textproduct: Pocatello

KEY MESSAGES

- After a brief relative cooldown Monday and Tuesday, the dry and warming trend returns through the end of the week.

- Inversions may break provided there is sufficient mixing Monday and Tuesday, but stagnant conditions will return for the latter half of the week.

SHORT TERM /THROUGH MONDAY NIGHT/

Issued at 144 PM MST Sun Feb 1 2026

Satellite imagery shows upper ridge axis over East Idaho flattening ahead of shortwave feature moving through Oregon today. Moisture moving into the region is continuing to produce cloud cover over Idaho, but not sufficient to produce any precipitation today. The shortwave shifts across the panhandle tonight and through western Montana on Monday. Short range ensembles and NBM means remain very dry, but the very high end probabilistic data does produce a few hundredths of liquid precipitation across a few higher elevation regions. There is an extremely low chance (less than 10%) of a few places seeing 1" of snow accumulation, mainly back-country ridges north of the Sawtooths Monday and along the Continental Divide and Yellowstone regions through Monday night. For the majority of East Idaho, the primary impact will be a slight dip in daytime highs and a slight increase in afternoon winds.

LONG TERM /TUESDAY THROUGH SATURDAY/

Issued at 144 PM MST Sun Feb 1 2026

Second shortwave drops through northwest flow Monday night into Tuesday, grazing the northeast portions of the forecast area. Much like the Monday system, this one also contains little to no moisture for most of the region. Similarly, the probability of producing any snow accumulations more than a dusting are around or less than 10%, and the forecast remains dry. For the remainder of the work week, the ridge rebounds over the region, returning East Idaho to a warming trend and potential stagnant air mass. There is a hint of a potential change arriving by late in the weekend. Ensemble and clusters hint at a pattern change by late weekend as a deep Pacific trough moves inland and the upper ridge shifts east. Current ensemble clusters show significant spread regarding the details of this transition, particularly given the amplified blocking pattern over the Western U.S. The NBM introduces light precipitation late Sunday at the end of the forecast period. Are we confident on this? Not at all. Highly amplified blocking patterns can be hard to break down, and models can be too aggressive in doing so especially this far out in time. But it will be worth keeping on eye on this week.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1016 AM MST Sun Feb 1 2026

A weak shortwave passing through the area this evening will flatten the ridge of high pressure overhead. VFR conditions will continue through the rest of today with winds increasing just slightly, though no impacts are expected from this. The NBM is giving about a 10 to 20 percent chance of MVFR CIGs early Monday morning through the Snake River Plain behind the shortwave. Low confidence in any actual impacts if this develops, but have alluded to this with some SCT030 in the TAFs for all sites except for SUN.

AIR QUALITY

Issued at 144 PM MST Sun Feb 1 2026

The ridge of high pressure over East Idaho is beginning to flatten slightly under the influence of an encroaching shortwave feature over Oregon, with another shortwave feature expected for Tuesday. These features should be enough to mix out the lower atmosphere, limiting the surface-based inversions and increasing winds slightly for both days. By Wednesday, the upper ridge is forecast to shift across East Idaho once again, returning the potential for stagnant air mass through the end of the week.

PIH WATCHES/WARNINGS/ADVISORIES

Air Stagnation Advisory until noon MST Monday for IDZ054-059.