Area Forecast Discussion
Issued by NWS Pendleton, OR

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000
FXUS66 KPDT 302142
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
242 PM PDT WED JUL 30 2014

.SHORT TERM...TONIGHT THROUGH SATURDAY...AN UPPER LEVEL RIDGE WILL
REMAIN OVER THE WESTERN U.S. THROUGH THIS PERIOD. AS A RESULT THE
UPPER LEVEL FLOW OVER THE PACIFIC NORTHWEST WILL RUN SOUTHWEST TO
WEST-SOUTHWEST. WEAK DISTURBANCES EMBEDDED WITHIN THIS FLOW WILL
PERIODICALLY MOVE ACROSS THE REGION. THESE WAVES WILL GRAB PIECES OF
THE SUBTROPICAL MOISTURE COVERING THE SOUTHWEST U.S., BUT THE PACNW
WILL NOT SEE A FULL TAP INTO THIS MOISTURE. THESE WAVES, COMBINED
WITH DAYTIME HEATING, WILL RESULT IN SHOWERS AND THUNDERSTORMS OF
VARYING COVERAGES THROUGH SATURDAY. THE MAIN AREA AFFECTED INTO THIS
EVENING WILL BE ACROSS CENTRAL AND EAST-CENTRAL OREGON WITH LESSER
COVERAGES INTO THE BLUES AND WALLOWAS. COVERAGES OF STORMS WILL
INCREASE THURSDAY AND FRIDAY AS THE WAVE EXPECTED LATE THURSDAY INTO
FRIDAY LOOKS TO BE THE STRONGEST OF THE SERIES. THUS WILL PUSH
SCATTERED COVERAGE INTO NORTHEAST OREGON THURSDAY AND ALSO CONTINUE
TO INDICATE A SLIGHT CHANCE OF LINGERING STORMS OVERNIGHT INTO
FRIDAY. THERE IS SOME INDICATION IN THE GFS AND ECMWF MODELS THAT
SOME OF OUR WESTERN ZONES MAY SEE INCREASING DRYING SATURDAY
AFTERNOON. THIS WOULD LIMIT SHOWER AND STORM DEVELOPMENT IN THESE
ZONES. FOR NOW WILL INDICATE AN AREA OF DRYING INTO THE AREA AROUND
THE GORGE, BUT LEAVE SHOWERS/STORMS MENTIONED ELSEWHERE.
TEMPERATURES WILL REMAIN ABOVE SEASONAL, BUT WITH INCREASING
MOISTURE AND CLOUDINESS SHOULD SEE TEMPS COOL A FEW DEGREES. THUS
WILL NOT EXTEND THE CURRENT HEAT ADVISORIES BEYOND THEIR EXPIRATION
THIS EVENING. 90

.LONG TERM...SUNDAY NIGHT THROUGH WEDNESDAY AFTERNOON...AMPLIFIED
MID/UPPER LEVEL RIDGE OF HIGH PRESSURE IS STILL FORECAST TO RELAX
HEIGHTS ON THE NORTHERN FLANK OF THE RIDGE FROM MONDAY THROUGH
WEDNESDAY, BUT OTHERWISE MAINTAIN ITS ORIENTATION ACROSS THE
SOUTHWESTERN UNITED STATES.

SOUTHERLY TRANSPORT OF MID LEVEL MONSOONAL MOISTURE SHOULD REACH A
PEAK ON SUNDAY. DAYTIME SURFACE HEATING WILL DESTABILIZE THE
ATMOSPHERE SUNDAY AFTERNOON/EVENING FOR A CHANCE OF AFTERNOON AND
EVENING THUNDERSTORMS ACROSS THE OCHOCO-JOHN DAY HIGHLANDS, THE
SOUTHERN BLUE MOUNTAINS AND THE WALLOWA MOUNTAINS. MONDAY AND
TUESDAY THE RIDGE LOSES AMPLITUDE OVER THE PACIFIC NORTHWEST IN
RESPONSE TO AN UPSTREAM TROUGH IN THE NORTHEAST PACIFIC. THIS SYSTEM
IS PROGGED TO APPROACH THE COAST ON WEDNESDAY. DAYTIME HIGH
TEMPERATURES WILL REMAIN NEAR TO ABOVE NORMAL IN THE PACIFIC
NORTHWEST WITH HIGHS IN THE LOWER COLUMBIA BASIN OF AROUND 100
DEGREES EACH DAY THROUGH TUESDAY. HOWEVER, HIGHS ON WEDNESDAY WILL
BE MODERATED A BIT BY VIRTUE OF A WEAK MARINE PUSH ON WEDNESDAY.
POLAN

