Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 020443 AAA
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
935 PM PDT WED APR 1 2015

.UPDATE...SHOWERS WERE PERSISTING OVER OUR EXTREME NORTHERN ZONES
AND THE GRIDS WERE UPDATED TO REFLECT THIS ALONG WITH THE SKY
CONDITIONS. MEANWHILE THE LARGE AREA OF ISOLD SHOWERS OVER THE
REGION WERE DECREASING WITH THE LACK OF DAYTIME HEATING BUT MAY
LINGER OVER THE AREA MOUNTAINS OVERNIGHT. LOW TEMPS ARE EXPECTED TO
DIP TOWARD FREEZING OR LOWER OVER PORTIONS OF THE REGION AND THE
FREEZE WARNING WILL BE ALLOWED TO CONTINUE. OTHERWISE THE PRESENT
SHORT TERM FORECAST APPEARS ON TRACK FOR NOW.

&&

.PREV DISC... /ISSUED 349 PM PDT WED APR 1 2015/

SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT...ISOLATED TO SCATTERED
SHOWERS CONTINUE TO DEVELOP ACROSS THE AREA THIS AFTERNOON. THE
INSTABILITY DRIVING THESE SHOWERS HAS THE POTENTIAL TO BE LOCALLY
STRONG ENOUGH TO CAUSE STRAY THUNDERSTORMS AS WELL. EXPECT THESE
SHOWERS AND ANY STORMS TO PERSIST INTO THE EVENING. THE
THUNDERSTORMS SHOULD END AROUND SUNSET. NORTHWEST FLOW WILL KEEP
SOME SHOWERS GOING OVER THE INTERIOR MOUNTAINS AND NEAR THE CASCADE
CREST OVERNIGHT INTO WEDNESDAY. SNOW LEVELS WILL REMAIN LOW, BUT
ACCUMULATIONS WILL BE LIGHT AND LOCALIZED. EXPECT TO SEE DECENT
CLEARING OVER NORTH CENTRAL OREGON AND SOUTH CENTRAL WASHINGTON
AFTER SUNSET. THIS CLEARING, COMBINED WITH A DRY AIR MASS AND
DECREASING WINDS, WILL LEAD TO GOOD RADIATIONAL COOLING. OVERNIGHT
LOW TEMPS IN THE YAKIMA VALLEY, KITTITAS VALLEY AND NORTH CENTRAL
OREGON ARE EXPECTED TO RUN BETWEEN 28 AND 34 DEGREES. THOUGH ZONE
COVERAGE OF FREEZING TEMPS IN THESE AREAS WILL NOT BE COMPLETE,
ISSUES FOR SENSITIVE VEGETATION WILL STILL BE POSSIBLE. THUS HAVE
ISSUED FREEZE WARNINGS FOR THE ABOVE MENTIONED ZONES. ANOTHER
PACIFIC SYSTEM WILL APPROACH THE REGION FRIDAY. PRECIP WILL REACH
THE CASCADE EAST SLOPES FRIDAY MORNING AND THE NORTHEAST OREGON
MOUNTAINS BY FRIDAY AFTERNOON. THE SYSTEM`S COLD FRONT WILL SWING
ACROSS THE REGION FRIDAY NIGHT BRINGING VARYING PRECIP CHANCES TO
MUCH OF THE AREA. 90

LONG TERM...SATURDAY THROUGH WEDNESDAY...AN UPPER LEVEL LOW WILL
SLOWLY MOVE SEWD ONTO THE PACIFIC NORTHWEST COAST AND ACROSS THE
REGION THROUGH THE FORECAST PERIOD.  UNSETTLED WEATHER WILL OCCUR AS
A RESULT WITH A CHANCE FOR SHOWERS AND MOUNTAIN SNOW SHOWERS
EXPECTED THROUGH TUESDAY OVER THE TWO-STATE AREA.  AS THE UPPER
LEVEL LOW APPROACHES THE REGION SUNDAY AFTERNOON AND EVENING...MID
AND UPPER LEVEL COOLING WILL ALLOW FOR SOME INSTABILITY OVER CENTRAL
OREGON AND PORTIONS OF THE JOHN DAY HIGHLANDS.  HAVE RETAINED THE
SLIGHT CHANCE OF THUNDERSTORMS FROM PRIOR SHIFT WITH SOME
ADJUSTMENTS BASED UPON A BLEND OF MODEL GUIDANCE INSTABILITY
PARAMETERS.  THE UPPER LOW WILL OPEN UP ON MONDAY AND DIG SEWD
ACROSS SOUTHERN OREGON AND NORTHERN CALIFORNIA THROUGH TUESDAY NIGHT
WITH THE MOST FAVORABLE DYNAMICS IN OUR FORECAST AREA FAVORING
CENTRAL OREGON.  SUFFICIENT INSTABILITY REMAINS ON MONDAY TO
CONTINUE A MENTION OF A SLIGHT CHANCE OF THUNDERSTORMS THROUGH THE
HIGHLANDS OF CENTRAL TO NORTHEAST OREGON.  A SHORTWAVE RIDGE WILL
BUILD IN BEHIND THE TROUGH AS IT EXITS THE AREA ON WEDNESDAY
HERALDING A START TO A WARMING AND DRYING TREND.  DAYTIME HIGH
TEMPERATURES DURING THE PERIOD WILL BE IN THE LOWER 40S TO LOWER 50S
ALONG THE HIGHLANDS AND NEAR 60 IN THE LOWER COLUMBIA BASIN SATURDAY
THROUGH MONDAY.  HIGH TEMPERATURES WILL GRADUALLY WARM A DEGREE OR
TWO PER DAY TUESDAY AND WEDNESDAY.  LOW TEMPERATURES WILL BE BELOW
FREEZING EACH NIGHT ALONG THE HIGHLANDS OF WASHINGTON AND
OREGON...AND NEAR TO SLIGHTLY ABOVE FREEZING IN THE LOWER COLUMBIA
BASIN. BIEDA

AVIATION...00Z TAFS...VFR CONDITIONS WILL PREVAIL DURING THE
FORECAST PERIOD.  PASSING CONVECTIVE SHOWERS WITH CIG AOA 6K FT AGL
WILL CONTINUE THRU 02/04Z...WITH BEST CHANCE MAINTAINED AT SITES
WITH A VICINITY MENTION GIVEN THE HIT OR MISS NATURE.  WEST WINDS
BTWN 10 TO 20 KTS WITH HIGHER GUSTS WILL CONTINUE THRU SUNSET
TONIGHT BEFORE DROPPING TO 5 TO 15 KTS.  GUSTY WEST WINDS BTWN 10 TO
20 KTS WILL RETURN AFT 02/18Z.  OTHERWISE...CIG WILL GRADUALLY RISE
AS STORM SYSTEM MOVES OUT AFT 02/04Z.  BIEDA

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  34  56  33  61 /  20  10  10  10
ALW  38  58  37  63 /  20  10  10  10
PSC  33  62  32  65 /  20  10   0  10
YKM  32  59  30  60 /  20  10  10  20
HRI  34  60  30  64 /  20  10   0  10
ELN  33  58  29  57 /  20  10  10  20
RDM  20  53  20  57 /  20   0   0  20
LGD  30  51  25  58 /  20  20  10  10
GCD  28  53  28  58 /  20  20  10  10
DLS  39  61  35  61 /  20  10  10  20

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...FREEZE WARNING UNTIL 9 AM PDT THURSDAY ORZ510.

WA...FREEZE WARNING UNTIL 9 AM PDT THURSDAY WAZ026-027.

&&

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

$$

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