528
FXUS65 KPIH 161452
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
852 AM MDT Sat Aug 16 2025

.KEY MESSAGES...

- Near critical to critical fire weather conditions will
  continue through the weekend due to gusty winds, low relative
  humidity, and isolated to scattered thunderstorms.

- Shower and thunderstorm chances will continue today and
  tomorrow, with stronger storms capable of producing gusty
  outflow winds.

- Temperatures next week will remain near normal to above normal
  with highs in the 80s/90s.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 845 AM MDT Sat Aug 16 2025
Updated the forecast this morning to include a little broader
coverage of thunderstorms in the Snake Plain, particularly in
the upper portion of the Plain near the St. Anthony Sand Dunes
where we have the Sand Creek Fire. Due to this broadening, we`ve
expanded the Red Flag Warning as well.

Issued at 204 AM MDT Sat Aug 16 2025
Radar is picking up on a few returns this morning, though that
appears to be catching some of the increasing cloud cover as our
atmospheric moisture begins to increase over the area for this
weekend thanks to a deepening of the trough over the West Coast.
Expect isolated to scattered storms across Eastern Idaho again
today, very similar to what we saw yesterday, and with a bit
more activity in the Central Mountains this afternoon, too. It
is most likely that storms will produce some brief downpours and
wind gusts of 50 to 60 mph. There still isn`t a ton of moisture
to rain out today, so the wetter storms will produce about a
tenth to a quarter inch of QPF. The HREF is highlighting a
fairly small area between Pocatello and Idaho Falls for about a
10 percent chance for any wind gusts of 60+ mph later today.
Outside of any thunderstorm activity today, it will still be
breezy with wind gusts of 20 to 30 mph for many. Our "cooling"
trend continues for the weekend, but in this case "cool" is
highs in the upper 80s to low 90s this afternoon and widespread
80s on Sunday. Look for more showers and thunderstorms on Sunday
with an uptick in moisture moving into the Central Mountains
area. Wind gusts outside of thunderstorms will be a bit lighter
on Sunday, only around 15 to 20 mph.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 204 AM MDT Sat Aug 16 2025

Under the increasing influence of high pressure early next week, hot
and dry conditions will prevail as highs climb back into the upper
80s to upper 90s in the valleys starting Tuesday. These temperatures
are about 6 to 12 degrees above normal for this time of year,
meaning our latest forecast comes within around 1-4 degrees of daily
record highs at our official climate sites, a solution supported
amongst ensemble model guidance. Temperatures look to peak on
Tuesday and Wednesday, where around a 5-15% chance exists across the
Snake River Plain of reaching 100 degrees or warmer. Above normal
temperatures are then expected to continue through next weekend as
we remain situated under a broad ridge of high pressure.

Early indications amongst ECMWF/GFS ensembles and deterministic
model solutions show the potential for monsoonal moisture flow out
of the SW CONUS building into eastern Idaho late next week on the
west side of this ridge of high pressure. The latest NBM continues
to lean more towards the wetter solution on the ECMWF versus the GFS
which remains the drier of the two. The biggest factor will
ultimately end up being if we are able to keep an overall S/SW
mid/upper-level flow pattern around to support that monsoonal
moisture axis lifting up into our region, as opposed to a more
westerly flow which would bring in drier air from the PacNW. At this
time, the NBM slowly increases shower and thunderstorm chances
starting Thursday through next weekend, which we will continue to
monitor over the coming days to see exactly where that monsoon
moisture axis sets up.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 505 AM MDT Sat Aug 16 2025

No major forecast changes this morning. VFR conditions are expected
today, but we will see isolated to scattered storms once again.
The smallest storm chance (~20 percent) will exist at SUN where
VCSH has been added in for the afternoon/evening. Elsewhere,
storm chances are higher and PROB30s begin around 21Z for PIH,
IDA, BYI, and DIJ. Storms will be capable of producing gusts of
at least 40 kts. CAMs are showing the potential for some spotty
showers to continue into tonight, but will leave any mention of
VCSH out of the TAFs for that timeframe for now. It may just be
picking up on cloud cover from increasing moisture rather than
actual rain showers, but will continue to evaluate the trend.
Sunday will be nearly a repeat of today.

&&

.FIRE WEATHER...
Issued at 845 AM MDT Sat Aug 16 2025
Updated the forecast this morning to include a little broader
coverage of thunderstorms in the Snake Plain, particularly in
the upper portion of the Plain near the St. Anthony Sand Dunes
where we have the Sand Creek Fire. Due to this broadening, we`ve
expanded the Red Flag Warning as well. Anywhere where
thunderstorms develop could see gusty outflow winds driving any
existing wildfires or new wildfire starts.

Issued at 204 AM MDT Sat Aug 16 2025
Near critical to critical fire weather conditions will continue
across central and eastern Idaho through the weekend due to a
combination of isolated to scattered thunderstorms and breezy
winds, in addition to low relative humidity today ahead of an
improvement tomorrow. As a result, Red Flag Warnings are in
effect today from 12 PM to 9 PM MDT for Idaho FWZ 411, 413, 475,
and 476 where best scattered thunderstorm coverage will exist.
Outside of these zones, coverage will remain more isolated in
nature, with the exception being Idaho FWZ 410 where coverage
will be isolated to scattered. Given a very dry environment at
the surface with RHs this afternoon in the teens/20s, stronger
showers/storms and outflow boundaries regionwide will be capable
of producing wind gusts up to 50-60 mph, with brief heavy rain
and small hail also possible. Activity will peak during the
afternoon hours before subsiding in the evening, with very
isolated showers/virga possible during the morning and overnight
hours. Highs today will be in the low 80s to low 90s in the
valleys with synoptic winds outside of any convection peaking
around 10-20 mph with gusts to 20-35 mph.

For Sunday, look for another round of isolated to scattered showers
and thunderstorms regionwide with best scattered coverage in the
mountains. Given this trend, best candidates for Red Flag Warnings
due to scattered thunderstorms will remain focused in Idaho FWZ 411,
413, 422, 427, 475, and 476 which will need to be coordinated on the
day shift with our regional fire partners. Stronger shower/storms
and outflow boundaries will continue to support wind gusts up to 50-
60 mph, brief heavy rain, and small hail.

Under the increasing influence of high pressure starting Monday, hot
and dry conditions will return to eastern Idaho regionwide with
above normal temperatures then expected through all of next week.
While we may ultimately see some increasing shower and
thunderstorm chances and rising RHs later in the week dependent on
where a monsoonal moisture axis sets up, conditions are looking very
dry for the bulk of next week with afternoon RHs each day in the
single digits/teens. At this time, there does not seem to be a great
deal of areal coverage of an overlap of gusty winds and low RH,
meaning gusts each afternoon should peak around 20-30 mph, with only
locally stronger winds possible.

&&

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

&&

$$

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