105
FXUS65 KPIH 052304
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
504 PM MDT Tue Aug 5 2025

.KEY MESSAGES...

- Next Chance of Storms Wednesday Night-Friday

- Near Critical Fire Weather Conditions Possible

- Temperatures Vary Quite A Bit This Week

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 225 PM MDT Tue Aug 5 2025

Satellite imagery shows dry southwest flow aloft over East Idaho
today with nearly clear skies everywhere. Still expecting a few
afternoon build ups over higher terrain but forecast remains dry
into Wednesday. Breezy winds this afternoon due to deep mixing
potential into stronger winds aloft, which also continues on
Wednesday. Wednesday should remain the warmest day of the week, with
afternoon highs climbing back into the upper 80s and lower/mid 90s
most lower elevation areas. The biggest concern in the short term
will be the amount of smoke able to push north into East Idaho from
active fires south of the region. HRRR smoke not overly impressive
with respect to surface based smoke that would be able to restrict
visibility, but does show an increase in vertically integrated smoke
that would lead to hazy skies. Will leave smoke impacts out of the
forecast for now.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 225 PM MDT Tue Aug 5 2025

Next upper trough shifts inland along the Canadian border through
the PacNW Thursday and Friday. There will be a return of moisture
for mainly isolated showers and thunderstorms, generally to the
northern tier zones. Humidity profiles look similar to patterns from
the past couple weeks, so storms should remain on the dry side with
gusty outflow potential. Breezy winds are expected both Thursday and
Friday, which may bring us into Fire Weather concerns, though cooler
temperatures will help mitigate humidity concerns those days. Friday
could be the coolest day of the week with NBM means only hitting the
mid/upper 70s most areas with some lower 80s possible closer to the
Utah border. Looking into the weekend and early next week, high
pressure tries to re-establish itself across the western US. GFS and
ECMWF both amplify a high stretched between the desert southwest and
a stronger center located off the PacNW coast. Dry conditions should
return with northwest flow across the region.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 501 PM MDT Tue Aug 5 2025

Will have widespread VFR conditions through Wednesday with clear
skies overnight and light winds. Will see a wind increase again
Wednesday after 18Z with 10 to 15 knots at PIH, IDA and DIJ with
again some gusts near 20 knots. No impacts other than the
diurnal wind increases.

&&

.FIRE WEATHER...
Issued at 225 PM MDT Tue Aug 5 2025

Large portions of southeast Idaho are forecast to experience near-
critical fire weather conditions each of the next several days, but
for different reasons, and confidence of reaching critical
thresholds across enough areal coverage of any given fire weather
zone is not quite enough at this juncture for any Fire Weather
Watches or Red Flag Warnings. Overall, Wednesday and Thursday remain
the days to watch the closest.

Wednesday trends just slightly warmer, slightly drier, and slightly
breezier than today. Minimum afternoon RH values will run 10-18
percent across all zones except 475 (19-28 percent there) with
critical values across most of Zone 410 and Zone 413, but critical
winds will only overlap critical RHs in small portions of southern
Zone 476, northern Zone 410, and perhaps a few spots in 413. Briefly
considered targeting Zone 410 for a Red Flag Warning driven by
conditions from Idaho National Laboratory up across Mud Lake to
Ashton, but winds still seem marginal, our wind/RH forecast has
already been adjusted to be slightly drier and breezier than
straight NBM guidance based on observational trends over the past
several days, and HDWI 75th and 90th percentiles aren`t super
concerning either. Regionally, expect diurnal WSW winds reaching 10-
20 MPH gusting 20-30 MPH depending on your location. Certainly still
a day where caution and fire safety messaging would remain quite
valid for just about everyone.

Thursday trends breezier still, BUT with slightly cooler
temperatures and slightly more moisture compared to Wednesday as a
low pressure system impinges on the region from the north. So, we
start to get into a "mixed mode" for critical fire weather concerns.
This forcing/lift and slightly increased moisture may support at
least isolated, if not scattered thunderstorms across large portions
of Zones 475 and 476 (where not all fuels are fully critical yet),
as well as Zone 411 (critical), while at the same time...near-
critical to critical RH values lingering across the south
(especially Zone 413) may see some overlap with near-critical to
critical wind gusts at or above 25 MPH. Precipitable water values
running 0.5 to 0.8 regionwide still generally signal dry-leaning
thunderstorms for most cells. Once again, most areas seem "marginal"
for triggering a Red Flag. We will watch any trends in the guidance
closely as more high-res model data gets ingested into the mix over
the next 24 hours.

Friday and Saturday will feature the coolest temperatures of the
week (highs generally in the 70s...whoa!) as RH values hold somewhat
steady, winds gradually decrease, and thunderstorm potential holds
on for portions of Friday before ending Saturday as the low pulls
away. Scattered thunderstorm coverage can`t be ruled out for one
more day Friday in Zone 411, but coverage leans isolated
elsewhere.

&&

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

&&

$$

SHORT TERM...DMH
LONG TERM...DMH
AVIATION...GK
FIRE WEATHER...01