textproduct: Pocatello

KEY MESSAGES

- Showers and thunderstorms will persist across the central mountains through Saturday becoming more widespread Sunday and Labor Day

- Locally heavy rainfall is possibly later Sunday and Labor, potentially creating issues on/around steep slopes and burn scars

- Much cooler weather expected on Labor Day

DISCUSSION

Issued at 1237 PM MDT Fri Sep 4 2026

We continue to watch the potential for showers and isolated thunderstorms across the central mountains through Sunday morning. There will be a potential for some locally heavier rainfall, especially tonight. That said, a more prolonged and widespread issue with heavy rain is not expected. We will let the FLASH FLOOD WATCH for the Wapiti burn scar expire this evening. Across the rest of eastern Idaho, the dry slot remains in place along with gusty winds at times during the same period. Gusts up to 30-35 mph are possible, especially at night where downslope occurs or where areas remain above any weak inversion, and during the afternoon with full mixing. Temperatures will warm up a bit, with some low to mid 80s popping up across lowest elevations.

The focus for the next chance of showers and storms will occur later Sunday through Labor Day. The low that has been sitting along the coast will swing across the state on Monday. Ahead of that, we will pull in some monsoon moisture to help fuel this round of showers and storms. It looks like at the moment, any moisture from Marie will get pushed to our southeast. We will likely get a small boost, especially closer to the Wyoming border. Otherwise, rainfall will come from whatever moisture is wrapping around the main low itself...separate from the monsoon push. The best chance of rain will be Sunday night and Labor Day, with a very strong dry slot wrapping back into eastern Idaho later in the day. Rainfall amounts across the Snake Plain, Magic Valley, and South Hills/Albion Mountains will range from a few hundredths to close to 0.25" north of Idaho Falls. Rainfall across the central mountains should range from 0.10-0.30", EXCEPT across the higher ranges (Sawtooths, Lost River, and Lemhi) where up 0.60" is possible. Temperatures may be cold enough Monday, for a shorter period of rain and snow across the higher peaks like Borah, etc. For the eastern and southeast highlands, amounts currently fall in the 0.20-0.50"...locally higher around Island Park where up to 0.70" MIGHT fall. If we see heavier storms or multiple storms over the same area, we could see some issue with localized flooding in steeper slope areas and burn scars. It is possible we may need to issue a FLASH FLOOD WATCH to later on to cover the impacts. Winds will pick up on the back side of the low, especially when the dry slot moves in. The strongest winds will be across the Snake Plain north across the border into southwest Montana. It is possible a WIND ADVISORY is needed for those areas. We should fall short of any thresholds for a LAKE WIND ADVISORY for American Falls Reservoir. Temperatures Sunday will be similar to tomorrow, but much cooler Monday with lower elevations highs MAYBE reaching 70. Mountain temperatures will be in the 50s and low 60s, with highest elevations not getting out of the 40s.

We get a brief break midweek, but southwest flow returns and we see some monsoon moisture moving back into state after that. Expect highs to return to the 70s and 80s and at least a low end potential (for now) of showers and thunderstorms.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1118 AM MDT Fri Sep 4 2026

Very little change is expected with going forecasts. SUN remains on the edge of upper low with continued threat of SHRA into this evening, then a break is expected. All terminals remain VFR. Winds decrease to light and variable into tonight, but there is potential for PIH and IDA to see a brief return to breezy 10-15kt sustained winds after midnight.

FIRE WEATHER

Issued at 1237 PM MDT Fri Sep 4 2026

Showers and isolated thunderstorms will remain confined to the central mountains through Sunday morning. There is a low chance of locally heavier rainfall mainly north of Stanley and across the Frank Church. Otherwise, gusty winds will remain across the rest of eastern Idaho through the same period. We will see near-critical to locally critical fire weather conditions due to the wind and afternoon humidity drop to near 15 percent. Through this evening, this will be an issue across the southeast corner (Zone 413), and tomorrow across Zones 410, 413, 427 and most of Zone 425. We may also see this be an issue Sunday ahead of the monsoon push across the Snake Plain (410) and most, if not all of Zones 425 and 427.

Showers and thunderstorms will increase Sunday night and continue through most of Labor Day, although this will quickly shut off across the Snake Plain (410), Magic Valley and South Hills/Albion Mountains (425 and 427) as a dry slot quickly wraps back into eastern Idaho. It looks like the super majority of the moisture from Marie stays to our southeast, with a very small amount pulled into areas east of I-15. There is a separate batch of moisture wrapping around the low itself that will be the source of precipitation as the low crosses the central mountains and Panhandle. For Zones 410, 425, and 427 look for amounts from a few hundredths up to 0.25", highest across the north end of Zone 410. Across the central mountains (422, 475, and 476), amounts of 0.10-0.30" are possible, but closer to 0.60" across higher elevations north of Stanley and Zones 475/476. There even could be a rain/snow mix for peaks like Borah, etc. For higher elevations east of I-15, look for 0.20-0.50" EXCEPT around Island Park where up to 0.70" is possible. This could cause some issues for any burn scars or steeper slope areas.

PIH WATCHES/WARNINGS/ADVISORIES

None.