332
FXUS65 KPIH 210339
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
939 PM MDT WED MAY 20 2026
KEY MESSAGES
- FROST & FREEZE CONDITIONS FLUCTUATE THROUGH THE REST OF THE
WEEK
- SHOWERS AND THUNDERSTORMS TONIGHT AND THURSDAY
- TEMPERATURES RETURN TO 10-15 DEGREES ABOVE AVERAGE OVER THE
WEEKEND
UPDATE
ISSUED AT 938 PM MDT WED MAY 20 2026
ISSUED LAKE WIND ADVISORY FOR AF RESERVOIR WITH BRISK NORTH TO
NORTHEAST WINDS HIGHLY LIKELY DURING THE AFTERNOON AND INTO THE
EVENING.
DISCUSSION
ISSUED AT 138 PM MDT WED MAY 20 2026
NORTHWEST FLOW REMAINS IN PLACE ACROSS EAST IDAHO UNDER
INFLUENCE OF LOW OVER ALBERTA/SASKATCHEWAN CANADA, WITH
SHORTWAVE DROPPING THROUGH THE IDAHO PANHANDLE AND WESTERN
MONTANA PER SATELLITE IMAGERY. SHORT TERM HIGH-RES MODELS
CONTINUE TO INDICATE AREAS OF SHOWERS AND ISOLATED THUNDERSTORMS
LATE THIS AFTERNOON INTO THE EVENING. SHOWERS CONTINUE TO SAG
SOUTH TOWARD THE SOUTHEAST CORNER OF THE FORECAST AREA TONIGHT
INTO THURSDAY. GREATEST PRECIPITATION STILL LOOKS CONCENTRATED
NORTHEAST OF A LINE FROM CHALLIS TO POCATELLO TO PRESTON THROUGH
THE DAY THURSDAY. WEST OF THAT LINE, MODEL MEANS GENERATE VERY
LITTLE TO UNDER A TENTH OF PRECIPITATION. AMOUNTS INCREASE EAST
OF THAT LINE, RISING TO 0.35-0.50" IN HIGHLANDS ALONG THE
WYOMING BORDER. HEAVIER SHOWERS COULD DROP PRECIPITATION AMOUNTS
EXCEEDING 0.50", AND THE HIGHEST PROBABILITIES FOR THIS ARE
40-60% IN THE VICINITY OF THE BIG HOLE RANGE AND TETON VALLEY.
TEMPERATURES REMAIN COOL OVERNIGHT BUT GENERALLY ABOVE FREEZING
SO SNOW LEVELS REMAIN CONFINED TO AREAS ABOVE 6500 FT ACROSS THE
NORTH, AND ABOVE 7500 FT ACROSS THE SOUTH. SNOW ACCUMULATION
WILL REMAIN LIGHT, EVEN AT HIGHER ELEVATIONS. SHORTWAVE SLIPS
SOUTHEAST THROUGH THE DAY THURSDAY, ALLOWING NORTHERLY GRADIENT
AND COOL TEMPERATURES TO RESETTLE INTO EAST IDAHO. BREEZY
NORTHEAST WINDS MAY NECESSITATE A LAKE WIND ADVISORY FOR
AMERICAN FALLS RESERVOIR. ANOTHER NIGHT OF FROST AND/OR FREEZE
HEADLINES ARE LIKELY THURSDAY NIGHT, WITH A GREATER THAN 75%
CHANCE OF TEMPERATURES DROPPING BELOW 36F FOR ALL AREAS NORTH OF
A LINE FROM POCATELLO TO ARCO. SOME OF THOSE AREAS HAVE A
GREATER THAN 50% CHANCE OF TEMPERATURES BELOW FREEZING, BUT LESS
THAN A 15% OF REACHING HARD FREEZE AT 28F.
MOVING INTO THE WEEKEND, A RIDGE OF HIGH PRESSURE REDEVELOPS
BEHIND DEPARTING SHORTWAVE AND AHEAD OF NEXT PACIFIC SYSTEM DUE
TO ARRIVE NEXT WEEK. TEMPERATURES BEGIN TO RISE AGAIN THROUGH
THE WEEKEND, MITIGATING CHANCES FOR ADDITIONAL FROST OR FREEZE
HEADLINES. THERE IS VERY WEAK CHANCES OF ISOLATED SHOWERS INTO
THE WEEKEND, BUT CONFIDENCE IS LOW FOR ANY ONE AREA OVER ANOTHER
TO SEE EVEN LIGHT PRECIPITATION. A FEW ENSEMBLE MEMBERS BEGIN TO
INTRODUCE BETTER CHANCES OF SHOWERS BY SUNDAY, BUT MORE
WIDESPREAD UNSETTLED CONDITIONS ARE NOT EXPECTED UNTIL TUESDAY,
CONTINUING INTO MOST OF THE REMAINDER OF THE WEEK.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 938 PM MDT WED MAY 20 2026
COLD FRONT IS ADVANCING SOUTH. EXPECT TO SEE WIND SWITCHES TO
THE NORTH AT SOME POINT WITH THE FASTER TRANSITION FROM EAST TO
WEST AS THE COLD AIR POURS DOWN THE SNAKE RIVER PLAIN. CEILINGS
SHOULD REMAIN VFR AT MOST LOCATIONS. DIJ WILL PROBABLY HAVE THE
BIGGEST IMPACTS WITH A TRANSITION TO WET SNOW POSSIBLE WHICH
COULD RESULT IN IFR CONDITIONS. THINK WINDS AT SUN WILL STAY
DOWNVALLEY ON THURSDAY AS A RESULT OF THE STRONGER NORTHERLY
WINDS BEHIND THE FRONT.
PIH WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...13
DISCUSSION...DMH
AVIATION...13
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