Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 151442
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
842 AM MDT FRI AUG 15 2014

.UPDATE...UPPER LOW CENTERED OVER WESTERN WASHINGTON PER WV SAT
IMAGERY THIS MORNING. WEAK SHORTWAVE ROTATING THROUGH IDAHO THIS
MORNING PRODUCING SHALLOW CUMULUS DECK OVER CENTRAL PORTIONS OF
FCST AREA. A FEW WEAK SHOWERS HAVE DEVELOPED ALONG FOOTHILLS OF
CENTRAL MTNS EXTENDING INTO THE SNAKE PLAIN. HAVE NUDGED
SKY/POP/QPF UPWARDS SLIGHTLY FOR THIS MORNING TO MEET THIS TREND.
OTHERWISE EXPECT SLIGHTLY STRONGER SHORTWAVES ROUNDING THROUGH
NRN OREGON THIS MORNING TO EJECT ACROSS THE REGION THIS AFTERNOON
AS LOW SLOWLY SHIFTS NORTHEAST INTO THE PANHANDLE. MODELS STILL
WEAK ON CONVECTIVE DEVELOPMENT FOR THIS AFTERNOON WITH DRY SLOT
MID LEVEL FLOW EXPECTED TO WORK ACROSS THE REGION AROUND THE LOW.
WILL KEEP ISOLATED POPS THIS AFTERNOON HIGHER ELEVATIONS. NO OTHER
UPDATES ANTICIPATED. DMH

&&

.PREV DISCUSSION... /ISSUED 215 AM MDT FRI AUG 15 2014/

DISCUSSION...UPPER LOW OVER WASHINGTON HAS MOVED VERY LITTLE OVER
THE LAST 24 HOURS. THE FLOW OVER SOUTHEAST IDAHO IS BECOMING MORE
SOUTHWESTERLY AS THE DOWNSTREAM SUBTROPICAL RIDGE WEAKENS. THIS
SHIFT IS INTRODUCING SOME DRIER AIR OVER THE REGION AND PUSHING
MONSOONAL MOISTURE OFF TO THE EAST. CONCERN TODAY WILL BE IMPULSES
AROUND THE PERIPHERY OF THE UPPER LOW WHICH MAY TRIGGER SHOWERS AND
THUNDERSTORMS. NAM/WRF MODELS ARE CURRENTLY SUGGESTING DEVELOPMENT
TO BE CONFINED TO THE SOUTHEASTERN HIGHLANDS AND POSSIBLY THE
CENTRAL MOUNTAINS. THE LOW WILL FINALLY BEGIN TO OPEN UP AND SHIFT
EASTWARD LATE THIS AFTERNOON ALONG THE CANADIAN BORDER. THUS
MAINTAINING SOME POP MENTION OVER THE NORTHERN PORTIONS OF THE
FORECAST AREA THROUGH TONIGHT.

UPPER RIDGING WILL BEGIN TO BUILD BACK INTO THE GREAT BASIN ON
SATURDAY USHERING IN MUCH DRIER WEATHER WITH TEMPERATURES REACHING
INTO THE UPPER 80S EARLY NEXT WEEK. MODELS AGAIN DEVELOP ANOTHER
UPPER LOW OFF THE OREGON COAST AS EARLY AS SUNDAY WHILE MAINTAINING
UPPER RIDGING OVER SOUTHEAST IDAHO. ECMWF SUGGEST SOME PRECIP WILL
DEVELOP OVER THE REGION ON MONDAY AS THE NEWLY FORMED UPPER LOW
SHIFTS INLAND...BUT GFS REMAINS DRIER WITH A MORE SOUTHWARD TRACK OF
THE UPPER LOW. BOTH MODELS BREAK DOWN THE UPPER RIDGE AND HINT AT A
DEEPENING TROUGH COMING OUT OF THE NORTHWEST. THE ECMWF IS MUCH
FASTER WITH THE TIMING OF THE TROUGH...BRINGING IT OVER IDAHO BY
TUESDAY NIGHT...WHILE THE GFS HOLDS OFF UNTIL THURSDAY NIGHT. HAVE
TRENDED THURSDAY AND FRIDAY A BIT WETTER AND COOLER. HINSBERGER

AVIATION...A DISTURBANCE IS EXPECTED TO EJECT FROM THE NRN OREGON
LOW ACROSS CNTRL IDAHO TODAY RESULTING IN A CHANCE OF THUNDERSTORMS
ACROSS THE CNTRL AND ERN HIGHLANDS PER THE LATEST NUMERICAL FORECAST
CHARTS. RESIDUAL LOW LEVEL MOISTURE NOTED ON THE MORNING
OBSERVATIONS MAY HELP TO BOOST THE POTENTIAL FOR CONVECTION ACROSS
THE AREA OVER AND ABOVE WHAT THE MODELS ARE CURRENTLY INDICATING. WE
WILL EVALUATE WHETHER SOME VICINITY TSTM VERBIAGE IS REQUIRED IN THE
MORNING TERMINAL FORECAST PACKAGE...BUT FOR NOW...VFR SCT CONDITIONS
ARE EXPECTED TO PREVAIL. HUSTON

FIRE WEATHER...A CLOSED UPPER LOW WAS POSITIONED OVER NORTH-CNTRL
OREGON EARLY THIS MORNING WITH A DRIER SW FLOW ALOFT OVERSPREADING
SRN IDAHO. A WELL DEFINED DISTURBANCE WAS ROTATING THROUGH THE BASE
OF THE LOW AND SHOULD EJECT NE THROUGH CNTRL IDAHO TODAY RESULTING
IN A CHANCE OF THUNDERSTORMS ACROSS THE CNTRL AND ERN MOUNTAINS.
ELEVATED LOW LEVEL MOISTURE WAS LINGERING OVER THE REGION PER THE
LATEST OBSERVATION SET WHICH MAY HELP TO BOOST THE POTENTIAL FOR
CONVECTION ACROSS THE AREA THIS AFTERNOON. THE UPPER LOW LIFTS INTO
NE WASHINGTON LATE THIS AFTERNOON AND THEN INTO SRN CANADA BY NOON
SATURDAY AS AN INCREASINGLY DRY AND STABLE SW TO WEST FLOW
OVERSPREADS SRN IDAHO. MOSTLY DRY CONDITIONS PREVAIL THROUGH THE
WEEKEND AND INTO THE EARLY PART OF NEXT WEEK AS A MODEST RIDGE OF
HIGH PRESSURE EXPANDS ACROSS THE REGION. THE MODELS CONTINUED THE
TREND OBSERVED YESTERDAY AFTERNOON SHOWING A FAIRLY ROBUST TROUGH
DIGGING INTO THE NW STATES WEDNESDAY AFTERNOON/THURSDAY RESULTING IN
A FAIRLY DEEP SOUTHERLY FETCH ACROSS THE REGION WITH A RENEWED
THREAT OF MONSOON THUNDERSTORM ACTIVITY FRIDAY AND SATURDAY. HUSTON

&&

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

$$







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