textproduct: Pocatello

KEY MESSAGES

- Late Week Heat Surge: Temperatures will steadily rise, reaching the low-to-upper 90s across lower valleys today and Friday. Heat advisories are in effect for today and Friday.

- Monsoon Moisture Returns: Models show a high pressure ridge shifting east with an approaching low system, which will bring moisture from our south back into the area. Wetter and cooler conditions will return for the weekend into next week.

- Increased Fire Danger Saturday: Models show scattered thunderstorm coverage, which will increase fire danger across the area.

DISCUSSION

Issued at 229 AM MDT Thu Aug 20 2026

Dry conditions are in store through Friday as high pressure builds over the region, allowing southeast Idaho to warm back into above-normal territory through Friday. HEAT ADVISORIES are in effect for many valley locations as widespread temperatures in the advised areas will range 93 to 98 degrees, with some even reaching triple digits as the ridge axis shifts directly overhead.

Models continue to show an upper low setting up along the PacNW coast and thus shifting the ridge eastward this weekend. This will open up the door for the return of monsoon moisture. The ECMWF ensemble indicates precipitation as early as Thursday evening while the GFS ensemble has trended a bit earlier with the introduction of accumulating precipitation late Thursday/overnight into Friday morning. While isolated activity is anticipated on Friday, Saturday still looks to be the busiest weather day for Southeast Idaho with scattered thunderstorms for portions of the region.

Storm activity will trend isolated again heading into the later weekend, although the active pattern will continue into at least the first part of the next week as low pressure remains off the coast with an area of high pressure set up over the Southwest.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 500 AM MDT Thu Aug 20 2026

Expect VFR conditions and overall light winds through the period with high pressure overhead. Expect overall clear skies this morning before mid-level and high-level clouds start approaching. Models are showing some convection, at this point, well south of BYI for late this afternoon into the early evening. Have left convection out of all TAF sites for this period.

FIRE WEATHER

Issued at 203 PM MDT Wed Aug 19 2026

High pressure ridging will be directly overhead of southeast Idaho most of today and will continue to lead to dry conditions and hot temperatures. Very isolated storms are possible this afternoon, mainly in the Bear Lake region. Min HRs are ranging from about 10 to 20 percent today and winds remain on the lighter side, gusting to around 20 mph.

Over the next few days, the high pressure ridge over southeast Idaho will be pushed just slightly eastward as an area of low pressure off the coast of the PNW moves into the area. The high pressure moving east will allow some monsoon moisture to works its way back into Eastern Idaho as early as this afternoon. Though, as mentioned above, the potential for isolated storms this afternoon remains quite low, generally less than 15 percent. Convective activity begins to increase on Friday, but still looks to be mostly isolated. This weekend is when storms become more scattered. So, Saturday looks like the next best day for any Red Flag Warning potential, and perhaps Sunday. However, activity will become a bit more isolated for some locations in the second half of the weekend. The area won't totally dry out as we head into next week. In fact, isolated storm chances will likely continue through at least the first half of next week.

PIH WATCHES/WARNINGS/ADVISORIES

Heat Advisory from noon today to 10 PM MDT this evening for IDZ051-054>057-075. Heat Advisory from noon to 10 PM MDT Friday for IDZ051>059-075.