990
FXUS65 KPIH 202036
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
136 PM MST Thu Nov 20 2025

.KEY MESSAGES...

- Still mild today, about 5 degrees cooler for Friday.

- Isolated rain and snow showers continue through tonight with
  little accumulation expected.

- Mostly dry and just a few degrees warmer for the weekend.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 132 PM MST Thu Nov 20 2025

As an area of low pressure continues moving southward down the West
Coast, moisture wrapping around it is moving northward through parts
of Eastern Idaho, particularly through the Central Mountains
today. However, an isolated shower is possible pretty much
anywhere within our CWA today. We will continue to see these
isolated rain and snow showers through the evening and tonight
along with a few lingering showers early tomorrow in the South
Hills and Southeastern Highlands. Any additional snow with these
showers today and tomorrow morning will be minimal with only
another inch or two around Galena Summit and even less at any
elevation below pass level. The movement of this low will open
the door for some cooler air to make its way into our area with
highs going from upper 40s and low 50s today to low and mid 40s
for most tomorrow. More impactful for tonight/tomorrow morning
will be the potential for some more dense fog and freezing fog
through portions of the eastern Magic Valley, Snake River Plain,
South Hills, and Southeastern Highlands. Unsurprisingly, the
CAMs show a few different solutions for both placement and
density of this fog. The HREF shows widespread 50 to 60 percent
chance of visibility less than a half mild from Shoshone to
Aberdeen and 30 to 50 percent chance of the same from Burley all
the way along I-86 and up I-15 to Rigby. This seems to be
heavily weighted by the HRRR as the NAM Nest does show some
patchy dense fog, but not nearly as widespread. The NBM is also
not nearly as pessimistic as the HRRR. Given the uncertainty of
actual coverage, will keep the mention of patchy dense fog and
areas of dense fog in the forecast, but will not be issuing any
advisory ahead of time, we will want to watch for development
later tonight.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Issued at 132 PM MST Thu Nov 20 2025

Mostly quiet pattern on tap leading into the Thanksgiving holiday
for East Idaho as split flow pattern continues. Models and ensemble
clusters are in good agreement throughout. Deep low over the
southwest states ejects eastward with upper ridge for East Idaho
over the weekend. Expect mild temperatures and dry conditions. Weak
system drives through the northern stream flow on Monday. bringing a
slight chance of showers to the higher elevations Sunday night
through early Tuesday. Cold front passage associated with this
system briefly drops daytime high temperatures for Tuesday. Upper
ridge rebounds for the middle to latter half of the week, for dry
and mild conditions for Thanksgiving Day.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1050 AM MST Thu Nov 20 2025

SHRA continue to impact SUN late this morning, but area of
precipitation appears to be mainly shifting north, which should
keep minimal impact at SUN moving into the afternoon and
evening. Next area of moisture wrapping north from Utah could
produce some SHRA at PIH and BYI. There is very weak model
consensus, and not enough confidence to introduce VCSH anywhere
else. Partial clearing later this evening could allow for
fog/stratus formation by sunrise. Probabilities support 35-55%
chance of VIS < 3SM at BYI, PIH, and IDA mainly 09Z-15Z. Some
model soundings appear to support better chance at MVFR stratus
for these stations, with around a 20% chance of CIGS dropping to
IFR. Given the uncertainty and lack of a consistent signal in
model guidance, opted to trend toward the MVFR potential for
now. A PROB30 3SM BR or VCFG may be necessary with the next
scheduled forecast issuance, depending how the guidance evolves
over the day.

&&

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

&&

$$

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