301
FXUS65 KPIH 241928
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
128 PM MDT Mon Aug 24 2026

.KEY MESSAGES...

- Marginal Severe Risk Today: Monsoonal moisture pushing across
  the northern Great Basin will trigger afternoon and evening
  showers and thunderstorms, with SPC maintaining a Marginal
  Risk across the southern two-thirds of the area for gusty
  winds and small hail.

- Warm & Moderating Mid-Week (TueThu): Rain chances taper off
  into isolated, weaker coverage as a high-pressure ridge subtly
  builds over the Intermountain West, pushing lower- elevation
  highs back into the lower 90s through Thursday.

- Late-Week PacNW Trough & Cooldown: A prolonged upper-level
  trough establishing over the Pacific Northwest late Thursday
  into the weekend will tighten pressure gradients, resulting in
  breezy conditions, H5 height falls, and below-normal weekend
  temperatures.


&&

.DISCUSSION...
Issued at 124 PM MDT Mon Aug 24 2026

Afternoon satellite imagery reveals a gradually expanding
cumulus field across the northern Great Basin as another plume
of monsoonal moisture pushes into eastern Idaho. Similar to
recent days, another round of afternoon and evening showers and
thunderstorms is expected to develop across the forecast area.
While overall thermodynamic and shear parameters are less
favorable for widespread severe convection than yesterday, an
isolated severe storm cannot be entirely ruled out. The primary
threats with stronger cores will be localized gusty outflow
winds and small hail. The Storm Prediction Center (SPC)
maintains a Marginal Risk for severe thunderstorms across the
southern two-thirds of the forecast area through this evening,
with activity tapering off into the night.

The marginal severe threat is expected to subside by Tuesday
morning as atmospheric forcing weakens. From Tuesday through
Thursday, weak high-pressure ridging will rebuild across the
region, leading to diminishing precipitation chances and overall
weaker thunderstorm intensity. While isolated diurnal showers
and storms remain possible each afternoon, coverage will be far
more sparse. High pressure will also drive a warming trend, with
afternoon maximum temperatures returning to the lower 90s
across lower-elevation valleys through Thursday.

By late Thursday and continuing into Friday, eastern Idaho will
begin feeling the influence of a prolonged upper-level trough
establishing itself across the Pacific Northwest. As this
feature interacts with the ridge to our south, the regional
surface pressure gradient will tighten significantly, generating
increasingly breezy conditions Friday through the weekend. In
addition to the wind, incoming H5 height falls will suppress the
Great Basin ridge, initiating a cooling trend that will drop
weekend temperatures to the cooler side of seasonal averages.
Latest model guidance continues to introduce low-end
precipitation chances as energy moves around the trough axis.
Model guidance still exhibits minor variance regarding the exact
depth and track of the core low as it shifts north of the
region, which will dictate final wind speeds and precipitation
distribution, but at least a modest cooldown remains high-
confidence for the weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1041 AM MDT Mon Aug 24 2026

The daily pattern of showers and thunderstorms is still around.
Expect an increase by mid afternoon and continue through mid
evening across eastern Idaho. We have included PROB30 for each
TAF site at some point during this timeframe. We have gusts to
45kts, but higher gusts are possible especially for PIH and BYI.
Some of the higher resolution models do show some potential for
overnight showers and even a thunderstorm. Right now, we do not
have anything reflecting that but may need add that later today
or this evening.

&&

.FIRE WEATHER...
Issued at 124 PM MDT Mon Aug 24 2026

Monsoon moisture continue to bring showers and
thunderstorms across central and eastern Idaho throughout much of
this week. The best chance through this evening will be south of a
Hailey to Driggs line. The chance of wetting rains south of that
line are in the 20-40% range, although we expect a decent mix of wet
and dry thunderstorms. There is a HIGH likelihood for gusts over 35
mph and again potentially reaching/exceeding 60 mph with some storms
or outflow boundaries. Farther north where we storms, the chance is
20-50% for gusts over 35 mph and topping out around 45 mph. We are
borderline for scattered lightning coverage across 413, 425 and 427,
but will not opt for an 11th hour RED FLAG WARNING due to lower
confidence. It does look like we will see some showers, and maybe
even a thunderstorm, overnight but chances right now remain under
20%. We see a slight decrease in monsoon moisture and subsequently
the chance of showers and storms Tuesday. Right now, isolated storms
are most likely across portions of 411, 413, 425, 427, 475 and 476.
We may see a storm or two, or outflow boundaries elsewhere but the
chance is 10% or less at the moment. That could easily change in the
next 12-24 hours. The chance of wetting rain is lower tomorrow (15%
or less) and the chance for outflow gusts over 35 mph is down to 20-
50% areawide. Based on the current trend, there will be an uptick in
showers and thunderstorms across the central mountains
(422/475/476), Magic Valley (425), and South Hills/Albion Mountains
(427) on Wednesday. On the flip side, it looks like wetting rain
potential barely increases and an increase in stronger gusty winds
indicates more dry than wet thunderstorms. This would be our next
potential day for thunderstorm coverage to reach critical fire
weather thresholds. We will see how things trend in the next 24
hours in that regard. We might see a slight break over the central
mountains Thursday, and areawide Sunday and/or Monday from monsoon
moisture impacting us. Otherwise, the potential for seeing
thunderstorms really doesn`t go away for several days.

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...McKaughan
AVIATION...Keyes
FIRE WEATHER...Keyes