Area Forecast Discussion
Issued by NWS Pocatello, ID

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000
FXUS65 KPIH 181932
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
133 PM MDT THU SEP 18 2014

.SHORT TERM...TONIGHT THROUGH FRIDAY. REGIONAL SATELLITE IMAGERY WAS
SHOWING A SPLITTING UPPER TROUGH OVER THE PAC COAST EARLY THIS
AFTERNOON. WEAK TO MODEST INSTABILITY AND MOISTURE AVAILABILITY ARE
EXPECTED TO COMBINE WITH DEEP LAYER SHEAR EXTENDING FROM NE NEVADA
THROUGH SW MONTANA THIS AFTERNOON TO PRODUCE SCATTERED STRONG
THUNDERSTORM DEVELOPMENT. PRECIPITABLE VALUES OF .75 TO 1.00 INCHES
WILL SUPPORT BRIEF HEAVY RAIN...ALTHOUGH THE FLASH FLOODING THREAT
APPEARS TO BE MINIMAL AT THIS POINT DUE TO THE SPEED WITH WHICH THE
CELLS WILL LIKELY BE MOVING. WINDEX VALUES UP TO 40 COMBINED WITH
AMBIENT BREEZY CONDITIONS MAY PRODUCE WIND GUSTS OF 40 TO 50 MPH
WITH THUNDERSTORMS THIS AFTERNOON/EARLY EVE. AT THIS POINT...THE
FAVORED AREAS FOR STRONGEST DEVELOPMENT APPEARS TO BE THE MACKAY TO
DILLON CORRIDOR AND MALTA TO CHESTERFIELD CORRIDOR. THE SRN PORTION
OF INCOMING TROUGH SPLITS FROM THE NRN BRANCH FLOW TONIGHT AS IT
DRIFTS SOUTH INTO CNTRL CALIFORNIA. THE LOCATION OF LOW AND
ASSOCIATED DYNAMICS/MOISTURE WILL PROMOTE ONGOING SHOWERS/CONVECTION
OVER SE IDAHO LATE TONIGHT. THE NRN BRANCH TROUGH AXIS SWEEPS
THROUGH THE REGION FRIDAY BRINGING A DISTINCT DRYING TREND TO THE
AREA. HUSTON

.LONG TERM...FRIDAY NIGHT THROUGH NEXT THURSDAY. THE UPPER LOW
DRIFTS SOUTH INTO THE SRN CALIFORNIA COASTAL AREA SATURDAY BEFORE
LIFTING NE INTO NEVADA LATE SATURDAY NIGHT WITH ATTENDING
PRECIPITATION SHIELD OVERSPREADING SE IDAHO SUNDAY AND CONTINUING
THROUGH MONDAY AS THE LOW WORKS EAST INTO WYOMING (PER THE GFS). THE
ECMWF (00Z) HAS A SIMILAR DEPICTION BUT IS MUCH MORE PROLIFIC WITH
PRECIPITATION PRODUCTION. FAVORING THE GFS SOLUTION IN THIS REGARD.
DRY CONDITIONS ARE EXPECTED BEHIND THE EXITING LOW AS THE NEXT PAC
TROUGH SPREADS INTO THE NW COASTAL WATERS TUESDAY/WEDNESDAY. BY
THURSDAY...THE MODELS BEGIN TO SHOW THE TROUGH WORKING INLAND...THE
ECMWF ADVERTISING ANOTHER SPLITTING TROUGH AND THE GFS SOMEWHAT MORE
CONSOLIDATED INITIALLY (THURSDAY) BUT QUICKLY TRENDING TOWARD A
SPLITTING SOLUTION FRIDAY. SPLITTING THE DIFFERENCE HERE (NO PUN
INTENDED) UNTIL MODELS SHOW SOME CONSOLIDATION...THUS CONTINUING
CLIMO-LOOKING PRECIP POTENTIAL THURSDAY/THURSDAY NIGHT. HUSTON
&&

.AVIATION...A STRONG UPPER JET IS BISECTING THE THE REGION THIS
AFTERNOON...WHICH IS PRODUCING SCATTERED SHOWERS AND
THUNDERSTORMS...BUT CONDITIONS WILL REMAIN VFR. EXPECT SOUTHWEST
WINDS GUSTING 20 TO 25 KTS IN THE SNAKE PLAIN THROUGH SUNSET.
TOMORROW WILL BE DRIER WITH ANOTHER BREEZY AFTERNOON.
&&

.FIRE WEATHER...SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED
THROUGHOUT THE REST OF TODAY. BREEZY CONDITIONS WILL REMAIN IN THE
SNAKE PLAIN THROUGH SUNSET. OVERNIGHT TONIGHT...SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS WILL REMAIN...MAINLY IN ZONE 413.
OTHERWISE...A DRYING TREND IS EXPECTED FRIDAY THROUGH AT LEAST
SUNDAY AFTERNOON.
&&


.PIH WATCHES/WARNINGS/ADVISORIES...NONE.
&&

$$








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