FXUS66 KPDT 222223
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
223 PM PST TUE DEC 22 2009
.SHORT TERM...TONIGHT THROUGH FRIDAY...LARGELY TRANQUIL WEATHER
PATTERN IN STORE FOR THE NEXT FEW DAYS. UPPER LOW IS NOW MOVING INTO
THE NW CORNER OF NV AND TAKING MOST OF THE PRECIPITATION WITH IT.
WILL KEEP ISOLATED SNOW SHOWERS IN THE NORTHEAST MOUNTAINS FOR THIS
EVENING BUT THEY SHOULD BE FEW AND FAR BETWEEN. ANOTHER WEAKER WAVE
IS DIGGING SOUTHEAST OUT OF BRITISH COLUMBIA AND THAT WILL GRAZE THE
NORTHEAST PORTION OF THE FORECAST AREA LATER TONIGHT AND WEDNESDAY.
THIS FEATURE WILL BRING INCREASED CLOUD COVER AND A FEW SNOW SHOWERS
BUT DON'T EXPECT WIDESPREAD SNOW OR SUBSTANTIAL ACCUMULATIONS.
BY WEDNESDAY NIGHT EXPECT CLEARING SKIES AND COLD TEMPERATURES WITH
THIS TREND TO CONTINUE THROUGH FRIDAY. INVERSIONS WILL STRENGTHEN
THURSDAY NIGHT ACROSS THE LOWER ELEVATIONS WITH FREEZING FOG LIKELY
FORMING AT ELEVATIONS BELOW 1500 FEET DURING THE OVERNIGHT HOURS AND
PERSISTING INTO THE DAY ON FRIDAY. HAVE NARROWED THE DIURNAL
TEMPERATURE RANGE IN THESE AREAS THURSDAY NIGHT AND FRIDAY DUE TO
THE EXPECTED LOW CLOUD COVER. 78
.LONG TERM...FRIDAY NIGHT THROUGH TUESDAY...MOSTLY DRY CONDITIONS
CONTINUE IN THE EXTENDED AS AN UPPER LEVEL RIDGE BUILDS OVER THE
PACIFIC NORTHWEST. SHOWER ACTIVITY WILL BE MOSTLY CONFINED TO THE
WEST SIDE OF THE CASCADES DURING THIS TIME PERIOD. MONDAY THE RIDGE
WILL BEGIN TO SHIFT EASTWARD AS AN UPPER LEVEL SHORTWAVE MOVES
ACROSS THE AREA. MODELS ARE NOT PUTTING OUT MUCH QPF AT ALL WITH THE
SYSTEM AND RAIN SHOWERS WILL PROBABLY BE LIMITED TO UPSLOPE ALONG
THE MOUNTAINS OF EASTERN OREGON...AND SPILL OVER ALONG THE EAST
SLOPES OF THE CASCADES.
THE BIG ISSUE WITH THE BUILDING RIDGE WILL BE COLD AIR BECOMING ONCE
AGAIN TRAPPED IN THE LOWER ELEVATIONS..SO HAVE ADDED AREAS OF
FREEZING FOG ACROSS THE LOWER COLUMBIA BASIN...THE FOOTHILLS OF THE
BLUE MOUNTAINS...AND THE YAKIMA VALLEY THROUGH SUNDAY MORNING. 850
MB WINDS STILL LOOK FAIRLY LIGHT MONDAY SO THE SHORTWAVE MAY NOT
PROVIDE ENOUGH ENERGY TO MIX OUT THE LOW LEVEL FOG/STRATUS
DECK...BUT FOR NOW HAVE KEPT AREAS OF FOG OUT FOR MONDAY ONWARD.
WEBER
&&
.AVIATION...18Z TAFS...VFR CONDITIONS ARE EXPECTED TO PREVAIL OVER
THE NEXT 24 HOURS. KRDM MAY SEE ANOTHER BRIEF SNOW SHOWER OR TWO
THIS MORNING...LOWERING CIGS AND VIS...BUT SHOULD REBOUND QUICKLY.
WINDS WILL BE LIGHT LESS THAN 15KTS AT ALL TAF SITES. CIGS WILL BE
MAINLY FEW TO SCATTERED MID LEVEL CLOUDS...WITH PERHAPS AN EARLY
MORNING LOW LEVEL STRATUS DECK. WEBER
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 37 24 34 17 / 10 10 10 0
ALW 39 27 35 20 / 10 10 20 0
PSC 42 23 34 16 / 10 10 10 0
YKM 36 19 32 16 / 0 10 0 0
HRI 41 23 34 16 / 10 10 0 0
ELN 36 20 32 15 / 0 10 0 0
RDM 37 14 37 13 / 30 10 0 0
LGD 35 20 32 8 / 20 10 10 0
GCD 33 20 35 13 / 20 10 0 0
DLS 41 25 37 22 / 20 10 0 0
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
&&
THREAT INDEX
TODAY : GREEN
WEDNESDAY : GREEN
THURSDAY : 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
$$
78/89/89
