textproduct: Pocatello

KEY MESSAGES

- Increasing clouds this afternoon with isolated thunderstorms.

- Wet weather arrives by Saturday for parts of east Idaho.

- Chilly weather over the weekend into early next week.

DISCUSSION

Issued at 134 PM MDT Fri May 29 2026

Satellite imagery shows two distinct circulations within incoming upper trough - one over SE Oregon and one over central Nevada. Nevada circulation shifts northeast into Utah overnight tonight, with Oregon feature moving into western Idaho/panhandle. High-res models still produce mainly isolated convection late this afternoon into this evening across portions of East Idaho. Main precipitation begins during the overnight across the southeast. Wrap-around moisture shifts ahead of the southern low, ahead of main trough axis during the day Saturday. Heaviest precipitation is still expected to lie along/northeast of a line roughly from Challis/Stanley to Bear Lake. Southwest of that line, tight gradient from wetting rains to nothing is forecast. Higher elevations across the eastern highlands should see the highest rainfall totals, trending highest to the northeast corner, where totals through Sunday could approach or exceed one inch before the trough exits. Temperatures cool into the 60s under the influence of the low for both Saturday and Sunday. Breezy winds are expected, and we may see speeds bump up against the lower thresholds for a LAKE WIND ADVISORY on American Falls Reservoir.

Trough axis shifts north into Montana late Sunday into Sunday night, but general troughiness lingers into the early part of the week. Lingering rainfall along the Divide late Sunday dwindles through the night, leaving dry conditions across East Idaho. Temperatures should be at their coolest Sunday night, and there are still expectations for portions of the Snake Plain to flirt with FROST ADVISORY conditions with lows around or just below 36 degrees, but remaining above freezing. Could see a few showers return during the day Monday under the influence of continued broad trough across the PacNW, but most of the region should remain dry. Operational GFS/ECMWF both push a weak shortwave through the flow in the Wednesday/Thursday time frame, but these appear to be outliers compared to most of the ensemble solutions. Current forecast remains dry for most areas at this time.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/

Issued at 1012 PM MDT Fri May 29 2026

TAFs have overall trended worse with the next feature that begins its approach in a few hours. The TAFs are quite disparate in conditions, so it will be best to take them one at a time, starting with the easiest.

KBYI main forecast problem is wind. Moderate to strong wind expected, staying nearly entirely out of the west, with a peak of G30KT starting around 30/08Z and continuing until early afternoon. No precipitation, and almost no CIGs expected, and no impacts to VSBY.

KSUN. Typical downslope wind staying light to moderate with no CIG until possibly with TSRA develop, starting around 30/18Z. TSRA will bring CIG to 6000ft AGL or so. TSRA ending around 31/02Z, so moderate downslope resumes with some low clouds, depening on how much moisture is dropped in the Wood River valley from this event.

KPIH. The most difficult forecast as this region is on the fringe of the bad weather. SHRA on and off and not expecting TSRA in this area at all. By 30/14Z, expecting marginal VFR due to CIGs and VSBY in some BR. By 30/19Z temperatures will have warmed enough to evaporate the BR and keep CIGs low but solid VFR. Wind only gusty late tonight, G30KT, but by the time the airdrome opens, G20KT or so is the most expected.

KIDA. Ugly. SHRA/BR with plenty of marginal VFR expected starting 30/12Z. By 30/19Z, add TSRA to the mix. This will include a risk of VSBY going to IFR conditions in the TSRA, even in the afternoon. Wind is gusty tonight, and just plain erratic in direction and elevated, but not really gusty during the day.

KDIJ. SHRA starts up again around 30/11Z. Plenty of marginal VFR for CIGs and VSBY, then by mid morning IFR conditions as it just continues to rain and rain. This is both CIG and VSBY. There is even a risk of TSRA starting 30/21Z. Outside of TSRA, wind is nor much of a factor here.

FIRE WEATHER

Issued at 200 AM MDT Fri May 29 2026

An approaching low pressure system will bring increasing clouds this afternoon. This will produce cooler temps and slightly higher humidity this afternoon. A few isolated dry thunderstorms are possible this afternoon and evening. Gusty erratic winds are possible near storms. Much cooler weather with higher humidity is likely for Saturday. Wetting rains are likely for much of Salmon-Challis and East Idaho on Saturday, but not so much for South Idaho.

PIH WATCHES/WARNINGS/ADVISORIES

None.