Area Forecast Discussion
Issued by NWS Pendleton, OR

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS66 KPDT 020400
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
900 PM PDT TUE SEP 1 2015

.SHORT TERM...TONIGHT THROUGH WEDNESDAY AFTERNOON...SATELLITE
WATER VAPOR LOOP SHOWS A DEEPENING LONG WAVE OFFSHORE, WHICH WILL
PUSH A COLD FRONT INLAND TONIGHT AND THROUGH THE FORECAST AREA
DURING DAYLIGHT HOURS TOMORROW. THE FRONT WILL BRING INCREASING
CLOUDINESS OVERNIGHT AND WEDNESDAY. OROGRAPHIC LIFT AND DYNAMIC
LIFT ALONG THE FRONT WILL COMBINE TO INCREASE THE CHANCE OF
MEASURABLE RAIN FROM SHOWERS ALONG AND AHEAD OF THE FRONT ON
WEDNESDAY. THUS MOST OF THE MEASURABLE RAIN IS EXPECTED AT HIGHER
TERRAIN ELEVATIONS WITH THE FRONT. POLAN

&&

.AVIATION...06Z TAFS...VFR CONDITIONS WILL OCCUR FOR THE NEXT 24
HOURS. INCREASING HIGH CLOUDS TONIGHT. LOWERING CIGS OVERNIGHT
AS A COLD FRONT MOVES SLOWLY THROUGH AFTER DAYBREAK THROUGH
WEDNESDAY AFTERNOON. WHILE LIGHT RAIN SHOWERS ARE POSSIBLE AFTER
08Z AT MOST TAF LOCATIONS DID NOT INCLUDE IN TAFS, EXCEPT AT KPDT
AND KALW, WHERE OROGRAPHIC LIFT AND DYNAMIC LIFT ALONG THE FRONT
COMBINE TO INCREASE CHANCE OF SHOWERS. WINDS INCREASE TOMORROW
BEHIND FRONT.  POLAN

&&

.PREVIOUS DISCUSSION... /ISSUED 325 PM PDT TUE SEP 1 2015/

SHORT TERM...TONIGHT THROUGH FRIDAY...THE BROAD UPPER LEVEL TROUGH
OVER THE AREA WILL BE TRANSITIONING TO A DEEP TROUGH CENTERED OVER
THE PACIFIC NORTHWEST BY FRIDAY. THIS TRANSITION WILL BEGIN LATE
TONIGHT AND WEDNESDAY AS SHORTWAVE ENERGY DROPS DOWN THE CANADIAN
COAST TOWARDS VANCOUVER ISLAND. THIS WILL ADVANCE A COLD FRONT INTO
THE FORECAST AREA EARLY WEDNESDAY THEN SLOWLY MOVE EASTWARD THROUGH
THE DAY AND OVERNIGHT. THERE WILL BE SOME PRECIPITATION ASSOCIATED
WITH THE FRONT AND A TENTH TO TWO TENTHS COULD BE POSSIBLE MAINLY
OVER THE EASTERN MOUNTAINS AND ALONG THE CASCADES. VERY LITTLE
PRECIPITATION IS EXPECTED IN THE COLUMBIA BASIN BUT THE FOOTHILLS OF
THE BLUE MOUNTAINS EAST OF HERMISTON AND PASCO COULD SEE A FEW
HUNDRETHS. TEMPERATURES WILL BEGIN TO COOL ON WEDNESDAY AS THE COLD
FRONT PASSES THROUGH THE AREA. THIS WILL BE THE BEGINNING OF SOME
UNSEASONABLY COOL WEATHER THROUGH THE REST OF THE WEEK. THE TROUGH
WILL DEEPEN FURTHER ON THURSDAY WITH MOST OF THE ENERGY REMAINING
WEST OF THE CASCADES. THIS ENERGY WILL BEGIN TO SHIFT INTO EASTERN
OREGON AND WASHINGTON ON FRIDAY ALONG WITH THE COOLEST AIR. THE
POTENTIAL IS THERE FOR THIS TO BECOME A MAJOR RAIN PRODUCER LATE
FRIDAY ESPECIALLY OVER THE EASTERN PORTION OF THE FORECAST AREA.
HAVE BEGUN TO INCREASE THE CHANCE OF PRECIPITATION FOR THIS TIME
PERIOD.

LONG TERM...FRIDAY NIGHT THROUGH TUESDAY...AN UPPER LEVEL LOW WILL
MOVE EAST FROM CENTRAL OREGON FRIDAY AFTERNOON TO IDAHO SATURDAY.
SHOWERS AND THUNDERSTORMS WILL DECREASE OVERNIGHT FRIDAY. THE ECMWF
IS SLOWER IN MOVING THE SYSTEM OUT (SATURDAY EVENING) AND PROVIDES
MORE PRECIPITATION THAN THE GFS (SATURDAY MORNING). ENSEMBLE SPREAD
COVERS BOTH SOLUTIONS SO KEPT A FEW LINGERING SHOWERS OVER THE
EASTERN MOUNTAINS SATURDAY NIGHT AND SUNDAY. SUNDAY NIGHT AND
MONDAY DRY NORTHWESTERLY FLOW WILL BE OVER EASTERN WASHINGTON AND
OREGON WITH DRY CONDITIONS AND MODERATING TEMPERATURES. MONDAY NIGHT
AND TUESDAY ANOTHER LOW WILL DROP FROM THE GULF OF ALASKA TO
VANCOUVER ISLAND. THIS WILL BRING SHOWERS TO THE CASCADES BY
TUESDAY. THE FRONT AHEAD OF THE LOW MAY BRING A FEW SHOWERS TO THE
NORTHEAST MOUNTAINS TUESDAY NIGHT AS WELL.

SATURDAY AND SUNDAY TEMPERATURES WILL BE 5 TO 10 DEGREES BELOW
NORMAL FOR THIS TIME OF YEAR AND IT WILL BE QUITE COLD IN THE
MOUNTAINS AT NIGHT DEPENDING ON CLOUD COVER. LOW TEMPERATURES IN THE
MOUNTAIN VALLEYS COULD FALL TO FREEZING OR BELOW.   COONFIELD

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  54  72  47  69 /  10  30  10  10
ALW  59  74  53  70 /  10  30  10  10
PSC  59  77  49  73 /  10  20   0  10
YKM  52  70  44  67 /  10  10  10  10
HRI  59  75  49  72 /  10  20  10  10
ELN  50  70  45  70 /  20  20  10  10
RDM  43  69  36  67 /  10  20  10  10
LGD  50  68  41  68 /  10  30  20  10
GCD  47  74  40  70 /  10  20  20  10
DLS  59  75  52  74 /  20  20  10  10

&&

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

&&

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

$$

99/91/76



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.