416
FXUS65 KPIH 212329
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
529 PM MDT THU MAY 21 2026
KEY MESSAGES
- SHOWERS AND ISOLATED THUNDERSTORMS SHOULD END BY EARLY EVENING
- GUSTY NORTHERLY WINDS EXPECTED THROUGH THIS EVENING
- MUCH WARMER AND MOSTLY DRY WEATHER FOR MEMORIAL DAY WEEKEND
DISCUSSION
ISSUED AT 119 PM MDT THU MAY 21 2026
UPPER TROUGH SHIFTING SOUTHEAST ACROSS THE REGION TODAY.
NORTHERLY FLOW IN PLACE BEHIND THE TROUGH AXIS CONTINUES TO
PRODUCE GUSTY NORTHERLY WINDS THROUGH THE SNAKE PLAIN, AND A
LAKE WIND ADVISORY REMAINS IN PLACE FOR AMERICAN FALLS RESERVOIR
THROUGH THE EVENING. MAINLY ISOLATED SHOWERS AND THUNDERSTORM
OR TWO WILL CONTINUE PRIMARILY OVER HIGHER TERRAIN. HIGHLANDS
EAST OF I-15 COULD SEE A FEW STRONGER CELLS PRODUCE
PRECIPITATION APPROACHING 0.25" TODAY, BUT MOST CONVECTION
EXPECTED TO REMAIN LIGHT. COLD TEMPERATURES IN PLACE ONCE AGAIN
TONIGHT. PROBABILITIES SUPPORT A SLIGHTLY BETTER THAN 50% CHANCE
OF TEMPERATURES DROPPING BELOW 32 DEGREES ACROSS THE SNAKE
PLAIN NORTH OF A LINE FROM POCATELLO TO ARCO. DETERMINISTIC NBM
TEMPERATURES ARE LARGELY ABOVE 32 DEGREES FOR MOST OF THE
POPULATED AREAS. THUS WILL MAINTAIN THE FROST ADVISORY, AND
UPDATE THE WORDING TO SUGGEST THAT A FEW LOCATIONS COULD SEE
TEMPERATURES BELOW FREEZING. THE THREAT FOR A HARD FREEZE (BELOW
28 DEGREES FOR LOWS) IS MINIMAL.
MODELS SLOWLY BUILD THE RIDGE INTO EAST IDAHO THROUGH THE
WEEKEND. WEAK IMPULSES MAY BE ENOUGH TO ALLOW ISOLATED SHOWERS
AND A THUNDERSTORM OR TWO TO DEVELOP PRIMARILY OVER HIGHER
TERRAIN EACH DAY INTO THE MEMORIAL DAY WEEKEND. MOISTURE REMAINS
QUITE LIMITED TO ANY PRECIPITATION THAT CAN DEVELOP IS EXPECTED
TO BE LIMITED TO A FEW HUNDREDTHS, AT BEST, AND POTENTIALLY
INDUCE SOME GUSTY WINDS. OTHERWISE, WARMING TREND LOOKS TO
REMAIN IN PLACE INTO THE WEEKEND WITH DAYTIME HIGHS INCREASING
INTO THE 80S SATURDAY THROUGH MONDAY.
BY TUESDAY, MODELS CONTINUE TO PROGRESS THE NEXT PACIFIC LOW
INLAND, BUT THERE IS STILL A LOT OF UNCERTAINTY AMONG THE
ENSEMBLES AND CLUSTERS ON HOW THAT ACTUALLY OCCURS. SO WHILE
THERE IS CONFIDENCE ON CONDITIONS BECOMING INCREASINGLY
UNSETTLED BY MID WEEK NEXT WEEK, THE DETAILS REMAIN MUDDLED.
