textproduct: Pocatello

KEY MESSAGES

- Flood Watch In Effect (SaturdayMonday): A Flood Watch covers most of eastern Idahoincluding Sun Valley east through the Magic Valley, Snake Plain, and Eastern/Southeastern Highlandsfor a multi-day rainfall event of 1.0 to 2.0 inches, with localized totals up to 3.0 inches possible near Island Park and into the eastern Highlands. NBM guidance shows an 80% to 100% probability of exceeding 1.0 inch of rainfall along/east of the I-15 corridor and the South Hills, with a 30% to 80% probability of exceeding 2.0 inches.

- Dramatic Weekend Cooldown: Today's upper 70s and 80s mark the final warm day of the season. Highs drop below 70 on Saturday and plummet into the 40s and 50s on Sunday.

- Frost/Freeze Headlines Ahead: Widespread cool temperatures will bring frost/freeze risks starting Sunday morning, becoming more likely Monday through mid-week before headlines are suspended for the season.

DISCUSSION

Issued at 206 PM MDT Fri Oct 9 2026

A major pattern shift gets underway across the Intermountain West today. Satellite imagery shows increasing cloudiness over eastern Washington and Oregon associated with an approaching upper-level trough. Temperatures today have climbed quickly into the 70s and 80s, marking the final day of 80-degree warmth for the foreseeable future. Saturday represents the leading edge of the cooler, wetter air mass, with lower-elevation maximum temperatures struggling to reach 70 degrees. Showers and embedded thunderstorms will develop during the day on Saturday, elevating localized rainfall rates and initiating a multi-day precipitation event.

Sunday will be the wettest and most impactful day of the forecast period as the upper-level low tracks slowly across the Great Basin. A Flood Watch has been issued for most of eastern Idaho, extending from Sun Valley eastward across the Magic Valley, Snake Plain, and the Eastern and Southeastern Highlands. Widespread rainfall totals of 1.0 to 2.0 inches are very likely between Saturday and Monday. National Blend of Models (NBM) probabilities for storm totals exceeding 1.0 inch reach 80% to 100% along and east of the I-15 corridor and into the South Hills, with 2.0-inch probabilities ranging from 30% to 80%. The highest QPF footprint is focused across the Eastern Highlands and toward Island Park, where localized 3.0-inch totals are possible. While persistent light-to-moderate rain is the primary driver, embedded Saturday/Sunday convection could boost localized totals and create localized flooding concerns. Strong cold advection on Sunday will hold daytime highs in the 40s and 50s.

As the primary upper low slowly crosses the Intermountain West, precipitation chances will linger through Monday and Tuesday. Rainfall intensity will wane compared to Sunday, with conditions gradually drying out by mid-week. Unseasonably cool air will remain locked over the region, holding daytime highs in the 50s through much of next week, with a slight recovery toward the lower 60s possible by late week. With cold air established behind the departing system, attention shifts to overnight freeze risks. Frost and freeze headlines may be needed as early as Sunday morning, with a much higher likelihood Monday morning through mid-week as skies clear during overnight hours. These chilly nights will likely result in the seasonal suspension of Frost/Freeze headlines for eastern Idaho at some point mid-week.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 457 PM MDT Fri Oct 9 2026

Conditions are certainly changing this evening/tonight as a cold front moves into the area and quite a bit of moisture takes aim at Eastern Idaho for the weekend. There are a few showers out there already this evening, so added some VCSH at DIJ. Showers look more likely to remain south of BYI, PIH, IDA, and SUN for the rest of this evening. Look for a quick round of showers early Saturday before a brief break ahead of isolated to scattered showers and storms Saturday afternoon. The intensity of thunderstorms on Saturday afternoon remains questionable as temperatures will be dropping by that point. We remain breezy this evening with gusts around 20-25 kts, but will diminish briefly overnight before picking up to 20-25kts again on Saturday. SUN looks to stay the driest on Saturday, but should join in on the action by late Saturday night or early Sunday morning. At this point, mostly VFR conditions will continue, but that becomes less likely as clouds lower and rainfall increases Saturday night into Sunday.

FIRE WEATHER

Issued at 206 PM MDT Fri Oct 9 2026

Fall arrives this weekend across East Idaho. Winds remain gusty this afternoon, with critical or near critical conditions especially across the southwest amid very dry humidities.A Red Flag Warning remains in effect until 8 pm for Zone 427. Winds remain breezy overnight, but humidities rise after sunset. Moisture continues to increase overnight as remnants of tropical system Rachel begin to push through the Great Basin ahead of upper low dropping through the Pacific Northwest. The combination of these features will result in a rapid change in the pattern through the weekend, with onset of isolated to widely scattered showers arriving as early as tonight across the central mountains, spreading across the remainder of East Idaho through the day Saturday. Rainfall continues into early next week, but Sunday looks to be the heaviest day for most areas. Overall totals Saturday through Monday are forecast to range 0.35-0.50" for zones 475 and 476, 0.50-1.50" for much of the Snake Plain. More widespread totals for the 3 day period are across the southern and eastern highlands, zones 427, 413, and 411, where some locations will exceed 2" of liquid precipitation. A Flood Watch is now in effect Saturday afternoon through Monday for regions expected to see the highest rainfall totals. Much cooler temperatures drop into East Idaho along with the rainfall, which means accumulation of snow at higher elevations, briefly dipping to mid-slopes especially across the central mountains during overnight hours. The greatest affects will be above 7500-8000 ft elevations.

PIH WATCHES/WARNINGS/ADVISORIES

Flood Watch from Saturday afternoon through Monday afternoon for IDZ051>067-073-075. Red Flag Warning until 8 PM MDT this evening for IDZ427.