125
FXUS65 KPIH 240441
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
1041 PM MDT Sun Aug 23 2026

.KEY MESSAGES...

- Slight Risk Today (6080 mph Severe Gusts): The Storm
  Prediction Center (SPC) maintains a Slight Risk across the
  southeast corner of the regionincluding the South Hills,
  lower Snake Plain, and southeast highlands toward Bear Lake.
  Steep lapse rates and high moisture will support severe
  downburst winds of 60 to 80 mph and localized small hail
  through late evening.

- Repeat Threat Tomorrow: Near-identical synoptic conditions on
  Monday will keep scattered thunderstorm potential elevated
  across the same southeastern footprint, with localized
  damaging gusts remaining the primary hazard.

- Mid-Week Ridge & Late-Week Wind Surge: High pressure rebuilds
  Tuesday and Wednesday, bringing above-normal temperatures in
  the upper 80s to lower 90s alongside isolated afternoon
  storms. A passing northern shortwave on Thursday and Friday
  will increase regional winds and moderate weekend temperatures
  back toward seasonal averages in the low-to-mid 80s.

&&

.DISCUSSION...
Issued at 156 PM MDT Sun Aug 23 2026

An active afternoon and evening are expected across eastern
Idaho as an unusually moist and unstable air mass remains
entrenched across the southeastern portion of the forecast area.
Surface temperatures climbing into the 80s paired with surface
dewpoints in the mid-50s are providing sufficient thermodynamic
instability for robust convective development. The Storm
Prediction Center (SPC) maintains a Slight Risk for severe
thunderstorms across the southeast corner, encompassing the
South Hills, the lower Snake Plain, and the southeastern
highlands around Bear Lake. Soundings reveal steep low-to-mid
level lapse rates, creating an environment characterized by
strong evaporative cooling within convective cores. Stronger
thunderstorm cores and organized outflows will be capable of
generating scattered severe wind gusts of 60 to 80 mph within
the Slight Risk zone, with a lower but non-negligible wind
threat extending across the rest of eastern Idaho. Small hail
will also be possible within the strongest cores. High-
resolution convective-allowing models (CAMs) show storm activity
persisting through late evening before tapering off around
midnight.

Synoptically, Monday presents a near-identical setup. High-
resolution model guidance targets the same general footprint
across the South Hills, Snake Plain, and southeastern highlands
for afternoon shower and thunderstorm coverage. SPC currently
carries a Marginal Risk for severe gusts across the area.
However, if daytime destabilization matches today`s parameters,
localized severe downburst wind gusts will once again be the
primary operational threat.

As the upper-level trough assisting current convective activity
exits into Western Canada, high-pressure ridging will attempt
to rebuild over the Great Basin Tuesday through mid-week.
Residual low-level moisture trapped beneath the ridge axis will
maintain low-end daily shower and thunderstorm chances.
Afternoon maximum temperatures will run a few degrees above
seasonal climatological norms, reaching the upper 80s to lower
90s across lower-elevation valleys.

Heading into the late-week period, a shortwave trough tracking
into Washington and British Columbia on Thursday will tighten
regional pressure gradients, increasing wind speeds across
eastern Idaho on Thursday and Friday. This northern feature will
partially suppress the Great Basin ridge Friday into the
weekend, potentially lowering valley temperatures back toward
seasonal benchmarks in the low-to-mid 80s. However, considerable
spread remains among model ensemble guidance regarding the exact
magnitude of this weekend cooling trend.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1041 PM MDT Sun Aug 23 2026

Expect virga showers to remain south of TAF sites overnight.
Most likely looking at convection once again Monday afternoon
with 30% chance of storms at TAF locations. Gusty winds and
brief heavy downpours reducing visibilities are main impacts.

&&

.FIRE WEATHER...
Issued at 156 PM MDT Sun Aug 23 2026

Another day with monsoon moisture across Idaho means another
day with showers and thunderstorms. We will see isolated
thunderstorms across the central mountains (Zone 476) and along
the Montana border for Zone 411. There is a 10-40% chance for
gusts over 35 mph. There is a better chance south of the Snake
River across Zones 427 and 413, although coverage remains
borderline for scattered and Red Flag Warning thresholds. Down
south is also where we expect for a slightly higher chance for
wetting rainfall, but it is still only 15-30%. There is also a
50-90% chance for gusts over 35 mph. Any thunderstorms today
have the potential for gusts over 60 mph, similar to yesterday,
but the chance for those types of gusts is highest down south.
While there is no strong indication outflow boundaries or storms
are expected across Zones 410 and 425, we will be watching for
that as well. Outside of storms and outflow potential, gusty
winds will develop across the central mountains(422/475/476),
the Arco Desert and Upper Snake Plain (410) and along the
Montana border (411). Gusts in the 25-40 mph range are expected.
There will be pockets of lower humidity (around or below 15%),
but the potential looks too sporadic for widespread critical
conditions and Red Flag Warnings. Monsoon moisture spreads back
north across eastern Idaho tonight and tomorrow. We will be
borderline again across Zones 413 and 427 tomorrow for scattered
coverage. We expect isolated storms across a good chunk of
eastern Idaho, outside of Zone 475. The chance of wetting rain
is similar to today (15-30%) but the footprint is a bit bigger
overall, but still look for a mix of wet and dry storms. There
is a less than 50% chance for gusts over 35 mph closer to the
Montana border, but 70- 90% across the rest of eastern Idaho
where storms develop, with a distinct possibility again for
gusts over 60 mph with stronger storms and outflow boundaries.
The risk of showers and storms continues until the end of the
week. We may see another low pass to our north, which would
suppress deeper moisture to south of the Snake Plain over the
weekend. Right now, there is quite a range on what might have
with the storm track, and the Blend of Models does include a few
showers and storms across a good portion of eastern Idaho
especially on Saturday.

&&

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

&&

$$

DISCUSSION...McKaughan
AVIATION...13
FIRE WEATHER...Keyes