textproduct: Pocatello

KEY MESSAGES

- Unseasonably Cool & Active Weekend: Strong southwesterly flow between a West Texas ridge and a digging Pacific Northwest trough will draw deep moisture into eastern Idaho, keeping temperatures 10 to 15 degrees below normal (highs in the 60s and 70s) alongside widespread rain through Saturday.

- Saturday Severe Thunderstorm Risk: The Storm Prediction Center (SPC) has placed all of eastern Idaho in a Marginal Risk for severe storms on Saturday, with a localized Slight Risk across the far southeast corner (Pocatello south to the Utah border). Strong QG ascent, effective bulk shear exceeding 40 knots, and CAPE greater than 1000 J/kg will support supercells capable of localized severe wind gusts.

- Weekend Rainfall Distribution: Total precipitation through Sunday will range from ~0.10" across the central mountains and western zones to 0.15"0.50" in the Snake Plain, and 0.50"1.00" across the Eastern Highlands.

- Fall-Like Early September: Broad troughing will persist over the Pacific Northwest through next week, keeping daytime highs cool and dropping overnight lows into the 40s and low 50s across lower elevations.

DISCUSSION

Issued at 108 PM MDT Fri Aug 28 2026

Several waves in strong southwest flow will continue to push moisture into southeast Idaho through Saturday. Will have widespread rain showers through tonight. Complete overcast today has kept temperatures from rising and have well below normal high temperatures for the first time in awhile and this trend will continue through Sunday. Thunderstorms have been slow to develop today but still expect at least isoalted coverage this afternoon. Saturday is more interesting with especially the eastern zones in extensive shear and instability and much of Idaho is in a marginal risk for severe thunderstorms and the extreme southeast an even more elevated slight risk. High temperatures Saturday mainly in the mid to upper 70s low elevations and 60s to lower 70s mountains. Showers and thunderstorms will continue overnight Saturday night into Sunday with most thunderstorms by Sunday afternoon along the Wyoming border as moisture finally moves east. Highs on Sunday again mainly 60s mountains and 70s valleys.

Next week expect some warming back closer to normal but still below with showers and thunderstorms mainly in the south Monday and north on Tuesday. Highs in the 60s to 70s mountains and 70s to lower 80s valleys. Expect mainly mountain isolated to scattered showers and thunderstorms Wednesday through Friday with some cooling expected once again with highs 60s mountains and 70s valleys in the middle to latter part of next week. May see some breezy to windy conditions next Tuesday into Thursday with strong pre and post cold frontal passage winds.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1147 AM MDT Fri Aug 28 2026

Showers are ongoing across much of the area so far today. We will watch for some clearing mainly over the southeastern corner of the state this afternoon to see if we can get some isolated thunderstorms going. There will likely be some isolated storms embedded in afternoon showers, so continuing with VCSH and PROB30 groups. Confidence is a bit lower in storms impacting KSUN today and as mentioned, we may need some clearing around BYI, PIH, and IDA to get more robust storms there, so timing has been pushed back at these sites a few hours. The best chance likely exists at DIJ this afternoon. Expect another round of showers overnight into Saturday morning with continued potential for storms Saturday afternoon at all sites. Even with the cloud cover, VFR conditions are expected aside from when a shower or storm moves directly over a terminal, then we have seen brief drops to MVFR VIS.

FIRE WEATHER

Issued at 151 PM MDT Fri Aug 28 2026

Our overall pattern is undergoing quite the change today as an area of low pressure north of us moves eastward through the weekend. Showers have been continued throughout the morning hours over much of our coverage area. They will do so on and off throughout the rest of today and we will watch for pockets of clearing this afternoon to support some isolated to nearly scattered thunderstorm development later this evening with this second round of showers and storms expected through Fire Weather Zones 413 and 427 with some spillover into 410 and 425. More showery activity will be found in our other zones. PWATs continue to range from 0.80-1.10" throughout the area and will remain elevated through at least the first half of Saturday before falling on Sunday. So, while thunderstorms do become scattered in coverage, storms are expected to be efficient rain- makers, thus negating the need for Red Flag Warnings across the area late today through Saturday. The highest rainfall amounts are expected across the Eastern Highlands and in parts of the South Hills, pushing the 0.50-0.75" range for total amounts by Sunday evening. Elsewhere, look for about a tenth to a quarter of an inch of rainfall. In addition to the moisture, we are seeing a significant cool down across the area from upper 80s and 90s yesterday to struggling to make it into the low to mid 80s this afternoon. Highs will be in the 70s to near 80 on Saturday and solidly in the low to mid 70s area wide by Sunday afternoon. A few isolated storms will linger in the east on Sunday, but drier air begins to quickly return and we will likely see a few areas out across the desert return to min RHs in the teens on Sunday with gusting winds of 25-30 mph. The overall pattern remains unsettled during the week ahead with isolated rain and storm chances most afternoons and long-range models showing another deep low impacting the West in the second half of next week. Of course, we will see how that trend continues over the next several days.

PIH WATCHES/WARNINGS/ADVISORIES

None.