Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 161955
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
155 PM MDT THU APR 16 2015

.SHORT TERM...TONIGHT THROUGH SUNDAY. YESTERDAYS UPPER LOW WAS
POSITIONED NEAR THE 4-CORNERS REGION EARLY THIS AFTERNOON AND IS
EXPECTED TO LIFT SLOWLY NNE THROUGH COLORADO TONIGHT THROUGH
SATURDAY PROVIDING A WEAK THREAT OF MAINLY AFTERNOON INSTABILITY
SHOWERS OVER THE SE CORNER/BEAR LAKE REGION FRIDAY/SATURDAY. THE
MODELS CONTINUE TO SHOW A PAC DISTURBANCE TOPPING THE WEST COAST
RIDGE FRIDAY AFTERNOON WHICH DIGS SSE ACROSS MONTANA SATURDAY
CLIPPING THE NE HIGHLANDS AND PROVIDING THE NECESSARY DYNAMICS AND
SUPPORT FOR SCATTERED SHOWER ACTIVITY. THE GFS IS SHOWING A BAND OF
PRECIPITATION PUSHING DOWN THE SNAKE RIVER PLAIN ASSOCIATED WITH A
NORTHERLY SURFACE CONVERGENCE AREA WHEREAS THE NAM IS DRY. HAVE
SPLIT THE DIFFERENCE HERE...OFFERING UP A SLIGHT CHANCE MENTION OF
SHOWERS WITHIN THE SE SNAKE PLAIN UNDER UPSLOPE CONDITIONS. DRIER
CONDITIONS FOLLOW SUNDAY ALTHOUGH THE BACK EDGE OF THE TROUGH WILL
BE TRAILING OVER THE AREA PROVIDING A WEAKLY SUPPORTIVE ENVIRONMENT
FOR ISOLATED SHOWERS OVER THE MONTANA/WYOMING DIVIDE REGIONS.
TEMPERATURES SHOULD WARM THROUGH FRIDAY/SATURDAY THEN COOL SUNDAY
BEHIND THE EXITING TROUGH. HUSTON

.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY. MODEL AND MODEL ENSEMBLES
PLACE UPPER RIDGING OVER PAC NW AND KEEP SOUTHEAST IDAHO UNDER A
STABLE NORTHWESTERLY FLOW ALOFT. MADE NO MAJOR CHANGES TO CURRENT
FORECAST UNTIL TUESDAY. GFS DROPS A WEAK UPPER WAVE ALONG THE DIVIDE
AND MAY TRIGGER SOME SHOWERS OVER THE CENTRAL MOUNTAINS TUESDAY
AFTERNOON AROUND MAX HEATING. ECMWF SPREADS IT INTO SOUTHEASTERN
HIGHLANDS AS WELL. BOTH GFS AND ECMWF DEVELOP A CUT-OFF LOW OFF THE
CALIFORNIA COAST AND ARE AT ODDS WITH EACH OTHER WITH REGARDS TO ITS
TRACK AND INTENSITY AROUND TUESDAY NIGHT. THE GFS PROJECTS THE LOW
TO LIFT ACROSS NV/UT WEDNESDAY WHILE THE ECMWF FLOATS IT ACROSS THE
US/MEXICO BORDER. BOTH MODELS HOWEVER DEVELOP ANOTHER UPPER LOW OFF
THE COAST AND DRIVE IT INTO THE DESERT SOUTHWEST THURSDAY AND
FRIDAY. BOTH THE ECMWF AND GFS KEEP PRECIP CHANCES ALIVE AFTER MID-
WEEK...BUT DUE TO A GREAT DEAL OF UNCERTAINTY IN THEIR ENSEMBLE
MEMBERS...HAVE MADE ONLY MINOR TWEAKS TO POPS IN THE EXTENDED
PERIODS. HINSBERGER
&&

.AVIATION...EXPECT CONTINUED VFR CONDITIONS UNDER UPPER RIDGING.
WINDS GENERALLY WILL BE FROM THE NORTH ACROSS THE SNAKE PLAIN WITH
LIGHT UP-VALLEY WINDS AT KSUN THIS AFTERNOON. HINSBERGER
&&

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

$$


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