Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 210235
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
835 PM MDT MON OCT 20 2014

.UPDATE...VIGOROUS UPPER TROUGH HAS MOVED INLAND WITH DEEP SOUTH
FLOW OVER MOST OF EAST IDAHO AHEAD OF ADVANCING SHORTWAVE. SAT
IMAGERY SHOWS COLDEST TOPS ASSOCIATED WITH STRONGEST ENERGY STILL
OVER OREGON BUT CLOUD COVER FILLING IN OVER WESTERN PORTIONS OF
FORECAST AREA. RADAR SHOWED 20-30DBZ ECHOES OVER LEE EDGE OF
CENTRAL MOUNTAINS EARLY THIS EVENING AND ADDITIONAL SIMILAR ECHOES
ADVANCING ON CENTRAL MOUNTAIN ZONES. SFC DEWPOINT DEPRESSIONS
STILL DEEP SO QUESTION OF HOW MUCH PRECIP ACTUALLY REACHING GROUND
BUT CANT RULE OUT IN HIGHER ELEVATIONS. MODELS REMAIN SIMILAR
EARLY THIS EVENING WITH WEAK MAINLY ISOLATED SHOWERS IN WESTERN
HALF OF FORECAST AREA BEFORE 06Z THEN FILLING IN BETWEEN 06Z-12Z.
THIS ON TRACK WITH EARLIER RUNS AND CURRENT FORECAST. HAVE NUDGED POPS
UPWARD SLIGHTLY THIS EVENING FOR CURRENT RADAR AND SAT TRENDS. NO
OTHER UPDATES ANTICIPATED. DMH



&&

.PREV DISCUSSION... /ISSUED 152 PM MDT MON OCT 20 2014/

SHORT TERM...LOW PRESSURE TROUGH WILL MOVE INLAND LATE TONIGHT AND
BRING RAIN SHOWERS TO THE CENTRAL MOUNTAINS BEFORE TUESDAY MORNING.
ASSOCIATED SURFACE FRONT WILL REACH STANLEY ABOUT 5-6 AM TUESDAY. A
QUARTER TO HALF INCH OF RAIN IS POSSIBLE IN WESTERN CUSTER AND BUTTE
COUNTY WITH THE DEEPER MOISTURE TRACKING TO THE NORTHEAST. SNOW
LEVELS DIP TO ABOUT 8700 FEET...1-2 INCHES ACCUMULATION POSSIBLE
BETWEEN 7800-8500 FEET...UP TO 5 INCHES ON THE HIGHEST PEAKS. THE
MAIN DISTURBANCE TRACKS NORTHEAST TOWARDS MONTANA...WHILE THE
ASSOCIATED SURFACE FRONT TRAILS ACROSS THE SNAKE PLAIN DURING THE
AFTERNOON HOURS. IT WILL BE ON THE WINDY SIDE DURING THE AFTERNOON.
A WIND ADVISORY HAS BEEN ISSUED FOR THE LOWER SNAKE PLAIN. TUESDAY
HIGHS ONLY IN THE UPPER 50S TO LOWER 60S. SHOWERS ARE EXPECTED TO
END TUESDAY NIGHT...FOLLOWED BY A WEAK HIGH PRESSURE RIDGE ON
WEDNESDAY WITH LIGHTER WINDS AND MAINLY MIDDLE AND HIGH LEVEL CLOUDS
ACROSS THIS AREA. RS

LONG TERM...THU NIGHT THROUGH NEXT MON NIGHT. 500MB 5-WAVE PROG
INDICATES A SLOW CHANGE FROM BETWEEN A COASTAL LOW AND GREAT PLAINS
HIGH WITH A LOW AMPLITUDE PATTERN...TO TROUGHING OVER THE NORTHERN
ROCKIES AND NORTHERN GREAT BASIN. THUS EXPECT WETTER CONDITIONS BY
THE WEEKEND WITH EVEN THE LONGWAVE DEVELOPING A TROUGH. BOTH THE GFS
AND THE ECMWF ARE IN FAIRLY GOOD AGREEMENT ON AN UPPER LEVEL
TROUGH/SURFACE FRONTAL PASSAGE SAT NIGHT/SUN...SO HAVE INCREASED
POPS AND CLOUDS FOR THOSE PERIODS AND THE OTHER TWO SURROUNDING THEM
TO REFLECT UNCERTAINTY IN TIMING. THIS SHOULD ALSO BRING SOME WINDY
CONDITIONS...BUT CURRENTLY APPEARS BELOW ADVISORY CRITERIA. MESSICK

AVIATION...INCOMING COLD FRONT ARRIVES SHORTLY AFTER MIDNIGHT IN
THE WEST AND SPREADS EASTWARD DURING THE EARLY MORNING. GOOD CHANCE
OF AIRDROME CLOSURE AT KSUN TUE MORNING WITH THE AMOUNT OF INCOMING
MOISTURE DUE TO CIG. ELSEWHERE...CIGS SHOULD STAY VFR THROUGH AT
LEAST THE MORNING. VSBY SHOULD ALSO STAY GOOD VFR WITH ONLY -RA TYPE
OF PRECIPITATION EXPECTED BELOW 8000 FT ELEVATION. WIND SHIFT WITH
THE FRONT AND VERY WINDY CONDITIONS EXPECTED DURING THE MORNING AND
EARLY AFTERNOON...THOUGH PEAKING SHORTLY AFTER 21/1800Z SO INCLUDED
IN TAFS AFTER THE 21/00Z ARE ISSUED. MESSICK

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM NOON TO 6 PM MDT TUESDAY IDZ021.

&&

$$






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