Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 262020
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
220 PM MDT SUN JUL 26 2015

.SHORT TERM...SIGNIFICANT CHANGES EXPECTED IN THE WEATHER OVER
THE NEXT 12 TO 24 HOURS RESULTING IN A MYRIAD OF POTENTIAL
IMPACTS. SHARP TROUGH IS CRASHING ASHORE OF THE BRITISH
COLUMBIA AND WA COAST AS OF THIS WRITING. THIS TROUGH
WILL CONTINUE TO STRENGTHEN AS IT SWEEPS THROUGH THE REGION
THROUGH LATE MONDAY AND INTO EARLY TUESDAY. A COLD FRONT
ATTENDANT TO THE TROUGH WILL ZIP FROM WEST TO EAST ACROSS THE
FORECAST AREA TOMORROW...PASSING THROUGH THE CENTRAL MOUNTAINS
AROUND SUNRISE AND THROUGH THE SNAKE RIVER PLAIN BY MID
MORNING...THEN EXITING INTO WYOMING DURING THE MID AFTERNOON.
MULTIPLE IMPACTS ANTICIPATED IN ASSOCIATION THE PASSAGE OF THIS
FRONT. THE MOST WIDESPREAD IMPACTS WILL COME IN THE FORM OF
WINDS...WITH GUSTS IN THE 20-30 MPH RANGE EXPECTED FOR MOUNTAIN
PEAKS...WITH GUSTS IN THE 40-45 MPH RANGE EXPECTED ACROSS THE
SNAKE RIVER PLAIN DEVELOPING DURING THE LATE MORNING HOURS. THIS
WILL POTENTIALLY CAUSE BLOWING DUST ISSUES...AS WELL AS CREATE
CHOP ON AREA LAKES AND DIFFICULT TRAVEL FOR HIGH PROFILE VEHICLES.
THUS WILL HOIST A WIND ADVISORY FOR SNAKE PLAIN ZONES TO ACCOUNT
FOR THIS IMPACT. WINDS WILL GRADUALLY DIMINSISH TOMORROW NIGHT.

A SECONDARY IMPACT IN ASSOCIATION WITH THE FRONTAL BOUNDARY WILL
BE THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS. INCREASED POPS
TO INCLUDE THIS POTENTIAL FOR THE SNAKE PLAIN...WITH ISOLATED
SHOWERS AND STORMS NEAR THE UT BORDER INCREASING TO LIKELY SHOWERS
WITH ISOLATED TO SCATTERED THUNDERSTORMS FOR THE UPPER SNAKE
HIGHLANDS. SOME CONCERN OVER THE UPPER SNAKE HIGHLANDS FOR THE
DEVELOPMENT OF A STRONG THUNDERSTORM OR TWO...AS THE COMBINATION
OF ENOUGH INSTABILITY...MOISTURE AND DEEP LAYER SHEAR WILL
BE REALIZED IN ADVANCE OF THE FRONT. THIS POTENTIAL WARRANTED THE
INCLUSION OF A MENTION OF GUSTY WINDS AND SMALL HAIL IN THE
FORECAST GRIDS OVER THIS AREA.

