textproduct: Pocatello

KEY MESSAGES

- Flood Watch in Effect: A Flood Watch remains active across much of eastern Idaho for a multi-day rainfall event. Widespread totals of 1.0 to 2.0 inches are expected across the Magic Valley, Snake Plain, and eastern highlands, with localized amounts up to 3.0 inches possible. NBM guidance shows 70% to 100% probabilities for rainfall exceeding 1.0 inch in the aforementioned areas. Probabilities for exceeding 2.0 inches range from 20% to 50%, peaking at 60% to 80% around Island Park.

- Sharp Weekend Cooldown: Temperatures today are already 15 to 20 degrees cooler than 24 hours ago. Another 10 to 15-degree drop is expected for Sunday, capping highs in the upper 40s to upper 50s.

- Lingering Cool & Wet Pattern: Precipitation and well-below- normal temperatures will persist into the middle of next week as an upper low slowly crosses the Intermountain West.

DISCUSSION

Issued at 149 PM MDT Sat Oct 10 2026

Afternoon satellite imagery shows cloud cover increasing across eastern Idaho as an upper-level trough continues to dig into the Pacific Northwest. Well to our south, tropical moisture associated with Tropical Storm Rachel is surging northward into California and the southern Great Basin. We could see just enough breaks in cloud cover this afternoon to yield marginal instability, supporting an isolated thunderstorm threat later today, though the vast majority of precipitation is expected to fall as showers. A Flood Watch became effective earlier this afternoon and continues across much of eastern Idaho. The bulk of the precipitation will overspread the area during the overnight hours and continue throughout the day tomorrow. Temperatures today are already 15 to 20 degrees cooler than 24 hours ago.

Rainfall will peak on Sunday as tropical moisture interacts with the incoming trough. Forecast precipitation amounts remain largely on track, with a broad swath of 1.0 to 2.0 inches expected across the Magic Valley, the Snake Plain, and into the eastern highlands. National Blend of Models (NBM) probabilities remain high, showing a 70% to 100% chance of exceeding 1.0 inch in these areas. Probabilities for exceeding 2.0 inches are generally coming in lower around 20% to 50%, though they peak at 60% to 80% around Island Park. Before all is said and done, localized totals could certainly climb above 2.0 to 3.0 inches, especially across the eastern highlands and higher terrain where orographic lift will be maximized. Meanwhile, totals across the central mountains are currently running in the 0.33 to 0.66 inch range, though there is still a bit that can change.

In addition to the heavy rain, temperatures will drop another 10 to 15 degrees as we move into Sunday. Daytime highs tomorrow will only top out in the upper 40s to upper 50s across the region. Despite the cold surface temperatures, snow levels will remain high enough to limit any frozen precipitation strictly to the highest terrain and mountain peaks.

Precipitation chances will linger into the early part of the workweek as the low will be slow to depart the area. Models keep the low moving slowly across the Intermountain West until Wednesday or Thursday. This will result in temperatures staying well below seasonal norms, with highs mainly in the 50s until perhaps Thursday. By Thursday, ridging slowly builds over the area, finally replacing the persistent troughiness over the Pacific Northwest and allowing conditions to moderate.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1203 PM MDT Sat Oct 10 2026

A line of -SHRA extends from just south of BYI to north of DIJ. Pockets of clearing behind this band has the potential to generate enough instability for TSRA formation. Winds are also locally quite gusty across portions of East Idaho, with gusts around 35kts. Clearing has the potential to increase the coverage of these winds this afternoon before the winds decrease overnight. More widespread RA develops overnight and continues through Sunday across most of the region, though SUN and BYI may flirt with the western edge of the main event. CIGS decrease to MVFR with potential for VIS to drop that low as well.

PIH WATCHES/WARNINGS/ADVISORIES

Flood Watch through Monday afternoon for IDZ051>067-073-075.