Area Forecast Discussion
Issued by NWS Pocatello, ID

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000
FXUS65 KPIH 052100
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
200 PM MST FRI FEB 5 2016

.SHORT TERM...TONIGHT THROUGH MONDAY. EARLY AFTERNOON SATELLITE
IMAGERY WAS SHOWING A LOW PRESSURE TROUGH ADVANCING INTO THE NW
COASTAL WATERS. MODELS DRIVE THIS WAVE EAST ALONG THE CANADIAN
BORDER LATE TONIGHT/SATURDAY WITH LIGHT SNOWFALL IMPACTING MAINLY
THE NRN HALF OF THE FORECAST AREA (MUCH LESS AREA AND LIGHTER
AMOUNTS THAN PREVIOUS DAYS FORECASTS...SO TRENDING FURTHER NORTH
WITH THE IMPACTS). AN ASSOCIATED COLD FRONT WILL SWEEP THROUGH THE
SNAKE RIVER PLAIN LATE SATURDAY MORNING WITH INCREASING WSW WINDS
EXPECTED ACROSS THE REGION SATURDAY AFTERNOON AND CONTINUING INTO
THE EARLY EVENING HOURS BEFORE DECOUPLING FROM THE FLOW ALOFT ALONG
WITH AN EASING SURFACE PRESSURE GRADIENT. WINDS LOOK TO REMAIN BELOW
ADVISORY LEVELS AT THIS TIME. AN AMPLIFIED RIDGE THEN BUILDS OVER
THE COASTAL STATES SUNDAY AND MONDAY PROVIDING DRY CONDITIONS ACROSS
THE REGION WHILE PROMOTING VALLEY INVERSIONS AND DETERIORATING AIR
QUALITY. THE MOUNTAINS LOOK TO WARM NICELY EXTENDING INTO THE 40S AT
PLACES LIKE STANLEY AND ISLAND PARK BY MONDAY. HUSTON

.LONG TERM...TUESDAY NIGHT THROUGH NEXT FRIDAY. THE EARLY PART OF
NEXT WEEK WILL BE DOMINATED BY A STRONG RIDGE. SOME INDICATIONS ARE
THAT THIS TYPE OF RIDGE IS VERY RARE FOR THIS TIME OF YEAR. WE ARE
FAIRLY CONFIDENT WITH STRONG INVERSIONS AND LOW CLOUDS...FOG AND/OR
HAZE THROUGH THE PERIOD. WHERE WE CAN GET GAP WINDS WE SHOULD BE
ABLE TO PUSH INTO THE 40S...BUT WHAT IS LIKELY TO HAPPEN IS THAT
MOST VALLEYS STAY IN THE 20-35 DEGREE RANGE. IF YOU WANT A BREAK
FROM THE COLD...HEAD UP INTO THE MOUNTAINS. ABOVE THE INVERSION...WE
ARE EXPECTING 40S AND 50S FOR HIGHS WITH VERY MILD OVERNIGHT
TEMPERATURES. WHILE THAT MAY SEEM NICE FOR SOME...THIS MEANS THERE
ARE INCREASING CONCERNS FOR MELTING SNOW AND EVEN SOME MINOR
FLOODING OR RUNOFF. THERE WOULD ALSO BE SOME CONCERN FOR INCREASING
SLIDE/AVALANCHE DANGER. THE END OF THE WEEK DOES SHOW THE RIDGE
FLATTENING A BIT. WE WILL SEE TEMPERATURES MODERATING A
BIT...COOLING THE MOUNTAINS AND ACTUAL WARMING IN THE VALLEYS AS THE
INVERSIONS WEAKEN. THE MODELS AND ENSEMBLES ARE HAVING A VERY HARD
TIME ON THE DEGREE OF WEAKENING AS SHOWN IN THE LARGE VARIABILITY IN
THE ENSEMBLE DATA. DESPITE THAT...IT DOES LOOK LIKE BY FRIDAY THERE
WILL BE SOME AMOUNT OF INCREASE FOR RAIN AND SNOW ACROSS EASTERN
IDAHO. KEYES
&&

.AVIATION...LOW CLOUDS AND FOG HAVE BEEN SLOW TO CLEAR BUT NOT
EXPECTED IN EASTERN IDAHO. EVERYTHING SUGGESTS THAT BY SOMETIME THIS
EVENING OR OVERNIGHT...WE SHOULD SEE MVFR AND EVEN VFR WEATHER FOR
ALL TAF SITES. WE`VE ALREADY SEEN THAT AT KBYI. KSUN WILL BE ON THE
FENCE AGAIN AS THE LOW CLOUDS ARE NOT TOO FAR SOUTH OF THE AIRPORT
AND COULD EASILY PUSH BACK INTO THE WOOD RIVER VALLEY AS THE WINDS
WEAKEN AND TURN SOUTHERLY. THAT WOULD GO AWAY THOUGH LATE THIS
EVENING AS THE WINDS DO THEIR USUAL SWITCH TO THE NORTHWEST. IT WILL
PROBABLY TAKE THE NEXT STORM DROPPING TOWARD THE STATE TO FINALLY
CLEAR OUT KPIH AND KIDA. WINDS WILL INCREASE TONIGHT AND SATURDAY AS
15-25KT WINDS DEVELOP OVER MOST AREAS WITH HIGHER GUSTS. RIGHT NOW
RAIN OR SNOW CHANCES ARE TOO LOW TO MENTION VCSH AT KSUN OR KIDA.
KPIH AND KBYI COULD SEE A SHOWER OR TWO...BUT THE CHANCE IS EVEN
LOWER AT THOSE AIRPORTS. KEYES
&&

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

$$


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