Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 260206
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
806 PM MDT SAT OCT 25 2014

.SHORT TERM...TONIGHT THROUGH TUESDAY. A SECOND UPDATE THIS EVENING
TO ADD SHOWERS IN THE ERN MAGIC VALLEY. SEE PREVIOUS DISCUSSION
BELOW. HUSTON

WINDS HAVE FALLEN JUST BELOW ADVISORY LEVELS ACROSS INL EARLY THIS
EVENING. HOWEVER...A STRONG SURFACE TROUGH WAS DEEPENING ACROSS NE
NEVADA AND IS EXPECTED TO LIFT RAPIDLY NE THROUGH THE SNAKE PLAIN
LATE THIS EVENING WITH AN ATTENDING FRONT AND STRONG WINDS PUSHING
THROUGH THE MAGIC VALLEY AND SNAKE PLAIN BETWEEN 9 PM AND 2 AM. THUS
HAVE ADJUSTED THE CURRENT WIND ADVISORY TO ACCOUNT FOR THIS
DEVELOPMENT. 18Z MODEL RUNS WERE SHOWING A SLIGHT THREAT OF
CONVECTION CONCOMITANT WITH THE FRONTAL PASSAGE LATE THIS EVENING
AND HAVE ADDED A MENTION OF PRECIPITATION WITHIN THE SNAKE PLAIN
LATE THIS EVENING. SEE PREVIOUS DISCUSSION BELOW. HUSTON

AWAITING THE ARRIVAL OF THE NEXT STORM SYSTEM WHICH IS MOVING
ONSHORE THIS AFTERNOON. WINDS ARE PICKING UP AHEAD OF THIS SYSTEM
AND ARE HIGHER THAN MODELS SUGGESTED. WINDS ARE REACHING ADVISORY
LEVELS IN THE POCATELLO AREA AND WILL ISSUE A WIND ADVISORY FOR
THE POCATELLO AREA UNTIL 8PM TONIGHT. MODELS ARE INDICATING
MARGINAL WIND ADVISORY LEVEL WINDS FOR SUNDAY AFTERNOON ACROSS
PORTIONS OF THE SNAKE PLAIN. GIVEN THAT WINDS ARE STRONGER TODAY
THAN MODELS SUGGESTED...BELIEVE WIND ADVISORY SPEEDS LIKELY FOR
SUNDAY AFTERNOON ACROSS FROM THE RAFT RIVER AREA TO POCATELLO TO
ARCO/IDAHO FALLS. ALSO BELIEVE THERE WILL BE SOME CLEARING IN THE
SKIES ACROSS THE SNAKE PLAIN DURING THE AFTERNOON BECAUSE OF THE
STRONG WINDS. SOME AREAS OF BLOWING DUST IS POSSIBLE AS WELL. MUCH
COLDER AIR WILL ACCOMPANY THIS SYSTEM. SUNDAY HIGH TEMPS WILL BE
20 TO 25 DEGREES COLDER THAN TODAY. STILL EXPECT RAIN/SNOW SHOWERS
ACROSS THE MOUNTAINS AND HIGHLANDS BEGINNING TONIGHT AND
PERSISTING THROUGH SUNDAY EVENING. SNOW LEVELS WILL BE AROUND 5500
FEET IN THE CENTRAL MOUNTAINS TO AROUND 6500 FEET IN THE EASTERN
HIGHLANDS. WARM SOIL TEMPS WILL PROBABLY LIMIT SNOWFALL AMOUNTS.
THEREFORE NOT EXPECTING MUCH SNOW ACCUMULATION IN THE
EASTERN/SOUTHERN HIGHLANDS ON SUNDAY. HOWEVER STILL EXPECT 2 TO 6
INCHES FROM GALENA SUMMIT TO THE STANLEY AREA. DRIER WEATHER WILL
RETURN FOR MONDAY AND TUESDAY. VALLE

.LONG TERM...TUE NIGHT THROUGH NEXT SAT NIGHT. TROUGH PASSAGE
EXPECTED DURING THE EARLY PART OF THIS TIME HAS SHIFTED TO FARTHER
NORTH IN ITS PATTERN...LEAVING POPS 10 TO 15 PERCENT LOWER THAN
EXPECTED YESTERDAY AND BOTH THE GFS AND ECMWF DEVELOP STRONG RIDGING
DURING THE MIDDLE PART OF THIS FORECAST FROM WED THROUGH FRI. THE
ECMWF IS QUICKER TO BREAK DOWN THIS RIDGE ON SAT/SAT NIGHT. HAVE
COMPROMISED BETWEEN THE TWO SOLUTION IN THIS DIVERGENT PART...AND
HAD TO LEAVE SOME POPS IN DURING THE RIDGE SITUATION TO STAY IN
COORDINATION WITH SURROUNDING OFFICES. WITH THE TROUGH PASSING
FARTHER TO THE NORTH...THE WIND IS ALSO NOT FORECAST TO BE AS STRONG
AS PREVIOUS THINKING EITHER...AND TEMPERATURES STAY WARMER AND THUS
WARM MORE DURING THE RIDGE TIME PERIOD...MORE THAN 10 DEG F ABOVE
NORMAL HIGHS FOR THIS TIME OF YEAR. MESSICK
&&

.AVIATION...MID-LEVEL CIGS TO DEVELOP DURING THE EVENING TONIGHT
WITH VERY LITTLE RAIN EXPECTED. CIGS SHOULD LOWER TO BELOW 6000 FT
BY AIRDROME OPENING ON SUN MORNING. KSUN IS THE MOST AT RISK FOR
MARGINAL VFR...BUT STATISTICS SAY NO...SO HAVE LEFT IT JUST ABOVE
MARGINAL VFR FOR CIGS. SHOULD STAY AS ALL -RA EVENT...SO NO IMPACT
TO VSBY. WIND WILL SUBSIDE AND SHIFT DURING THE LATE AFTERNOON/EARLY
EVENING...THEN ANOTHER SHIFT DURING SUN MORNING. WIND SHOULD STAY
ELEVATED IN THE THREE VALLEY AIRPORTS...BUT KSUN HAS THE TRICKIEST
AND LOWEST CONFIDENCE FORECAST FOR WIND IN THAT IT IS USUAL THAT THE
FRONT WILL PASS OVERHEAD AND LEAVE WIND LIGHT AND VARIABLE...BUT
WITH THE LATE NIGHT CLOUDS AND STRONG WINDS...THE INVERSION MAY NOT
SET UP AND ALLOW THE ATMOSPHERE TO DE-COUPLE. MESSICK
&&

.PIH WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 2 AM MDT SUNDAY MORNING IDZ020-021.
WIND ADVISORY FROM 9 PM TO 2 AM MDT SUNDAY MORNING IDZ017.

WIND ADVISORY FROM NOON TO 8 PM MDT SUNDAY IDZ020-021.
&&

$$










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