959
FXUS65 KPIH 091147
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
547 AM MDT Wed Jul 9 2025

.KEY MESSAGES...

- Hot weather this afternoon.

- Cold front arrives this afternoon bringing isolated to
  scattered thunderstorms with gusty outflow winds.

- Red flag conditions today for wind and humidity.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 229 AM MDT Wed Jul 9 2025

A low pressure system near the Oregon/California border will
move east throughout the day. We`ll see isolated dry
thunderstorms develop across central and east Idaho late this
afternoon and evening. Storms will most likely develop first in
the central mountains during the afternoon. As we approach the
early evening storms will being to develop in the southern
highlands and Magic Valley. Model then begin to diverge on storm
propagation through the evening, but general thought is most of
east Idaho will have at least a slight chance for storms
tomorrow evening. Temperatures expected to be hot once again
today with mid 90s pretty common across the lower elevations.
Also, we`ll see wind increase ahead of the low pressure system
with gusts of 20 to 30 mph likely by late afternoon. Factoring
in steep lapse rates from the temps and the already gusty
conditions, we will likely see strong outflow winds across
central and into parts of east Idaho this afternoon and evening.
Some of this convection could linger into the overnight hours
as this system will be near the Wyoming border by 12z Thursday.
Expect breezy conditions for Thursday with gusts in the 20 to 30
mph range common once again. Temperatures will be noticeably
cooler Thursday with highs in the mid 80s over the lower
elevations. A stray shower may still be possible near the Island
Park region Thursday afternoon, but most of the area should be
mainly dry.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Issued at 229 AM MDT Wed Jul 9 2025

Under the increasing influence of high pressure Friday into the
weekend, temperatures will see a warming trend from near normal
highs in 70s/80s on Friday to above normal highs into the
80s/90s starting Saturday. Courtesy of this ridge of high
pressure overhead, conditions look to remain dry into early next
week. Looking ahead, ensemble model guidance supports a series
of shortwave troughs working up and over this ridge feature
along the Continental Divide, supporting isolated showers and
thunderstorms primarily in the mountains during the
afternoon/evening hours starting Sunday into the work week in
that 10-20% chance range. Given the bulk of moisture looks to
stay east of the Divide with these shortwaves, coverage here in
southeast Idaho will remain focused along the Montana Divide
into the Eastern Highlands while dry conditions prevail
elsewhere. Our latest NBM forecast supports this solution well
with around a 10-20% chance of isolated showers and storms
further northeast Sunday through Wednesday, keeping predominant
dry conditions going outside of some isolated activity.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 547 AM MDT Wed Jul 9 2025

Departing high pressure to the east today will give way to a
cold front building in this afternoon/evening into tonight with
breezy winds and isolated to scattered showers/thunderstorms.
The HREF model probability of thunder today shows a 40-50%
chance at KIDA, KSUN, and KDIJ with a 20-40% chance at KPIH and
KBYI. Given higher variability in model guidance in placement
and timing of convection and or outflow boundaries, have held
off on any TS mention from the TAFs but this will need to be
monitored for subsequent updates later today. As it stands now,
synoptic wind gusts outside of thunderstorms should peak around
20-30 kts with thunderstorm outflow wind potential around 30-50
kts. Given a very dry airmass in place at the surface, gusty
winds will be the primary hazard versus rain and or hail with a
wet/dry microburst storm environment setup. These wind impacts
may ultimately need to be handled with a TEMPO or PROB30 group
to capture potential impacts, so stay tuned later today for any
updates. Convective initiation will begin this afternoon,
continue through this evening while shifting east, before ending
Thursday morning as clearer skies build in out of the west.
Winds will remain elevated overnight and throughout the day on
Thursday with another round of isolated shower and thunderstorm
activity remaining confined to the Montana Divide and Eastern
Highlands region into Wyoming.

&&

.FIRE WEATHER...
Issued at 229 AM MDT Wed Jul 9 2025

As a shortwave trough and cold front track east across
southeast Idaho today, critical fire weather conditions are
expected regionwide today due to a combination of gusty winds,
low relative humidity, and isolated to scattered wet/dry
thunderstorms. A Red Flag Warning remains in effect today for
Idaho FWZ 410, 413, 425, and 427 where fuels are deemed
critical. While similar conditions are expected in Idaho FWZ
411, 422, 475, and 476, fuels have not been deemed critical so
we have held off on any issuance further north. The HREF model
probability of thunder today shows a 30-70% chance regionwide,
which coupled with a hot and dry environment with steep lapse
rates, will remain conducive for strong gusty outflow winds in a
wet/dry microburst environment. As evident yesterday by the
isolated activity producing strong wind gusts, today`s storms
will be in a similar environment with more of a forcing
mechanism given the passage of the trough. This as a result will
support a mix of virga/showers and wet/dry thunderstorms that
are capable of producing wind gusts of 40-60 mph, locally
stronger up to 70 mph. Stronger storms primarily in the Central
Mountains may also support small hail and moderate to heavy
rain. Timing still remains focused this afternoon and evening,
with activity continuing into the overnight hours, shifting
southeast and ultimately east into Wyoming ahead of dry
conditions back regionwide for Thursday morning.

Temperatures will cool by 6-12 degrees behind the cold front
for Thursday and Friday as RHs see an increase and dry
conditions prevail. While we may see some isolated showers and
thunderstorms in the Eastern Highlands up along the Montana
Divide for Thursday and Friday, conditions overall are expected
to remain dry. Winds will remain breezy again on Thursday ahead
of lighter winds back for Friday. Under the increasing influence
of high pressure for the weekend, highs in the 70s/80s for
Thursday and Friday will climb to the 80s/90s starting Saturday
as conditions remain dry. A series of shortwaves working up and
over this ridge feature will lead to perhaps some isolated
showers and storms further northeast starting Sunday into the
work week. Given the overall very dry airmass in place, we will
continue to monitor for any overlap of wind and low RH for any
additional fire weather headlines heading into next week.

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 3 PM this afternoon to 9 PM MDT this
evening for IDZ410-413-425-427.

&&

$$

SHORT TERM...13
LONG TERM...MacKay
AVIATION...MacKay
FIRE WEATHER...MacKay