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FXUS65 KPIH 082309
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
509 PM MDT Tue Sep 8 2026

.KEY MESSAGES...

- High pressure will keep clear skies with a warming trend
  through Thursday.

- A trough approaching from the northwest will increase wind on
  Thursday afternoon, allowing humidity and wind to combine to
  potentially bring critical fire weather conditions. Breezy to
  windy conditions expected Friday in the Snake River Plain.

- Next chance of precipitation and risk of thunderstorms could
  be as early as Friday with more widespread precipitation
  Sunday as upper level low moves overhead.

&&

.DISCUSSION...
Issued at 128 PM MDT Tue Sep 8 2026

No impacts related to the weather through Wednesday as clear
skies continue. After the very cool conditions Tuesday expect
temperatures back near seasonal normal on Wednesday and then
well above normal Thursday as a much stronger zonal westerly
flow aloft moves into Idaho. Many low elevation high
temperatures back to around 80 degrees on Wednesday then mid to
even upper 80s by Thursday. Mountains likely well into the 70s
most locations on Thursday as well. Winds in the 10 to 20 mph
range Thursday then in the 15 to 30 mph range on Friday mainly
in the Snake River Plain and Arco Desert. Models indicating a
chance of an upper level low pressure and strong cold front
moving through next Sunday increasing a chance of showers and
thunderstorms mainly in the mountains but mainly another
significant cool down Sunday into next Monday before warming
commences again. Upcoming seasonal change being indicated as
each cold front brings even cooler conditions than the previous
one. Overall not expecting significant rainfall through the next
week.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 508 PM MDT Tue Sep 8 2026

Winds will diminish this evening and give way to light and variable
winds overnight. VFR conditions are expected throughout the
forecast period with little to no cloud cover.

&&

.FIRE WEATHER...
Issued at 146 PM MDT Tue Sep 8 2026

Conditions will trend warmer and drier through Thursday under mostly
clear skies. Flow aloft will remain westerly through late week with
an area of high pressure to our south and troughing to our north.
Daytime highs will return to the 70s and 80s by mid-week, after
which temperatures cool again with widespread highs in the 60s by
late weekend. Winds will increase again Thursday through Saturday as
a PacNW trough deepens and the pressure gradient tightens. During
the weekend timeframe, models continue to show the center of low
pressure tracking over the northern extent of our CWA, bringing the
best precipitation chances to our northern mountains. Prior to this
increase in moisture, we will observe areas of near-critical to
critical fire weather conditions across southeast Idaho on Thursday,
where areas of relative humidity ranging 10 to 15 will overlap with
wind gusts over 25 to 30 mph. The only three zones in eastern Idaho
distinguished as having "critical" fuels are Fire Weather Zones 422,
425, and 427. Of those three, approximately only the northeastern
third of FWZ 425 and the extreme southeast corner of 422 are
forecast to reach critical wind speeds in combination with critical
RH values between around 3 PM and 8 PM Thursday. Considering
critical thresholds are currently not expected to be reached on a
widespread level across these three Zones, we have opted to hold off
on any Fire Weather Watch coordination for south-central Idaho.

&&

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

&&

$$

DISCUSSION...GK
AVIATION...AMM
FIRE WEATHER...Cropp