Area Forecast Discussion
Issued by NWS Pendleton, OR

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS66 KPDT 271447
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
746 AM PDT WED MAY 27 2015

.SHORT TERM...TODAY AND TONIGHT...UPPER LEVEL CLOSED LOW PRESSURE
SYSTEM CONTINUES TO SLOWLY DRIFT SOUTHEASTWARD. YESTERDAY IT WAS
OVER EASTERN WASHINGTON. THIS MORNING IT IS OVER SOUTHEAST
WASHINGTON AND BY THIS AFTERNOON IT WILL BE OVER WALLOWA COUNTY IN
NORTHEAST OREGON AND ON ITS WAY INTO CENTRAL IDAHO THIS EVENING.
EXPECT THE ATMOSPHERE TO BECOME INCREASINGLY UNSTABLE THROUGH THE
DAY AS SOLAR HEATING HEATS THE GROUND AND THUS THE LOWER ATMOSPHERE.
BEST INSTABILITY LEADING TO SHOWERS AND POTENTIAL THUNDERSTORMS WILL
BE OVER THE EASTERN PORTION OF THE FORECAST AREA NEARER THE TRACK OF
THE UPPER LEVEL LOW AS DESCRIBED. SOME WEAKER INSTABILITY WILL OCCUR
NEAR THE CASCADES WHILE AN AREA OF FROM THE LOWERS COLUMBIA BASIN TO
CENTRAL OREGON SHOULD REMAIN SHOWER FREE TODAY. SHOWERS AND POSSIBLE
THUNDERSTORMS WILL LINGERING INTO THE EVENING AND THEN BEGIN TO
TAPPER OFF NEAR SUNSET AND COME TO AN END FOR MOST OF THE FORECAST
AREA BEFORE MIDNIGHT. A FEW SHOWERS COULD PERSIST AFTER SUNSET NEAR
THE IDAHO BORDER.




&&

.PREV DISCUSSION... /ISSUED 458 AM PDT WED MAY 27 2015/

SHORT TERM...TODAY THROUGH FRIDAY...AN UPPER LOW PRESSURE SYSTEM
CURRENTLY OVER THE TRIPLE POINT OF OREGON...WASHINGTON AND IDAHO.
THIS LOW HAS MOISTURE CIRCULATING AROUND IT AND INTO THE PACIFIC
NORTHWEST ON THE NORTH SIDE OF THE LOW. THERE HAVE BEEN SOME SHOWERS
AND ISOLATED THUNDERSTORMS OVER PORTIONS OF THE FORECAST
AREA...MAINLY EASTERN MOST AREAS YESTERDAY AND LAST EVENING. THE
UPPER LOW IS EXPECTED TO MOVE TO THE SOUTHEAST TODAY AND THEN INTO
IDAHO AND WESTERN MONTANA...AND OUT OF THE CWA...TONIGHT.
HOWEVER...THERE COULD ONCE AGAIN BE SHOWERS AND POSSIBLE AFTERNOON
THUNDERSTORMS AGAIN TODAY OVER EASTERN AREAS WHERE THIS UPPER LOW
HAS THE MOST INFLUENCE ON THE CWA. HOWEVER THERE WILL ALSO BE SOME
MOISTURE AND INSTABILITY ALONG THE CASCADE EAST SLOPES AND HAVE A
SLIGHT CHANCE OF THUNDERSTORMS MENTIONED THERE AS WELL TODAY THROUGH
THIS EVENING. THERE WILL BE A DRYING AND WARMING TREND AFTER TODAY
OVER THE CWA. THE ATMOSPHERE WILL BECOME WARMER AS AN UPPER RIDGE
BUILDS OVER THE REGION THURSDAY THROUGH THE END OF THE WEEK. IT WILL
BE DRIER...BUT THERE MAY STILL BE ENOUGH MID LEVEL MOISTURE AND
INSTABILITY FOR A SLIGHT CHANCE OF SHOWERS AND AFTERNOON
THUNDERSTORMS THURSDAY AND FRIDAY AFTERNOONS OVER THE MOUNTAINS. BY
FRIDAY MAXIMUM TEMPERATURES WILL REACH UPPER 80S TO AROUND 90 IN THE
LOWER ELEVATIONS...MAKING THIS THE WARMEST DAY OF THE YEAR SO FAR.
THE VERY WARM WEATHER WILL CONTINUE INTO THE EXTENDED FORECAST
PERIOD. WINDS WILL BE MOSTLY LIGHT THROUGH THE SHORT TERM PERIOD
(THROUGH FRIDAY). 88

