textproduct: Pocatello

KEY MESSAGES

- Showers and a few thunderstorms possible through Saturday mainly across the central mountains

- Breezy conditions across the rest of eastern Idaho through Friday

- Shower and thunderstorm chances increase as low pressure interacts with moisture from Marie with the question being how much of moisture from this tropical low impacts eastern Idaho

DISCUSSION

Issued at 1143 AM MDT Wed Sep 2 2026

Showers and storms continue to quickly exit the central mountains this afternoon, with a few other showers and storms trying to form east of I-15 in the mountains. The latter area of storms should remain isolated with coverage remaining under 15%. The bigger story is cooler temperatures and wind behind the cold front. Gusts will continue to flirt with LAKE WIND ADVISORY criteria on American Falls Reservoir and WIND ADVISORY from Craters through Monida Pass. For now, it looks like the potential is too low and not widespread enough to issue any headlines. Some folks have likely already seen highs for the day, or will be back within a couple of degrees of where they were ahead of the front. Afternoon temperatures in the central mountains should remain in the 50s and 60s, with 60s and 70s elsewhere. Parts of the Stanley Basin may struggle to get above 50. Starting tonight and continuing through Saturday, any potential for showers and storms should remain mostly over the central mountains. We may see a few light showers and a few storms during that period across the rest of eastern Idaho, but this should be very limited in terms of time. Otherwise, it will remain breezy through Friday. Gusts will be lighter than today, but still 25-35 mph at times...maybe pushing 40 mph in a few spots. Highs will slowly creep back up, but most of the time remaining in the 60s and 70s. A few low 80s may pop up on a thermometer across portions of the Snake Plain, Magic Valley, and valleys closer to the Utah border on Saturday.

Showers and storms increase areawide Sunday and Monday. Low pressure that will have been setting to our northwest swings farther inland and to our northeast. This will draw moisture from the southwest, and try to tap into moisture from eventual Hurricane Marie off the coast of Baja. The question is how much will make it into Idaho. Trends this week have been 1)to keep the low itself across the Pacific and not drawn into low pressure across the western states, and 2) shunt most of the moisture across Utah, Wyoming, and Colorado. There continues to be fluctuations daily with the official forecast (WPC-based) for precipitation. Compared to 24 hours ago, the forecast has doubled (nearly tripled) for Sunday and Monday. The latest has 0.25-0.50" for the Snake Plain and Magic Valley, and 0.40-0.90" for higher elevations (highest across the eastern and southeast highlands). The placement of higher amounts seems reasonable due to trending more south and east with the main push of moisture from Marie. The amounts seem overdone based on the trends we mentioned. When looking at the raw Blend of Models "middle of the road" forecast, it is showing 0.10-0.33" for the Snake Plain and Magic Valley and 0.25-0.75" for the mountains with locally higher amounts. This seems more reasonable and also what previous WPC-based forecasts looked like. The higher end of the forecast range shows widespread 1"+ amounts except for the Magic Valley which is still 0.75-1.0". Considering the trends, that would definitely fall under "low probability/high impact". Even if we see less cloud cover and precipitation, we will stay cooler overall. Stay tuned.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1136 AM MDT Wed Sep 2 2026

Satellite and radar imagery show main swath of convection has moved northeast of SUN, limiting potential for additional SHRA or TSRA through the remainder of the afternoon. A few SHRA present along the WY border could be very close to DIJ, and will watch for additions to the terminal early this afternoon. Winds remain gusty for the East Idaho terminals this afternoon but with a decreasing trend, becoming light and variable overnight. Another round of showers may be possible for SUN during the overnight.

FIRE WEATHER

Issued at 1143 AM MDT Wed Sep 2 2026

The threat of showers and storms across the central mountains is almost over, as the bulk of this has shifted into Montana. The tail end of this should clear the state by mid afternoon. We will go ahead and end the RED FLAG WARNING for Zone 422 early. A few other showers and storms are possible mainly east of I-15 and actually mostly like east of the state through this afternoon. Otherwise, it will be breezy with near-critical or locally critical fire conditions across the rest of eastern Idaho. Humidity should hold around 15% or higher where drier air has moved in. Gusts of 25-45 mph are expected through this evening. The bulk of any showers and thunderstorms through Saturday will be across the central mountains, closer to low pressure settling in along the coast, and where moisture will persist. There will be the potential for a few showers or storms elsewhere, but any widespread or prolonged potential isn't there. The trend for breezy conditions will remain with gusts 25-35 mph at times. Lower humidity for Thursday will confined to mainly the southeast corner across Zone 413, and still limited to 15% or higher. Humidity will rise Friday and Saturday and not be an issue.

Showers and thunderstorms increase Sunday and Monday. The question becomes how much moisture will fall, which is dependent on Hurricane Marie. The latest "official forecast" calls for 0.25-0.50" for Zones 410 and 425. The rest of central and eastern Idaho would see 0.40-0.90". This is a huge increase from previous forecasts, 0.10-0.33" and 0.25-0.75", respectively. The raw Blend of Models "middle of the road forecast" basically shows the latter set of amounts. The higher end of the Blend has more widespread 1"+ amounts with 0.75-1.0" for the Magic Valley (Zone 425). The trends AWAY for deeper moisture from Marie would suggest these higher end amounts have a low probability of occurring. The more likely forecast seems to be the "middle of the road" forecasts from the Blend. We will likely continue to see fluctuations in the amounts until the models get a better handle on where most of the moisture of Marie ends up travelling across the southwest U.S.

PIH WATCHES/WARNINGS/ADVISORIES

None.