806
FXUS65 KPIH 211032
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
432 AM MDT Sun Sep 21 2025

.KEY MESSAGES...

- Showers and thunderstorms likely today

- Some storms may produce gusty winds and moderate to heavy
  rainfall

- Cooler temperature Monday before warming back up mid to late
  week

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 1254 AM MDT Sun Sep 21 2025

Early morning satellite imagery shows a complex of clouds along the
borders of Idaho, Nevada and Utah slowly spiraling up into the south
hills region. Radar returns have been generally void of anything of
significance but hi-res CAMs show this activity increasing in
coverage an intensity later this morning as is pushes through the
central part of the forecast area. Showers, maybe some
thunderstorms, will be possible with this during the overnight but
more likely just beyond daybreak as upper level dynamics become a
bit more favorable. Meanwhile to our NW, an upper level trough will
push south into the northern part of the state later today pushing a
frontal boundary through the area later tonight and into Monday.
What does this mean for sensible weather across the region? Well, it
looks like things will be rather cloudy today with widespread shower
and storm chances. The highest PoPs are focused across the higher
terrain but the lower valleys will not be exempt from precipitation
either. Given the convective (hit-or-miss) nature of the precip,
some folks will see some decent rain today while others will not and
it`s difficult to pinpoint exactly where that`ll be. What is more
certain is that the day will be mostly cloudy to cloudy across the
region which will keep temperatures a touch cooler than Saturday.
Valley temps from the low to upper 70s are expected with 60s in the
higher terrain. Not expecting too much of a severe threat today but
HREF does show about a 30-50 percent probability of storms producing
gusts in excess of 40 mph, with the highest probability focused
across the Magic Valley/South Hills where instability looks to be a
bit more favorable. Post frontal passage look for cooler
temperatures as we move into Monday.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 130 PM MDT Sat Sep 20 2025

Showers and storms persist through Monday evening over the
eastern half of our area. It does appear that as the winds
switch to a northerly direction, a convergence band develops and
impacts the northern half of the Snake Plain and into the
eastern highlands. Rainfall amounts look lighter, but we still
could see some localized moderate rainfall rates and
accumulation. Monday will be much cooler with northerly flow and
cooler air briefly spilling into eastern Idaho. Highs may barely
push 70 in some spots. Dry weather returns for the middle part
of next week. We are still looking to see if a low cutting
through the ridge ends up far enough north for a chance of
showers and thunderstorms...especially along the Utah border.
The Blend of Models is trending drier although not necessarily
indicating there is NO CHANCE. Both the GFS and ECMWF do
indicate we could see some clouds and at least a slight chance
of rain and thunder. We shall see what happens in a few days.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 431 AM MDT Sun Sep 21 2025

VFR expected to prevail outside of showers and thunderstorms but
skies will be mostly cloudy to cloudy for much of the day. Winds
should be light however outside of any convective activity.
Maintained existing PROB30s for thunderstorm potential and only made
minor adjustments to the previous forecast. Should start to see some
clearing late in the period at KSUN and KBYI but it will likely take
until the second half of the day on Monday to see any clearing at
KPIH, KIDA and KDIJ.

&&

.FIRE WEATHER...
Issued at 1254 AM MDT Sun Sep 21 2025

Will begin to see an increase in showers and storms across the
southern portion of the area during the overnight and early morning
hours. By the afternoon, showers and thunderstorms increase in
coverage across the region. Scattered to numerous showers and
isolated to scattered thunderstorms are forecast for the afternoon
and evening. Wetting rain chances have risen to 45-70% for all
higher elevation zones outside the Snake Plain for the 12-hr period
from noon to midnight. Coupled with the increased daytime humidity
for today, critical fire conditions are NOT expected. The
thunderstorm coverage decreases after sunset, but showers and
isolated thunderstorms continue, shifting focus to the eastern half
of the region overnight into the first part of the day Monday. Drier
air mass shifts into place for late Monday through the rest of the
week as a ridge of high pressure builds into the western states.
Things look to remain dry into next weekend with above normal
temperatures likely to continue aside from a brief cooldown on
Monday and Tuesday.

&&

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

&&

$$

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