425
FXUS66 KPDT 082336 AAA
AFDPDT
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
337 PM PST SUN NOV 8 2009
UPDATED AVIATION DISCUSSION.
SHORT TERM...TONIGHT THROUGH WEDNESDAY
ISOLATED SHOWERS THIS
EVENING ACROSS THE WASHINGTON BLUE MOUNTAINS AND FOOTHILLS. TONIGHT
A WEAK RIDGE WILL BEGIN TO BUILD OVER THE IDAHO...MONTANA AREA. AT
THE SAME TIME AN UPPER LEVEL TROUGH WILL SLOWLY CONTINUE TO DEEPEN
OVER THE NORTHERN PACIFIC COAST. THIS WILL SHIFT THE ZONAL FLOW
ALOFT TO SOUTHWEST...WITH WAA INCREASING SNOW LEVELS ACROSS THE CWA
THROUGH MID WEEK. MAIN CONCERN FOR SNOW WILL BE ALONG THE WASHINGTON
CASCADE CREST. THE UPPER LEVEL TROUGH WILL SLOWLY PUSH EASTWARD
UNTIL WEDNESDAY WHEN THE COOLER AIR ARRIVES AND SNOW LEVELS WILL
DECREASE TO AROUND 3500. SHOWER ACTIVITY WILL BE ON AND OFF AHEAD OF
THIS SYSTEM FOR ALL AREAS...WITH CHANCE TO LIKELY POPS IN THE
MOUNTAINS AND SLIGHT CHANCE TO CHANCE POPS IN THE LOWER ELEVATIONS.
WEBER
LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY NIGHT
MODELS AGREE IN
BRINGING A FRONT AND UPPER LEVEL TROUGH THROUGH THE AREA THURSDAY
NIGHT THOUGH THEY DISAGREE SOMEWHAT AS TO THE STRENGTH OF THE
SYSTEM. IN A DEPARTURE FROM PREVIOUS RUNS... THE GFS DEVELOPS A
CLOSED LOW AND MOVES IT THROUGH THE AREA MORE SLOWLY. THE ECMWF
KEEPS A WEAKER OPEN TROUGH AND MOVES IT THROUGH FASTER. HAVE LEANED
TOWARDS THE ECMWF SOLUTION AND GIVEN THE AREA RAIN WITH A CHANCE OF
SNOW ABOVE 2500 TO 3000 FEET WEDNESDAY NIGHT. THURSDAY THE LOWER
ELEVATIONS BEGIN TO DRY OUT WHILE THE MOUNTAINS CONTINUE TO SEE A
CHANCE OF RAIN AND SNOW. THURSDAY NIGHT THE GFS WANTS TO BRING COLD
AIR ON A NORTH TO NORTHEASTERLY FLOW WHILE THE ECMWF HAS US IN A
SLIGHTLY WARMER NORTH TO NORTHWESTERLY FLOW. AGAIN LEANED MORE
TOWARDS THE ECMWF BUT IN EITHER CASE THE AREA SHOULD CONTINUE TO BE
MOSTLY DRY WITH A SLIGHT CHANCE OF RAIN AND SNOW IN THE EASTERN
MOUNTAINS. FRIDAY THROUGH SATURDAY MORNING WILL SEE WEAK RIDGING
OVER THE AREA AS THE TROUGH EXITS TO THE EAST. THIS WILL GIVE THE
AREA MOSTLY DRY CONDITIONS ALTHOUGH BY SATURDAY THE NEXT SYSTEM WILL
BE APPROACHING AND PUT A CHANCE OF RAIN AND SNOW INTO THE MOUNTAINS
AS NORTHWEST FLOW WILL CREATE A FEW UPSLOPE SHOWERS AHEAD OF THE
SYSTEM. THE SYSTEM MOVING IN SUNDAY LOOKS FAIRLY STRONG WITH THE
WARM FRONT PROVIDING SHOWERS SATURDAY NIGHT FOLLOWED BY THE COLD
FRONT SUNDAY WITH MORE RAIN AND SNOW TAPERING OFF SUNDAY NIGHT.
TEMPERATURES WILL BE COOL AND MAINLY IN THE 40S WITH MID 30S TO
LOWER 40S IN THE MOUNTAINS. PERRY
AVIATION...00Z TAFS
VFR CONDITIONS WILL BE PREVALENT FOR THE NEXT
24 HOURS. CEILINGS WILL BE SCATTERED TO BROKEN ABOVE 5000 FEET AGL
THROUGH 09/15Z. A DISTURBANCE WILL MOVE INTO THE AREA TOMORROW
MORNING AND AFTERNOON WITH LOWERING CEILINGS AND A SLIGHT CHANCE OF
SHOWERS IN AND NEAR THE CASCADES AFTER 09/18Z...AFFECTING KDLS AND
KYKM. CEILINGS MAY APPROACH MVFR LEVELS IN THE HEAVIER SHOWERS NEAR
KDLS AND KYKM. OTHERWISE BROKEN SKIES WILL CONTINUE ABOVE 5000 FEET
AGL. SURFACE WINDS WILL BE LESS THAN 15 KTS THROUGH THE PERIOD. PERRY
PRELIMINARY POINT TEMPS/POPS
PDT 33 54 38 53 / 10 10 40 20
ALW 35 54 41 54 / 20 10 30 20
PSC 33 50 36 54 / 10 10 50 10
YKM 31 47 35 51 / 10 20 30 10
HRI 30 51 38 55 / 10 10 30 10
ELN 30 46 34 49 / 20 30 40 10
RDM 25 47 34 51 / 10 10 50 20
LGD 29 51 36 52 / 0 10 30 20
GCD 27 52 36 52 / 0 10 30 20
DLS 34 46 38 55 / 10 40 30 20
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
89/83/83
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