970
FXUS65 KPIH 252137
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
337 PM MDT Tue Aug 25 2026

.KEY MESSAGES...

- Diurnal Afternoon Storms Through Thursday: Isolated afternoon
  and evening showers and thunderstorms will continue daily
  through Thursday as moisture from Nevada feeds into the
  western periphery of the Four Corners ridge.

- Breezy & Noticeably Cooler Weekend: An upper-level trough
  moving into the Pacific Northwest late Thursday into Friday
  will suppress the ridge, tightening regional pressure
  gradients and dropping weekend highs into the upper 70s to
  around 80F.

- Scattered Weekend Precip Chances: Embedded shortwave energy
  will bring precipitation chances through the weekend, with
  Saturday standing out as the wettest day.

&&

.DISCUSSION...
Issued at 120 PM MDT Tue Aug 25 2026

Afternoon satellite imagery shows mostly clear skies across
eastern Idaho, though mid and high-level cloudiness is actively
streaming out of northern Nevada. This cloud deck will
overspread the region over the next few hours, combining with
high-elevation cumulus development to spark another round of
isolated afternoon and evening showers and thunderstorms. The
broad Four Corners high-pressure ridge will remain the dominant
synoptic feature through midweek. Consequently, Wednesday and
Thursday will showcase a near-identical weather pattern driven
by a classic diurnal cycle of afternoon instability and terrain-
forced convection with temperatures around 90 in the lower
elevations.

A pattern shift begins late Thursday night into Friday as an
upper-level trough moves toward the lower British Columbia
coastline. This feature will push the Four Corners ridge
southward, lowering 500 mb heights across the Intermountain
West. Afternoon temperatures will begin their downward trend on
Friday, falling from midweek maximums to near-seasonal averages
in the mid-80s. As the core low-pressure system settles to our
north over the weekend, valley temperatures will drop further
into the upper 70s to around 80F. In addition to the cooler
temperatures, the tightening surface pressure gradient between
the building trough and southern ridge will bring increasingly
breezy conditions Friday through Sunday. Shower and thunderstorm
chances will linger throughout the weekend, with model guidance
continuing to highlight Saturday as the wettest day of the
event.

Global model ensembles show several shortwave impulses embedded
within the broader cyclonic flow swinging down from Western
Canada through the early part of next week. This will maintain
persistent troughing across the Pacific Northwest into the start
of the new workweek. As a result, temperatures across eastern
Idaho will remain at or slightly below normal as we wrap up
August and transition into early September.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 336 PM MDT Tue Aug 25 2026

Isolated to scattered storms will pose an outside threat to TAF
sites this evening. Main threat would be strong gusty winds.
Most convection should diminish this evening. Repeat performance
for Wednesday afternoon.

&&

.FIRE WEATHER...
Issued at 120 PM MDT Tue Aug 25 2026

A weak ridge of high pressure remains overhead for the next several
days and will keep our overall pattern fairly steady. Each afternoon
will bring isolated to nearly scattered thunderstorm activity to
most of our Fire Weather Zones, but especially parts of the South
Hills and Central Mountains, or zones 413, 427, 475, and 476. That
said, pretty much any area could see a few isolated storms any
afternoon. Through the week, most of these storms will produce
little precipitation, so expect mainly dry storms with gusty outflow
winds around 50 mph and lightning. That said, you could get some
actual rainfall if you manage to be directly under a thunderstorm
any afternoon.

Beginning late Friday and continuing through the weekend, a weak
cold front will make its way through Idaho. This will bring some
better organized showers and storms (and slightly improved
precipitation chances) to the area. It will also bring breezy winds
Friday, Saturday, and Sunday with gusts around 30 to 35 mph
throughout the Snake River Plain and a cool down for the weekend
where we will see highs fall into the upper 70s to near 80 degrees
for both days.

&&

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

&&

$$

DISCUSSION...McKaughan
AVIATION...13
FIRE WEATHER...AMM