631
FXUS65 KPIH 010803
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
203 AM MDT Tue Sep 1 2026

.KEY MESSAGES...

- Red Flag Warning & Scattered Storms Today: Overnight showers
  over the Snake Plain and Eastern Highlands will clear this
  morning, followed by an afternoon flare-up of showers and
  thunderstorms. A **Red Flag Warning** remains in effect for
  Fire Zone 422 due to scattered thunderstorm coverage.

- Breezy to Windy Mid-Week: A tight pressure gradient will
  produce widespread breezy to windy conditions Wednesday
  through Friday, with some valley corridors flirting with Wind
  Advisory criteria.

- Below-Normal Temperatures: Afternoon highs will remain
  suppressed in the mid-to-upper 70s across lower valleys and
  60s to low 70s in the mountains, though a brief recovery into
  the lower 80s is expected today and possible again on
  Saturday.

- Unsettled Labor Day Weekend Outlook: Unsettled conditions and
  rain chances increase late in the holiday weekend, with high
  confidence in cool, below-normal temperatures persisting into
  the first week of September.

&&

.DISCUSSION...
Issued at 155 AM MDT Tue Sep 1 2026

Overnight rain showers continue to stream across the Snake
Plain and Eastern Highlands early this morning. High-resolution
convective-allowing models (CAMs) show this initial wave exiting
by mid-morning, yielding a brief lull in precipitation.
However, incoming upper-level shortwave energy and lingering
atmospheric moisture will spark a secondary round of showers and
thunderstorms by early-to-mid afternoon. While forcing and QPF
will focus heavily over the Central Mountains and along the
Continental Divide, latest model trends indicate an isolated
shower or storm is possible nearly anywhere across eastern
Idaho. Given the scattered nature of lightning strikes on dry
fuels, a Red Flag Warning remains active for Fire Zone 422
today. Convective activity will taper off late this evening,
with most showers diminishing by midnight.

Broad upper-level troughing anchored over the Pacific Northwest
will dictate regional weather through the remainder of the
workweek. Embedded impulses rotating around the parent low will
track through the flow, with one prominent lobe crossing the
region on Wednesday. Because the core energy will remain shunted
to our north and west, shower and thunderstorm chances
Wednesday and Thursday will be largely restricted to the Central
Mountains. The more widespread operational impact mid-week will
be strong afternoon winds driven by a tight regional pressure
gradient. Several wind-prone valley corridors will flirt with
Wind Advisory thresholds each afternoon. Fortunately,
unseasonably cool air will hold minimum relative humidity values
above critical thresholds. Afternoon highs Wednesday through
Friday will top out in the mid-to-upper 70s in lower elevations
and mid-60s to lower 70s across mountain zones.

Lower elevations may see a brief temperature recovery into the
lower 80s on Saturday before the next weather system approaches.
Guidance indicates a potentially unsettled pattern taking hold
for the latter half of the Labor Day holiday weekend, with rain
chances trending upward Sunday into Monday. While global models
continue to struggle with the exact synoptic placement of the
upper low and deepest moisture plumes, confidence remains high
that below-normal temperatures will persist through much of the
first week of September.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 911 PM MDT Mon Aug 31 2026

A few thunderstorms are on the leading band of moisture working
northward. Most of the thunderstorms should diminish by 06z.
Showers will pass through east Idaho overnight into Tuesday
morning. Gusty winds are likely during the overnight hours but
should relax Tuesday morning. Another round of convection is
expected Tuesday afternoon.

&&

.FIRE WEATHER...
Issued at 155 AM MDT Tue Sep 1 2026

The primary operational fire hazard today is scattered
thunderstorm activity across south-central Idaho, where a Red
Flag Warning remains active for Fire Zone 422. While wetting
rain will accompany stronger cores, lightning ignitions outside
rain shafts remain a concern. Wednesday through Friday will
bring strong, breezy west-to-southwest wind gusts across all
zones as pressure gradients tighten. However, unseasonably cool
temperatures holding in the 60s and 70s will keep daytime
relative humidity recoveries elevated above critical thresholds.

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 1 PM this afternoon to 9 PM MDT this
evening for IDZ422.

&&

$$

DISCUSSION...McKaughan
AVIATION...13
FIRE WEATHER...McKaughan