textproduct: Pocatello

KEY MESSAGES

- Scattered thunderstorms return to all of southern Idaho. Thunderstorms continue through the next seven days for many locations in southern Idaho.

- Red Flag Warnings in place for scattered thunderstorms today for all of Central Idaho Dispatch area, Southern Idaho Dispatch area, and portions of the Eastern Idaho Dispatch area.

- After record heat the past two days, clouds and precipitation will cool afternoon highs significantly today, then continue a weak overall cooling trend through Friday.

DISCUSSION

Issued at 124 PM MDT Sat Aug 22 2026

A ridge of high pressure over the southwest combined with an upper low off the Pacific coast will support the flow of monsoon moisture into Southeast Idaho over the next several days in southwest flow aloft. Shower and thunderstorm coverage will become more widespread again this afternoon and evening as an embedded shortwave works through. The Storm Prediction Center has included almost the entirety of the CWA in a Marginal Risk of severe weather today. The storm environment becomes more favorable heading into the afternoon through mid-evening hours, with models indicating 0-6km shear increasing to 40 to 50 knots across portions of the CWA. The threat of gusty winds increases as well, with RRFS DCAPE values ranging around 1000 to 1400 J/kg. Thunderstorms will be capable of outflows ranging 50 to 60 mph. Otherwise, moderate to heavy rain will be possible with storms with models indicating precipitable water ranging 0.70" to 1.4" today. Outside of thunderstorms, winds will remain fairly weak today. Temperatures today will run 5 to 10 degrees cooler than yesterday's record temperatures.

The main upper level low pressure system will continue to track northward into Canada throughout the day Sunday, resulting in less widespread storm coverage on Sunday with activity more limited to the higher terrain. On the other hand, winds will increase outside of storms with gusts across the Snake River Plain, Arco Desert, and portions of the central mountains ranging 30 to 40 mph. The suppression of the ridge will mean a continuation of gradually cooling temperatures through Monday before the ridge attempts to rebound. During this time, temperatures will briefly warm by several degrees, but ensembles show the next PacNW low reaching the coast and flattening the ridge again come mid-week which will take our temperatures back into seasonable territory or just below for the latter half of next week. Southwest flow aloft will keep enough monsoon moisture lifting northward to support daily chances of showers and thunderstorms throughout next week.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 1033 PM MDT Sat Aug 22 2026

It will be another round of TSRA developing 23/18Z-23/20Z for all airdromes except one. KSUN appears to dry out to SKC before convection can get going, and, at least for now, does not look to be hampered by TSRA in the afternoon and evening. For the rest, SPC has put them in an area of slight chance of severe TSRA, so have outflow wind of 35G50KT for all of them during the strength of afternoon heating. If the PROB30 group had to be broken up due to increasing clouds, then the evening should not be as strong, perhaps 30G45KT instead. CIGs stay above FL100 except in TSRA, but even then stays VFR. VSBYs could also be reduce to marginal VFR, but only in a TSRA.

Final thing is the wind. KSUN, KIDA are both in areas where gusty wind has been expected, so they have some SW wind of 15G25KT likely in the afternoon. KPIH is a close second with sustained at 15KT. The other two KDIJ and KBYI should peak out at around 10KT.

FIRE WEATHER

Issued at 124 PM MDT Sat Aug 22 2026

We will continue with a RED FLAG WARNING for all zones EXCEPT 413. There will be a mix of wet and dry thunderstorms, with the main impact being storms potentially producing gusts 35-60 mph, if not a bit higher with some storms across the Snake Plain and Magic Valley (410, 425). There is a 30-50% chance of wetting rains across central and eastern Idaho through this evening. Morning cloud cover had muddied the picture a bit on where higher coverage will be, but not enough to make any changes to the warning layout. With this monsoon push, we are expecting pockets of showers across our area overnight, with a 10% chance or less of seeing an overnight thunderstorm or two. As low pressure scoots northeast tomorrow, we are expecting an increase in winds outside of any thunderstorms. Gusts of 25-40 mph are expected across portions of the Snake Plain (410), Lava Beds in the Magic Valley (425), the central mountains (422, 475, 476), and along the Montana border in Zone 411. There is some question on how much dry air works in across those areas. Right now, the best chance of seeing much lower humidity is across the central mountains. We will likely see pockets of critical fire weather conditions, but at the moment will hold off on any RED FLAG WARNINGS for that combination. Elsewhere we are going to be borderline for thunderstorm coverage across Zones 427 and 413. We are also expecting similar issues, in addition to the overall wind, across Zone 411. Again, with borderline conditions (coverage should be much lower than today), we will not go with any warnings for thunderstorms. Outflow gust potential for 35+ mph is lower tomorrow (10-40%) vs today (40-90%). The chance of wetting rain is lower overall 15-30% and more spotty as well. Expect more of the same on Monday. The footprint for showers and storms increases, at least based on current trends, but thunderstorm potential is still borderline for more widespread coverage. Monsoon moisture looks to stick around most of this week, potentially decreasing toward the end of it. We will to watch trends over the next few days to see how long it may be with us and how much precipitation we could see.

PIH WATCHES/WARNINGS/ADVISORIES