Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 310556 AAB
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1050 PM PDT MON MAR 30 2015

UPDATED THE AVIATION DISCUSSION

.UPDATE...A COLD FRONT WAS APPROACHING THE PACNW COAST AND IS
FORECAST TO MOVE ACROSS THE AREA TOMORROW MORNING. PRIOR TO THIS THE
MODELS WERE HINTING AT A DISTURBANCE AHEAD OF THE FRONT THAT MAY
DRIFT ACROSS THE REGION OVERNIGHT WHICH COULD PRODUCE AN ISOLD
SHOWER MAINLY OVER OUR EASTERN ZONES SUCH AS THE BLUE/WALLOWA MTNS
LOCATIONS. OTHERWISE CLOUDS WILL BE ON THE INCREASE TOWARD MORNING
AND THE FORECAST LOW TEMPS APPEAR ON TRACK FOR NOW.

.AVIATION...SOME CLOUDS AND POSSIBLY A SHOWER COULD OCCUR CREATING
MVFR CONDITIONS AT TAF SITES KPDT AND KALW BETWEEN 08Z TO 12Z.

OTHERWISE MOSTLY VFR CONDITIONS ARE EXPECTED UNTIL A COLD FRONT
APPROACHES THE REGION TOMORROW MORNING WITH AREAS OF WIND GUSTS TO
35 KTS EXPECTED ACROSS ALL TAFS. IN ADDITION AREAS OF MVFR CEILINGS
ARE LIKELY AFTER 12Z IN AND NEAR SHOWERS STARTING AT TAF SITE
KDLS...KYKM...AND KRDM AND THEN THESE CONDITIONS WILL EFFECT TAF
SITES KPDT...KPSC...KALW AFTER 15Z AND CONTINUE INTO THE EVENING.

&&

.PREV DISC... /ISSUED 429 PM PDT MON MAR 30 2015/

SHORT TERM...TONIGHT THROUGH THURSDAY...AN UPPER LEVEL TROUGH WILL
MOVE INTO THE PACIFIC NORTHWEST LATE TONIGHT AND TUESDAY. THIS
TROUGH WILL PUSH A COLD FRONT THROUGH THE REGION BETWEEN MIDNIGHT
AND NOON TUESDAY. WINDS WILL INCREASE WITH AND BEHIND THIS FRONT.
SUSTAINED WINDS OF 20 TO 30 MPH ARE EXPECTED OVER MUCH OF THE
COLUMBIA BASIN FROM LATE TUESDAY MORNING INTO THE EARLY EVENING.
LOCATIONS SUCH AS THE KITTITAS VALLEY AND THE BLUE MOUNTAIN
FOOTHILLS WILL SEE THE STRONGEST WINDS. AT THIS TIME AM CONFIDENT
THAT THE KITTITAS VALLEY WILL SEE SUSTAINED WINDS OF 30 TO 35 MPH,
ESPECIALLY OVER THE NORTHERN SIDE OF THE VALLEY. THUS HAVE ISSUED A
WIND ADVISORY FOR THE KITTITAS VALLEY. WINDS IN THE BLUE MOUNTAIN
FOOTHILLS MAY BECOME EQUALLY STRONG, BUT CONFIDENCE IS LOWER AND
WILL HOLD OFF ON HIGHLIGHTS FOR NOW. MAY SEE A FEW SHOWERS AND EVEN
A STRAY THUNDERSTORM OVER THE NORTHERN BLUES, THE ADJACENT FOOTHILLS
AND THE GRANDE RONDE VALLEY OVERNIGHT AHEAD OF THE COLD FRONT. THESE
SHOWERS AND POSSIBLE STORMS WILL BE CAUSED BY ELEVATED INSTABILITY.
RAIN WILL ACCOMPANY THE COLD FRONT AS IT MOVES THROUGH TUESDAY
MORNING. COLD AIR ALOFT WILL ALLOW FOR THE DEVELOPMENT OF ISOLATED
TO SCATTERED SHOWERS AND A FEW STRAY THUNDERSTORMS TUESDAY AFTERNOON
AND EVENING. SHOWER COVERAGE WILL DECREASE TUESDAY EVENING INTO
WEDNESDAY MORNING. ALSO SNOW LEVELS WILL FALL TUESDAY NIGHT, BUT
ACCUMULATIONS WILL BE LIMITED BY THE SHOWERY NATURE OF THE PRECIP.
COLD AIR ALOFT WILL CONTINUE OVER THE AREA WEDNESDAY. THUS EXPECT
ISOLATED TO SCATTERED SHOWERS AND A FEW STRAY THUNDERSTORMS TO AGAIN
OCCUR WEDNESDAY AFTERNOON AND EVENING. NORTHWEST FLOW WILL KEEP A
FEW SHOWERS GOING OVER THE MOUNTAINS INTO THURSDAY. 90

