037
FXUS65 KPIH 220530
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
1030 PM MST Fri Nov 21 2025

.KEY MESSAGES...

- Dense Fog Advisory from 11PM tonight to 10AM tomorrow morning
  for many.

- Remaining dry through the weekend before Monday cold front.

- Unsettled conditions may continue through the Thanksgiving holiday,
  but no significant impacts are expected at this time.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 155 PM MST Fri Nov 21 2025

Most of this morning`s fog has lifted enough to "just" be low
stratus now. While we are getting a little break this afternoon, it
looks to be pretty short-lived before the low stratus and fog return
tonight through early tomorrow morning. Given what we saw this
morning, we have decided to go ahead and issue a Dense Fog
Advisory for portions of the eastern Magic Valley, Arco desert
area, Snake River Plain, and Teton Valley from 11PM tonight to
10AM tomorrow. While some of these spots may not be at or below
1/4 mile visibility the whole time, models are showing about a
30 percent chance of VIS less than a half inch from Burley to
Rexburg with a 50 to 70 percent chance of the same from Shoshone
across the Arco desert up to Mud Lake. The HRRR, which handled
last night`s fog fairly well, does keep it a bit farther north
and out of Pocatello which may be due to it picking up on some
increased winds, but confidence in that is low enough to still
include these areas in the advisory. Either way, prepare to hit
some pockets of very low to near 0 visibility if you are
traveling late tonight into early tomorrow. Even a few areas
outside of the advisory area have about a 20 percent chance to
see visibility below a half mile in parts of the South Hills and
Southeastern Highlands.

The fog and stratus are holding our temperatures fairly steady
across much of Eastern Idaho today with temps this afternoon hanging
out right around 40 degrees or just on either side of it. By
Saturday afternoon, temperatures may warm just a couple of degrees,
but not by much. As temperatures fall into the 20s and 30s today
with more fog around, watch for some slick spots on roads and
especially on bridges or other elevated surfaces.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 155 PM MST Fri Nov 21 2025

The next shortwave feature arrives late Sunday through early
Tuesday, with cold front passage during the day Monday. Current NBM
means increase the winds along and behind the front to between 25
and 30 mph with gust potential over 40 mph. Light precipitation
appears mainly confined to higher elevations at this time. Cooler
temperatures follow Tuesday, with lower elevation highs dropping
into the 30s. For the holiday period, models are showing signs of
shifting gears again. Although the ensemble clusters agree on a
ridge through the western states, some of the deterministic runs are
a bit flatter with the flow aloft, leading to energy pushing through
the PacNW and producing light precipitation across the northern tier
states. Temperatures remain mostly mild, which would keep snow
generally above valley floors, and thus limiting impacts for holiday
travel concerns for Wednesday through Friday. At least for now.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1025 PM MST Fri Nov 21 2025

Stratus is present at DIJ, PIH and IDA with MVFR heights and
expect to persist through the night. Think the stratus may limit
dense fog forming at those sites but will be straddling MVFR and
IFR conditions with some visibility restrictions toward sunrise.
Moisture has spread unexpectedly northwest into SUN and LIFR
conditions have developed in the southerly flow. Expect the
normal downslope northwesterly winds to return and VFR
conditions to return after 08Z. Expect much of the lower
ceilings to dissipate after 19Z Saturday afternoon at the DIJ,
PIH and IDA sites. Light winds expected through Saturday as
well.

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 10 AM MST Saturday for IDZ051>055-
065>067.

&&

$$

SHORT TERM...AMM
LONG TERM...DMH
AVIATION...GK