Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 130925
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
325 AM MDT MON APR 13 2015

.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT.
COMPLEX SHORT TERM FORECAST WITH SEVERAL ITEMS TO CONSIDER. THE
CULPRIT WILL BE A VERY STRONG COLD FRONT WHICH WILL MOVE THROUGH
EASTERN IDAHO TUESDAY MORNING AND USHER IN STRONG WINDS AND VERY
COLD TEMPERATURES BEHIND THE FRONT. EXPECT MOUNTAIN SNOW TUESDAY
AND TUESDAY NIGHT WITH SNOW ALSO LIKELY DEVELOPING IN THE SNAKE
RIVER PLAIN TUESDAY NIGHT AS WELL. STRONG WINDS ARE ALSO LIKELY
BEHIND THE COLD FRONT AND A HIGH WIND WATCH HAS BEEN ISSUED FOR
THE EASTERN MAGIC VALLEY AND SNAKE PLAIN AND SOUTH CENTRAL
HIGHLANDS TUESDAY AFTERNOON. WILL LEAVE THAT OUT AND ALLOW FOR
MORE MODEL RUNS TO DECIDE ON ADVISORIES OR WARNINGS. SNOW AMOUNTS
ARE DIFFICULT AS WELL. THINK HEAVIEST AMOUNTS WILL BE IN SOUTHEAST
MOUNTAINS NEAR UTAH AND WYOMING BORDER. FOR NOW HAVE GENERALLY 1
TO 4 INCHES IN CENTRAL MOUNTAINS AND 2 TO 5 INCHES IN THE SOUTHERN
AND EASTERN HIGHLANDS AND 1 TO 2 INCHES IN SNAKE RIVER PLAIN.
THERE IS THE POTENTIAL FOR HIGHER AMOUNTS IN THE SNAKE PLAIN AND
SOUTHEAST HIGHLANDS BUT DUE TO MODEL DIFFERENCES IN LOCATIONS OF
UPPER LEVEL FEATURES CONFIDENCE IS NOT HIGH WITH SNOW AMOUNT
FORECAST. FOR NOW FORECASTING WIDESPREAD LIGHT ACCUMULATIONS EVEN
AT LOW ELEVATIONS THROUGH TUESDAY NIGHT. LIGHT SNOW WILL LIKELY
CONTINUE WEDNESDAY MORNING AND AFTERNOON IN EASTERN HIGHLANDS
BEFORE ENDING WEDNESDAY EVENING WITH DRY CONDITIONS WEDNESDAY
NIGHT. EXPECT VERY WARM CONDITIONS TODAY WITH TEMPERATURES WELL
ABOVE NORMAL BEFORE THE COLD FRONT TUESDAY DRIVES TEMPERATURES
WELL BELOW NORMAL TUESDAY AND WEDNESDAY. IT APPEARS AS IF IT WILL
BE A BRIEF RETURN TO WINTER CONDITIONS BUT ANYONE TRAVELING
TUESDAY THROUGH WEDNESDAY MORNING IN SOUTHEAST IDAHO COULD
EXPERIENCE SNOW...WINDS OR A COMBINATION OF BOTH.
GK

.LONG TERM...THURSDAY THROUGH NEXT SUNDAY. BY THURSDAY MORNING...THE
CLOSED UPPER LOW MOVES TOWARDS THE FOUR CORNERS AREA. MODELS HAVE
NOT BEEN CONSISTENT WITH THIS AND AT TIMES HAVE WRAP AROUND MOISTURE
VICINITY OF BEAR LAKE THURSDAY MORNING. OTHERWISE...THURSDAY AND
FRIDAY SHOULD BE MOSTLY SUNNY UNDER A HIGH PRESSURE RIDGE. A
DISTURBANCE WILL CROSS NORTHERN IDAHO AND MONTANA SATURDAY WITH
SHOWERS CLIPPING THE UPPER SNAKE HIGHLANDS. THE NEW TWIST HERE IS
THIS DISTURBANCE DROPS SHARPLY ALONG THE DIVIDE ON SUNDAY WITH THE
POSSIBILITY OF SHOWERS OVER THE EASTERN HIGHLANDS FROM ISLAND PARK
TO BEAR LAKE. FORECAST HIGH TEMPERATURES THURSDAY AND FRIDAY ARE
COOLER THAN THE GFS MOS NUMBERS OWING TO NORTHERLY SURFACE WINDS ON
THOSE DAYS. RS

&&

.AVIATION....SOUTHEAST IDAHO REMAINS UNDER A HIGH PRESSURE RIDGE
TODAY WITH WIDESPREAD VFR CONDITIONS. A STRONG COLD FRONT COMES
THROUGH TUESDAY MORNING. THE NAM12 SUGGESTS SOUTH WINDS UP TO 45 KTS
ON THE UPPER THIRD OF THE TERRAIN ABOUT 15 MILES SOUTH OF KPIH
14/09Z TO 14/12Z. THERE MAY BE A RISK OF DAMAGING HIGH WINDS FOR
THOSE FEW HOURS. MOST OF THE DAY LOOKS MORE ADVISORY LEVEL IN THE
SNAKE PLAIN. THERE IS ALSO A SURGE OF COLD AIR AROUND KPIH NEAR
15/00Z THAT MIGHT HELP WIND GUSTS GET ABOVE 40 KTS. JUST FOR GOOD
MEASURE...WE HAVE INCLUDED ISOLATED THUNDERSTORMS FOR BOTH KIDA AND
KPIH TUESDAY AFTERNOON. SNOW LEVEL ALSO DIPS TO 4500-5000 FT MSL
LEVEL IN COLD AIR BE HIND THE FRONT TOMORROW AFTERNOON. THIS ALSO
COULD LOWER CEILINGS TO MVFR RANGE AT KIDA AND KPIH 14/21Z THROUGH
WEDNESDAY MORNING 15/15Z. FOR KBYI...KPIH AND KIDA...MAIN THREAT OF
PRECIPITATION IS TUESDAY NIGHT WITH SNOW LEVELS LOWERING TO VALLEY
FLOOR. A HALF TO ONE INCH ACCUMULATION NOT OUR OF THE
QUESTION...ESPECIALLY WITH CONVECTIVE SHOWERS. RS

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY EVENING
IDZ017-020>022.

&&

$$







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