Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 230521 AAA
AFDPDT

AREA FORECAST DISCUSSION...UPDATED AVIATION DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1020 PM PDT FRI MAY 22 2015

.UPDATE...ONE LAST AREA OF STRONGER THUNDERSTORMS ARE MOVING
THROUGH NORTHERN BENTON COUNTY AT THIS TIME AS OTHER SHOWERS AND
THUNDERSTORMS ARE ENDING. LARGE UPPER TROUGH REMAINS OVER THE WEST
WITH WRAP AROUND MOISTURE OVER OREGON AND NEXT UPPER LEVEL LOW IS
MOVING SOUTH OVER VANCOUVER ISLAND AND WILL CONTINUE INTO THE AREA
OVERNIGHT. I EXPECTED THUNDERSTORMS TO END...BUT SOME SHOWERS WILL
CONTINUE OVER THE EASTERN PORTIONS OF THE FORECAST AREA THROUGH
MORNING. 93

&&

.PREV DISCUSSION... /ISSUED 400 PM PDT FRI MAY 22 2015/

SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT...LOW PRESSURE TO THE
SOUTH WAS PUSHING ABUNDANT MOISTURE NORTH AND INTO THE TWO STATE
AREA THIS AFTERNOON THAT WILL PERSIST INTO THIS EVENING WITH SHOWERS
AND THUNDERSTORMS EXPECTED. PWATS WERE AROUND AN INCH AND SOME
THUNDERSTORMS WILL CONTINUE PRODUCING HEAVY RAIN ESPECIALLY IN THE
FLASH FLOOD WATCH AREAS THAT INCLUDE ALONG THE EAST SLOPES OF THE
WASHINGTON CASCADES AND OVER THE BLUE/WALLOWA/JOHN DAY HIGHLANDS. IN
ADDITION HAIL WILL BE POSSIBLE WITH THE STRONGEST STORMS. THE STORMS
WILL DECREASE AFTER SUNSET AND THE BULK OF THE PCPN SHOULD BE OVER
THE CENTRAL PORTIONS OF THE AREA TOWARD MORNING. ANOTHER ROUND OF
SHOWERS/TSRA ARE EXPECTED TO DEVELOP AND EXPAND IN COVERAGE SATURDAY
AFTERNOON AND CONTINUE INTO SATURDAY NIGHT. AS THE LOW DRIFTS AWAY
FROM THE REGION DRIER AIR WILL MOVE INTO THE TWO STATE AREA SUNDAY.
HOWEVER A DISTURBANCE IS FORECAST TO MOVE ACROSS THE AREA SUNDAY
AFTN THAT WILL COMBINE WITH DAYTIME HEATING TO PRODUCE SHOWERS AND
ISOLD TSRA AGAIN OVER PORTIONS OF THE REGION INTO SUNDAY NIGHT.

AFTERNOON TEMPS WILL BE NEAR NORMAL SATURDAY WITH A WARMING TREND
EXPECTED INTO SUNDAY.

LONG TERM...MEMORIAL DAY THROUGH FRIDAY.  MODELS ARE IN BETTER
AGREEMENT BUT CONTINUE TO HAVE DISCREPANCIES ON THE PLACEMENT OF THE
UPPER LOW MOVING SOUTH ACROSS WA/OR EARLY IN THE PERIOD.  IN
GENERAL...THERE WILL BE A SLIGHT CHANCE TO A CHANCE OF SHOWERS AND
THUNDERSTORMS ON MEMORIAL DAY THROUGH TUESDAY.  THIS COULD CONTINUE
INTO WEDNESDAY DEPENDING IF THE GFS AND CANADIAN VERIFY WHICH KEEP
THE LOW EAST OF THE CASCADES UNLIKE THE ECMWF WHICH PUSHES IT
EASTWARD.  MODELS HAVE A HISTORY OF POOR PLACEMENT OF CLOSED LOWS
AND TEND TO FORCE LOWS OUT OF THE REGION TOO FAST.  KEEPING THIS IN
MIND...WILL FOLLOW THE SLOWER SOLUTIONS OF GFS/CANADIAN.  THE LONG
DURATION OF THE BROAD UPPER LEVEL TROUGH AND CYCLONIC FLOW MAY
FINALLY TRANSITION TO A DRIER RIDGE PATTERN BY THE END OF THE WORK
WEEK.  WILL LOWER POPS AND KEEP ABOVE SEASONAL TEMPERATURES IN THE
FORECAST BY FRIDAY.  WISTER

AVIATION...06Z TAFS. VFR CONDITIONS WILL PREVAIL OVER THE NEXT 24
HOURS.  SCT-BKN CLOUDS WITH CIGS 050-080 AGL WILL CONTINUE OVERNIGHT
WITH SOME LIGHT RAIN. THERE CONTINUES TO BE SOME ISOLATED TSTMS
ALONG THE BLUE MOUNTAIN FOOTHILL FROM KPDT TO KALW THROUGH 08Z.
ADDITIONAL SHOWERS AND ISOLATED TSTMS ARE POSSIBLE MAINLY OVER THE
MOUNTAINS ON SATURDAY.  WESTERLY WINDS WILL CONTINUE AT 15 TO 25 KT
AT THE KDLS.  93

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  54  75  51  73 /  60  40  20  10
ALW  56  77  55  77 /  60  40  20  10
PSC  58  82  54  82 /  50  40  10  10
YKM  59  81  55  81 /  40  40  10  10
HRI  57  80  53  78 /  50  40  10  10
ELN  56  80  54  80 /  30  40  20  10
RDM  44  70  39  72 /  20  20  10  10
LGD  54  70  50  70 /  70  40  30  30
GCD  49  71  45  72 /  70  30  20  10
DLS  57  70  54  79 /  20  20  10  10

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...FLASH FLOOD WATCH UNTIL 9 PM PDT THIS EVENING FOR ORZ049-050-502-
     503-505-506.

WA...FLASH FLOOD WATCH UNTIL 9 PM PDT THIS EVENING FOR WAZ030-520.

&&

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

$$

93/85/93


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