CLUSTERS ARE FAIRLY EVENING SPLIT BY MIDWEEK BETWEEN DEVELOPING
A CLOSED SPLIT FLOW LOW OVER THE GREAT BASIN, AND PROGRESSING AN
OPEN TROUGH ACROSS THE ROCKIES TOWARDS THE PLAINS. TEMPERATURES
DO COOL OFF BEGINNING TUESDAY AND PRECIPITATION CHANCES INCREASE
FOR THE REMAINDER OF THE WEEK.
AVIATION /00Z TAFS THROUGH 00Z SATURDAY/
ISSUED AT 527 PM MDT THU MAY 21 2026
ISOLATED TO SCATTERED SHOWERS IN THE EASTERN HIGHLANDS AROUND DIJ
WILL TAPER OFF OVER THE NEXT SEVERAL HOURS, SO VCSH REMAINS IN
THE TAF FOR NOW, BUT DRIER CONDITIONS WILL RETURN FOR TONIGHT
AND FRIDAY. BREEZY WINDS WILL ALSO DIMINISH OVERNIGHT INTO
FRIDAY MORNING AND STAY LIGHTER ON FRIDAY AFTERNOON WITH GUSTS
TO OR BELOW 15 KTS AT ALL SITES. WHILE IT WILL BE MOSTLY DRY ON
FRIDAY, THERE WILL BE SOME MID AND UPPER LEVEL SCT TO BKN CLOUDS
PASSING THROUGH DURING THE DAY. OVERALL, VFR CONDITIONS WILL
PERSIST THROUGH THE FORECAST PERIOD.
FIRE WEATHER
ISSUED AT 1225 AM MDT THU MAY 21 2026
SHOWERS WITH A FEW THUNDERSTORMS WILL PERSIST THROUGH MOST OF
THE DAY, WITH THE BULK OF THE MOISTURE EXPECTED ALONG THE
WYOMING BORDER. THE PORTION OF ZONE 411 IN WESTERN WYOMING WILL
LIKELY SEE THE HIGHEST AMOUNTS OF MOISTURE, 0.20-0.40" WITH
LIGHT SNOW ACCUMULATIONS ON THE HIGHER PEAKS AND RIDGELINES.
THERE HAVE BEEN A FEW THUNDERSTORMS OVERNIGHT, AND WOULD EXPECT
THAT POTENTIAL TO LAST THROUGH THE DAY, WITH AN UPTICK EXPECT
TOWARD SCATTERED COVERAGE POTENTIALLY ACROSS HIGHER TERRAIN FROM
DRIGGS SOUTH THROUGH BEAR LAKE (411 AND 413). GUSTY NORTHERLY
WINDS WILL DEVELOP AS A COLD FRONT SWEEPS SOUTH ACROSS CENTRAL
AND EASTERN IDAHO. HEADING INTO MEMORIAL DAY WEEKEND, TEMPERATURES
RAPIDLY WARM UP TO 10-15 DEGREES ABOVE AVERAGE. THE QUESTION IS
WILL WE REMAIN DRY OR STORM FREE. THERE ARE INDICATIONS THAT
LIMITED MID LEVEL MOISTURE OCCASIONALLY SLIDES ACROSS THE STATE,
WHICH COULD HELP INDUCE AT LEAST SOME VIRGA OR SPRINKLES, OR AN
ISOLATED STORM. RIGHT NOW, THE POTENTIAL FOR THAT IS 15% OR LESS
FOR ANY GIVEN DAY, BUT WE WILL NEED TO MONITOR THIS CLOSELY EACH
DAY TO SEE IF WE NEED TO PUSH THAT POTENTIAL UP A BIT MORE. BY
THE MIDDLE OF NEXT WEEK, ANOTHER ROUND OF SHOWERS AND STORMS
AND COOLER TEMPERATURES ARE EXPECTED.
PIH WATCHES/WARNINGS/ADVISORIES
FROST ADVISORY FROM 3 AM TO 9 AM MDT FRIDAY FOR IDZ052>054.
DISCUSSION...DMH
AVIATION...AMM
FIRE WEATHER...KEYES
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