441
FXUS65 KPIH 022257
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
357 PM MST Mon Nov 2 2026

.KEY MESSAGES...

- Fog/Stratus Return Possible Tonight: Morning low stratus is
  gradually eroding this afternoon, though lingering low-level
  moisture over saturated soils may support the redevelopment of
  low stratus and patchy fog tonight into Tuesday morning.

- Chilly & Stagnant Workweek Temperatures: Daytime highs will
  remain suppressed in the 40s today due to persistent low
  clouds. Temperatures will remain generally stagnant with
  minimal day-to-day fluctuations through Friday.

- Weak Mid-to-Late Week Impulses: Dry conditions prevail across
  eastern Idaho, though a series of weak upper-level impulses
  will bring periodic cloud cover and low-end precipitation
  chances mid-to-late week with no major weather systems
  expected.

- Building Weekend Ridge & Above-Normal Warmth: Global models
  remain steadfast in building and strengthening an upper-level
  ridge directly over the region this weekend, ensuring dry
  weather and driving temperatures to above-normal levels late
  this weekend into next week.

&&

.DISCUSSION...
Issued at 145 PM MST Mon Nov 2 2026

Afternoon satellite imagery reveals a gradual erosion of the
low stratus deck that lingered across much of the area through
the morning hours. Extensive morning cloud cover severely
hindered diurnal warming, keeping temperatures unseasonably cool
with much of the region remaining in the 40s this afternoon.

With precipitation having fully exited eastern Idaho, the
primary short-term operational concern shifts to nighttime
boundary-layer evolution. While confidence in complete boundary-
layer decoupling remains moderate, abundant residual low-level
moisture makes the redevelopment of low stratus and patchy fog
probable overnight into Tuesday morning. Areas that see
sustained clearing around sunset will have the highest
likelihood of seeing fog formation before boundary-layer mixing
resumes Tuesday afternoon.

A tranquil and predominantly dry pattern will dominate the
remainder of the workweek. Operational guidance continues to
track a series of weak upper-level impulses crossing the region
mid-to-late week late tomorrow and again Thursday PM into Friday
AM. These disturbances will periodically increase cloud cover
and could generate isolated, low-end precipitation chances over
the mountains, but dynamic lift is weak and no organized,
impactful storm systems are expected. Temperature profiles will
remain largely stagnant day-to-day through Friday, with
afternoon highs continuing near or slightly below late-autumn
climatology.

Medium-range model guidance remains in strong consensus
regarding a pronounced pattern change heading into the upcoming
weekend. Ensembles are steadfast in building and amplifying an
upper-level ridge directly over the Intermountain West. Strong
subsidence beneath the ridge will maintain completely dry
conditions across eastern Idaho, while rising 500 mb heights
initiate a steady warming trend. Daytime maximum temperatures
will rebound to above-normal levels starting late this weekend
and likely holding into early next week.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 353 PM MST Mon Nov 2 2026

The primary challenge then shifts to overnight redevelopment.
With abundant boundary layer moisture from recent rainfall,
decoupling winds, and clearing skies aloft, high-res guidance
and model soundings strongly favor fog and low stratus
development tonight. The greatest potential resides along the
southern and eastern periphery of the Snake River Plain and into
the Teton Valley. Introduced prevailing MVFR visibilities with
VCFG mentions after 06Z-09Z for BYI, PIH, IDA, and DIJ, with
localized IFR/LIFR restrictions possible towards daybreak. We
did stick in some lower clouds at BYI as there is some hint that
some fog or low clouds develop and get pushed back toward Boise.
SUN was cautiously kept VFR overnight, banking on nocturnal
downvalley northerly flow to keep the moisture pushed
southward...and stratus that exists in the Magic Valley
dissipates before getting caught up in afternoon upvalley wind
shift. We should see VFR conditions at all sites by tomorrow
afternoon.

&&

.FIRE WEATHER...
Issued at 134 AM MST Mon Nov 2 2026

Cold temperatures and high humidity will continue through at
least Tue. High pressure will allow more significant lowering of
humidity on Tue afternoon/Wed. Conditions should become dry
after today with no precipitation expected until possibly late
in the upcoming weekend. Stratus and fog will be affecting areas
both tonight and Tue night. Gusty wind today in the Southern
Idaho Dispatch area will decrease during the afternoon.

&&

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

&&

$$

DISCUSSION...McKaughan
AVIATION...DMH/Keyes
FIRE WEATHER...Messick