029
FXUS65 KPIH 181003
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
403 AM MDT Sat Jul 18 2026

.KEY MESSAGES...

- Showers and thunderstorms dwindle through Monday before
  monsoon moisture returns Tuesday

- Gusty winds, locally heavy rainfall, and small hail possible
  with some stronger thunderstorms

&&

.DISCUSSION...
Issued at 1258 AM MDT Sat Jul 18 2026

A few showers and a thunderstorm are possible early this
morning, before we see increasing coverage this afternoon and
evening across central and eastern Idaho. The best chance will
remain over higher elevations, although a few storms are
possible (especially with any outflow boundaries) across
portions of the Magic Valley and Snake Plain. There is a risk of
stronger outflow winds again this afternoon. There is a 20-50%
chance for gusts over 35 mph with any outflow across the Snake
Plain and Magic Valley. There is a 50-90% chance across higher
terrain, especially for the central mountains and closer to the
Utah border west of I-15. Stronger storms will again be capable
of dropping small hail and locally heavy rainfall. There is a
MARGINAL RISK for severe storms today for the central mountains,
Arco Desert, and eastern highlands. Drier air works in over the
weekend, BUT not enough to keep us storm free necessarily. We
do end up with dry air at the surface Sunday and Monday.
However, there is enough mid level moisture for a few showers
and storms Sunday from around Hailey to Gilmore Summit to Island
Park...as well as along the Utah border. With the drop off in
deeper moisture, the potential measurable rainfall really drops.
For Monday, as the ridge shifts back to the north and west,
deeper monsoon moisture initially is pushed far enough west that
we MAY not see any storms. It does look like virga could be an
issue over the central mountains Monday. Temperatures will
remain in the upper 80s and 90s for valley locations through
Monday. It is not out of the question we see some spots
approaching 100 across the Magic Valley and South Hills/Albion
Mountains. The current HeatRisk does indicate we could reach
advisory levels on Monday. At the moment, we will not be
jumping on any type of headline for that.

Monsoon moisture returns starting Tuesday and will be back in
place through most of next week. We will see temperatures
slipping back into the 80s to low 90s by midweek due to
increasing clouds, although as before daily highs will be very
dependent on cloud cover.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 401 AM MDT Sat Jul 18 2026

More showers and thunderstorms are expected this afternoon and
evening. We did include PROB30 due to proximity of thunderstorms
and/or potential for outflow-induced storms to impact an
airport, with the exception being IDA. Gusts of 30-45kts are
possible, along with brief heavy rainfall, and small hail. This
risk should end by late evening.

&&

.FIRE WEATHER...
Issued at 1258 AM MDT Sat Jul 18 2026

A few showers and even a thunderstorm remain possible this
morning, before a resurgence takes place this afternoon and
evening. The best chance for showers and storms will be across
higher elevations, especially the central mountains and closer
to the Utah border. We will be watching for any outflow
boundaries and potential storms along those boundaries through
sunset, with higher potential for that across the Magic Valley
and Craters of the Moon (425). Coverage will be isolated,
although we will be just bumping scattered coverage (25-30%)
across the central mountains and also across Zones 413 and
427. We currently do not have any RED FLAG WARNINGs out for
today, but that is something the day shift may to consider early
on. There is a risk for stronger outflow winds over 35 mph over
higher terrain (50-90%), trying to peak around 55 mph across
for the same zones. Elsewhere, 35+mph gust potential is 20-50%.
Locally heavy rainfall and small hail are still possible with
lingering monsoon moisture today. Drier air works in for Sunday
and Monday, which definitely leads to lower afternoon
humidity...BUT not necessarily cutting off thunderstorm
potential. For Sunday, enough mid level moisture should remain
for isolated dry storms across Zones 422/476, from Hailey to
Gilmore Summit), along the Montana border (411) and closer to
the Utah border in Zones 413 and 427. It does look like on
Monday, storm chances should drop below 10% although we may see
some virga across the central mountains. With drier air and less
clouds, expect warmer afternoon highs with temperatures
approaching 100 in typical warmer spots Monday.

Deeper monsoon moisture returns starting Tuesday as the ridge
shifts back to north and west, and keep the deeper monsoon
plume in place through most of next week.

&&

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

&&

$$

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