textproduct: Pocatello

KEY MESSAGES

- Nighttime Showers East of I-15: An approaching upper-level trough will increase clouds tonight, bringing a brief round of showers and isolated thunderstorms primarily along and east of the I-15 corridor, focusing over the Eastern Highlands.

- Noticeably Cooler Monday: Showers exit rapidly Monday with clearing skies. Post-frontal air will drop valley daytime highs into the 60sroughly 10 degrees cooler than today's readings.

- Early October Warming Trend: High pressure builds over the Intermountain West starting Wednesday, keeping the remainder of the 7-day forecast completely dry while pushing lower- elevation highs into the mid-to-upper 70s by late week.

DISCUSSION

Issued at 101 PM MDT Sun Sep 27 2026

Afternoon satellite imagery shows increasing cloud cover across eastern Idaho as southwesterly flow strengthens ahead of an approaching upper-level trough. Temperatures have climbed into the 60s across lower elevations and will reach the 70s before peak diurnal heating concludes. As the trough axis approaches tonight, cloud cover will thicken, bringing a brief return of showers and potential isolated thunderstorms to the eastern half of the forecast area. The highest precipitation probabilities will align along and east of the I-15 corridor, with the Eastern Highlands serving as the primary focus area. This feature will move through quickly, with clearing conditions spreading across the region throughout the daytime hours on Monday. The system will usher in a cooler air mass, dropping valley highs back into the 60s on Mondayapproximately 10 degrees below today's maximums.

Upper-level flow transitions to predominantly zonal Tuesday into Wednesday as high pressure begins to organize over the Southwestern U.S.. Temperatures will hover near seasonal climatological norms for the first part of the workweek, accompanied by dry conditions and light surface winds. Upper- level ridging will build directly over the Intermountain West starting Wednesday and remain established through next weekend. This will drive a warming trend that will push afternoon temperatures above seasonal averages. Highs in lower-elevation valleys will reach the mid-to-upper 70s by Thursday and hold there through the weekend. With atmospheric moisture shunted well away from the region, the forecast remains completely void of precipitation chances beyond Monday, ensuring a dry, pleasant start to October.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1134 AM MDT Sun Sep 27 2026

VFR conditions will continue at all sites through the forecast period. Moisture spreading into the region will allow for SHRA to develop across the region this evening. The best chances for predominate SHRA will be at DIJ overnight but will carry VCSH at all sites. Cannot completely rule out ISO TSRA, but confidence is low. Precipitation shifts east of the region during the morning Monday.

FIRE WEATHER

Issued at 101 PM MDT Sun Sep 27 2026

Moisture streaming into East Idaho will allow for showers and isolated thunderstorms overnight. Slightly cooler temperatures arrive Monday behind the departing system. A shallow ridge of high pressure builds back into East Idaho for much of the week, with a gradual warming trend and dry conditions. Models have backed off on a system for the weekend and are now just swinging a weak system past to the north, so precipitation chances have lessened.

PIH WATCHES/WARNINGS/ADVISORIES

None.