textproduct: Pocatello

KEY MESSAGES

- Will see many 100 degree temperatures this afternoon with slight cooling expected Tuesday. Heat risk highest today, especially across the Magic Valley, Snake River Plain, and South Hills.

- Monsoon moisture increases beginning this evening. More widespread storms later evening through mid-week. Wednesday should be most widespread day of showers and thunderstorms with cooler temperatures.

DISCUSSION

Issued at 121 PM MDT Mon Jul 20 2026

Main impact today remains heat advisory in effect until 8 pm for much of southeast Idaho. Temperatures will reach 100 in many locations late this afternoon. Expect isolated thunderstorms mainly over the southern hills once again this afternoon and do expect nocturnal showers overnight again mainly in high elevations. It will remain hot Tuesday but will cool a couple of degrees and convective activity will be more widespread. By Wednesday an embedded short wave moving through Idaho should enhance significantly the shower and thunderstorm coverage with significantly cooler temperatures with many low elevation highs down to the upper 80s. Expecting much drier conditions Thursday through next Monday with only isolated mountain storms expected. Hot temperatures return with low elevations mainly in the 90s Friday through Monday and mountains in the 80s.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 535 PM MDT Mon Jul 20 2026

VFR conditions generally expected through the period. Monsoonal moisture will be on the increase over the next 24 to 36 hours allowing for more mid/high level clouds later this evening and into Tuesday. Hi-res models continue to show some potential for some overnight/early morning shower activity which could impact all terminals. Given the dry air, these will likely be of the dry variety but could have some gusty outflow winds. For now, maintained VCSH given the uncertainty on timing and location. Winds will remain light outside of any influence from the aforementioned convective activity.

Models show more more widespread shower/storm coverage tomorrow after 00Z, just beyond this current period. This next round will come up from Utah and will likely bring thunderstorms to at least BYI and PIH before 6Z and vicinity thunderstorms for the rest of the TAF sites in the early evening as well.

FIRE WEATHER

Issued at 414 AM MDT Mon Jul 20 2026

Excessive heat peaks today with many valley locations warming to around 100 degrees, although heating could be inhibited in areas where extensive cloud cover develops. Monsoonal moisture will support daily shower and thunderstorm chances through mid to late week. High resolution models show activity primarily concentrated across Fire Weather Zones 475 and 476 this evening with development further east across 410 and 413 during the late night and overnight hours. Widespread Min RH today will range 13 to 16 percent across Fire Weather Zones 410 and 425, but Min RH will raise to 25 percent and higher beginning Tuesday as monsoonal moisture lifts northward. Isolated, mostly dry storms today will trend wetter and more scattered heading later into the week with locally heavy rainfall possible and outflow winds of 40 to 50 mph. Certainly possible for Red Flag conditions on Wednesday but cloud cover could limit instability and overall tstm coverage so this will be something to monitor and coordinate. Things look to dry out later in the week and into the weekend with above normal temperatures expected to linger over the region.

PIH WATCHES/WARNINGS/ADVISORIES

Heat Advisory until 8 PM MDT this evening for IDZ051>059.