&&

.AVIATION...00Z TAFS...VFR CONDITIONS ARE EXPECTED FOR THE NEXT 24
HOURS. FEW-SCT MID AND HIGH LEVEL CLOUDS FROM THUNDERSTORM ANVIL
BLOWOFF OVER THE OCHOCO-JOHN DAY HIGHLANDS AND CENTRAL OREGON THIS
AFTERNOON WILL BE POSSIBLE AT KDLS, KPDT AND KALW AFTER 22Z. THIS
AFTERNOON EXPECT A REPEAT OF THUNDERSTORMS IN CENTRAL OREGON AFTER
21Z AND HAVE VCTS IN THE TAFS AT KBDN AND KRDM STARTING AT 22Z.
SURFACE WINDS WILL REMAIN BELOW 15 KTS FOR THE NEXT 24 HOURS, EXCEPT
KDLS MAY HAVE SOME GUSTS UP TO 26 KTS THIS AFTERNOON. KRDM AND KBDN
WILL HAVE SUSTAINED NORTHERLY WINDS OF 10-15 KTS FOR THE REMAINDER
THIS AFTERNOON AND UNTIL SUNSET, EXCEPT WHEN THUNDERSTORMS ARE IN
THE VICINITY WHICH MAY PRODUCE OUTFLOW GUST FRONTS WITH VARIABLE
WINDS 20-25 KTS WITH HIGHER GUSTS TO 35 KTS.  POLAN

&&

.FIRE WX...WARM AND DRY CONDITIONS WILL PERSIST AS A RIDGE OF HIGH
PRESSURE REMAINS OVER THE REGION. OVERNIGHT HUMIDITY RECOVERY WILL
BE POOR TO MODERATE. EACH DAY THIS WEEK...THUNDERSTORM CHANCES WILL
INCREASE AND SPREAD NORTH AND EAST AS SEVERAL WEAK DISTURBANCES
INTERACT WITH MONSOON FLOW. MOST THUNDERSTORMS SHOULD STAY SOUTH OF
THE WASHINGTON BORDER UNTIL FRIDAY AND SATURDAY. STORMS THAT DEVELOP
WILL BE A MIXTURE OF WET AND DRY WITH PRECIPITATION RANGING FROM A
FEW HUNDREDTHS OF AN INCH TO AROUND A QUARTER OF AN INCH. RED FLAG
WARNINGS ARE IN EFFECT FOR ABUNDANT LIGHTNING ACROSS CENTRAL OREGON
THROUGH SATURDAY. OVER THE NORTHEAST MOUNTAINS...ONLY ISOLATED
THUNDERSTORMS ARE EXPECTED TODAY. SCATTERED THUNDERSTORMS WILL THEN
BE POSSIBLE ACROSS A LARGER AREA ON THURSDAY...AND RED FLAG WARNINGS
FOR THE NORTHEAST MOUNTAINS BEGIN THURSDAY AFTERNOON. COBB

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  67  98  67  96 /  10  10  10  20
ALW  72  98  72  97 /  10  10  10  20
PSC  65 101  67 100 /   0  10  10  20
YKM  64  98  66  96 /   0   0  10  20
HRI  65 100  66  99 /   0  10  10  20
ELN  60  99  61  98 /   0   0  10  20
RDM  55  94  56  92 /  30  30  30  30
LGD  61  93  59  91 /  20  30  30  30
GCD  61  96  62  94 /  30  30  30  30
DLS  67  96  67  94 /  10  10  10  20

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING UNTIL 11 PM PDT SATURDAY ORZ503-505-506-509>511.

     RED FLAG WARNING FROM 1 PM THURSDAY TO 11 PM PDT SATURDAY
     ORZ050-502-507.

     HEAT ADVISORY UNTIL 9 PM PDT THIS EVENING ORZ044-507.

     RED FLAG WARNING UNTIL 11 PM PDT SATURDAY ORZ049.

WA...RED FLAG WARNING FROM 1 PM THURSDAY TO 11 PM PDT SATURDAY WAZ030.

     HEAT ADVISORY UNTIL 9 PM PDT THIS EVENING WAZ027-029.

     HEAT ADVISORY UNTIL 9 PM PDT THIS EVENING WAZ028.

&&

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

$$

90/99/99/82






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