777
FXUS65 KPIH 031230
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
630 AM MDT Thu Sep 3 2026

.KEY MESSAGES...

- Flash Flood Watch for Wapiti Burn Scar: A localized Flash
  Flood Watch is in effect for the Wapiti burn scar near
  Stanley. Repeated rounds of showers and thunderstorms over the
  Central Mountains today could trigger rapid runoff and debris
  flows in the burn area.

- Breezy but Weaker Winds Today: Winds will remain breezy this
  afternoon across the Snake Plain and Magic Valley, but peak
  gusts are expected to be slightly weaker than what was
  observed on Wednesday.

- Brief Warming Trend Through Saturday: Daytime temperatures
  will warm slightly each day through Saturday, briefly
  returning lower-elevation highs to the upper 70s and lower
  80s.

- Major Pattern Shift for Labor Day: High confidence remains for
  a potent Pacific storm system to arrive late in the holiday
  weekend. Expect widespread wetting rains and a 10 to 15-degree
  drop in temperatures from Sunday into Labor Day.

&&

.DISCUSSION...
Issued at 234 AM MDT Thu Sep 3 2026

The broad upper-level trough over the Pacific Northwest
continues to govern our weather pattern. Moisture streaming into
the region remains focused primarily across the Central
Mountains. High-resolution convective-allowing models (CAMs)
continue to indicate multiple rounds of showers and embedded
thunderstorms traversing the higher terrain today. Given the
convective nature of the precipitation and the potential for
brief, heavy downpours, a localized Flash Flood Watch has been
issued for the Wapiti burn scar near Stanley. Hydrophobic soils
within the burn perimeter make this area highly susceptible to
rapid runoff and debris flows, even with modest rainfall rates.

Elsewhere across eastern Idaho, conditions will remain largely
dry. Winds across the Snake Plain, Magic Valley, and Arco Desert
will remain breezy out of the west-southwest this afternoon,
but peak gusts are expected to be a few notches lower than
Wednesday`s near-advisory levels. High temperatures today will
remain cooler than normal, holding in the 60s and 70s but a few
degrees warmer across the Snake Plain and Magic Valley compared
to yesterday.

As the initial waves of energy lift out of the region, we will
see a brief reprieve on Friday and Saturday. Precipitation
coverage will wane, and a subtle warming trend will take hold.
Expect afternoon maximum temperatures to increase slightly each
day, pushing lower-elevation valleys back into the upper 70s
and lower 80s by Saturday afternoon. Breezy afternoon winds will
persist, but overall weather impacts will be minimal ahead of
our next major system.

Confidence continues to increase regarding a significant pattern
shift for the latter half of the holiday weekend. Global model
ensembles are in excellent agreement that the parent upper-level
low anchored off the Pacific Northwest coast will finally eject
eastward, digging directly into the Intermountain West on Sunday
and Monday. This system will bring a surge of strong atmospheric
lift and deep moisture, resulting in high probabilities for
widespread wetting rains across all of eastern Idaho. Still some
uncertainty with respect to precip amounts, which have trended
back down, but high confidence in below normal temps on the
Labor Day holiday with many locations likely staying in the 60s.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 626 AM MDT Thu Sep 3 2026

VFR expected through the period. KSUN will see some showers in
the vicinity through midday before the better precip potential
pushes north of the area. Elsewhere, no precip expected with
just mid/high level clouds streaking through the region. Will be
breezy but lower than what we saw yesterday. Sustained 10-15 kt
with gusts around 20kt at best.

&&

.FIRE WEATHER...
Issued at 234 AM MDT Thu Sep 3 2026

Precipitation focus now shifts to the Central Mountains, where
repeated rounds of showers and thunderstorms today pose a
localized flash flood and debris flow risk, specifically over
the Wapiti burn scar. Breezy west-southwest winds will continue
across the Snake Plain and Magic Valley today and Friday, but
minimum relative humidity values will get close, but stay above
critical thresholds. A low pressure system in the latter part of
the holiday weekend looks to bring cooler temps and precip to
the region although just how much precip remains the forecast
challenge. A drying trend looks likely beyond the Labor Day
holiday with a slow up-tick in temperatures.

&&

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

&&

$$

DISCUSSION...McKaughan
AVIATION...McKaughan
FIRE WEATHER...McKaughan