Area Forecast Discussion
Issued by NWS Pendleton, OR

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000
FXUS66 KPDT 031720 AAA
AFDPDT

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE PENDLETON OR
1020 AM PDT MON AUG 3 2015

UPDATED FOR AVIATION DISCUSSION

.SHORT TERM...TODAY AND TONIGHT...SOUTHERLY FLOW CONTINUES TO PUMP
MOISTURE INTO THE REGION TODAY PRODUCING MOSTLY CLOUDY SKIES. THERE
WILL BE SOME ISOLATED TO SCATTERED SHOWERS OVER CENTRAL AND EASTERN
OREGON MAINLY THIS AFTERNOON AND EVENING ALONG WITH A FEW ISOLATED
THUNDERSTORMS. REST OF THE FORECAST AREA WILL SEE MOSTLY CLOUDY
CONDITIONS WITH PERHAPS SOME BRIEF SPRINKLES BUT NOT EXPECTING ANY
MEASURABLE RAINFALL. CLOUDY COVER WILL HELP HOLD TEMPERATURES DOWN
TODAY SO AS TO NOT BE SO HOT AS PAST DAYS. ALSO EXPECT SOME
INCREASING BREEZY WESTERLY WINDS DURING THE AFTERNOON AND EVENING
PERIOD THEN DECREASING OVERNIGHT.

&&

.AVIATION...18Z TAFS...VFR CONDITIONS WILL PREVAIL DURING THE NEXT
24 HOURS AT ALL TAF SITES. THERE MAY BE BRIEF MVFR AT KBDN AND KRDM
THIS AFTERNOON DUE TO SHOWERS.  THUNDERSTORMS WILL BE POSSIBLE AS
WELL...BUT WILL WAIT AND AMEND TAFS AS NEEDED...DUE TO LOW
CONFIDENCE. WINDS WILL INCREASE FROM THE WEST MAINLY IN THE LOWER
COLUMBIA BASIN AND THE GORGE AREA.  EXPECT WINDS TO BE 15-25KTS.
WEBER

&&

.FIRE WEATHER...FIRE WEATHER WATCHES FOR THE LOWER COLUMBIA BASIN
AND THE EAST SLOPES OF THE WASHINGTON AND OREGON CASCADES HAVE BEEN
UPGRADED TO RED FLAG WARNINGS IN EFFECT FROM NOON TODAY THROUGH 9 PM
TUESDAY EVENING DUE TO GUSTY WINDS AND LOW RELATIVE HUMIDITY.  THE
UPPER LOW MOVING SOUTH FROM BRITISH COLUMBIA WILL CREATE A WESTERLY
FLOW OVER WASHINGTON AND NORTHERN OREGON AND WILL ALSO ALLOW THE
ONSHORE FLOW TO DEEPEN THE MARINE LAYER WEST OF THE CASCADES. THIS
WILL CAUSE MARINE AIR TO SPILL THROUGH THE CASCADE GAPS AND THE
COLUMBIA RIVER GORGE FOR INCREASING WIND IN THE WARNING AREAS. RH`S
HAVE BEEN BRUTALLY LOW OVER THE WEEKEND (5-15 PERCENT) AND WILL ONLY
INCREASE INTO THE TEENS TO LOWER 20S TODAY AND TUESDAY. WISTER


&&

.PREV DISCUSSION... /ISSUED 300 AM PDT MON AUG 3 2015/

SHORT TERM...TODAY THROUGH TUESDAY NIGHT...AN UPPER LEVEL TROUGH OF
LOW PRESSURE WILL SETTLE OVER BRITISH COLUMBIA AND THE PACIFIC
NORTHWEST THROUGH THIS PERIOD. THE CENTRAL LOW PRESSURE WITH THIS
TROUGH WILL REMAIN OVER BRITISH COLUMBIA. THUS WILL SEE THE SOUTH-
SOUTHWEST FLOW OVER THE REGION GRADUALLY SHIFT TO THE WEST-
SOUTHWEST. THUS WILL GRADUALLY SEE MUCH OF THE MOISTURE OVER THE
PACNW BE PUSHED EAST OF THE REGION. THERE WILL REMAIN THE POTENTIAL
FOR THUNDERSTORMS OVER THE REGION TODAY. THE BEST CHANCES LOOK TO BE
ACROSS CENTRAL AND EAST-CENTRAL OREGON, WITH LESSER CHANCES INTO THE
BLUE MOUNTAINS, GRANDE RONDE VALLEY AND WALLOWA COUNTY. ELSEWHERE
TODAY EXPECT ONLY A FEW SHOWERS OR LIGHT SPRINKLES. LOW LEVEL FLOW
WILL BE INCREASINGLY WESTERLY TODAY. THUS EXPECT COOLER HIGH TEMPS
AT MOST, IF NOT ALL, LOCATIONS. AS THE MOISTURE OVER THE REGION
SHIFTS EAST TONIGHT AND ON TUESDAY WILL SEE CHANCES OF SHOWERS OR
THUNDERSTORMS DECREASE SUCH THAT ONLY OUR EASTERN AND SOUTHERN MOST
AREAS SHOULD BE AFFECTED. 90

