345 
FXUS66 KPDT 072230
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
230 PM PST MON MAR 7 2016

.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT...A BROAD TROUGH IS OVER
WASHINGTON AND OREGON WITH WATER VAPOR SATELLITE SHOWING THREE
LOWS...ONE NORTH OF VANCOUVER ISLAND...ONE OVER NORTHWEST
WASHINGTON...AND ONE OVER SOUTHERN CALIFORNIA. RIGHT NOW THE CWA IS
BETWEEN THE LAST TWO CENTERS. CUMULUS CLOUDS ARE INCREASING OVER THE
CWA DUE TO SURFACE HEATING. THE BROAD TROUGH WILL MOVE THROUGH
EASTERN WASHINGTON AND OREGON TONIGHT WITH SHOWERS PERSISTING IN THE
MOUNTAINS. THERE WILL BE A BRIEF BREAK IN PRECIPITATION AND CLEARING
SKIES EARLY TUESDAY AS A TRANSITORY RIDGE MOVES THROUGH THE AREA.
ANOTHER WEAK FRONT WILL MOVE THROUGH TUESDAY AFTERNOON AND EVENING.
THIS SYSTEM WILL BREAK UP AS IT PASSES THE CASCADES BECAUSE THE
UPPER LEVEL FLOW SUPPORTING IT SPLITS. 

WEDNESDAY AN UPPER LEVEL RIDGE WILL BUILD IN THE WARM ADVECTION
AHEAD OF THE NEXT SYSTEM. SNOW LEVELS WILL START 2500-4000 FT THEN
RISE OVER THE CWA EXCEPT IN YAKIMA AND KITTITAS COUNTIES WHERE
UPSLOPE LOW LEVEL FLOW WILL TRAP COLDER AIR NEAR THE SURFACE. SNOW
ACCUMULATIONS ON THE EAST SLOPES ARE EXPECTED TO REMAIN BELOW
ADVISORY CRITERIA DUE TO WARM ADVECTION. THERE COULD BE CONCERN FOR
SOME SMALL CREEKS AND STREAMS TO FLOOD AGAIN IN YAKIMA AND KITTITAS
COUNTIES...DEPENDING ON HOW MUCH PRECIPITATION FALLS. THERE WILL BE
MARGINAL INSTABILITY OVER THE EAST SLOPES OF THE CASCADES IN
WASHINGTON...BUT MODELS INDICATE THAT SNOW LEVELS WILL BE LOW ENOUGH
THAT SNOW MELT WILL NOT BE A PROBLEM. RAIN OR SNOW CHANGING TO RAIN
WILL SPREAD OVER EASTERN OREGON AND THE REST OF EASTERN WASHINGTON
AS THIS SYSTEM MOVES INTO THE AREA. BREEZY SOUTHERLY WINDS WILL
DEVELOP OVER HIGHER ELEVATIONS IN OREGON...BUT MIXING WILL BE
LIMITED SO HIGHER WINDS WILL BE LOCALIZED.  COONFIELD

.LONG TERM...THURSDAY THROUGH MONDAY...UNSETTLED WEATHER WILL
CONTINUE LATE THIS WEEK INTO EARLY NEXT WEEK. THURSDAY MORNING A
SYSTEM WILL BE MOVING INTO THE AREA. THE WARM FRONT WITH THE SYSTEM
WILL HAVE MOVED NORTH OF THE AREA IN THE EARLY MORNING AND A COLD
FRONT WILL BE CROSSING THE CASCADES WITH A CHANCE OF RAIN WITH A
CHANCE OF SNOW CONFINED TO ABOVE 5500 FEET IN THE MOUNTAINS. THE
FRONT WILL EXIT TO THE EAST THURSDAY NIGHT WITH THE LOWER ELEVATIONS
DRYING OUT IN THE EVENING AND A CHANCE OF RAIN AND SHOWERS LINGERING
IN THE MOUNTAINS THROUGH THE NIGHT. ANOTHER SYSTEM WILL APPROACH THE
NORTHERN CALIFORNIA COAST LATE THURSDAY NIGHT AND SLIDE NORTHEAST
INTO OUR AREA ON FRIDAY. THE WARM FRONT WITH THIS SYSTEM WILL MOVE
INTO THE SOUTHERN HALF OF OUR AREA FRIDAY MORNING AND ACROSS THE
REST OF THE AREA IN THE AFTERNOON. THIS WILL GIVE US A CHANCE OF
MAINLY RAIN AS SNOW LEVELS WILL REMAIN AROUND 5500 FEET. THE COLD
FRONT OF THE SYSTEM WILL MOVE IN FRIDAY NIGHT BUT IT WILL BE FALLING
APART AS IT ARRIVES. HAVE A CHANCE OF RAIN ACROSS THE AREA THOUGH
AMOUNTS SHOULD BE LIGHT. A STRONGER FRONT WILL ARRIVE SATURDAY
AFTERNOON AND NIGHT. THIS WILL GIVE US ANOTHER CHANCE OF RAIN WITH
SNOW ABOVE 4500 FEET. BEHIND THIS FRONT AN UPPER LOW AND TROUGH WILL
BE PARKED ALONG THE PACIFIC NORTHWEST COAST AND SEND A STREAM OF
MOISTURE INTO THE AREA SUNDAY THROUGH MONDAY. THIS WILL KEEP A
CHANCE OF RAIN OVER THE AREA WITH SNOW LEVELS DROPPING TO 3500 FEET.
TEMPERATURES WILL BE IN THE MID 50S TO LOWER 60S WITH MID 40S TO MID
50S IN THE MOUNTAINS. PERRY


&&

.AVIATION...18Z TAFS...VFR CONDITIONS ARE EXPECTED THROUGH THE NEXT
24 HOURS. GENERALLY SCATTERED CIGS BETWEEN 4000 AND 10000 FEET AGL
WITH SCATTERED TO BROKEN HIGH CLOUDS AT AROUND 20000 FEET AGL ARE
EXPECTED. VERY ISOLATED LIGHT SHOWERS ARE POSSIBLE THIS AFTERNOON
FROM 21Z-02Z BUT THE CHANCES WERE SO LOW AT TAF SITES THAT ONLY
MENTIONED VCSH AT KDLS, KRDM AND KBDN. AFTER PARTIAL CLEARING
OVERNIGHT, CLOUDS WILL BEGIN INCREASING AFTER 15Z IN ADVANCE OF THE
NEXT SYSTEM. WINDS TODAY WILL REACH 10 TO 20 KTS WITH GUSTS TO 25
KTS THROUGH 02Z THEN DROP BELOW 15 KTS THROUGH 18Z TOMORROW MORNING.
PERRY



&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  31  52  34  55 /  10  10  30  50 
ALW  33  54  37  57 /  20  10  30  40 
PSC  33  55  35  54 /  10   0  20  40 
YKM  30  52  30  49 /  10  10  30  60 
HRI  32  54  34  55 /  10  10  30  50 
ELN  28  47  29  43 /  10  10  30  60 
RDM  24  49  31  53 /  10  30  30  50 
LGD  28  48  32  49 /  20  10  30  50 
GCD  27  48  31  50 /  20  20  40  50 
DLS  32  51  36  49 /  20  30  40  80 

&&

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

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

$$

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