490
FXUS65 KPIH 121125
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
525 AM MDT Sat Sep 12 2026

.KEY MESSAGES...

- Red Flag Warning in effect this afternoon and evening for Fire
  Weather Zone 427 (South portion of Sawtooth NF) for low
  humidity and gusty wind.

- Windy conditions Sunday with strong cooling to temperatures.
  Wind Advisory may be needed.

- More cooling from Sunday to Monday. Light wind and dry
  conditions through at least Thursday.

&&

.DISCUSSION...
Issued at 155 AM MDT Sat Sep 12 2026

Today through Mon night...Canadian trough continues to move
eastward, but the pressure gradient is still strong enough to
keep wind gusty. With the trough departing, temperatures will
warm compared to Fri. This will, in turn, lower humidity. The
overlap of critical humidity below 15 percent, wind gusts over
25 mph, and critical fuels will be Fire Weather Zone 427, the
southern hills and Raft River region. There is some instability
and moisture in the Bear Lake basin that could trigger showers
and thunderstorms today.

A low will be moving into the panhandle late tonight, and
slowly moving into extreme northwest MT on Sun. This puts
eastern Idaho in the position of having a jet streak overhead.
Current expectations are that Wind Advisory thresholds will be
met in the afternoon and early evening in Zones 51 and 52, the
Lava Beds and the Arco area/Mud Lake Desert.

The low moves into north central MT Sun night, reducing the
wind and allowing colder air to move into east Idaho.
Surprisingly, there is quite a bit of cold dry air and very
little cloudiness is expected with the surface cold front, and
even less precipitation.

High temperatures, after warming today, will cool 10 to 16 deg F
on Sun, and another 1 to 7 deg F from Sun to Mon.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 521 AM MDT Sat Sep 12 2026

Nothing but leftover dry air today from the passing trough, but
a low coming in tonight will bring a CIG back for some
locations. It is all mid-level and higher cloudiness though, so
not impactful. VSBY also stays excellent and unlimited.

Wind will be the most difficult part of the forecast. The
departing trough will keep KDIJ, KIDA, and KPIH gusty today. The
incoming low tonight will make KSUN gusty by afternoon from the
southwest, then tougher to get downslope wind tonight at KSUN.
Wind will be more easterly at KBYI and KPIH with this
approaching low as well.

&&

.FIRE WEATHER...
Issued at 155 AM MDT Sat Sep 12 2026

Canadian trough continues to move eastward, but the pressure
gradient is still strong enough to keep wind gusty. With the
trough departing, temperatures will warm compared to Fri. This
will, in turn, lower humidity. The overlap of critical humidity
below 15 percent, wind gusts over 25 mph, and critical fuels
will be Fire Weather Zone 427, the southern hills and Raft River
region. There is some instability and moisture in the Bear Lake
basin that could trigger showers and thunderstorms today.

As a closed low moving through the Panhandle tonight and western
MT Sunday, wind will increase to critical levels again in some
areas; however, the tremendous decrease in temperature will mean
a requisite increase in humidity, with even 20 percent readings
in the afternoon very limited in coverage.

High pressure returns Mon, weakening wind and allowing a
continued cool-down in temperature and a raising of the minimum
humidity.

&&

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

&&

$$

DISCUSSION...Messick
AVIATION...Messick
FIRE WEATHER...Messick