LONG TERM...FRIDAY NIGHT THROUGH TUESDAY...WEAK UPPER LEVEL RIDGING
WITH A SOUTHWEST TO WEST-SOUTHWEST UPPER FLOW FRIDAY NIGHT THROUGH
SUNDAY. OTHER THAN A FEW MOUNTAIN SHOWERS OR THUNDERSTORMS FRIDAY
EVENING, CONDITIONS SHOULD BE DRY AND FAIR FRIDAY NIGHT INTO
SATURDAY MORNING. DAYTIME HIGH TEMPS WILL BE QUITE WARM FOR THIS
TIME OF YEAR, RANGING FROM THE UPPER 70S TO LOWER 90S SATURDAY AND
SUNDAY. THIS HEATING COMBINED WITH SOME MOISTURE WITHIN THE UPPER
LEVEL FLOW SHOULD RESULT IN ISOLATED TO SCATTERED SHOWERS WITH
ISOLATED THUNDERSTORMS AFTERNOONS AND EVENINGS SATURDAY AND SUNDAY.
THESE SHOWERS AND STORMS SHOULD BE MAINLY OVER CENTRAL AND NORTH
CENTRAL OREGON EAST TO GRANT AND WALLOWA COUNTIES, AND INTO EXTREME
SOUTHEAST WASHINGTON. AN UPPER LEVEL LOW STILL LOOKS TO MOVE INTO
AND THROUGH THE REGION SUNDAY NIGHT THROUGH TUESDAY. THIS SYSTEM
WILL BRING VARYING CHANCES OF SHOWERS TO THE ENTIRE AREA THROUGH
THIS PERIOD. THE SYSTEM IS LOOKING TO BE A BIT MORE PROGRESSIVE,
THUS THE POTENTIAL FOR THUNDERSTORMS NO LONGER LOOKS TO COVER THE
ENTIRE AREA MONDAY. WILL RUN THE THUNDERSTORM THREAT MONDAY
AFTERNOON AND EVENING FROM CENTRAL OREGON TO THE BLUE MOUNTAINS AND
THEIR ASSOCIATED FOOTHILLS, AND EAST TO GRANT AND WALLOWA COUNTIES.
FOR NOW THE THUNDERSTORM THREAT TUESDAY AFTERNOON AND EVENING IS
LOOKING TO BE EVEN MORE LIMITED, BUT WILL CONTINUE TO INDICATE SOME
STORMS OVER OUR EASTERN MOUNTAIN ZONES. 90

AVIATION...12Z TAFS...VFR CONDITIONS WILL PREVAIL OVER THE NEXT 24
HOURS. ISOLATED SHOWERS NEAR KPSC WILL DRIFT TOWARDS KALW AND
POSSIBLY KPDT, EARLY IN THIS PERIOD. ELSEWHERE CONDITIONS WILL BE
FAIR AND DRY THIS MORNING. AN UPPER LOW OVER THE AREA WILL KEEP THE
AIR MASS OVER THE REGION UNSTABLE. AS A RESULT, SHOWERS AND POSSIBLE
THUNDERSTORMS WILL DEVELOP THIS AFTERNOON. THE BEST CHANCES FOR A
SHOWER, WITH AN OUTSIDE CHANCE OF A THUNDERSTORM, WILL BE SEEN AT
KALW AND KPDT. THUNDERSTORMS WILL MORE LIKELY OCCUR OVER THE
MOUNTAINS EAST OF KALW AND KPDT. SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO DEVELOP OVER THE CASCADE EAST SLOPES AS WELL. DIRECTION
OF MOVEMENT OF THESE SHOWERS/STORMS IS EXPECTED TO BE FROM THE
NORTH. THUS AT THIS TIME EXPECT SHOWERS AND STORMS TO STAY WEST OF
KYKM, KDLS, KRDM AND KBDN. CEILINGS, WHEN THEY OCCUR, WILL MAINLY BE
BETWEEN 7000 AND 10000 FT AGL. 90

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  76  52  79  55 /  20  20  10  10
ALW  77  57  82  61 /  30  30  10  10
PSC  82  56  86  58 /  10  10  10  10
YKM  80  55  83  56 /  20  20  10  10
HRI  80  55  85  56 /  20  20   0   0
ELN  80  53  85  55 /  20  20  10  10
RDM  75  44  78  47 /  10  10   0   0
LGD  69  47  75  49 /  40  40  20  20
GCD  73  46  78  48 /  30  30  10  10
DLS  82  57  86  58 /  10  10   0   0

&&

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

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

$$

91/91/91



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.