Roy, Idaho Weather Forecast Discussion

641
FXUS65 KPIH 291004
AFDPIH
Area Forecast Discussion
National Weather Service Pocatello ID
404 AM MDT Mon Sep 29 2025
.KEY MESSAGES...
- Increasing risk of showers and thunderstorms across the entire
  forecast area today, peaking on Tuesday.
- Much cooler temperatures for Tuesday.
&&
.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 103 AM MDT Mon Sep 29 2025
A slow moving cold front will approach the region today. We will
showers and thunderstorms mainly across the Magic Valley into the
central mountains today. As we move through the night, the band of
showers will follow the front and linger into Tuesday morning. It
looks like we may clear enough and become unstable in the afternoon
for isolated to scattered showers and thunderstorms Tuesday
afternoon. The only real area that we have for potential flooding
would be around Stanley with the Wapiti burn scar. Rainfall amounts
of 0.50 to 1.00 inches seems likely Tuesday night. Although most of
this rain may be falling over several hours and part of this rain
may soak into the soil.  Elsewhere rainfall amounts are around 0.25
inch for this event. Although there is roughly a 25% chance that
much of east Idaho may only see 0.10 inches or less. On the other
hand, there is a 10% chance central and east Idaho may see 0.50
inches of rain. High temps on Monday are above normal with
temperatures in the mid to upper 70s across the Snake Plain and
Magic Valley. But on Tuesday, highs fall to the mid and upper 60s
for those same areas.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Issued at 156 PM MDT Sun Sep 28 2025
Southwest flow aloft continues with upper low churning off
Seattle/Vancouver coast. Ensembles begin to shift the low inland
Wednesday, opening it up and ejecting a weak shortwave across the
region. Showers and a few thunderstorms remain possible Wednesday,
but the main trough passage appears to be Thursday to Friday. There
are significant differences in how the ensemble clusters portray
passage of the trough. NBM blend brings the greatest precipitation
chances Friday, but spread the chances out from Thursday night into
Saturday. Breezy conditions accompany another cooldown, this time
lasting into the weekend with deterministic NBM reaching only into
the 50s for lower elevations both Saturday and Sunday. It is worth
nothing that there is roughly a 15 degree spread between low-end and
high-end temperatures, so not a lot of confidence yet. That said,
the late week frontal system does look more robust and amplified
than the previous features ejecting across the region.
&&
.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 404 AM MDT Mon Sep 29 2025
VFR conditions at IDA, PIH and DIJ today with showers
not arriving until late tonight. Continuing the PROB30s at SUN and
BYI this afternoon with high res models showing scattered
thunderstorms developing across the Magic Valley late this
afternoon. Widespread showers will likely develop this evening at
SUN and BYI. At this point, not expecting anything lower than VFR
ceilings with SUN and BYI sporting less than a 20% chance of
reaching MVFR conditions tonight.
&&
.FIRE WEATHER...
Issued at 103 AM MDT Mon Sep 29 2025
A slow moving cold front will bring wetting rains to
the region. South Idaho and Central Idaho will see most of its rain
Monday afternoon and Monday Night while East Idaho will see it
Monday Night and Tuesday. Rainfall totals of 0.50 to 1.00 inches of
rain will fall across much of 422, 475 and 476. Valley locations
around Salmon and south may see closer to 0.25 inches. Most other
locations should see 0.10 to 0.25 inches.
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...13
LONG TERM...DMH
AVIATION...13
FIRE WEATHER...13

NWS PIH Office Area Forecast Discussion