textproduct: Pocatello

KEY MESSAGES

- Showers and isolated thunderstorms should end by early evening

- Gusty northerly winds expected through this evening

- Much warmer and mostly dry weather for Memorial Day Weekend

DISCUSSION

Issued at 1225 AM MDT Thu May 21 2026

Low pressure will continue to slide southeast today and push a cold front through eastern Idaho. For most areas, light amounts of moisture are expected. For areas along the Montana border down through the Big Holes could pick up around 0.25", especially with any heavier showers or storms that can overcome drier air in place. Otherwise, light amounts of precipitation (including light amounts of snow on higher ridgelines and peaks). With the cold front dropping south into our area today, gusty northerly winds are expected. The front appears to hang up over the Magic Valley and surrounding areas for a few hours this afternoon. This may cause a few showers across the Lower Snake Plain out into the Magic Valley to stick around this afternoon, as the bulk of the moisture shifts into Wyoming. Winds will be strong enough to meet the lower speed thresholds for a northeast LAKE WIND ADVISORY on American Falls Reservoir through most of the day. Despite some clouds over central and eastern Idaho tonight, we should more concerns with frost and freeze conditions. A FROST ADVISORY will be needed for the Snake Plain as temperatures will be mostly in 32-36 range, with more rural areas possibly dropping to around 30 and above 36 along the I-15 corridor.

For Friday through Monday, temperatures will be quickly rebounding with highs in the 70s and 80s for Memorial Day Weekend. The concern is that we may NOT be totally shower or thunderstorm free. We are seeing some potential for mid level cloud cover to cross the state from time to time, but it may not be anything more than virga or sprinkles. Right now, any given day's forecast has 15% or less for a chance of showers or storms through Memorial Day. We will need to monitor closely day to day and see if we need start including a higher chance of showers and storms. If you are getting a head start on the weekend, keep this in mind and find a way to follow the forecast trends in case things do change. Trends toward the middle of next continue to show and increasing chance of showers and storms along with cooler temperatures. The models and ensembles are struggling with low pressure setting up shop over the Pacific Northwest or swinging that storm through us. The progress of the low will determine how much cooler it could get and how long any chance of precipitation sticks around. To give you an idea on the range of temperatures possible, the official forecast has highs by Wednesday in the 60s to near 70 for lower elevations. The warmest end of the range maintains highs in the 70s and 80s. The coldest end of the range, which would more closely follow a closed settling in, has highs in the 40s and 50s. Stay tuned.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 938 PM MDT Wed May 20 2026

Cold front is advancing south. Expect to see wind switches to the north at some point with the faster transition from east to west as the cold air pours down the Snake River Plain. Ceilings should remain vfr at most locations. DIJ will probably have the biggest impacts with a transition to wet snow possible which could result in IFR conditions. Think winds at SUN will stay downvalley on Thursday as a result of the stronger northerly winds behind the front.

FIRE WEATHER

Issued at 1225 AM MDT Thu May 21 2026

Showers with a few thunderstorms will persist through most of the day, with the bulk of the moisture expected along the Wyoming border. The portion of Zone 411 in western Wyoming will likely see the highest amounts of moisture, 0.20-0.40" with light snow accumulations on the higher peaks and ridgelines. There have been a few thunderstorms overnight, and would expect that potential to last through the day, with an uptick expect toward scattered coverage potentially across higher terrain from Driggs south through Bear Lake (411 and 413). Gusty northerly winds will develop as a cold front sweeps south across central and eastern Idaho. Heading into Memorial Day Weekend, temperatures rapidly warm up to 10-15 degrees ABOVE AVERAGE. The question is will we remain dry or storm free. There are indications that limited mid level moisture occasionally slides across the state, which COULD help induce at least some virga or sprinkles, or an isolated storm. Right now, the potential for that is 15% or less for any given day, BUT we will need to monitor this closely each day to see if we need to push that potential up a bit more. By the middle of next week, another round of showers and storms and cooler temperatures are expected.

PIH WATCHES/WARNINGS/ADVISORIES

Lake Wind Advisory from 11 AM to 9 PM MDT Today for IDZ054. Frost Advisory from 3 AM to 9 AM MDT Friday for IDZ052>054.