287
FXUS65 KPIH 261120
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
520 AM MDT Sat Jul 26 2025

.KEY MESSAGES...

- Daily, isolated to scattered shower and thunderstorms chances
  will continue through the weekend in the Central Mountains
  east along the Montana Divide, peaking in coverage each
  afternoon/evening.

- Conditions will remain very dry outside of any showers or
  storms, supporting elevated fire weather conditions due to a
  combination of low relative humidity and breezy winds.

- Temperatures will remain steady through Sunday, ahead of a
  warming trend starting Monday.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 215 AM MDT Sat Jul 26 2025

Early morning satellite imagery shows a mid/upper-level low
centered over California as a series of shortwave troughs
continue to lift northeast out of the Sierra Nevada and Great
Basin into eastern Idaho. These shortwaves will bring with them
increased cloud cover and moisture, supporting continued daily
shower and thunderstorm chances. Today looks to be a near repeat
of yesterday, with another round of isolated to scattered
showers and thunderstorms in the Central Mountains and Montana
Divide, now also including better coverage out across western
Idaho. Further north is where the HREF model probability of
thunder shows a 20-50% chance, locally higher up to a 50-70%
chance in Lemhi County. Outside of this area, isolated showers
and or virga will remain possible in that 5-15% range (primarily
in the mountains), but we have maintained a dry forecast for
now elsewhere with the primary hazard with any of this isolated
activity centering around gusty winds. Stronger storms further
north today will again be capable of producing wind gusts up to
40-50 mph, small hail, brief heavy rain, and frequent lightning.
Activity will subside after sunset as dry conditions return
regionwide tonight into Sunday morning. Highs will be slightly
cooler than yesterday courtesy of increased cloud cover in the
low 80s to low 90s, with wind gusts peaking outside of any
convection this afternoon around 20-35 mph.

For Sunday, another round of isolated to scattered showers and
thunderstorms are expected to develop again during the afternoon
and evening hours in the Central Mountains east along the
Montana Divide. Stronger storms further north today will again
be capable of producing wind gusts up to 40-50 mph, small hail,
brief heavy rain, and frequent lightning. Dry conditions will
return after sunset regionwide Sunday night into Monday morning.
Highs on Sunday will remain similar to Saturday, again in the
low 80s to low 90s, with wind gusts outside of any convection
peaking around 20-35 mph.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 215 AM MDT Sat Jul 26 2025

Southwest flow will transition to carrying more of a southerly
component throughout the work week next week, supporting warmer
temperatures as daily, isolated to scattered shower and
thunderstorm chances continue each afternoon and evening
primarily in the mountains. Highs Monday through Wednesday will
be near normal to above normal in the mid 80s to mid 90s, with
afternoon wind gusts peaking each day around 20-30 mph. As a
mid/upper-level trough moves onshore to the Pacific Coast for
Wednesday into Thursday, shower and thunderstorm chances will
see an increase as this trough taps into southerly monsoonal
moisture flow out of the Desert Southwest. The only caveat to
this will be how much dry air is entrained in the trough as it
moves further inland, which could suppress and limit
precipitation chances. At this time, the NBM maintains a
reasonable, middle of the road approach and carries at least
isolated shower and thunderstorm chances through the remainder
of next week, which we will continue to monitor should there be
any bigger changes with that monsoonal moisture fetch. During
this time as dew points see a slight increase, cooler more near
normal temperatures will return starting Thursday through the
weekend with highs in the low 80s to low 90s each day. Winds
will also remain slightly breezy each afternoon, with gusts
peaking around 20-30 mph.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 520 AM MDT Fri Jul 25 2025

Predominant VFR and dry conditions will continue for Saturday
into Sunday morning under partly to mostly cloudy skies. A
shortwave trough passing overhead today will help kick off
another round of isolated to scattered showers/thunderstorms,
primarily in the Central Mountains east along the Montana
Divide. As a result, best thunderstorm chances will remain
confined north of KSUN with a 10-20% chance at KSUN. Elsewhere
at other terminals, there will be a nonzero 5-10% chance of
isolated showers/virga, but have kept the mention out of any of
the TAFs in the latest 12Z update. Winds will see a diurnal
increase again this afternoon, with gusts peaking ~15-25 kts.

&&

.FIRE WEATHER...
Issued at 215 AM MDT Sat Jul 26 2025

A series of shortwave troughs passing over eastern Idaho
through the weekend will support daily isolated to scattered
showers and thunderstorms, peaking in coverage each afternoon
and evening. Best coverage of thunderstorms will remain in the
Central Mountains east along the Montana Divide, with very
isolated showers/virga possible outside of this area. Scattered
thunderstorm coverage looks to remain confined to Idaho FWZ 475
and 476 and to a lesser extent in FWZ 422, with stronger storms
each day capable of producing gusty outflow wind gusts up to 50
mph, small hail, brief heavy rain, and frequent lightning.
Elevated to near critical fire weather conditions will also
continue each day into early next week due to a combination of
afternoon RHs mostly in single digits/teens combined with wind
gusts peaking around 20-35 mph outside of any convection.

Temperatures will hold steady through the weekend ahead of
mid/upper-level SW flow changing to being more southerly
starting Monday. This will allow for warmer and drier conditions
to prevail to start the work week as thunderstorm chances
become increasingly isolated and confined to Lemhi and Custer
Counties east along the Montana Divide. Starting midweek,
increasing confidence supports monsoonal moisture lifting north
into eastern Idaho, leading to daily isolated to scattered
thunderstorm chances expanding in coverage starting Wednesday.
While the exact details will come into focus over the coming
days, the bulk of ensemble model guidance continues to support
this solution. Daily thunderstorm chances are then expected to
continue through next weekend as temperatures see a gradual
cooling trend given increased cloud cover and slightly higher
dew points.

&&

.AIR QUALITY...
Issued at 215 AM MDT Sat Jul 26 2025

The latest HRRR smoke model this morning shows a plume of
wildfire smoke lifting north into eastern Idaho out of the Great
Basin after sunrise, leading to possible hazy/smoky skies
throughout the day. Given the bulk of this smoke will be aloft,
that will likely lead to lesser air quality impacts at the
surface, with the near surface smoke component of the HRRR smoke
model showing less smoke concentrations closer to the surface.

&&

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

&&

$$

SHORT TERM.....MacKay
LONG TERM......MacKay
AVIATION.......MacKay
FIRE WEATHER...MacKay
AIR QUALITY....MacKay