739
FXUS65 KPIH 121724
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
1124 AM MDT Sat Jul 12 2025

.KEY MESSAGES...

- Temperatures Continue To Warm Into the 90s

- Isolated Dry Storms Sunday and Monday Up North

- Flirting With Critical Fire Weather Conditions Sunday/Monday

&&

.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 155 AM MDT Sat Jul 12 2025

We remain on the northern fringes of high pressure across
portions of the southwestern U.S. That puts under constant
northwest flow off the surface through the beginning of next
week. Saturday will remain dry it looks like, although we may
see afternoon cloud build ups WITHOUT virga impacts. A couple of
"weak waves" drifting across the state Sunday and Monday are
expected to bump up dry thunderstorm chances a bit. We have
isolated storms Sunday from Copper Basin to near Island Park,
and similar areas Monday with a better potential of something
drifting across the Snake Plain. Little to no rain is forecast
with gusty outflow winds. Outside of thunderstorms, we are also
forecasting an uptick in overall wind. Gusts in the 20-25 mph
range are possible Sunday across Snake Plain, Magic Valley and
South Hills/Albion Mountains. Those types of gusts are more
widespread Monday, with the potential of gusts to 35 mph across
the Magic Valley and South Hills/Albion Mountains. Probability
forecasts actually show a 40-75% chance (location/elevation
dependent) of exceeding 35 mph in those areas. At the moment, no
wind-related headlines (at least outside of the fire side of
things) are anticipated.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Issued at 155 AM MDT Sat Jul 12 2025

Increasing confidence supports a H5 low working south of
British Columbia and Alberta into the northern PacNW and Montana
Tuesday into Wednesday, with the main circulation staying north
of the Montana Divide. The passage of this system will lead to
an uptick in winds Tuesday afternoon (peaking around 15-30 mph
with gusts to around 25-45 mph) along with isolated to scattered
showers and thunderstorms with best chances in the eastern
Central Mountains, Upper Snake River Plain, and Eastern
Highlands in that 15-30% chance range. Given the track of this
system through Montana, best chances will be further northeast
along the Continental Divide as the bulk of precipitation remain
situated further north of our area. As this system works east
through Montana and Wyoming for Wednesday, lighter winds will
return overall with a 10-20% of isolated showers and
thunderstorms along the Montana and Wyoming border regions.
Highs in the 80s and 90s on Tuesday will cool slightly around
4-8 degrees for Wednesday with highs in the upper 70s to low
90s. It is notable that there are some differences in the models
with respect to the track and speed of this system, so stay
tuned regarding any changes over the coming days.

Looking ahead towards later in the week, predominant zonal flow
will keep conditions dry as temperatures see a warming trend
into the weekend. Southeast Idaho will remain situated between
several systems during this timeframe: a series of troughs
working east through Canada and northern Idaho/Montana and a
plume of monsoonal moisture over the Desert Southwest to our
south. At this time, there are some differences in the overall
track and placement of this moisture but given a large fetch of
dry air building in out of Oregon from the Pacific during this
time, any shower or thunderstorm coverage should remain more
isolated and confined to the mountains as conditions remain
predominantly dry.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1120 AM MDT Sat Jul 12 2025

High pressure continues to intensify over southern Idaho. Expect
SKC-FEW cloud cover in the 5000ft AGL to 9000ft AGL range.
Unlimited VSBY. Wind will increase this afternoon, but only
eastern Magic Valley appears to get gusty, so only KBYI will be
appended with gusts. Sustained wind of 15KT for the afternoon at
KIDA and KPIH. Wind direction dominated by slope-valley wind
effect.

&&

.FIRE WEATHER...
Issued at 155 AM MDT Sat Jul 12 2025

Hotter temperatures and lowering humidities (including poor
overnight recovery in some areas) are on tap through Monday. We
will also see an uptick in isolated dry thunderstorms to start
out the week. We COULD see some afternoon cumulus and very
isolated virga issues today, but the potential at the moment
looks minimal at best. Isolated dry storms are forecast at the
moment from basically Copper Basin to near Island Park Sunday
and Monday. On Monday, there appears to be a better chance of
storms making out into the Snake Plain...so we expanded that
chance for this morning`s forecast. We MIGHT see a few storms
make into areas south of Twin Falls and Burley (Zone 427) later
Monday evening, but left that out for now. We will also see
winds picking up OUTSIDE of thunderstorms. We currently have
gusts 20-25 mph across Zones 410, 425 and 427 Sunday afternoon
and evening. That does put us close to critical thresholds in
Zone 427 when combined with afternoon humidity of 10-15%. In
fact, humidity values outside of the central mountains Sunday
(except lower valleys) will be in the 10-15% range, with 15-25%
elsewhere. Gusty winds will be more widespread on Monday.
Humidity values do come up a bit, but are still in the general
10-15% for lower elevations and 15-25% elsewhere. Outside of
areas from Island Park to Driggs, gusts of 20-30 mph are
forecast, with some gusts hitting 35 mph across portions of
Zones 425 and 427. In fact, probabilistic forecasts show a
40-75% chance of exceeding that mark in those areas. There is
also a 30-50% chance of gusts higher than 35 mph across the
higher elevations of the central mountains across Zone 413
(south and east of the Snake Plain). We will need to watch
trends for both days to see if we might need Red Flag Warnings.
Beyond that, we should cool down a bit as we end up being
sandwiched between low pressure along the US/Canada border and
high pressure to our south. While it does look continuously
breezy in this pattern, humidities do increase a bit. The Blend
of Models doesn`t have much in the way of thunderstorm chances
daily, nor showing any type of confidence WHERE that might
happen. Stay tuned.

&&

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

&&

$$

SHORT TERM...Keyes
LONG TERM...MacKay
AVIATION...Messick
FIRE WEATHER...Keyes