LONG TERM...THURSDAY NIGHT THROUGH MONDAY...THURSDAY NIGHT WILL SEE
A TROUGH DEPARTING TO THE EAST AND WEAK TEMPORARY RIDGING OVER THE
AREA AS A FRONT APPROACHES OUT IN THE EASTERN PACIFIC. THERE WILL BE
SOME LINGERING LIGHT SNOW SHOWERS IN THE HIGHER MOUNTAINS OF EASTERN
OREGON AND ALONG THE WASHINGTON CASCADE CREST. FRIDAY WILL BE MAINLY
DRY WITH INCREASING CLOUDS THROUGH THE DAY. THE FRONT WILL ARRIVE IN
THE LATE AFTERNOON AND EVENING WITH A CHANCE OF RAIN AND SNOW
SHOWERS REACHING AS FAR AS YAKIMA AND ELLENSBURG DURING THE DAY THEN
SPREADING A CHANCE OF RAIN AND SNOW IN THE MOUNTAINS AND A SLIGHT
CHANCE OF RAIN IN THE LOWER ELEVATIONS FRIDAY NIGHT. SNOW LEVELS
WILL BE 2500 TO 3500 FEET IN THE CASCADES AND 3500 TO 4500 FEET IN
THE EASTERN MOUNTAINS. THIS SYSTEM LOOKS MOISTURE DEFICIENT SO
EXPECT FEW HUNDREDTHS OF AN INCH OF RAIN IN MOST PLACES AND AN INCH
OR LESS IN THE MOUNTAINS. FRIDAY NIGHT AND SATURDAY AN UPPER LOW
MOVES SOUTH OUT OF THE GULF OF ALASKA AND DEVELOPS A TROUGH ALONG
THE COAST. MOISTURE MOVING INTO THE AREA ON A WEST TO SOUTHWEST FLOW
WILL KEEP A CHANCE OF RAIN AND SNOW SHOWERS IN THE MOUNTAINS AND A
SLIGHT CHANCE OF RAIN IN THE LOWER ELEVATIONS. SNOW LEVELS WILL BE
BACK AT 3000 TO 4000 FEET BY SATURDAY. MODELS DIVERGE WITH THE
HANDLING OF THE TROUGH AT THIS POINT WITH THE ECMWF KEEPING IT
OFFSHORE AND EXPANDING SOUTH THROUGH MONDAY. THE GFS MOVES THE
TROUGH ASHORE SUNDAY AND THROUGH THE AREA BY MONDAY. BOTH SCENARIOS
LOOK WET FOR US SO HAVE IN GENERAL KEPT A CHANCE OF RAIN AND SNOW IN
THE MOUNTAINS AND A SLIGHT CHANCE OF RAIN IN THE LOWER ELEVATIONS.
SUNDAY LOOKS UNSTABLE IN THE GFS SO HAVE A CHANCE OF RAIN IN THE
LOWER ELEVATIONS FOR THAT PERIOD. IF THE GFS IS RIGHT, WOULD EXPECT
SOME THUNDERSTORMS TO DEVELOP ON SUNDAY, BUT WILL HOLD OFF UNTIL
SOME BETTER AGREEMENT IS FOUND IN THE MODELS. HIGHS WILL BE AROUND
NORMAL WITH HIGHS IN THE MID 50S TO LOWER 60S AND MID 40S TO MID 50S
IN THE MOUNTAINS. LOWS WILL BE IN THE 30S AND LOWER 40S WITH MAINLY
20S IN THE MOUNTAINS. PERRY

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  44  56  35  55 /  20  50  20  30
ALW  49  58  40  57 /  20  40  20  30
PSC  46  63  38  62 /  10  30  10  30
YKM  42  60  34  59 /  20  20  10  30
HRI  45  62  37  60 /  10  30  10  30
ELN  42  56  33  55 /  20  20  10  30
RDM  37  51  24  50 /  20  40  10  40
LGD  43  53  34  51 /  20  60  20  40
GCD  39  50  29  50 /  10  50  20  30
DLS  46  60  39  59 /  20  40  20  40

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...WIND ADVISORY FROM 11 AM TO 9 PM PDT TUESDAY WAZ026.

&&

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

$$

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