Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 312146
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
246 PM PDT THU JUL 31 2014

.SHORT TERM...TONIGHT THROUGH SUNDAY...AN UPPER RIDGE WILL CONTINUE
OVER THE WESTERN U.S., WITH AN AXIS LARGELY RUNNING THROUGH NEVADA
INTO IDAHO, TONIGHT AND FRIDAY. THE RIDGE AXIS WILL SLOWLY SHIFT
EAST TO NEAR THE ROCKIES BY SUNDAY. THE UPPER LEVEL FLOW OVER THE
PACNW WILL BE GENERALLY SOUTH TO SOUTHWESTERLY THROUGH EARLY
SATURDAY. THE UPPER FLOW THEN LOOKS TO GRADUALLY SHIFT MORE TO THE
WEST-SOUTHWEST SATURDAY INTO SUNDAY. A FAIRLY MOIST AIR MASS WILL
REMAIN OVER THE REGION TONIGHT INTO SATURDAY. MEANWHILE DISTURBANCES
WITHIN THE UPPER FLOW WILL CAUSE SHOWERS AND THUNDERSTORMS TO
DEVELOP AT TIMES, ESPECIALLY IN THE AFTERNOONS AND EVENINGS. ONE
SUCH WAVE IS MOVING THROUGH EXTREME EASTERN OREGON WHILE ANOTHER
WAVE IS MOVING INTO SOUTHWEST OREGON THIS AFTERNOON. THE FIRST
SYSTEM IS CAUSING STORMS OVER WALLOWA COUNTY AND EASTERN GRANT
COUNTY, AND THE SECOND SYSTEM IS NOW CAUSING STORMS IN DESCHUTES
COUNTY. EXPECT THE STORMS OVER THE EASTERN AREAS TO MOVE GRADUALLY
TOWARDS IDAHO, WHILE THE STORMS OVER DESCHUTES COUNTY WILL MOVE
NORTH ALONG AND PARALLEL TO THE OREGON CASCADES. A FEW OF THESE
SHOWERS/STORMS MAY DRIFT INTO SOUTH-CENTRAL WASHINGTON LATE TONIGHT,
AND WILL MENTION SHOWERS AND STORMS IN THIS AREA OVERNIGHT. THIS
SECOND WAVE WILL MOVE INTO NORTHEAST WASHINGTON FRIDAY AFTERNOON,
BUT THERE SHOULD BE ENOUGH MOISTURE AND INSTABILITY TO CAUSE VARYING
AMOUNTS OF SHOWERS AND STORMS OVER MUCH OF THE AREA FRIDAY AFTERNOON
AND EVENING. CONDITIONS SATURDAY WILL BE RELATIVELY SIMILAR TO
FRIDAY, THOUGH A GRADUAL SHIFT IN THE FLOW ALOFT TO WEST-SOUTHWEST
WILL LEAD TO SOME DRYING OF THE AIR MASS. THUS WILL CONTINUE TO
INDICATE DRY CONDITIONS IN AND NEAR THE COLUMBIA RIVER GORGE WHILE
CONTINUING A MENTION OF SHOWERS/STORMS ELSEWHERE. BY SUNDAY, EXPECT
THE DRYING TO SPREAD OVER A LARGER PORTION OF THE AREA AND WILL ONLY
INDICATE SHOWERS AND STORMS FROM CENTRAL OREGON EAST TO GRANT COUNTY
AND NORTHEAST TO THE BLUES AND WALLOWA COUNTY. TEMPS WILL CONTINUE
ABOVE SEASONAL, BUT WILL BE A BIT COOLER THAN IN RECENT DAYS. 90

.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...THE 12Z GFS AND ECMWF
RUNS SHOW A WEAK PACIFIC SHORT WAVE MOVING THROUGH THE RIDGE SUNDAY
NIGHT, MONDAY AND TUESDAY. SO I HAVE KEPT A SLIGHT CHANCE OF SHOWERS
AND THUNDERSTORMS FOR SUNDAY NIGHT INTO TUESDAY EVENING IN CENTRAL
OREGON AND OVER THE MOUNTAINS OF NORTHEAST OREGON. WEDNESDAY AND
THURSDAY AN AMPLIFYING MID/UPPER LEVEL RIDGE OF HIGH PRESSURE OVER
THE PACIFIC NORTHWEST AND BRITISH COLUMBIA WILL INITIATE A STRETCH
OF DRY AND STABLE WEATHER FOR THE FORECAST AREA FROM TUESDAY NIGHT
THROUGH THURSDAY NIGHT. POLAN

&&

.AVIATION...00Z TAFS...VFR CONDITIONS WILL PREVAIL THROUGH THE NEXT
24 HOURS. EXPECT MOSTLY BKN-OVC HIGH CLOUDS FROM CB THUNDERSTORM
ANVIL DEBRIS IN CENTRAL OREGON AND THE OCHOCO-JOHN DAY HIGHLANDS
BEGINNING LATER THIS AFTERNOON AND SCT-BKN MID LEVEL CLOUDS OVER NE
OREGON AND SE WASHINGTON ASSOCIATED WITH SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS OVER THE BLUE MOUNTAINS, THE ELKHORN
MOUNTAINS AND IN WALLOWA COUNTY THROUGH THIS AFTERNOON INTO THIS
EVENING. THUNDERSTORMS WILL DEVELOP THIS AFTERNOON STARTING AROUND
22Z IN CENTRAL AND EAST CENTRAL OREGON. KBDN AND KRDM HAVE VCTS
BEGINNING AROUND 22Z AND VCTS WILL BE POSSIBLE FOR SEVERAL HOURS
WITH THUNDERSTORMS LIKELY TO BE NEARBY. SUSTAINED WINDS WILL BE
LIGHT UPSLOPE LESS THAN 10 KTS, EXCEPT AT KDLS WHERE WINDS THIS
AFTERNOON WILL BE 12-15 KTS WITH GUSTS TO 20 KTS. POLAN

&&

.FIRE WX...WARM AND DRY CONDITIONS CONTINUE UNDER A RIDGE OF HIGH
PRESSURE WITH OVERNIGHT HUMIDITY RECOVERY POOR TO MODERATE.
THUNDERSTORM CHANCES WILL INCREASE AND SPREAD NORTH AND EAST EACH
DAY THROUGH THE WEEKEND. MOST STORMS 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...NORTH CENTRAL OREGON AND THE NORTHEAST MOUNTAINS THROUGH
SATURDAY. DMH

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  69  97  66  98 /  20  20  20  20
ALW  72  98  70  99 /  20  20  20  20
PSC  67 100  65 100 /  10  20  20  20
YKM  67  97  65  97 /  10  20  20  20
HRI  67  99  65  99 /  10  20  20  20
ELN  62  98  61  99 /  10  20  20  20
RDM  58  93  56  93 /  30  30  30  30
LGD  59  92  59  92 /  30  30  30  30
GCD  62  96  59  96 /  30  30  30  30
DLS  68  95  66  94 /  20  20  20  10

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING UNTIL 11 PM PDT SATURDAY ORZ041-510.

     RED FLAG WARNING UNTIL 11 PM PDT SATURDAY ORZ049-050-502-507.

     RED FLAG WARNING UNTIL 11 PM PDT SATURDAY ORZ503-505-506-509-511.

WA...RED FLAG WARNING UNTIL 11 PM PDT SATURDAY WAZ030.

&&

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

$$

90/99/99/84






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