Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 180222
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
722 PM PDT FRI APR 17 2015

.UPDATE...A VERY WEAK COLD FRONT IS MOVING ACROSS NORTHERN PORTIONS
OF THE CWA THIS EVENING WITH SOME MID AND HIGH CLOUDS. THIS SYSTEM
IS SHOWING NO SIGNS OF PRESENCE OVER OREGON. THIS FRONT HAS A WEAK
UPPER TROUGH ASSOCIATED WITH IT WHICH IS FLATTENING THE UPPER RIDGE
THAT HAS BEEN OVER THE CWA. THE MAIN EFFECT FROM THIS FRONT WILL BE
SLIGHTLY COOLER TEMPERATURES ON SATURDAY WITH MAXIMUM TEMPERATURE
READINGS A FEW DEGREES COOLER THAN TODAY. PRECIPITATION IS NOT
EXPECTED WITH THIS FRONT. THERE MAY ALSO BE A SLIGHT INCREASE IN
WINDS...ESPECIALLY ALONG THE CASCADE EAST SLOPES OF WASHINGTON AND
THROUGH THE EASTERN COLUMBIA RIVER GORGE TONIGHT AND SATURDAY. THE
STRONGEST WINDS WILL BE IN THE KITTITAS VALLEY TONIGHT. HIGH
PRESSURE ALOFT WITH DRY AND WARM CONDITIONS WILL REBUILD OVER THE
REGION ON SUNDAY AND CONTINUE INTO NEXT WEEK. THE NEXT WEATHER
SYSTEM AFTER THAT WILL ARRIVE LATE TUESDAY AND TUESDAY NIGHT INTO
WEDNESDAY WITH A PACIFIC UPPER TROUGH MOVING INTO THE REGION. UNTIL
THEN EXPECT WARM AND DRY CONDITIONS SUNDAY THROUGH TUESDAY. 88

&&

.AVIATION...06Z TAFS...VFR CONDITIONS WITH LIGHT WINDS ARE EXPECTED
AT ALL TAF SITES FOR THE NEXT 24 HOURS. 88

&&

.PREV DISC... /ISSUED 307 PM PDT FRI APR 17 2015/

SHORT TERM...TONIGHT THROUGH MONDAY...A WEAKENING PACIFIC SYSTEM
WILL SWING ACROSS THE PACIFIC NORTHWEST TONIGHT. THIS SYSTEM WILL
BRING A FEW HIGH CLOUDS AND SOME INCREASED WINDS, OTHERWISE IT WILL
HAVE LITTLE IMPACT. UPPER LEVEL HIGH PRESSURE WILL REBUILD ALONG THE
PACNW COAST SATURDAY, THEN SHIFT INLAND THROUGH THE REMAINDER OF
THIS PERIOD. SKIES WILL BE MOSTLY CLEAR WHILE WINDS WILL BE LIGHT AT
NIGHT AND NORTHERLY 5 TO 15 MPH IN THE AFTERNOONS SATURDAY THROUGH
MONDAY. HIGH TEMPS WILL RUN ABOVE SEASONAL WHILE OVERNIGHT LOWS WILL
BE AROUND SEASONAL. 90

LONG TERM...MONDAY NIGHT THROUGH FRIDAY...AN UPPER LEVEL RIDGE WILL
MOVE ACROSS EASTERN WASHINGTON AND OREGON MONDAY NIGHT WITH DRY AND
MILD CONDITIONS. TUESDAY AFTERNOON INCREASING MOISTURE AND
INSTABILITY IN THE SOUTHERLY FLOW BEHIND THE RIDGE MAY TRIGGER A FEW
THUNDERSTORMS...MAINLY IN OREGON. THE BEST INSTABILITY WILL BE IN
CENTRAL OREGON. TUESDAY NIGHT AND WEDNESDAY AN ELONGATED TROUGH WILL
APPROACH THE COAST. THE MODELS (INCLUDING ENSEMBLES) ARE SIMILAR IN
KEEPING A LARGE TROUGH NEAR THE COAST TUESDAY NIGHT THROUGH FRIDAY.
HOWEVER MODELS HAVE BEEN INCONSISTENT WITH LOCATION OF THE DETAILS
WITHIN THE TROUGH...SHOWING SPLIT FLOW AND DIFFERENT POSITIONS AND
DEVELOPMENT OF THE ASSOCIATED UPPER LEVEL LOWS...MOISTURE AND
INSTABILITY FROM RUN TO RUN. I INCREASED POPS ACROSS EASTERN
WASHINGTON AND OREGON WEDNESDAY THROUGH FRIDAY WITH THE MOISTURE AND
INSTABILITY ASSOCIATED WITH THE TROUGH BUT HAVE LOW CONFIDENCE ON
DETAILS...PARTICULARLY LOCATION OF HIGHER POPS. I LEFT LOWER POPS
FRIDAY NIGHT AS BOTH GFS AND ECMWF SHOW A DISTURBANCE PUSHING NORTH
FRIDAY AFTERNOON WITH DECREASING PRECIPITATION BEHIND IT.

TEMPERATURES WILL BE QUITE WARM ON MONDAY AND THEN COOL FOR THE REST
OF THE WEEK AS CLOUDS LIMIT DAYTIME HEATING AND LOWER TEMPERATURES
ALOFT FROM THE TROUGH MOVE CLOSER TO THE AREA. COONFIELD

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  42  70  37  73 /   0   0   0   0
ALW  45  70  42  73 /   0   0   0   0
PSC  40  74  35  75 /   0   0   0   0
YKM  40  72  38  74 /   0   0   0   0
HRI  37  73  33  76 /   0   0   0   0
ELN  41  72  36  76 /   0   0   0   0
RDM  29  72  26  74 /   0   0   0   0
LGD  35  67  30  70 /   0   0   0   0
GCD  34  71  33  74 /   0   0   0   0
DLS  43  78  40  80 /   0   0   0   0

&&

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

&&

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

$$

88/76/88








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