729
FXUS65 KPIH 212338
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
538 PM MDT Thu Aug 21 2025

.KEY MESSAGES...

- Mostly dry conditions through Saturday.

- Marginally critical fire weather conditions today and tomorrow
  due to winds and low relative humidity.

- Increase in wildfire smoke into Eastern Idaho.

- Monsoon moisture lifting north late Saturday into Sunday will
  support the return of daily shower and thunderstorm chances
  into early next week as temperatures trend cooler.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 229 PM MDT Thu Aug 21 2025

Conditions are much drier overall today, but if you`ve checked
satellite and radar at all today you`ve seen that we still have
some isolated storms throughout southeastern Idaho. These
isolated storms are expected to remain south of I-84/86 and east
of I-15 and will produce wind gusts around 30 mph. This is
thanks to the stalled trough over the area. Elsewhere, we remain
hot today with highs in the upper 80s and low 90s once again
with wind gusts around 20 to 25 mph for most. High pressure
continues to build over the desert Southwest, pushing the ridge
axis farther north into parts of Idaho on Friday to push any
remaining showers or isolated storms a bit farther to our east
and helping temperatures warm a few more degrees into the low to
mid 90s area wide. Winds remain pretty "typical" for Eastern
Idaho, with gusts around 20 to 25 mph in the afternoon.

The worst of the wildfire smoke has been confined up to our
north in Lemhi county for the most part today, but some of it
has been filtering farther southeast into parts of the Central
Mountains and upper Snake River Plain. The HRRR Smoke models
show more impactful smoke moving into the northwestern portion
of Custer county/Stanley area late tonight into tomorrow. It`s
also picking up on some smoke from the Cottonwood Peak fire in
north central Nevada, though that smoke will more likely remain
higher up in the atmosphere with less impact to air quality at
the surface.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 229 PM MDT Thu Aug 21 2025

The weekend begins with continued well above normal
temperatures as H5 heights top out on Saturday as a large area
of high pressure centered near the Four Corners region keeps its
hold on regional weather. This should lead to mostly clear
skies, no precipitation and daytime highs in the low to mid 90s
across the lower elevations. The pattern begins to change late
in the day Saturday and especially Sunday where more moisture
begins to surge into the region thus increasing cloud cover and
rain chances starting on Sunday and continuing throughout the
remainder of the extended portion of the forecast. Precipitable
water values climb throughout the upcoming workweek and look to
be around an inch, or more, for much of the area which is
abnormally high for this part of the country. This should set
the stage for our first decent stretch of wetting rainfall in
quite some time. Tuesday through Thursday looks to be the best
period for seeing wetting rainfall across the area. It`s a bit
too early to get caught up in specifics but confidence continues
to increase in our prolonged dry stretch coming to an end at
some point next week. There remains some model spread with
regards to temperatures next week due to model uncertainty on
clouds, precip, etc so expect to see some fluctuations over the
next few forecasts until model spread begins to decrease, at
least in theory.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 538 PM MDT Thu Aug 21 2025

VFR conditions are expected to continue through the forecast
period as high-level clouds build in out of the southwest. Winds
will generally remain light tonight and throughout the day on
Friday, 10 kts or less. We could see wildfire smoke/haze move
into the area tonight, but we are currently expecting the bulk
of smoke to remain in west-central Idaho away from terminals.

&&

.FIRE WEATHER...
Issued at 229 PM MDT Thu Aug 21 2025

Isolated showers and storms will continue across
parts of Fire Weather Zone 413 this afternoon and evening. Little to
no rain is expected and gusts will be around 25 to 30 mph.
Throughout the rest of our Fire Weather Zones expect very dry
conditions with min RHs this afternoon between 10 and 20 percent.
For the most part, wind gusts will be around 20 to 25 mph though we
may see a couple of gusts closer to 30 mph in the western half of
Zone 410 and northern half of Zone 425. These conditions won`t be
widespread enough to issue any Red Flag Warning today. Look for
nearly a repeat of the forecast on Friday, but with even fewer
isolated storms as the high pressure ridge axis builds north into
Idaho. Min RHs will decrease by just a few percentages and winds
will just slightly decrease, too. On Saturday, we`ll see a few more
isolated storms make their return, but the bigger chances will
arrive on Sunday as monsoon moisture arrives from the south and
brings scattered showers and storms and an increase in min RHs that
will continue through a good portion of next week.

&&

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

&&

$$

SHORT TERM...AMM
LONG TERM...McKaughan
AVIATION...MacKay
FIRE WEATHER...AMM