185
FXUS65 KPIH 020537
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
1037 PM MST Sun Feb 1 2026

.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 SUNDAY/...
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 /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1021 PM MST Sun Feb 1 2026

A weak short wave is moving through the area currently. There
are currently slightly elevated winds for the Snake River plain
TAF sites. Also, there are mid-level broken clouds. Models
continue to show a very low chance of MVFR CIGS for our northern
areas. Thus, have left SCT030 for IDA, DIJ, and PIH. Expect
overall clearing and overall weak southwest winds for most sites
tomorrow afternoon. Model guidance is showing a northerly wind
shift for KIDA for 3 to 5 hours by mid tomorrow morning and
continuing into early to mid afternoon tomorrow. Just put
variable at 6 knots for IDA for now. High pressure starts
building back in by tomorrow afternoon and continues to get
stronger into Tuesday. Expect very light winds tomorrow evening.
Models do show mid to upper level clouds moving through the
high pressure ridging tomorrow evening. Guidance does show a
chance of fog for IDA tomorrow night into Tuesday morning.

&&

.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.

&&

$$

SHORT TERM...DMH
LONG TERM...DMH
AVIATION...TW
AIR QUALITY...DMH