textproduct: Pocatello

KEY MESSAGES

- Sunny and warm into Tuesday with low elevation high temperatures in the middle to upper 70s, alpine basin highs middle 60s to middle 70s.

- Next storm arrives Tuesday night, spreading moderate to heavy rain and high elevation snow Wednesday morning through Friday afternoon, possibly continuing into the weekend for some.

- Widespread below freezing overnight lows for much of the Snake River plain Thursday night through Saturday night, with warming returning Sunday night.

- Very windy Wednesday with this next storm. Breezy afternoons otherwise.

DISCUSSION

Issued at 135 PM MDT Mon Apr 20 2026

Water vapor sat imagery show deep low off California coast, progged to swing inland and impact East Idaho late Tuesday through the remainder of the week. Increased southerly surface flow continues to nudge temperatures up Tuesday for the warmest day of the week. Precipitation chances increase overnight Tuesday night into Wednesday as first frontal boundary works through the region, followed by a significant drop in Wednesday's high temperatures. A WIND ADVISORY may be needed for Wednesday afternoon with NBM supporting a greater than 70% probability of wind gusts exceeding 45 mph across a wide swath of the Snake River Plain. A secondary cold front drives through during the afternoon, bringing isolated to scattered thunderstorm chances to the region as well. Snow levels fall through the day Wednesday, and the best chance for accumulating snow will be across the central mountains above 7000 ft. Above that elevation, accumulations generally range 3-8 inches, but even Galena Summit is at the low end of that range, with only 2-4 inches expected through midnight Wednesday night. Unless amounts tick higher with subsequent model runs, no winter- related headlines are anticipated at this time.

Second shortwave feature drops out of Canada behind main trough axis Thursday, bringing second round of mainly light precipitation to the region and reinforcement of the cooling trend. Accumulating snows drop closer to valley floors by midday Thursday, to roughly 5000-5500 ft, but the heaviest precipitation should be relegated to the northeast corner near Island Park. At this time, models support a spread of 2-5 inches to valley floors in this region, and 6-10 inches at higher elevations. Will hold off on headlines for now, but potential is there for winter-related headlines Thursday and Thursday night for the Island Park area and the Big Hole mountains. Elsewhere, temperatures remain just warm enough to preclude accumulating snows for majority of the Snake Plain and valleys south. The best chance for sub-freezing temperatures for lower elevations will be Thursday night and beyond, but by this time most of the precipitation will be showery and mainly confined to higher elevation regions. Models keep segments of the main low around the Northern Rockies into the weekend, but the uncertainty in the ensembles continues so confidence remains low on precipitation development.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1120 AM MDT Mon Apr 20 2026

Not expecting significant flying impacts through Tuesday morning. Widespread VFR with only some few to broken high cloud cover up around 20 thousand feet. May start to see southerly wind speeds increase close to 18Z tomorrow mainly at PIH, IDA and DIJ.

PIH WATCHES/WARNINGS/ADVISORIES

None.