS AND 20S AND
OVERNIGHT LOWS MAINLY RANGING FROM -5 TO 10 ABOVE. THERE WILL BE
INCREASING CLOUDS THURSDAY NIGHT WITH SLIGHTLY WARMER TEMPERATURES.
A WEAK UPPER LEVEL RIDGE WILL BEGIN SHIFTING EASTWARD ON FRIDAY WITH
INCREASING TEMPERATURES ALOFT...THUS THE MOUNTAINS WILL SEE A
WARMING TREND FRIDAY AND OVER THE WEEKEND BUT THE BASIN AND THE
LOWER MOUNTAIN VALLEYS WILL REMAIN TRAPPED IN THE COLD AIR. THE
ECMWF HAS BEEN THE MOST CONSISTENT MODEL ADVERTISING A SHORTWAVE
TROUGH MOVING INTO SW OREGON ON FRIDAY THEN EAST OF THE CASCADES
THIS WEEKEND. THE BIG QUESTION WILL BE THE TYPE OF PRECIPITATION AS
SNOW LEVELS INCREASE BUT FEEL THE WARM AIR ADVECTION ALOFT WILL
OVERRIDE THE COLD AIR AND BRING A WINTER MIX LATE SATURDAY NIGHT AND
SUNDAY IN THE COLUMBIA BASIN...THE EASTERN COLUMBIA RIVER
GORGE...AND THE EAST SLOPES OF THE WA CASCADES. THERE IS SOME
UNCERTAINTY ON THE STRENGTH OF THE WARM FRONT (GFS IS STRONGER THAN
THE ECMWF) SO WILL INTRODUCE A SLIGHT CHANCE OF LIGHT FREEZING RAIN
IN THESE AREAS FOR SUNDAY. JOHNSON
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 10 19 8 18 / 10 0 0 0
ALW 14 20 11 19 / 10 0 0 0
PSC 13 24 4 23 / 0 0 0 0
YKM 7 21 1 21 / 0 0 0 0
HRI 10 23 3 22 / 10 0 0 0
ELN 7 22 0 21 / 10 0 0 0
RDM 5 14 -4 16 / 50 20 10 0
LGD 6 20 4 18 / 10 10 10 0
GCD 7 20 5 19 / 30 20 10 0
DLS 14 25 10 23 / 10 0 0 0
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
&&
THREAT INDEX
MONDAY : GREEN
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
$$
83/85/83
