Area Forecast Discussion
Issued by NWS Pendleton, OR

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000
FXUS66 KPDT 170225
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
725 PM PDT TUE SEP 16 2014

.UPDATE...NEXT UPSTREAM SYSTEM IS CURRENTLY BEGINNING TO MOVE INTO
SOUTHWEST OREGON AT THIS TIME. HOWEVER MOSAIC RADAR IMAGERY IS NOT
SHOWING MUCH PRECIPITATION WITH IT MOVING IN WITH THE SYSTEM. GFS
HOLDS OFF ON PRECIPITATION UNTIL LATE WEDNESDAY MORNING AND
BEGINNING AS THUNDERSTORMS OVER THE CENTRAL OREGON CASCADE EAST
SLOPES WITH JUST SHOWERS ELSEWHERE ALONG THE EAST SLOPES BY 18Z
WEDNESDAY. THE NAM IS A LITTLE WETTER AND FASTER WITH THE SYSTEM BUT
GIVEN THE LACK OF PRECIPITATION ON THE RADARS AND THE DRYNESS OF THE
AIR CURRENTLY OVER THE CWA AM LEANING TOWARD THE GFS SOLUTION. THE
PRECIPITATION ADVANCES SLOWLY ACROSS THE CWA WEDNESDAY AFTERNOON AND
EVENING REACHING THE NORTHEAST MOUNTAINS BY 06Z WEDNESDAY EVENING. A
SECONDARY SURGE OF MOISTURE MOVES INTO THE REGION ON THURSDAY WITH A
BETTER CHANCE FOR SHOWERS (AND THUNDERSTORMS OVER SOUTHERN AND
EASTERN AREAS) THURSDAY AFTERNOON AND EVENING AS THE UPPER TROUGH
PASSES OVER THE CWA. HIGH PRESSURE WILL RETURN ON FRIDAY AND REBUILD
WITH A WARMING TREND FOR THE WEEKEND. 88

&&

.AVIATION...06Z TAFS...VFR CONDITIONS ARE EXPECTED FOR THE NEXT 24
HOURS. THERE WILL BE MID AND HIGH CLOUDS BETWEEN MAINLY 150-250 FT
TONIGHT AND WEDNESDAY. AT THIS TIME IT LOOKS LIKE ANY THUNDERSTORMS
WILL STAY TO THE WEST OF KRDM AND KBDN ON WEDNESDAY AFTERNOON. WINDS
WILL REMAIN GENERALLY LIGHT AND 15 KTS OR LESS THROUGH THE PERIOD. 88

&&

.PREV DISC... /ISSUED 230 PM PDT TUE SEP 16 2014/

SHORT TERM...TONIGHT THROUGH FRIDAY...HIGH PRESSURE CONTINUES TO
LINGER OVER THE REGION WITH A LARGE TROUGH OF LOW PRESSURE OFF THE
COAST. THIS TROUGH IS SLOWLY MOVING CLOSER TO THE COAST AND WILL
BEGIN TO SPREAD HIGH AND MID LEVEL CLOUDS OVER THE FORECAST AREA
OVERNIGHT AND WEDNESDAY. WE WILL CONTINUE TO BE UNDER THE RIDGE
WEDNESDAY SO LOOKING FOR ONE MORE HOT DAY. THE APPROACHING TROUGH
WILL CREATE A LITTLE INSTABILITY LEADING TO SOME SHOWERS ALONG THE
EAST SLOPES OF THE CASCADES LATE WEDNESDAY AND OVERNIGHT. A SLIGHT
CHANCE OF THUNDERSTORMS WILL OCCUR FOR THE OREGON PORTION OF THE
EAST SLOPES. ALSO LOOKING AT SOME INSTABILITY OVER SOUTHEAST OREGON
AND IDAHO WEDNESDAY NIGHT. SOME OF THIS COULD CLIP THE FAR EASTERN
ZONES WEDNESDAY NIGHT AND EARLY THURSDAY FOR SOME POSSIBLE SHOWERS.
ON THURSDAY THE TROUGH WILL BEGIN TO PASS OVER THE FORECAST AREA BUT
WILL BE WEAKENING AND SPLITTING APART AS IT DOES. THERE WILL BE SOME
ISOLATED TO SCATTERED SHOWERS POSSIBLE FOR THE FORECAST AREA ALONG
WITH SOME THUNDERSTORMS OVER THE EAST AND SOUTH PORTIONS OF THE
FORECAST AREA DURING THE AFTERNOON AND EVENING. THE TROUGH WILL
DEPART AND RIDGE OF HIGH PRESSURE WILL BEGIN REBUILDING OVER THE
REGION ON FRIDAY.

LONG TERM...FRIDAY NIGHT THROUGH MONDAY MORNING...A RIDGE OF HIGH
PRESSURE WILL BE OVER THE PACIFIC NORTHWEST FOR THE ENTIRE PERIOD.
THIS WILL RESULT IN DRY CONDITIONS FRIDAY NIGHT THROUGH EARLY
MONDAY. DAYTIME TEMPERATURES WILL BE WARM WITH HIGHS IN THE 80S
LOWER ELEVATIONS/70S MOUNTAINS. IT WILL COOL OFF AT NIGHT WITH CLEAR
SKIES. LOWS IN THE 40S TO LOWER 50S ARE EXPECTED IN THE LOWER
VALLEYS WITH MOSTLY 30S TO LOWER 40S MOUNTAINS. 78

..MONDAY AFTERNOON THROUGH WEDNESDAY MORNING...SOME DISCREPANCIES
IN THE MODELS DURING PERIOD AS THE LATEST GFS MODEL WANTS TO BUILD
AN EXPANSIVE UPPER LEVEL RIDGE OVER THE AREA WITH 500MB HEIGHTS
RISING TO 591DM BY WEDNESDAY MORNING. MEANWHILE THE LATEST ECWMF
MODEL WOULD ALLOW A STRONG LOW PRESSURE SYSTEM TO SWEEP A MOISTURE
LADEN FRONT INTO THE REGION BY WEDNESDAY MORNING. IT REMAINS TO BE
SEEN WHICH SOLUTION WILL ULTIMATELY PAN OUT...HOWEVER AT THIS TIME
DECIDED TO HEDGE LOW ON POPS TO REMAIN CONSISTENT WITH THE PREVIOUS
FORECAST. OTHERWISE...TEMPERATURES ARE EXPECTED TO REMAIN AT LEAST 5
TO 10 DEGREES ABOVE AVERAGE THROUGH THE PERIOD. 77

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  56  86  59  81 /   0   0  10  20
ALW  60  85  64  82 /   0   0  10  20
PSC  53  86  60  83 /   0   0  10  20
YKM  55  84  58  79 /   0  10  20  20
HRI  52  87  58  83 /   0   0  10  20
ELN  58  85  59  79 /   0  10  20  20
RDM  45  83  48  74 /   0  10  20  20
LGD  51  88  54  79 /  10   0  10  20
GCD  53  88  53  77 /  10  10  10  20
DLS  56  84  61  79 /  10  10  20  20

&&

.PDT WATCHES/WARNINGS/ADVISORIES...

OR...NONE.
WA...NONE.
&&

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

$$

88/78/88








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