LONG TERM...WEDNESDAY THROUGH SUNDAY NIGHT...A PROGRESSIVE ZONAL
PATTERN IN THE WESTERLIES WITH A LARGE LONGWAVE MID/UPPER LEVEL LOW
PRESSURE SYSTEM OVER BRITISH COLUMBIA ON WEDNESDAY SETS UP A
SOUTHWEST FLOW ALOFT ACROSS INTERIOR PACIFIC NORTHWEST WITH STABLE
AIRMASS FOR A SLIGHT CHANCE OF OROGRAPHIC SHOWERS OVER FAR EASTERN
MOUNTAINS OF OREGON WEDNESDAY MORNING. A WEAK LOW AMPLITUDE
SHORTWAVE MOVES RAPIDLY THROUGH SOUTHEAST WASHINGTON AND NORTHEAST
OREGON WEDNESDAY AFTERNOON/EVENING FOR A SLIGHT CHANCE OF AN
AFTERNOON THUNDERSTORM IN THE WALLOWA MOUNTAINS AND ALONG HIGH RIDGE
IN FAR EASTERN WALLOWA COUNTY. THE SLIGHT CHANCE OF THUNDERSTORMS
ENDS BEFORE SUNSET WEDNESDAY. WEDNESDAY NIGHT THE AFOREMENTIONED LOW
MOVES SOUTHEAST AND INTO IDAHO/MONTANA BY DAYBREAK THURSDAY. AS THE
FORECAST AREA WILL BE ON THE DRY SOUTHERN FLANK OF THE LOW, WE WILL
HAVE DRY CONDITIONS WEDNESDAY NIGHT AND THURSDAY. THURSDAY NIGHT
INTO FRIDAY MORNING A MIGRATORY HIGH PRESSURE RIDGE MOVES ACROSS
FORECAST AREA FOR DRY CONDITIONS. FRIDAY AFTERNOON A MID/UPPER
LEVEL LOW MOVES INTO CALIFORNIA AND ALLOWS SOME MID LEVEL MOISTURE
TO MOVE INTO CENTRAL OREGON FOR SLIGHT CHANCE OF AFTERNOON/EVENING
THUNDERSTORMS. THE LOW MOVES NORTHEAST THROUGH EASTERN OREGON FOR A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS FRIDAY NIGHT AND
SATURDAY. FRIDAY NIGHT THROUGH SUNDAY NIGHT A SOUTHWEST FLOW ALOFT
ALLOWS AN INFLUX OF ADDITIONAL MOISTURE INTO CENTRAL AND EASTERN
OREGON FOR A CHANCE OF SHOWERS AND THUNDERSTORMS. POLAN

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  91  64  91  56 /  10  10  10  10
ALW  92  68  92  63 /  10  10  10  10
PSC  95  64  95  56 /  10  10   0   0
YKM  89  62  91  55 /  10  10   0   0
HRI  94  64  94  55 /  10  10   0   0
ELN  91  65  87  58 /  10  10   0   0
RDM  86  50  88  46 /  20  20  10  10
LGD  87  55  88  49 /  20  20  20  10
GCD  90  56  91  50 /  20  20  20  10
DLS  91  67  88  58 /  10  10   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING FROM NOON TODAY TO 9 PM PDT TUESDAY FOR ORZ639-
     641.

WA...RED FLAG WARNING FROM NOON TODAY TO 9 PM PDT TUESDAY FOR WAZ639-
     641-675.

&&

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

$$

91/89/89


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