657
FXUS65 KPIH 250407
AFDPIH
Area Forecast Discussion
National Weather Service Pocatello ID
1007 PM MDT Tue Jun 24 2025
.KEY MESSAGES...
- Isolated thunderstorms ending in the early evening tonight.
- High pressure will keep skies clear with zero precipitation
starting Wednesday.
- Afternoon highs near normal by Wednesday, 3 to 8 degrees above
normal through the weekend, and 10 to 15 degrees above normal
by Monday.
&&
.SHORT TERM /THROUGH FRIDAY/...
Issued at 1244 PM MDT Tue Jun 24 2025
Weak trough moving through southern Canada and western Montana
has triggered some light showers (and maybe limited to virga)
this afternoon and there is a remote chance of isolated
thunderstorms that ends very early in the tonight period. The
upper level ridge strengthens for Wed, then holds its own for
Thu as another weak shortwave moves across the northern end of
this ridge. By Fri, this ridge is getting stronger, which
requires the temperature to start increasing.
The weak upper level trough on Thu does increase the wind, so
expect some gusty wind in the afternoon in the Snake River plain
and eastern Magic Valley. This may trigger some Fire Weather and
Lake Wind Advisory concerns.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Issued at 1244 PM MDT Tue Jun 24 2025
The upper level ridge continues to build, by Mon reaching a peak
of 5900m in height. This requires temperatures in the lower
elevations solidly in the 90s for eastern Idaho this time of
year. Which is what is expected for this time. The nearly clear
skies will mean overnight lows should be 35 to 40 deg F cooler
than the highs, which will hopefully mean no heat advisories of
any kind, but it bears some watching.
With this kind of massive high pressure, there are no
precipitation or even much in the way of thunderstorm concerns,
unless southerly airflow brings in any available monsoon
remnants from the desert southwest. Also, wind is not expected
to amount to more than terrain-driven diurnal wind.
&&
.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1005 PM MDT Tue Jun 24 2025
For the overnight, expecting clearing skies and light, variable
winds across eastern Idaho. More of this is expected for the
first part of the day on Wednesday before winds see a bit of an
uptick tomorrow afternoon (7-10 kts) with skies remaining mostly
clear and free of any precip concerns for regional terminals.
Some mid/high level clouds will develop tomorrow afternoon but
should have no impacts on aviation interests.
&&
.FIRE WEATHER...
Issued at 112 PM MDT Tue Jun 24 2025
The synoptic pattern will gradually transition from longwave
troughing this week to longwave ridging next week, with a gradual
warming and drying trend continuing throughout. Finer-scale
disturbances and shortwaves will govern periods of thunderstorm
potential and periods of increased winds. The first such feature...a
very weak, "sneaky" shortwave trough (detectable in pressure height
fields) will emerge out of Nevada today and ride northeast up the
eastern slope of the broader longwave troughing, providing just
enough lift for cumulus buildups and perhaps a few
showers/thunderstorms focused over mountain areas where terrain will
assist in updraft generation. HREF calibrated probability of thunder
focuses on the Central Idaho Mountains and Cassia County with a low-
end 10-20% chance, and the Upper Snake Highlands into the Big Holes
and Teton Valley (especially Zone 411) region with a better 20-40%
chance. Overall, CAMs look pretty isolated for most. The next (long-
advertised) period of interest is Thursday, Friday, and Saturday, as
more organized troughing brushes across the region from the north.
Most models are still not supporting much more than a few isolated
thunderstorms with this feature (especially north of the Snake
Plain), but a tighter pressure gradient will result in stronger
winds all three days, especially each afternoon. The NBM currently
features a 50-70% chance of wind gusts exceeding 25 MPH Thursday
afternoon across most of Zones 410, 411, and 476, and a 30-40%
chances across portions of Zones 427 (eastern) and 413. These
numbers look quite similar for Friday, perhaps even higher across
the Arco Desert and Mud Lake region with an 80% chance of exceeding
25 MPH and a 60-70% chance of exceeding 30 MPH. By this time, some
coverage of afternoon RH values less than 15% is expected as well in
all of the above mentioned areas, leading to increasing potential
for near-critical to critical fire weather conditions in areas where
finer fuels are receptive (wind/RH overlap will likely not be that
great though across most of Zones 425 and 427 where fuels are
currently classified as "approaching critical"). Beyond into the
weekend and next week, coverage of critically low RH values will
trend more widespread with hot temperatures, yet with lighter winds
currently forecast pending our next more organized disturbance.
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Messick
LONG TERM...Messick
AVIATION...McKaughan
FIRE WEATHER...01
