textproduct: Pocatello

KEY MESSAGES

- High pressure will keep skies nearly clear and a warming trend to temperatures through Thursday.

- A trough approaching from the northwest will increase wind on Thursday afternoon, allowing humidity and wind to combine to potentially bring critical fire weather conditions.

- Next chance of precipitation and risk of thunderstorms could be as early as Friday.

DISCUSSION

Issued at 201 AM MDT Tue Sep 8 2026

Today through Fri...A weak trough moving through western MT will bring only a slight chance threat of showers and thunderstorms to the upper Snake River highlands. By this evening, the trough is well east of the forecast area. West northwest flow continues Wed and shifts during the day Thu to more westerly. As the next trough approaches from western Canada, the gradient tightens on Thu and has the potential to reach just below Wind Advisory criteria on both Thu and Fri afternoons.

500mb heights rise the next two days, allowing some significant warming. The trough approaching for Fri should spread some clouds and bring in cooler air aloft, which should eventually bring cooler temperatures at the surface, likely on Fri.

Fri night through Mon...A low breaks off the trough, perhaps as this scenario is not featured in every solution cluster. This shifts the airflow to a southerly component that draws up subtropical moisture, as well as bringing some available moisture itself. This brings a risk of showers and thunderstorms to the forecast area. First, for the southern and eastern highlands, then on Sun, as the closed low moves through central and northern Idaho, to the centeral Idaho mountains. None of it appears very heavy, but it should be unstable enough to trigger thunderstorms. Strong wind possible Sat night/Sun morning as the low pushes through the northern half of the forecast area. Temperatures should sink to near to below normal for this period, with the coldest temperatures just after trough passage on Sun.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 443 AM MDT Tue Sep 8 2026

High pressure keeping skies nearly clear with a few cumulus this morning in the eastern airdromes. Wind is also light this morning, but afternoon should see some increase to around 15KT as a maximum. KSUN should only have two or three hours of south southeast wind, then shift to southwest. Overnight hours are mostly VRB for the other airports. Southwest to west northwest wind direction expected for the afternoon and early evening.

FIRE WEATHER

Issued at 201 AM MDT Tue Sep 8 2026

Warming and drying return today and continues through at least Thu afternoon. This will drive some low elevation humidity readings below the 15 percent critical threshold today, then becoming more widespread Wed and Thu. An approaching trough will increase the wind on Thu afternoon to exceed critical thresholds for both mountains and plains, so it is very likely Red Flag Warnings will be needed for Thu. Overnight, the approaching trough may keep the wind elevated, but it will also bring higher humidity for Fri. At least, it is expected. Showes and thunderstorms should return Sat and Sun as the trough traverses the northern half of the forecast area. The source region would indicate dry thunderstorms, and current forecasts would be for isolated coverage.

PIH WATCHES/WARNINGS/ADVISORIES

None.