Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 141117 AAA
AFDPDT

AREA FORECAST DISCUSSION...UPDATED AVIATION DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
330 AM PST SUN FEB 14 2016

.SHORT TERM...TODAY THROUGH TUESDAY...THE WEATHER SYSTEM THAT
BROUGHT A SIGNIFICANT AMOUNT OF RAIN WITH SOME HIGHER MOUNTAIN SNOW
TO THE FORECAST AREA HAS MOVED OFF TO THE SOUTHEAST IN A NORTHWEST
FLOW ALOFT. MOST OF THE PRECIPITATION WITH THAT SYSTEM HAS ALSO
MOVED TO THE SOUTHEAST. HOWEVER...MORE PRECIPITATION IS MOVING INTO
THE CWA AT THIS TIME WITH THE NEXT FAST APPROACHING WEATHER SYSTEM.
RADAR IMAGERY IS SHOWING THIS PRECIPITATION ALREADY FILLING UP THE
AREA AGAIN FROM THE NORTHWEST. THE NAM QPF GUIDANCE IS SHOWING MORE
ABUNDANT RAIN TO FALL OVER THE NORTHEAST MOUNTAIN AND THE CASCADES
FROM THIS MORNING THROUGH THIS EVENING. MAIN CONCERNS ARE HYDROLOGY
AS THERE WILL BE RAPID RISES ON RIVERS AND STREAMS DUE TO MELTING
SNOW AND RAINFALL. SNOW LEVELS ARE EXPECTED TO RISE TO ABOUT 6500 TO
NEAR 8000 FT MSL BY THIS EVENING. THE MOST LIKELY AREAS TO HAVE
HYDROLOGY IMPACTS ARE THE RIVERS FLOWING OUT OF THE EAST SLOPES OF
THE CASCADES OF SOUTHERN AND CENTRAL WASHINGTON AND SOME RIVERS
FLOWING OUT OF THE NORTHEAST MOUNTAINS. AT THIS TIME FLOODING IS NOT
FORECAST BUT SOME RIVERS ARE EXPECTED TO REACH OR EXCEED ACTION
STAGE. SURFACE PRESSURE ANALYSIS SHOWS A LEE SIDE TROUGH AGAINST THE
CASCADES...ESPECIALLY IN WASHINGTON...TODAY AND TONIGHT. 850 MB WIND
SPEEDS BY THE MODELS APPROACH OR EXCEED HIGH WIND WARNING CRITERIA.
THE BIG QUESTION IS WILL THESE WINDS MIX DOWN TO THE SURFACE.
LOOKING CLOSER AT CROSS SECTIONS AGAINST THE CASCADES SOME
ISENTROPIC DESCENT IS FORECAST OF THESE STRONGER WINDS ALOFT BUT
OTHER SOURCES SHOW GUSTS TO ONLY REACH ABOUT 35 MPH. WILL KEEP A
CLOSE EYE OF THIS SITUATION EARLY THIS MORNING AND WILL ADVISE THE
DAY SHIFT TO DO THE SAME TODAY. IN ANY CASE CAN EXPECT BREEZY TO
WINDY CONDITIONS OVER THESE PORTIONS OF THE CWA AND ALSO OVER
EXPOSED OPEN TERRAIN OF THE LOWER COLUMBIA BASIN AND ADJACENT
VALLEYS/BLUE MOUNTAIN FOOTHILLS. ON MONDAY THE WIND AND
PRECIPITATION WILL DECREASE AS A HIGH PRESSURE RIDGE BEGINS TO BUILD
AND PUSH THE MOISTURE NORTH OF THE CWA. THE DRYING TREND WILL
CONTINUE ON TUESDAY...THOUGH THERE COULD STILL BE SOME MOUNTAIN
SHOWERS BOTH MONDAY AND TUESDAY. TEMPERATURES WILL BE QUITE ABOVE
NORMAL THROUGH THE PERIOD WITH THE LOWER ELEVATION MAX TEMPERATURES
RISING TO THE LOWER TO MID 60S BY MONDAY AND TUESDAY. OVERNIGHT LOWS
ARE FORECAST TO REMAIN ABOVE FREEZING IN MOST AREAS TONIGHT AND
MONDAY NIGHT. 88

.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY. MODELS ARE IN FAIRLY
GOOD AGREEMENT THROUGH THE EXTENDED PERIOD. TUESDAY NIGHT AND
WEDNESDAY...A RIDGE MOVES THROUGH THE AREA WITH THE MOISTURE PUSHED
NORTH OF THE FORECAST AREA WHILE THE TROUGH OF LOW PRESSURE REMAINS
OFF THE COAST. WEDNESDAY NIGHT AND THURSDAY...THE TROUGH MOVES
ONSHORE AND ACROSS THE AREA WITH RAIN AND MOUNTAINS SNOW AS SNOW
LEVELS DECREASE TO 4000 TO 5000 FEET ON THURSDAY. THE TROUGH APPEARS
TO BE NEGATIVELY TILTED AS IT COMES THROUGH THURSDAY. THIS WILL LEAD
SOME INSTABILITY BY LATE THURSDAY...ALONG WITH WINDY CONDITIONS. THE
UNSETTLED CONDITIONS CONTINUE THROUGH FRIDAY AS ANOTHER SYSTEM MOVES
THROUGH THE AREA. IT SHOULD START DRYING OUT AGAIN ON SATURDAY WITH
A WESTERLY FLOW. THE MODELS ARE IN VERY GOOD AGREEMENT OF A RIDGE
BUILDING AT THE END OF THE PERIOD. IT WILL CONTINUE TO BE MILD WITH
ABOVE NORMAL TEMPERATURES. 93

&&

.AVIATION...12Z TAFS. PERIODS OF RAIN CAN BE EXPECTED THROUGH THE
PERIOD...ESPECIALLY AT KDLS, KPDT AND KALW. IN THESE
LOCATIONS...CIGS/VSBY WILL LOWER TO MVFR OR LESS AT TIMES. DUE TO A
WESTERLY FLOW ALOFT PROVIDING RAIN SHADOWING OFF THE CASCADE RANGE
AND A FLAT HIGH PRESSURE RIDGE OVER SOUTHERN OREGON...ONLY LIGHT
SHOWERS ARE EXPECTED AT THE OTHER TAF SITES WITH BETTER POTENTIAL
FOR PREVAILING VFR CONDITIONS. SW-W WINDS WILL BE 5-15 MPH WITH
GUSTS TO 20-25 MPH POSSIBLE ON THIS AFTERNOON AND EVENING. 93

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  58  48  64  44 /  60  50  10  10
ALW  59  50  66  47 /  70  50  10  10
PSC  58  49  66  46 /  50  20  10  10
YKM  55  42  63  42 /  20  20  10  10
HRI  59  49  66  44 /  60  30  10  10
ELN  51  42  58  38 /  20  20  10  10
RDM  56  41  62  39 /  40  30  10   0
LGD  52  46  59  39 /  80  60  20  10
GCD  55  43  60  37 /  70  40  10  10
DLS  56  48  63  45 /  50  30  20  10

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...AIR STAGNATION ADVISORY UNTIL 10 AM PST THIS MORNING FOR WAZ026-
     027.

&&

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

$$

88/93/93


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