Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 231051 AAA
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
350 AM PDT THU OCT 23 2014

...UPDATED AVIATION DISCUSSION...

.SHORT TERM...TODAY THROUGH SATURDAY...A LARGE AND PERSISTENT UPPER
TROUGH WILL CONTINUE OFF THE COAST THROUGH TODAY. A SHORT WAVE
ROTATING AROUND THE BOTTOM OF THE TROUGH IS PULLING SHOWERS UP AND
ACROSS THE CWA THIS MORNING. THERE ARE ABUNDANT SHOWERS BEING SHOWN
ON RADAR IMAGERY WITH THE SATELLITE SHOWING THE MOISTURE AND CLOUDS
STREAMING INTO THE REGION VIA AN ATMOSPHERIC RIVER OF MOISTURE. A
WAVE IS FORMING ALONG THIS BAND OF MOISTURE OVER SOUTHWEST OREGON
AND THIS WILL MOVE NORTHEAST ACROSS THE CWA TODAY. THE PRECIPITATION
WILL BECOME MORE SHOWERY THIS AFTERNOON BEHIND A COLD FRONT AND
CANNOT RULE OUT EVEN A THUNDERSTORM OVER THE NORTHERN BLUE MOUNTAINS
EASTWARD TO THE IDAHO BORDER. HOWEVER THE AMOUNT OF INSTABILITY AND
CONVECTIVE PARAMETERS DO NOT LOOK TOO IMPRESSIVE FOR THUNDERSTORMS
SO WILL ONLY GO WITH ISOLATED. AN UPPER RIDGE WILL BEGIN TO BUILD
INTO THE PACIFIC NORTHWEST TONIGHT WITH A WARM FRONT MOVING UP
ACROSS THE CWA WITH A BAND OF MOISTURE MOVING SOUTH TO NORTH
OVERNIGHT. ON SATURDAY DRYING WILL TAKE PLACE AS THE FORECAST AREA
WILL BE IN A WARM SECTOR OF A DEVELOPING LOW PRESSURE SYSTEM ALONG
THE COAST. THEN ANOTHER UPPER TROUGH WILL MOVE INTO THE REGION ON
SATURDAY WITH ANOTHER COLD FRONT TO FOLLOW SATURDAY NIGHT.
TEMPERATURES WILL COOL DOWN A COUPLE DEGREES EACH DAY FOR THE NEXT
FEW DAYS AND IT WILL BECOME LOCALLY BREEZY TO WINDY AT
TIMES...ESPECIALLY SATURDAY AFTERNOON IN SOUTHERN PORTIONS OF THE
CWA. 88

.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY. OVERALL CONFIDENCE IN
THE MEDIUM RANGE MODELS IS GOOD THROUGH TUESDAY BUT CONFIDENCE FADES
LATE IN THE PERIOD.  MODELS SHOW THE UPPER LEVEL TROUGH OFFSHORE
SHIFTING EASTWARD SATURDAY NIGHT AND SUNDAY.  HIGH CHANCE TO LIKELY
POPS ARE FORECAST DURING THIS PERIOD (CATEGORICAL OVER THE EAST
SLOPES OF THE CASCADES)...AND IT WILL BE VERY WINDY IN MANY AREAS. A
WIND ADVISORY MAY BE NEEDED FOR CENTRAL OREGON...THE SOUTHERN
FOOTHILLS OF THE BLUE MOUNTAINS...AND THE GRANDE RONDE VALLEY FOR
SATURDAY NIGHT.  SNOW LEVELS WILL LOWER TO NEAR 4500-5000 FEET LATE
SUNDAY AFTER THE PASSAGE OF A COLD FRONT...BUT SNOW ACCUMULATIONS
SHOULD BE LIGHT AS PRECIPITATION ALSO TAPERS OFF BEHIND THE COLD
FRONT.  ANY PRECIPITATION SUNDAY NIGHT AND MONDAY WILL BE ISOLATED
MOUNTAIN SHOWERS AS A SHORTWAVE RIDGE MOVES EAST OF THE CASCADES.
THE GFS AND ECMWF BECOME OUT OF PHASE DURING THE REMAINDER OF THE
PERIOD. THE GFS STRENGTHENS A HIGH PRESSURE RIDGE OVER THE WESTERN
U.S. DURING THE MID WEEK WHILE THE ECMWF DEEPENS A TROUGH OFFSHORE.
I AM LEANING TOWARDS THE ECMWF SOLUTION BUT WILL BE SLIGHTLY
CONSERVATIVE WITH POPS AND TEMPERATURES AND KEEP THE FORECAST CLOSE
TO CLIMATOLOGY.  WISTER

&&

.AVIATION...12Z TAFS...VFR CONDITIONS WILL PREVAIL WITH BKN-OVC
SKIES WITH BASES BETWEEN 4000-10000 FEET AND HIGHER CLOUDS ABOVE.
CIGS MAY BRIEFLY LOWER TO MVFR IN AREAS OF LIGHT RAIN...MAINLY NEAR
KRDM AND KBDN. SW-W WINDS 8-15 KNOTS GUSTING TO 25 KNOTS ARE
EXPECTED THROUGH THE PERIOD. WISTER

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  65  47  60  43 /  50  20  30  40
ALW  65  50  61  48 /  60  20  30  40
PSC  67  47  61  45 /  40  10  10  40
YKM  62  41  57  41 /  40  20  20  50
HRI  67  46  61  43 /  40  20  20  40
ELN  59  39  55  41 /  40  20  10  60
RDM  60  39  58  39 /  40  30  70  20
LGD  59  47  58  43 /  80  40  60  20
GCD  58  43  57  42 /  70  40  60  10
DLS  63  45  59  46 /  40  20  50  60

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.

&&

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

$$

88/85/85






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