A THIRD IMPACT IN ASSOCIATION WITH THIS SYSTEM WILL BE A DRAMATIC
DROP IN TEMPERATURES BEHIND THE FRONT...WITH TEMPERATURES
PLUMMETING TO 10-20 DEGREES BELOW NORMAL. A FEW RECORD LOW MAX
TEMPERATURES MAY BE CHALLENGED BOTH MONDAY AND TUESDAY...ALONG
WITH LOWS FLIRTING WITH RECORDS BOTH TUESDAY AND WEDNESDAY
MORNING...ESPECIALLY ACROSS THE SNAKE RIVER PLAIN. RECORD LOWS
BOTH MORNINGS ARE GENERALLY IN THE LOW 40S. WIDESPREAD SHOWERS
WITH AN ISOLATED THUNDERSTORM EXPECTED ACROSS THE CENTRAL
MOUNTAINS DEVELOPING AFTER MIDNIGHT TONIGHT AND CONTINUING THROUGH
MUCH OF MONDAY BEFORE TAPERING OFF MONDAY EVENING INTO MONDAY
NIGHT. ALSO EXPECT SIMILAR COVERAGE ACROSS THE UPPER SNAKE
HIGHLANDS...BUT FOR A SHORTER DURATION...LATER TOMORROW AFTERNOON
INTO TOMORROW EVENING. SNOW LEVELS DROP TO NEAR 9000 FT BY
TOMORROW AFTERNOON...SO LIGHT SNOW ACCUMULATIONS ANTICIPATED
ABOVE 9000 FT ACROSS THE CENTRAL MOUNTAINS. PREPARE FOR COLD AND
DAMP CONDITIONS IF PLANNING ON RECREATING IN THESE AREAS OVER THE
NEXT 48 HOURS OR SO.

.LONG TERM...UPPER TROUGH QUICKLY SCAMPERS OUT OF THE AREA ON
TUESDAY...LEADING TO A QUICK TRANSITION TO ZONAL FLOW...AND THUS A
FORMIDABLE WARMING AND DRYING TREND WILL COMMENCE BY
WEDNESDAY...WITH TEMPERATURES CONTINUING TO WARM THROUGH THE WEEK.
IN FACT...EXPECT TEMPERATURES TO CLIMB TO NEAR TO ABOVE AVERAGE BY
FRIDAY. UPPER RIDGE EXPECTED TO BECOME ESTABLISHED OVER THE FOUR
CORNERS BY THIS WEEKEND. MOIST MONSOONAL FLOW AROUND THIS RIDGE
WILL INCRINGE ON SE IDAHO...AND OPEN THE DOOR FOR ISOLATED SHOWERS
AND THUNDERSTORMS...MAINLY OVER HIGH TERRAIN AREAS FOR NEXT
WEEKEND. AD/GK


&&

.AVIATION...LARGE UPPER TROF AND COLD FRONT CONTINUE TO ADVANCE
TOWARD EASTERN IDAHO.   MAIN EFFECT AT TAF SITES WILL BE WINDS WITH
15 TO 25 KNOT SUSTAINED EXPECTED MONDAY AT BYI...PIH AND IDA.  GUSTS
IN THE 30 TO 40 KNOT RANGE EXPECTED.   HAVE VICINITY THUNDERSTORMS
AT ALL SITES LATE TONIGHT INTO MONDAY AS WELL.   10 TO 15 KNOT WINDS
THIS AFTERNOON AT BYI...PIH AND IDA SHOULD DIMINISH BY SUNSET BEFORE
PICKING UP AFTER MIDNIGHT ONCE AGAIN.
GK


&&

.FIRE WEATHER...A STRONG UPPER LEVEL SYSTEM AND ASSOCIATED COLD
FRONT WILL MOVE THROUGH THE DISTRICT TONIGHT AND MONDAY.   MAIN
THREATS WILL BE SHOWERS AND THUNDERSTORMS WITH POSSIBLE WETTING
RAINS MAINLY IN ZONES 422...475 AND 476.  WITH POSSIBLE 25 TO 35
MPH SUSTAINED WINDS IN ZONES 425 AND 410.  HUMIDITY WILL BE TOO HIGH
TO ISSUE ANY RED FLAG WARNINGS HOWEVER.  TEMPERATURES WILL BE WELL
BELOW NORMAL MONDAY AND MONDAY NIGHT WITH SOME LOWS IN THE 30S
EXPECTED TUESDAY MORNING.   DRY CONDITIONS ARE EXPECTED TUESDAY
THROUGH FRIDAY WITH A SIGNIFICANT WARMING TREND BY WEDNESDAY WITH
HOT AND VERY DRY CONDITIONS BY THURSDAY.
GK


&&

.PIH WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 9 AM TO 9 PM MDT MONDAY FOR IDZ017-020-021.

&&

$$



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