739
FXUS65 KPIH 120320
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
920 PM MDT Fri Sep 11 2026

.KEY MESSAGES...

- Red Flag Warning in the Snake River plain and Teton Valley
  (Fire Weather Zone 410) until 9 PM this evening for low
  humidity and gusty wind. Fire Weather Watch on Saturday noon
  to 9 pm due to low humidity and gusty wind.

- Saturday afternoon temperatures warm for most, then Sunday
  into Monday afternoon temperatures cool 10 to 15 degrees,
  ending critical fire weather conditions. Windy conditions
  through Sunday.

&&

.DISCUSSION...
Issued at 133 PM MDT Fri Sep 11 2026

Broad zonal flow in place today per satellite imagery. Light
showers from overnight have moved east of the region per
satellite and radar imagery, with only partly cloudy skies over
higher terrain areas. Steepened surface gradient in place behind
front, and windy conditions remain today across much of the
Snake Plain. A few locations across the Arco Desert may gust
over 40 mph into Wind Advisory criteria, but most of the region
should remain below thresholds, and will hold on a headline or
today. A few of the high-res CAMs still depict a brief period of
weak convective activity this afternoon across portions of the
southern highlands. There is a weak feature driving along the
northern Nevada border apparent on water vapor satellite
imagery, so it is difficult to completely dismiss the potential.
But do believe that the convective depiction is overdone.
Conversely, radar shows some development along the Divide, which
is NOT depicted well in the CAMs. That activity should remain
north of the Divide so will leave the forecast dry there as
well.

Saturday remains dry with locally gusty winds especially across
the southwest portions of the region. Temperatures rise a few
degrees over today`s readings. By Sunday, the upper low
approaches the region, slightly slower than previous runs. We
could see a few showers late Saturday night across portions of
the central mountains, but most of the region will remain dry in
pre-frontal airmass. Frontal passage is expected Sunday
morning, bringing the next round of winds to East Idaho. NBM
shows a strong signal for most of East Idaho to gust over 30
mph, with much of the Arco Desert and the Upper Snake Plain
expected to see gusts exceed 40 mph once again. Temperatures
into Sunday cool some 10-15 degrees, but the latest runs have
nudged Sunday`s highs a few degrees warmer than previous runs
and shifted the coldest day to Monday. As the upper low ejects
northeast, most of East Idaho stays in the dry slot ahead of the
main trough, so minimal precipitation is forecast at this time.


For the remainder of the forecast period, ensemble means slowly
transition the intermountain west from broad trough regime to a
broad ridge. Details are a little messy with the operational GFS
still depicting a split flow with passage of a small closed low
feature late in the week. Operational ECMWF shows a similar
feature, so there is some potential for precipitation late in
the week, which is depicted somewhat in the NBM as well.
Otherwise dry conditions are expected with a gradual warming
trend through the week.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 919 PM MDT Fri Sep 11 2026

Winds will continue to weaken through the night with mainly
high clouds drifting through. A few gusts to around 20kts are
likely Saturday afternoon.


&&

.FIRE WEATHER...
Issued at 133 PM MDT Fri Sep 11 2026

Strong upper level flow will be mixing down to the surface today.
This combined with continued very low humidity has lead to another
Red Flag Warning for Fire Zone 410. The area of strongest wind
shifts farther southward on Saturday, closer to the Utah and Nevada
borders and with warmer temperatures, red flag conditions could
transpire tomorrow afternoon. Thus a Fire Weather Watch continues
for Fire Weather Zone 427 on Sat and will likely be changed to a Red
Flag Warning later tonight once today`s headlines drop off. The
strongest wind is expected across the area on Sunday, as a trough
moving through Sat night brings the tightest gradient of the next
three days. However, cooler temps will keep afternoon humidity well
above the 15 percent critical threshold. Temperatures bottom out on
Mon, as wind dies down strongly and high pressure returns to the
northern Great Basin to start the next week.

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon to 9 PM MDT Saturday for IDZ427.

&&

$$

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