053
FXUS65 KPIH 220911
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
311 AM MDT Mon Jun 22 2026

.KEY MESSAGES...

- Red Flag Warning Today: Critical fire weather conditions will
  develop this afternoon and evening across the Snake Plain. A
  Red Flag Warning is in effect for Fire Weather Zone 425 from 1
  PM to 9 PM MDT due to wind gusts of 25 to 35 mph and minimum
  relative humidity plunging into the single digits and low
  teens.

- Warm and Dry Workweek: An amplifying upper-level ridge will
  bring a steady warming trend through Friday, pushing valley
  temperatures into the upper 80s and lower 90s. Near-critical
  fire weather conditions will be a daily fixture due to low
  humidity and breezy afternoon conditions.

- Late-Week Wind Surge: Ahead of an unusually strong early-
  summer storm system, the pressure gradient will tighten
  significantly on Thursday and Friday, causing winds to
  increase and elevating fire weather concerns.

- Dramatic Weekend Cooldown: A potent low-pressure system
  arrives Saturday, dropping temperatures 10 to 20 degrees below
  seasonal norms. While this will dramatically recover relative
  humidity values, strong and choppy winds will persist through
  the weekend.

&&

.DISCUSSION...
Issued at 252 AM MDT Mon Jun 22 2026

Convective activity continues along and just east of the I-15
corridor early this morning. High-resolution convective-allowing
models (CAMs) show these isolated showers and storms lingering
for a few more hours before tapering off entirely by sunrise. In
the wake of this departing activity, dry weather will take hold
for the remainder of the day, with CAM guidance showing no real
signature for re-development this afternoon or evening.

As skies clear, attention turns directly to fire weather
concerns driven by breezy afternoon winds and low relative
humidity values. This environment will be most critical across
Fire Weather Zone 425, where a Red Flag Warning has been issued
for Monday afternoon. Elevated fire danger will be a recurring
theme through the upcoming workweek as a stable, zonal upper-
level flow establishes itself over the Pacific Northwest.

Gradual rises in H5 heights are expected through mid-week as a
high-pressure ridge subtly amplifies over the region. This
configuration will drive a steady warming trend through Friday,
keeping temperatures on the warmer side of normal. Expect
daytime highs to scale into the upper 80s to lower 90s across
valley floors, while higher elevations max out in the upper 70s
to mid-80s.

A passing shortwave embedded within the zonal flow will bring
breezier conditions on Thursday. Winds will accelerate further
on Friday as the pressure gradient sharpens ahead of an
unusually deep, early-summer low-pressure system progged to move
inland for the weekend. Thursday and Friday will both require
close monitoring for widespread critical fire weather potential.
By Saturday and into early next week, the arrival of the core
low will trigger a dramatic downward plunge in
temperaturesrunning 10 to 20 degrees below normal. While this
pattern shift will deliver excellent overnight humidity
recoveries, it will keep ambient winds elevated and choppy
through the weekend.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1036 PM MDT Sun Jun 21 2026

Expect VFR conditions through the period for all TAF sites.
There will be some lingering FEW to SCT mid-level clouds early
tonight before skies clear out for the most part overnight.
There may just be a shower north of DIJ in the next couple of
hours. Winds currently are slightly breezy at DIJ. Expect winds
to drop off for all sites tonight. Winds will pick back up with
gusts of around 20 kts by tomorrow afternoon, especially for
IDA, DIJ, and PIH. Skies will be mostly clear tomorrow, though
there will likely be FEW to SCT mid-level clouds over nearby
mountains for most sites by tomorrow afternoon. Expect winds to
drop off and clouds to be mostly clear for all TAF sites by
early tomorrow evening.

&&

.FIRE WEATHER...
Issued at 252 AM MDT Mon Jun 22 2026

We begin a rapid drying trend today as yesterday`s shortwave
trough continues to track eastward out of the region. Minimum
relative humidity values this afternoon will fall into the upper
teens and low 20s across portions of eastern Idaho, paired with
breezy afternoon wind gusts of 20 to 25 mph. High-resolution
model guidance shows a completely dry forecast for the afternoon
and evening hours, shifting the primary operational fire concern
away from active convection and toward low humidity, winds, and
lightning holdovers from yesterday`s storms.

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 1 PM this afternoon to 9 PM MDT this
evening for IDZ425.

&&

$$

DISCUSSION...McKaughan
AVIATION...TW
FIRE WEATHER...McKaughan