000
FXUS66 KPDT 101521
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
820 AM PDT MON MAR 10 2014

.SHORT TERM...TODAY AND TONIGHT...UPPER LEVEL TROUGH IS MOVING INTO
THE PACIFIC NORTHWEST THIS MORNING. THIS IS PUSHING THE MAIN
MOISTURE PLUME EAST AND OUT OF THE FORECAST AREA AFTER HAVING
PRODUCED SOME SIGNIFICANT RAIN OVER PORTIONS OF EASTERN OREGON
OVERNIGHT...OVER AN INCH OF RAIN IN SOME PLACES. IT WILL ALSO USHER
IN COOLER BREEZY CONDITIONS TODAY AND BE UNSTABLE SO EXPECT SHOWERS
THROUGHOUT THE FORECAST AREA AND EVEN A SLIGHT CHANCE OF
THUNDERSTORMS MAINLY OVER THE EASTERN PORTION OF THE FORECAST AREA.
THE UPPER LEVEL TROUGH WILL EXIT THE REGION OVERNIGHT WITH HIGH
PRESSURE BUILDING IN FROM THE WEST. SHOWERS WILL DECREASE DURING THE
EVENING THEN END AFTER MIDNIGHT.


&&

.HYDROLOGY...THE HEAVY RAIN HAS ENDED ACROSS THE REGION...BUT IT
WILL TAKE SEVERAL MORE HOURS FOR WATER TO GET THROUGH THE SYSTEM.
THE FLOOD WATCH WILL BE ALLOWED TO EXPIRE WITH RIVER FLOOD WARNINGS
CONTINUING THROUGH THE DAY.  THE CONDITIONS WILL BE EVALUATED FOR
THE FLOOD ADVISORY AND MAY POSSIBLE BE EXTENDED THROUGH THE
AFTERNOON. ML


&&

.PREV DISC... /ISSUED 410 AM PDT MON MAR 10 2014/

SHORT TERM...TODAY THROUGH WEDNESDAY...A WET PACIFIC WEATHER SYSTEM
WILL CONTINUE TO CROSS THE REGION AND FORECAST AREA THIS MORNING
WITH STEADY RAINFALL THROUGH THE MORNING HOURS. WATER VAPOR
SATELLITE IMAGERY IS SHOWING A PLUME OF VERY MOIST TROPICAL AIR FROM
WESTERN OREGON AND WASHINGTON SOUTHWEST ACROSS THE PACIFIC TO ABOUT
140W/20N. THIS IS CONVEYING RAINFALL NORTHEAST ACROSS THE CWA...
ESPECIALLY IN THE SOUTHEAST TWO THIRDS OF THE CWA. IN ADDITION A
SURFACE LOW PRESSURE AREA IS CURRENTLY MOVING ACROSS THE EASTERN
FORECAST AREA HELPING TO ENHANCE THE STEADY RAINFALL. EXPECT THE
SURFACE LOW TO MOVE TO THE SOUTHEAST TO SOUTHWEST IDAHO BY 12Z AND A
COLD FRONT TO MOVE THROUGH THE CWA BETWEEN 12Z AND 18Z. ONCE THE
COLD FRONT MOVES ON BY THE PRECIPITATION WILL BECOME MORE SHOWERY IN
NATURE. THERE WILL BE SOME INSTABILITY THIS AFTERNOON AS WELL SO
WILL INCLUDE A SLIGHT CHANCE OF THUNDER FROM CENTRAL OREGON
NORTHEAST ACROSS THE JOHN DAY HIGHLANDS AND THE BLUE MOUNTAINS AND
FOOTHILLS. ANY CLEARING BEFORE THAT TIME WILL ONLY HELP TO
DESTABILIZE THE ATMOSPHERE MAKING IT MORE FAVORABLE FOR THUNDERSTORM
DEVELOPMENT. ALSO...AN UPPER TROUGH WILL MOVE ACROSS THE FORECAST
AREA THIS AFTERNOON WITH COLDER AIR ALOFT MOVING IN TO ALSO HELP
DESTABILIZE THE ATMOSPHERE. A NORTHWEST TO NORTHERLY FLOW WILL THEN
DEVELOP WITH DRIER AIR MOVING IN FROM THE WEST THIS EVENING AND
OVERNIGHT CAUSING THE SHOWERS TO DISSIPATE FROM WEST TO EAST WITH
THE BEST CHANCES TONIGHT OVER THE NORTHEAST MOUNTAINS. CONDITIONS
WILL CONTINUE TO DRY OUT ON TUESDAY AND WEDNESDAY AS AN UPPER RIDGE
BUILDS INTO THE REGION. TUESDAY WILL BE COOLER BUT THEN A WARMING
TREND WILL BEGIN IN RESPONSE TO THE BUILDING RIDGE ON WEDNESDAY WITH
SLIGHTLY ABOVE NORMAL TEMPERATURES BY WEDNESDAY AFTERNOON. LOCALLY
BREEZY TO WINDY CONDITIONS WILL PREVAIL THIS AFTERNOON AND EVENING
BEHIND THE COLD FRONT. THE WINDS WILL THEN DIMINISH OVERNIGHT
TONIGHT WITH LIGHT WINDS FROM TUESDAY ONWARD. 88

LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...A RIDGE OF HIGH
PRESSURE WILL BE OVER THE AREA THROUGH FRIDAY MORNING.  A FEW
SHORTWAVE TROUGHS WILL PASS TO THE NORTH OF THE REGION ON WEDNESDAY
NIGHT AND EARLY THURSDAY MORNING WITH THE MAIN EFFECT BEING SLIGHTLY
INCREASED WINDS.  OTHERWISE...A DRY AND WARM PERIOD IS EXPECTED
THROUGH AT LEAST FRIDAY MORNING.  HEADING INTO THE WEEKEND...A
STRONGER TROUGH IS EXPECTED TO APPROACH THE REGION WITH ALL LONG
RANGE MODELS AGREEING ON TIMING.  HOWEVER...THERE IS SOME
DISAGREEMENT BETWEEN THE GFS...DGEX AND ECMWF AS TO WHERE THE BEST
MOISTURE ADVECTION WILL OCCUR.  HAVE OPTED TO BLEND IN WITH THE DGEX
AND GFS SOLUTIONS WITH RAIN AND SNOW EXPECTED FOR THE WASHINGTON AND
OREGON CASCADES AS WELL AS THE BLUE MOUNTAINS OF NORTHEAST OREGON.
IT IS EXPECTED THAT SNOW LEVELS DURING THE PASSAGE OF THE SYSTEM
WILL BE AROUND 4500 TO 5500 FEET.  ALSO...FRONTAL BOUNDARY PASSAGE
LATE FRIDAY EVENING INTO EARLY SATURDAY MORNING MAY INCREASE THE
WINDS SOME.  BY SATURDAY EVENING INTO SUNDAY...A STRONGLY AMPLIFIED
RIDGE WILL PASS OVER THE REGION AHEAD OF ANOTHER SYSTEM ARRIVING
SUNDAY NIGHT.  SIMILAR TO THE PRIOR SYSTEM...THIS NEXT SYSTEM WILL
BRING A CHANCE OF RAIN AND SNOW MAINLY TO THE WASHINGTON AND OREGON
CASCADES AS WELL AS THE OREGON BLUE MOUNTAINS.  CONFIDENCE WITH THIS
SYSTEM IS NOT VERY HIGH GIVEN DIFFERENCES OF TIMING AND STRENGTH OF
THE SYSTEM.  HIGH TEMPERATURES ARE FORECASTED TO BE IN THE 50S TO
MID 60S.  OVERNIGHT LOWS ARE FORECASTED TO BE IN THE MID 30S TO MID
40S WITH UPPER 20S TO MID 30S IN THE MOUNTAINS.  BIEDA

AVIATION...12Z TAFS...A COLD FRONT IS PRESENTLY SWEEPING ACROSS THE
REGION THIS MORNING WITH S-SW WINDS AT 10 TO 15 KTS AHEAD OF IT AND
W-NW WINDS OF 15 TO 25 KTS BEHIND IT.  RAIN ASSOCIATED WITH THE
FRONT WILL REDUCE CIG DOWN TO BTWN 3500 TO 5000 FT AGL AND VIS DOWN
TO 3-5 SM AT TIMES.  A STRAY LIGHTNING STRIKE OR TWO IS ALSO
POSSIBLE...THOUGH CONFIDENCE IS NOT HIGH ENOUGH TO MENTION IN TAFS.
IT IS EXPECTED THAT THE FRONT WILL BE THRU THE REGION BY 11/00Z WITH
WINDS TAPERING OFF AFT 11/06Z.  SKIES SHOULD CLEAR AFT 11/06Z WITH
WINDS AOB 10 KTS.  BIEDA

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  52  34  50  31 /  70  20   0   0
ALW  54  35  51  35 /  80  20   0   0
PSC  58  34  57  33 /  30  10   0   0
YKM  56  30  53  31 /  20   0   0   0
HRI  57  34  56  32 /  50  10   0   0
ELN  53  30  50  31 /  20  10   0   0
RDM  44  26  52  24 /  40  10   0   0
LGD  44  29  46  30 / 100  30   0   0
GCD  42  30  48  30 /  90  30   0   0
DLS  54  34  55  33 /  40  10   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...FLOOD WATCH UNTIL 11 AM PDT THIS MORNING
     ORZ049-050-502-503-505>508.

WA...NONE.
&&

THREAT INDEX
TODAY : YELLOW
TUESDAY : GREEN
WEDNESDAY : GREEN

GREEN: NONE OR LIMITED NEED FOR WATCHES, WARNINGS, OR ADVISORIES.
YELLOW: A FEW WATCHES, WARNINGS, OR ADVISORIES POSSIBLE OR IN EFFECT.
RED: NUMEROUS WATCHES, WARNINGS, OR ADVISORIES POSSIBLE OR IN EFFECT.

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

$$

91/76/76