425 FXUS65 KPIH 121933 AFDPIHArea Forecast Discussion National Weather Service Pocatello ID 133 PM MDT Fri Sep 12 2025
.KEY MESSAGES...
- Cooler temperatures continue into early next week.
- Isolated to scattered showers and thunderstorms also continue, mainly over higher terrain.
- Drier and slightly warmer pattern for mid to late next week.
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.SHORT TERM /THROUGH SATURDAY NIGHT/... Issued at 133 PM MDT Fri Sep 12 2025
Upper trough continues to migrate across East Idaho today per satellite imagery. Early afternoon starting to see a few pockets of weak convective development, but so far the strongest convection remains in northeast Nevada. Forecast retains isolated to scattered showers and isolated thunderstorms across higher terrain this afternoon and evening. Could see a few showers sneak into the interstate corridors of the Snake Plain, but overall much of the Snake Plain expected to remain dry. Most of the activity dissipates with sunset, but there is potential for a few showers to continue past midnight tonight and/or redevelop before dawn mainly over the eastern or southeast highlands. Lows tonight are expected to be near or slightly warmer than last night, given the cloud cover anticipated overnight. A repeat is forecast for Saturday, with similar temperature profiles, and another round of mainly isolated showers and thunderstorms over higher terrain.
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.LONG TERM /SUNDAY THROUGH THURSDAY/... Issued at 133 PM MDT Fri Sep 12 2025
On Sunday, a transient ridge of high pressure is moving across Idaho with mostly dry conditions through at least the first half of the day. This ridge will allow temperatures to warm into the mid and upper 70s in the afternoon. In the second half of Sunday, this ridge will be exiting Eastern Idaho as an area of deep troughing begins to develop a low over central Idaho. This next system will bring rain chances back to the Central Mountains as early as Sunday afternoon/evening and then showers will spread eastward overnight into Monday. Highs on Monday will be running about 5 to 10 degrees below normal with many in the mid to upper 60s. Looking at the 48 hours from Sunday morning to Tuesday morning, the NBM shows about a 10 to 25 percent chance for at least a tenth of an inch of rain in the eastern Magic Valley and Snake River Plain. Those numbers increase to about a 30 to 50 percent chance in the Central Mountains and Eastern Highlands and even a bit higher to around a 60 percent chance up in the Island Park area. Winds gusts will increase a bit on Sunday and Monday, too, to around 20 to 25 mph each afternoon. We will dry out from west to east on Tuesday as this system departs and high pressure begins to build back in over the area. Highs on Tuesday will be just a couple of degrees warmer than Monday, but the warmer weather makes a return with high pressure on Wednesday, warming into the mid and upper 70s. Expect highs to be very similar on Thursday.
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.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1131 AM MDT Fri Sep 12 2025
Showers and storms this afternoon and evening will be a bit more isolated than yesterday. Given the latest HI-RES models, will go ahead and add a PROB30 for DIJ where the latest HREF 24-hour thunder probability has increased to about a 40 to 50 percent chance. For SUN and IDA, have VCSH in the TAFs due to low probability of occurrence and high uncertainty. A few of the models show spotty showers continuing into early Saturday morning. Outside of any storms, expect VFR conditions to continue.
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.FIRE WEATHER... Issued at 133 PM MDT Fri Sep 12 2025
Upper low moving over East Idaho today, with trough axis shifting east into Wyoming for Saturday. Rounds of isolated to widely scattered showers and thunderstorms will continue each afternoon and evening. A few showers will be possible overnight tonight across the Caribou-Targhee NF, though confidence is low. Unsettled conditions continue into early next week as a new system works across the region. Temperatures remain cool through early next week, with Monday and Tuesday the coolest days of the week for most. A ridge of high pressure looks to build back into the region for mid to late next week, with a slight bump in temperatures back toward seasonal normals.
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.PIH WATCHES/WARNINGS/ADVISORIES... None.
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SHORT TERM...DMH LONG TERM...AMM AVIATION...AMM FIRE WEATHER...DMH
NWS PIH Office Area Forecast Discussion