Weather Service Report


249 
FXUS66 KPDT 230257
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
757 PM PDT TUE APR 22 2014

.UPDATE...THE FORECAST AREA IS CURRENTLY IN A BREAK IN THE WEATHER 
WITH THE NEXT SYSTEM MOVING INTO THE PACIFIC NORTHWEST WEST OF THE 
CASCADES. RADAR IMAGERY IS SHOWING PRECIPITATION TO BE INCREASING 
WEST OF THE CASCADES. THIS PRECIPITATION WILL MOVE EAST OF THE 
CASCADES OVERNIGHT AND ON WEDNESDAY MORNING BRINGING MAINLY RAIN 
SHOWERS TO THE CWA. THIS SYSTEM WILL EXIT THE FORECAST AREA BY 
WEDNESDAY AFTERNOON BUT WILL BE QUICKLY FOLLOWED BY ANOTHER WEATHER 
SYSTEM FOR WEDNESDAY NIGHT INTO THURSDAY. A WARM FRONT WILL MOVE 
NORTH ACROSS THE CWA WEDNESDAY EVENING AND THEN A COLD FRONT WILL 
FOLLOW ON THURSDAY MORNING. PRECIPITATION TYPE WITH THESE TWO 
SYSTEMS WILL BE PRIMARILY RAIN BUT THERE MAY BE SOME WET SNOW IN THE 
HIGHEST ELEVATIONS OF THE NORTHEAST MOUNTAINS AND THE CASCADES. IT 
WILL ALSO BECOME BREEZY AT TIMES AS THESE SYSTEMS PASS OVER THE 
AREA. THE WEATHER PATTERN WILL REMAIN UNSETTLED WITH FREQUENT 
WEATHER SYSTEMS THROUGH THE WEEKEND INTO EARLY NEXT WEEK. 88

&&

.AVIATION...06Z TAFS...MAINLY VFR CONDITIONS WILL PREVAIL DURING THE 
NEXT 24 HOURS. THERE COULD BE BRIEF PERIODS OF MVFR OR IFR IN RAIN 
SHOWERS DURING THE DAY WEDNESDAY. WINDS WILL CONTINUE TO DIMINISH 
OVERNIGHT BUT THEN THEY WILL INCREASE AGAIN ON WEDNESDAY TO MOSTLY 
10 TO 20 KTS AND POSSIBLY 15 TO 25 KTS AT TIMES IN THE AFTERNOON. 88

&&

.PREV DISC... /ISSUED 440 PM PDT TUE APR 22 2014/ 

SHORT TERM...TONIGHT THROUGH THURSDAY. AN ACTIVE WEATHER PATTERN IS 
EXPECTED FOR THE NEXT FEW DAYS. SHOWERS WILL PERSIST ON AND OFF AND 
AS ONE STORM SYSTEM EXITS THE REGION TODAY LEAVING SOME SHOWERS AND 
WINDY CONDITIONS BEHIND IT...ANOTHER SYSTEM WILL REPLACE IT TONIGHT 
KEEPING THE THREAT FOR SHOWERS IN THE FORECAST INTO WEDNESDAY. A 
STRONGER SYSTEM MOVES INTO THE REGION WEDNESDAY NIGHT AND RAIN 
CHANCES WILL INCREASE. ALSO THE ATMOSPHERE BECOMES INCREASINGLY 
UNSTABLE THURSDAY AFTERNOON AND AN ISOLATED THUNDERSTORM IS POSSIBLE 
MAINLY OVER THE EASTERN THIRD OF THE AREA THAT INCLUDES THE 
BLUES/WALLOWAS. SNOW LEVELS WILL BE A CHALLENGE FLUCTUATING FROM 
3500 FEET TO 4500 FEET AND THERE REMAINS SOME CHANCE FOR EITHER A 
MIXTURE OF RAIN AND SNOW OR MAINLY SNOW WITH MINOR ACCUMULATIONS 
ACROSS THE HIGHER ELEVATIONS. TEMPERATURES WILL REMAIN SLIGHTLY 
BELOW NORMAL THROUGH THE PERIOD. 

LONG TERM...FRIDAY THROUGH TUESDAY...A HIGH AMPLITUDE UPPER LEVEL 
TROUGH WILL BE ALONG THE COAST FRIDAY SETTING UP A BROAD SOUTHERLY 
FLOW ALOFT OVER FORECAST AREA. 500 MB TEMPERATURES OF -25C TO -30C 
WILL FAVOR STEEP LAPSE RATES LEADING TO A MARGINAL UNSTABLE 
ATMOSPHERE FRIDAY AFTERNOON FOR SHOWERS LIKELY. THE 12Z ECMWF SHOWS 
CAPE OF 300 J/KG FRIDAY AFTERNOON OVER THE EASTERN OREGON MOUNTAINS. 
I THEREFORE ADDED A SLIGHT CHANCE OF THUNDERSTORMS FOR FRIDAY 
AFTERNOON. IN ADDITION, BOTH THE 12Z GFS AND THE 12Z ECMWF RUNS 
INDICATE DYNAMIC LIFT OVER EASTERN LIFT FOR STRONG FORCING ALONG 
WITH VERTICAL WIND SHEAR AROUND 40 KTS. FRIDAY NIGHT THE TROUGH 
MOVES OVER THE REGION FOR A CHANCE OF SHOWERS MAINLY OVER MOUNTAINS. 
SATURDAY THE TROUGH REMAINS OVER FORECAST AREA WHILE THE NEXT 
UPSTREAM SHORT WAVE APPROACHES THE COAST SATURDAY AFTERNOON WITH AN 
ATTENDANT COLD FRONT. THE SHORT WAVE MOVES ACROSS FORECAST AREA 
SATURDAY NIGHT/SUNDAY SWEEPING THE COLD FRONT INTO IDAHO/MONTANA 
SATURDAY NIGHT, THUS KEEPING A CHANCE OF SHOWERS IN THE EASTERN 
MOUNTAINS AND ALONG THE EAST SLOPES OF THE CASCADES. SUNDAY/SUNDAY 
NIGHT INTO MONDAY A WARM FRONT BRING RAIN INTO THE FORECAST AREA 
WITH THE BEST CHANCE OF RAIN IN THE MOUNTAINS WITH SNOW LEVELS OF 
4500-5500 FEET. MONDAY NIGHT AND TUESDAY A RIDGE OF HIGH PRESSURE 
BUILDS OVER THE REGION FOR DRY CONDITIONS.  POLAN

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  39  58  44  60 /  30  30  60  60 
ALW  43  57  46  60 /  30  30  60  70 
PSC  43  63  49  65 /  20  30  50  60 
YKM  37  59  40  60 /  20  20  50  60 
HRI  41  62  46  64 /  30  30  60  60 
ELN  38  58  39  60 /  20  20  60  60 
RDM  31  55  37  55 /  30  30  60  50 
LGD  36  53  40  55 /  30  40  70  80 
GCD  33  54  36  52 /  30  40  60  70 
DLS  42  61  46  60 /  30  40  70  70 

&&

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

&&

THREAT INDEX
WEDNESDAY : GREEN
THURSDAY : GREEN
FRIDAY : 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

$$

88/99/88






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