345
FXUS65 KPIH 291851
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
1251 PM MDT Mon Sep 29 2025

.KEY MESSAGES...

- Showers and storms increasing with the peak tonight

- More precipitation coming through the rest of the week

- Much cooler temperatures on the way

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 1251 PM MDT Mon Sep 29 2025

Showers and thunderstorms will peak tonight/early Tuesday, with
bulk of moisture falling across the central mountains. The range in
that area is still generally 0.50-1.0" this evening and
overnight. There is a bigger threat of thunder before midnight,
which lends some credence toward the higher end amounts. There
is a MARGINAL RISK for enhanced rainfall in place. In terms of
impacts for debris flows especially on the Wapiti, the risk will
likely be mitigated by a transition toward more widespread rain
and embedded heavier rain/thunderstorms vs just purely
convective and very high hourly rainfall rates. There is a
window where hourly rates could exceed 0.10", but the overall
risk is on the low end of things. There is a 10-30% chance of
gusts over 35 mph with stronger showers and storms as well. Other
more isolated showers and storms are expected elsewhere through
the overnight hours. As that main band shifts north and east,
it will weaken...but multiple bands/rounds of showers and storms
are forecast through tomorrow night. Precipitation amounts will
be lighter overall tomorrow, but we could still some decent
bursts of rainfall at times. There is a similar probability for
gusty winds tomorrow vs today. It will be noticeably cooler
tomorrow, with highs only in the 50s and 60s...and 40s if you
are headed to high country.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Issued at 1251 PM MDT Mon Sep 29 2025

We really don`t too much of a break in the chance of showers and
potential storms through the rest of the week. While we will be
"in between" lows Wednesday, there is still some chance mainly
over the mountains. The pattern for the rest of the week and
into next weekend will be showing a split flow pattern over the
western U.S. This means as each storm moves inland, we will the
pattern splitting with one or more closed lows developing
somewhere over the West. While this type of pattern has a bit
more difficulty with predicting where these closed lows end up,
it will remain showery at this point...along with even colder
temperatures likely. Our current Blend of Models forecast has
highs only in the 50s down low and 30s/40s up in the mountains.
This means we will see some potential for snow falling for our
higher peaks and ranges. Welcome to October!!

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1126 AM MDT Mon Sep 29 2025

Main impact will be increasing shower and thunderstorm activity
this afternoon and tonight. Have prob 30 thunderstorm chances
this afternoon after 21Z at SUN and BYI. Brought in predominant
showers at SUN at 02Z through 12Z and at the other sites after
06Z and continuing through 18Z Tuesday. Kept cloud ceilings at
VFR levels through Tuesday. No significant winds other than
gusts up to 20 mph near thunderstorms at SUN and BYI this
afternoon.

&&

.FIRE WEATHER...
Issued at 1251 PM MDT Mon Sep 29 2025

General trend is for chances of showers and thunderstorms daily
through next weekend.  The initial showers this afternoon through
Tuesday will likely provide amounts above a half inch to higher
elevations of zones 422, 475 and 476 with a lower chance of
approaching 1 inch total.  Lower elevations and throughout the other
zones amounts in the 0.10 to 0.25 range is most likely.
Temperatures will be closer to normal through Thursday with a
significant cool down expected Friday through Monday with highs in
the 40s mountains and 50s valleys expected.  Elevated humidity
expected through the remainder of the week with minimum staying
above 30 percent.

&&

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

&&

$$

SHORT TERM...Keyes
LONG TERM...Keyes
AVIATION...GK
FIRE WEATHER...GK