041
FXUS65 KPIH 231020
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
420 AM MDT Sat Aug 23 2025

.KEY MESSAGES...

- Hot and dry conditions continue for most areas this weekend,
  with shower and thunderstorm potential starting to increase
  across the southern highlands/Bear Lake Sunday afternoon.

- Regional wildfire smoke is forecast to increase again tonight
  and Sunday.

- Major changes arrive Monday and continue through the upcoming
  week due to a significant push of monsoon moisture, with
  higher humidity, more widespread clouds, cooler temperatures,
  and daily chances of showers and thunderstorms.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 241 AM MDT Sat Aug 23 2025

Today`s forecast will be almost a carbon copy of what we saw
Friday...hot and dry for almost everyone, with perhaps a stray
afternoon shower or dry-leaning thunderstorm along the Utah border
or in Cassia County. But, the monsoon is coming! The main push
really starts Monday (and continues throughout the week) with a
notable increase in humidity, cloud cover, and shower/thunderstorm
potential as well as cooler temperatures, but some effects will
start to be noticed Sunday afternoon across the southern highlands
and Bear Lake including at least a few showers and thunderstorms.
Meanwhile, models support an increase in regional wildfire smoke
from tonight into Sunday.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 116 PM MDT Fri Aug 22 2025

The seemingly endless pattern of hot and dry weather going back to
early July appears to be coming to an end as we move in to the final
week of August. The ridge over the Four Corners will shift south and
weaken in intensity beginning Sunday and a deep push of monsoonal
moisture will move into the region for much of next week. The
initial push looks to occur on Sunday. The most noticeable change,
initially, will be the increase in cloud cover area wide and we
certainly could see some isolated/scattered showers and storms
across the southern half of the forecast area but it looks like
we`ll have to wait until Monday to really see significantly higher
PoPs regionwide. From Monday afternoon through the day Thursday,
we`ll have a prolonged period of widespread cloud cover, precip
chances and cooler temperatures accordingly. Still seeing a pretty
wide spread amongst the model guidance with respect to temps and the
current forecast remains on the warmer side of guidance as the NBM
tends to have a hard time with a significant pattern change like
this. That being said, nudged things down ever so slightly but don`t
be surprised if forecast temps come in even cooler than currently
forecast over the days ahead. Still have some details to try to iron
out. Bottom line is expect our first chance for widespread wetting
rainfall in quite some time with daytime high temps also running on
the cooler side of normal.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 420 AM MDT Sat Aug 23 2025

It continues to look like we`ll pull off one more dry, low-impact
day for aviation before a significant push of monsoon moisture
arrives from the south between Sunday and Monday depending on the
terminal. Until then, winds will remain less than 10kts with just a
slow increase in FEW to SCT high-level clouds over the next 24-36
hours, with increasing potential for showers, thunderstorms, and
thicker clouds starting Sunday afternoon at least for KBYI and KPIH.
Today`s diurnal wind cycle at KSUN will likely again feature a shift
from SE to SW around 22z/4pm.

&&

.FIRE WEATHER...
Issued at 241 AM MDT Sat Aug 23 2025

Hot and dry conditions continue today across the region with minimum
afternoon RH values near or below critical thresholds, but winds
stay very light. A stray afternoon shower or dry thunderstorm can`t
be ruled out in Cassia County, or along the immediate Utah border.
BIG CHANGES are coming though...A significant push of monsoon
moisture will overtake the region Monday onward with high humidity,
increased cloud cover, cooler temperatures, and
showers/thunderstorms along with a chance of widespread wetting
rains in mountain areas in the Tuesday/Wednesday/Thursday timeframe,
but a hint of this new airmass will sneak into the southern
highlands and Bear Lake as early as Sunday afternoon with minimum RH
values of 20-35 percent and a few showers/thunderstorms (everyone
else stays dry and hot for one more day). Sunday will likely really
be our only "day of transition" as the near-surface airmass will
remain just dry enough to support mostly dry-leaning thunderstorms
with a risk of new fire starts due to lightning, before PWATs surge
and wetter cores begin to dominate from Monday afternoon onward.
Confidence on thunderstorm coverage reaching "scattered" Sunday
afternoon in the south remains low...in fact, the latest suite of
HREF CAMs suggests more isolated coverage at this time.

&&

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

&&

$$

SHORT TERM...01
LONG TERM...McKaughan
AVIATION...01
FIRE WEATHER...01