textproduct: Pocatello

KEY MESSAGES

- Mainly dry today. A few dry showers or thunderstorms may develop this afternoon across the Island Park/Yellowstone region.

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

- Chilly weather over the weekend into early next week.

DISCUSSION

Issued at 120 PM MDT Thu May 28 2026

Upper low in the western Great Basin ejecting shortwave energy through Nevada into Oregon and Western Idaho this afternoon. Most of East Idaho looks to remain in the dry slot today, with a weak pocket of moisture over the Island Park/Yellowstone region. There is also a very low chance of seeing some weak development across the Frank Church, otherwise most of the precipitation should stay west of the forecast area. High-res NAM indicating some potential development across the Southern Sawtooth region tonight, which may be remnants of Nevada convection today. Most likely impact will be a sprinkle at best and gusty winds overnight. By Friday, the upper trough begins to eject northeast through the Great Basin into Idaho, bringing additional moisture to the region. High-res models begin to introduce spotty weak development during the afternoon, but there is not a lot of confidence in where or how that would play out. Chances increase during the evening and especially the overnight into Saturday especially across the southern and eastern portions of the region. Interestingly, this morning's NAM run develops a more strongly split flow by Saturday with main low ejecting east across northern Utah and a more open trough ejecting northeast through Oregon, leaving East Idaho in somewhat of a split pattern and thus drier, not favored by the ensembles and probabilities. As the system continues to eject northeast out of the region, wrap around precipitation could persist into Monday, especially across the north. Forecast still paints significant total precipitation for this event across East Idaho late Friday night to Sunday night, with a strong gradient in liquid precipitation totals centered roughly on a line from Challis to Bear Lake. West of the line, precipitation tapers to nothing or very little while forecast amounts shifted higher east of the line. Total amounts for this event could exceed an inch in some places, mainly across the Island Park region of the forecast area. Cooler temperatures are still anticipated this weekend under the influence of the low and rain-cooled airmass. The coolest overnight lows look to be Sunday night/Monday morning, with a few outlying areas of the Snake Plain approaching frost territory, but at this time no headlines are anticipated.

For the rest of the forecast period, upper flow transitions to zonal flow or weak ridging behind the departing system. A few shortwaves could graze the area, mainly to the north, but dry conditions are forecast for most of East Idaho Tuesday through Thursday. Temperatures recover to the lower to mid 80s for daytime highs by mid-week.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 1120 AM MDT Thu May 28 2026

The main concern today will be gusty south to southeast winds. Gusts overall will run 15-30 kts. Any type of virga or thunderstorm potential will be at a minimum, and currently at 15% or less. At the moment, there isn't really any organized risk showing up, but it may be as simple as a mid level cloud producing enhanced gusts. Winds should decrease overnight but begin to pick up mid to late morning Friday. VFR weather is expected.

PIH WATCHES/WARNINGS/ADVISORIES

None.

PIH WATCHES/WARNINGS/ADVISORIES

None.