633
FXUS65 KPIH 171108
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
508 AM MDT Sun Aug 17 2025

.KEY MESSAGES...

- Critical fire weather conditions continue today with
  scattered thunderstorms and gusty winds.

- Scattered thunderstorms could be strong, producing brief
  downpours, small hail, and outflow winds of 50 to 60 mph.

- Drier conditions return for the bulk of next week with
  temperatures moving back above-normals.

&&

.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 243 AM MDT Sun Aug 17 2025

Today`s forecast will be nearly a repeat of the last several days
with scattered thunderstorms across much of Eastern Idaho once
again. Our overall moisture content is increasing today thanks to
moist southwest flow over the area. This will keep temperatures a
bit "cooler" this afternoon with highs in the 80s for everyone.
We`re already seeing some showers and a couple of isolated storms to
the Central Mountains and upper Snake River Plain early this
morning. We`ve even seen an outflow boundary produce wind gusts to
almost 50 mph just west of Idaho Falls. Activity will continue on
and off throughout the day with more thunderstorm development
expected in the South Hills and Eastern Highlands this afternoon, so
really, everyone has at least about a 20 to 25 percent chance to see
a thunderstorm today. These storms will be capable of producing some
brief downpours, small hail, and gusty winds of 50 to 60 mph as
DCAPE values are ranging between 850 to 1200 J/kg. A Red Flag
Warning will be in effect later today for all of our CWA due to
these storms. More on that below in the Fire Discussion. Storms
will taper off this evening and then drier conditions return as
we head into Monday. There is about a 10 percent chance of an
isolated shower or thunderstorm on Monday afternoon up around
the Challis area, but the rest of Eastern Idaho will remain dry.
Highs return to the low to mid 90s in the eastern Magic Valley
and Snake River Plain on Monday and this is just the start of
our warm up.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Issued at 243 AM MDT Sun Aug 17 2025

Under strengthening high pressure and southerly flow midweek, well
above normal temperatures and dry conditions will prevail with
afternoon highs Tuesday and Wednesday in the upper 80s to mid/upper
90s in the valleys. These two days are when the NBM shows a 5-15%
chance of exceeding 100 degrees across lower elevations of the Snake
River Plain and mountain valleys less than 5000-5500 feet elevation.
During this timeframe, near record to record warmth is expected with
our latest forecast coming within 1-3 degrees of setting record
daily high temperatures at our official climate sites especially on
Tuesday. Starting Wednesday into Thursday, monsoonal moisture
working up out of the SW CONUS associated with a broad ridge of high
pressure centered over the Four Corners region will lead to
increasing chances for afternoon showers and thunderstorms through
the weekend. As it currently stands, best chances look to be
south/east of the Snake River Plain Wednesday through Friday before
an expansion further north into the weekend, supporting at least
isolated coverage regionwide. During this timeframe, temperatures
will see a very gradual cooling trend into the weekend, still
ultimately remaining above normal for late August.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 508 AM MDT Sun Aug 17 2025

Early morning showers and thunderstorms have brought brief
moments of light rain to SUN and IDA and outflow winds have
already been around 40 kts. VFR conditions are expected outside
of thunderstorms and afternoon wind gusts will be around 20 kts,
but if/when a storm passes over a terminal there is the
potential for gusts around 40 kts or even just a bit higher and
brief drops to MVFR conditions. The stronger storms get going
this afternoon, so have PROB30 in for all sites starting around
20-21Z and lasting until 02-03Z. Dry conditions return overnight
and will continue through Monday.

&&

.FIRE WEATHER...
Issued at 243 AM MDT Sun Aug 17 2025

Critical fire weather conditions will continue regionwide today as
moist southwest flow and the passage of a shortwave trough work to
support another round of scattered thunderstorms across central and
eastern Idaho. Isolated virga/showers and thunderstorms are ongoing
out there this morning, with activity expected to pick up this
afternoon and continue through the early evening hours. As a result,
a Red Flag Warning is in effect from 12 PM to 9 PM MDT for Idaho FWZ
410/411/413/422/425/427/475/476, covering all of our region. The
only notable change to this list is the inclusion of FWZ 425 where
more scattered coverage is now expected. Stronger thunderstorms will
remain capable of producing wind gusts up to 50-60 mph, small hail,
and heavy rain. Isolated activity will linger after sunset into
Monday morning as best chances ultimately shift to the north as
predominant dry conditions return regionwide. For Monday, isolated
showers and storms will remain possible up in Lemhi County and along
the Montana Divide as hot and dry conditions prevail overall.

Under the increasing influence of high pressure starting Monday, hot
and dry conditions will return regionwide. Following cooler
conditions on Sunday with highs in the 70s/80s and minimum RHs in
the teens/20s/30s, highs will quickly rebound into the upper 80s to
upper 90s by Tuesday with minimum RHs dropping back into the single
digits/teens each day. While winds will see a diurnal increase each
afternoon, gusts each day should only peak up around 25-30 mph.

Starting Wednesday into Thursday, monsoonal moisture working up out
of the SW CONUS associated with a broad ridge of high pressure
centered over the Four Corners region will lead to increasing
chances for afternoon showers and thunderstorms through the weekend.
As it currently stands, best chances look to be south/east of the
Snake River Plain Wednesday through Friday before an expansion
further north into the weekend, supporting at least isolated
coverage regionwide. During this timeframe, temperatures will see a
very gradual cooling trend into the weekend, still ultimately
remaining above normal for late August.

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon today to 9 PM MDT this evening for
IDZ410-411-413-422-425-427-475-476.

&&

$$

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