Heman, Idaho Weather Forecast Discussion

922
FXUS65 KPIH 200731
AFDPIH
Area Forecast Discussion
National Weather Service Pocatello ID
131 AM MDT Sat Sep 20 2025
.KEY MESSAGES...
- Showers and Storms Over the Weekend, Especially Sunday
- Cooler than Normal Temps on Monday
- Above normal temps return Tuesday and into next weekend
  remaining mostly dry
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 129 AM MDT Sat Sep 20 2025
Early morning satellite imagery shows some mid/high level clouds
in place across the region this morning and clouds, and precip,
will be the main theme for the last weekend of summer.
Monsoonal moisture continues to stream north into the region and
today we should see some showers and thunderstorms develop
across the area. The best chances today look to be primarily
across the southern third of the region, namely across the south
hills, into the Raft River region and maybe sneaking in to the
southern Snake Plain. The atmosphere doesn`t appear to be overly
conducive for any significant winds from these thunderstorms
with HREF probabilities hovering around 10 percent or less for
wind gusts greater than 30 kts. CAMs do show some potential for
the precipitation to linger into the late evening and perhaps
into the overnight hours of Sunday AM so the forecast does carry
PoPs in spots accordingly. Temperatures tomorrow look to be
very similar to Friday`s values although spots closer to the
Utah border could end up a few degrees cooler with increased
cloud cover. Overnight lows look to be very mild for this time
of year, especially in the lower valleys with low to mid 50s,
maybe even some upper 50s possible. Mountain locations will
generally be in the 40s as we begin the day Sunday.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 105 PM MDT Fri Sep 19 2025
The best chance of showers and storms areawide will be Sunday,
and eastern areas on Monday. There is better agreement today on
what happens with the closed low early next week, which is to
close it off east of the Divide. We will see a decent amount of
moisture with the storm as it develops. Most of the
precipitation falls in higher elevations with this storm. There
is 15-35% chance of more than 0.25" in the central mountains and
up to 50-60% in the eastern and southeast highlands. The
potential for over 0.50" peaks between 20-50% along and east of
I-15 through Monday morning. Those chances are in a given 12
hour period anywhere from 6am Sunday - 6am Monday. Showers and
storms will linger east of I-15 Monday, but Tuesday and
Wednesday looks dry as high pressure rebuilds for a short time
over our area. The end of next week COULD be showery again. The
Blend of Models follows the trend of the GFS and ECMWF, which
brings a closed low far enough north to increase clouds and kick
off some showers and storms. Temperatures are trending much
cooler for Monday. Valley highs are now only expected to be in
the mid to upper 60s, which is 5-10 degrees BELOW AVERAGE. We
should rebound quickly next week and push back above average for
the end of September.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 927 PM MDT Fri Sep 19 2025
Low approaching from the south will bring on and off cirriform
CIGs tonight, then in the morning a low to mid- level cloud deck
should start moving in, first seen at KBYI and KPIH, then by
mid-day at KIDA, KDIJ, and KSUN. TSRA and SHRA will develop
during the afternoon or early evening, beginning at KBYI and
KPIH. These are the only airdromes that appear to be threatened
with thunder. KSUN and KDIJ have a threat of showers, with KSUN
in the evening (due to the low) and KDIJ in the afternoon (due
to afternoon heating). Only KIDA appears to avoid precipitation,
at least in the afternoon and evening. No impact to VSBY is
expected, and the risk of TSRA just barely rises to the PROB30
level.
Wind will not be as light, driven by slope-valley or just
variable in direction. Only KSUN appears to have the slope-
valley wind, and then just for the morning and early afternoon.
A southerly component should kick in during the day on Sat for
the other airports. Outside of TSRA, wind should not exceed
12KT. For thunderstorm outflow, there is not upper level support
for any moderate to strong outflow, so have put in a minimum of
15G30KT.
&&
.FIRE WEATHER...
Issued at 129 AM MDT Sat Sep 20 2025
Precipitation chances increase today for at least parts of the
region becoming more widespread on Sunday as a surge of moisture
moves in and a Pacific shortwave shifts inland. Sunday would be
the day with better chances of measurable precipitation, with
higher elevation regions seeing a 25-35% chance of a wetting
rain. Those chances rise to 35-45% east of I-15 for Sunday
evening and overnight as the frontal system associated with the
low shifts through the region. Following the frontal system,
temperatures will be below normal for Monday, with most lower
elevation highs in the mid 60s- low 70s. A ridge of high
pressure building into the region Monday through at least
Wednesday should keep the region dry. There is quite a bit of
uncertainty after midweek with respect to breaking down the
ridge and allowing another system into the state, but for now
any precipitation chances look isolated at best to round out the
week.
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...McKaughan
LONG TERM...Keyes
AVIATION...Messick
FIRE WEATHER...McKaughan

NWS PIH Office Area Forecast Discussion