009 FXUS65 KPIH 060410 AFDPIHArea Forecast Discussion National Weather Service Pocatello ID 1010 PM MDT Fri Sep 5 2025
.KEY MESSAGES...
- Isolated dry thunderstorms possible today
- Coverage for showers and thunderstorms still increases over the weekend
- Temps begin a downward trend early next week
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.SHORT TERM /THROUGH SATURDAY/... Issued at 208 PM MDT Fri Sep 5 2025
Afternoon satellite imagery shows mainly clear, albeit hazy, skies across eastern Idaho today. Smoke and haze from regional wildfires is obscuring visibilty across the area especially across parts of the central mountains and upper Snake Plain. Despite the haze, temperatures remain on the warmer side of normal for most locations with the lower elevations expected to climb into the low to mid 80s by the time afternoon is through. Hi-res models show a low, but non- zero, chance for a very isolated shower across the central mountains today but generally expecting things to be dry. Otherwise, things look quiet across the region today with light winds although haze will likely linger.
Things change tomorrow as moisture increases a bit from the south bringing increasing clouds as early as daybreak down along the Utah and Nevada borders, overspreading the rest of the area over throughout the day. CAMs show a much higher potential for showers/storms during the afternoon tomorrow basically anywhere with 20-40 PoPs in place over the area. Higher terrain areas look to have the best chances but can`t rule something in the Magic Valley and Snake Plain at some point in the day so some places will get some beneficial rainfall. Temps tomorrow will be a few degrees cooler with increased cloud cover and precip chances but these looks to continue to trend downward as we move into next week. More on that below.
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.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... Issued at 208 PM MDT Fri Sep 5 2025
Second significant shortwave of the weekend shifts through the region Sunday for another round of isolated to scattered thunderstorms across Southeast Idaho. There is at least a 10% chance of a tenth of an inch or better rainfall Sunday afternoon and evening for all of East Idaho Those chances raise significantly for the Pahsimeroi range northeast along the Divide and then south to around the Big Holes with greater than a 35% chance for these areas. Probabilities for more than a quarter inch of rainfall drop off significantly, maxing at 15-20% for areas around Island Park and the Big Holes. Drier conditions are in place for Monday following the departing system, but moisture returns for the remainder of the week. Ensemble means remain consistent with bringing center of Pacific low inland along the coast by Tuesday, gradually shifting east as an open trough to near or over East Idaho by Friday. There are slight differences in the ensemble clusters regarding the character of the trough as it encroaches into Idaho. Overall the general forecast remains similar to previous runs. Expect isolated to scattered showers and thunderstorms each day starting Tuesday, with temperatures dropping into the 70s for most if not all lower elevation areas.
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.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 958 PM MDT Fri Sep 5 2025
Main impact will be some minor smoke visibility restrictions but kept at 6 miles overnight. After that will start to see some shower and thunderstorm vicinity after 18Z tomorrow mainly at BYI and SUN expanding to the other sites after 22Z and continuing into Saturday night. Winds Saturday afternoon should shift to an up valley west to southwest direction but remaining about 10 knots sustained.
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.FIRE WEATHER... Issued at 208 PM MDT Fri Sep 5 2025
A few thunderstorms will be possible this afternoon, mainly across zone 422, the southern portions of 475 and 756, and along the Utah border for 413 and 427. Very little precipitation is expected from anything that can develop, and the remainder of the region will remain dry. More moisture moves into the region for the weekend, with better chances of afternoon and evening thunderstorms each day. Sunday looks to be the wetter day, with model probabilities supporting a 30-40% chance of wetting rains Sunday afternoon and evening for zone 411 and adjoining portions of 476 and 410. Probabilities of wetting rains drop off to 15-25% for the remainder of the higher elevation zones. The next surge of moisture arrives Tuesday through the remainder of the week with the upper ridge axis weakening and shifting east as a Pacific low shifts inland. Expect temperatures to cool into the 70s for most lower elevation areas by the latter half of the week, and isolated to scattered thunderstorms each day.
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.PIH WATCHES/WARNINGS/ADVISORIES... None.
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SHORT TERM...McKaughan LONG TERM...DMH AVIATION...GK FIRE WEATHER...DMH
NWS PIH Office Area Forecast Discussion