FXUS66 KPDT 071118 AAA
AFDPDT
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
320 AM PST MON DEC 7 2009
UPDATED AVIATION DISCUSSION
.SHORT TERM...TODAY THROUGH TUESDAY NIGHT...A VERY COLD AND DRY AIR
MASS CONTINUES TO PUSH INTO THE REGION A THIS TIME AND WILL CONTINUE
THOUGH TODAY AND TUESDAY. SINCE THERE IS VIRTUALLY NO SNOW COVER...
AM NOT EXPECTING ANY RECORD LOW TEMPS...HOWEVER TEMPS WILL STILL BE
VERY COLD AND WELL BELOW NORMAL UNDER THIS ARCTIC AIR MASS. ANOTHER
WAVE...THOUGH WEAK...WILL DROP DOWN OUT OF WESTERN CANADA TUESDAY
AFTERNOON AND TUESDAY NIGHT. THIS WILL BRING A REINFORCING SHOT OF
COLD AIR. AGAIN THERE IS VERY LITTLE MOISTURE WITH THIS NEXT SURGE
OF COLD AIR SO ANY SNOW WILL BE VERY LIGHT AND CONFINED TO THE
MOUNTAINS. THIS WEEK WILL EXPERIENCE THE COLDEST TEMPERATURES OF THE
SEASON SO FAR...BUT DUE TO THE LACK OF SNOW COVER RECORD LOWS WILL
BE UNLIKELY...AT LEAST FOR NOW. TEMPERATURES WILL MODERATE LATER
THIS WEEK AS THE FLOW BECOMES MORE NORTHWEST AND THEN WEST IN THE
EXTENDED FORECAST PERIOD. 88
.LONG TERM...WEDNESDAY THROUGH SUNDAY...A COLD DRY NORTHERLY FLOW
ALOFT WITH AN ARCTIC AIR MASS AT THE SURFACE WILL REMAIN OVER
EASTERN WASHINGTON AND OREGON WEDNESDAY AND THURSDAY. A WEAK UPPER
LEVEL RIDGE WILL BEGIN SHIFTING EASTWARD ON FRIDAY WITH INCREASING
TEMPERATURES ALOFT. THIS WILL START A WARMING TREND IN THE
MOUNTAINS...BUT THE COLUMBIA BASIN AND THE LOWER MOUNTAIN VALLEYS
WILL REMAIN TRAPPED IN THE COLD AIR. FRIDAY NIGHT THROUGH SUNDAY A
SERIES OF FRONTS WILL MOVE THROUGH THE PACIFIC NORTHWEST. THE BIG
QUESTION WILL BE THE TYPE OF PRECIPITATION AS SNOW LEVELS INCREASE.
IF THE WARM AIR ADVECTION ALOFT OVERRIDES THE COLD AIR IT WILL BRING
A WINTER MIX LATE SATURDAY NIGHT AND SUNDAY IN THE COLUMBIA
BASIN...THE EASTERN COLUMBIA RIVER GORGE...AND THE EAST SLOPES OF
THE WASHINGTON CASCADES. DID NOT CHANGE CURRENT FORECAST OF SLIGHT
CHANCE OF MIX OF SNOW AND LIGHT FREEZING RAIN IN THESE AREAS FOR
SUNDAY. COONFIELD
&&
.AVIATION...12Z TAFS...VFR CONDITIONS WILL BE PREVALENT FOR THE NEXT
24 HOURS. SKIES WILL GRADUALLY CLEAR FROM NORTH TO SOUTH THIS
MORNING WITH JUST FEW TO SCT CIRRUS ABOVE 20000 FT AGL AFTER 08/00Z.
WINDS WILL BE UNDER 12 KTS. 76
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 21 8 20 9 / 0 0 0 0
ALW 22 11 21 12 / 0 0 0 0
PSC 26 4 25 6 / 0 0 0 0
YKM 23 1 23 2 / 0 0 0 0
HRI 25 3 24 5 / 0 0 0 0
ELN 24 0 23 3 / 0 0 0 0
RDM 16 -4 18 -2 / 20 10 0 0
LGD 22 4 20 5 / 10 10 0 0
GCD 22 5 21 4 / 20 10 0 0
DLS 27 10 25 11 / 0 0 0 0
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
&&
THREAT INDEX
TODAY : 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
$$
88/76/76
