textproduct: Pocatello

KEY MESSAGES

- Storm Prediction Center has areas of marginal chance and slight chance of severe thunderstorms for today and tonight.

- Thunderstorms have less chance of occurrence, but greater severity potential today.

- Breezy conditions in the central Idaho mountains and Snake River plain today, even outside thunderstorm activity.

DISCUSSION

Issued at 138 AM MDT Sun Aug 23 2026

Southwest upper level flow will continue to bring moist and unstable air into the forecast area. SPC now has an area along the UT border that has a slight chance of severe thunderstorms, meaning large hail or gusts in excess of 50KT/58MPH. The marginal contour around it also covers a large amount of the forecast area. It mainly leaves out the central Idaho mountains, which are in general thunderstorm forecast area. The coverage of thunderstorms shrinks on Mon and Tue. The best thunderstorm coverage Mon is expected to be the highlands along the UT and WY borders. Then on Tue it shift to the north along the MT border.

Cloud cover actually decreases in the late morning, which is what allows enough destabilization to increase the intensity if not the coverage of the thunderstorms. Afternoon highs will be cooler today after the cooler air moved in during the evening and late night hours last night.

The final thing is that a low moving onshore and through southern Canada will push up the upper level wind over the central Idaho mountains and the northern part of the Snake River plain. This will bring G25KT to G30KT on the ridges in the central Idaho mountains, and G25KT to locations like Rexburg and Idaho Falls and the Arco Desert. Tuesday should be breezy to windy once again.

For the extended period, either a partial breakdown of the upper level ridge from a trough coming from the west or at least a flattening of the ridge over Idaho should continue the not as hot temperatures with dry westerly flow suppressing showers and thunderstorms, especially after Wed.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1107 AM MDT Sun Aug 23 2026

Today's rounds of showers and thunderstorms will mainly affect areas along and south of the Snake River. We carried over PROB30 with MVFR and gusts to 50kts from the previous forecast, with SUN not seeing any development at this point. This should continue into the early to mid evening hours before tapering off. There COULD be some showers pushing far enough north tonight and Monday morning to impact BYI and PIH, but for now we are keeping that out of this round of TAFs.

FIRE WEATHER

Issued at 138 AM MDT Sun Aug 23 2026

Abundant lightning yesterday over receptive fuels had at least several starts. The lightning show continues today, but in lower coverage or probability of occurrence. Best coverage will be along the WY border region of the Eastern Idaho Dispatch AoR. Over a good portion of that Dispatch area and the Southern Idaho Dispatch area the expectations are few thunderstorms, but much stronger in intensity, with solid chances of severe strength thunderstorms in both regions. Much of the Central Idaho dispatch area has only general thunderstorms, with the eastern areas getting closer to the marginal risk of severe storms.

Cooler air has moved in, but this will be partially offset in western areas by the strong sunshine with less cloudiness. Some lower elevation areas will see humidity readings drop below 15 percent, but it is low elevations from Salmon to Challis where that occurs, where wind will be somewhat lighter.

A low moving across the continent from west to east will increase wind today for the central Idaho mountains and portions of the Snake River plain. Critical fire weather conditions will be very close in that Salmon to Challis corridor, but otherwise not expecting anything close to critical.

PIH WATCHES/WARNINGS/ADVISORIES

None.