353
FXUS65 KPIH 081127
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
527 AM MDT Tue Jul 8 2025

.KEY MESSAGES...

- Hot weather for the first half of the week.

- Cold front arrives Wednesday bringing cooler weather for late
  week.

- Potential red flag conditions for wind and humidity Wednesday.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 145 AM MDT Tue Jul 8 2025

Ridge of high pressure will further amplify over central and
east Idaho today. This will allow for temps to climb higher
today and Wednesday. Most lower elevations will see highs in the
lower to mid 90s both days. Meanwhile a weak trough will be
working over the ridge. As it does so, expect isolated
thunderstorms to develop this afternoon. The main focus will be
across the central mountains and along the Montana border. Most
other areas should be capped by the ridge. These will be mostly
dry thunderstorms with gusty winds possible. Some models are
showing outflow boundaries from these storms working into the
upper Snake Plain late tomorrow afternoon. On Wednesday, a more
organized system will arrive late afternoon. This will allow for
isolated dry thunderstorms to develop initially over the
central mountains and Magic Valley. The potential for isolated
storms and gusty outflow winds will move east through the
evening. The higher resolution models support an isolated threat
for storms across most of east Idaho Wednesday evening and
possibly extending for a time into the overnight hours as the
system moves through east Idaho.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Issued at 145 AM MDT Tue Jul 8 2025

As a mostly dry cold front tracks east into Wyoming Thursday
morning, best chances for isolated showers and thunderstorms
will shift east as drier conditions build in out of the west. A
secondary trough working east through Montana throughout the day
Thursday will support another round of isolated showers and
storms further north and east along Montana Divide down into the
Eastern Highlands during the afternoon and evening hours
Thursday into early Friday morning. Courtesy of that trough
passage, winds will remain breezy again on Thursday, peaking
during the afternoon hours around 15-30 mph with gusts of 25-45
mph. Behind that exiting system, dry conditions will return
regionwide for Friday into the weekend under the increasing
influence of high pressure as temperature trends warmer each day
into early next week. A weak backdoor cold front Thursday night
into Friday will help transition winds from their typical
S/SW/W direction to carrying a N/NE component, keeping
temperatures cooler for Friday in similar fashion to Thursday.
These winds will also approach low-end criteria for a N/NE Lake
Wind Advisory issuance for American Falls Reservoir which will
need to be monitored over the coming days in future forecasts.
Near normal to below normal temperatures Thursday and Friday
with highs in the 70s/80s in the valleys will rebound quickly
into the 80s/90s starting this weekend. Early indications in
ensemble model guidance for much of next week keeps southeast
Idaho in a zonal/southwest flow pattern, allowing for warm and
dry conditions to persist.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 527 AM MDT Tue Jul 8 2025

Predominant VFR and dry conditions will continue across
southeast Idaho for Tuesday as a ridge axis of high pressure
shifts overhead. Skies will remain clear to start the day ahead
of increasing mid-level clouds building in this afternoon as a
shortwave trough moves in. This trough will support a 10-20%
chance of virga and or dry thunderstorms this afternoon and
evening in the Central Mountains, Upper Snake River Plain, and
Eastern Highlands with best chances around KIDA, KSUN, and KDIJ.
Given a very dry airmass in place at the surface, little to no
precipitation is expected but gusty winds will remain possible
associated with any development. Winds today will peak around
10-15 kts with gusts to 20-25 kts, following diurnal patterns.


&&

.FIRE WEATHER...
Issued at 145 AM MDT Tue Jul 8 2025

Strong high pressure overhead will peak this afternoon as a H5
ridge axis works over southeast Idaho, supporting the warmest
temperatures of the week with highs reaching the upper 80s to
upper 90s across lower elevations. A weak shortwave trough
working northeast today will help to support a 10-20% chance of
showers/virga and or dry thunderstorms in the Central Mountains
and Upper Snake River Plain, with little if any precipitation
expected given a very dry airmass in place at the surface. These
very dry conditions in place will support afternoon RHs in the
single digits and teens both today and Wednesday. Elevated to
near critical fire weather conditions are expected today due to
a combination of low relative humidity and wind gusts to around
20-30 mph, turning critical for Wednesday as stronger winds
build in along a mostly dry cold front with gusts to around
25-40 mph. As a result, a Fire Weather Watch has been issued
from 1500-2100 MDT Wednesday for Idaho FWZ 410, 413, 425, and
427, which will likely need to be upgraded to a Red Flag Warning
given the latest forecast supporting these critical fire
weather conditions. As that mostly dry cold front passes
overhead late Wednesday into early Thursday morning, a 10-20%
chance of virga/showers and a mix of wet/dry thunderstorms will
be possible regionwide.

A secondary trough working east through Montana throughout the
day Thursday will support another round of isolated showers and
storms further north and east along Montana Divide down into the
Eastern Highlands during the afternoon and evening hours
Thursday into early Friday morning. Behind that exiting system,
dry conditions will return regionwide for Friday into the
weekend under the increasing influence of high pressure as
temperature trends warmer each day into early next week. A weak
backdoor cold front Thursday night into Friday will help
transition winds from their typical S/SW/W direction to carrying
a N/NE component, keeping temperatures cooler for Friday in
similar fashion to Thursday. Near normal to below normal
temperatures Thursday and Friday with highs in the 70s/80s in
the valleys will rebound quickly into the 80s/90s starting this
weekend. Early indications in ensemble model guidance for much
of next week keeps southeast Idaho in a zonal/southwest flow
pattern, allowing for warm and dry conditions to persist.

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Wednesday afternoon through Wednesday
evening for IDZ410-413-425-427.

&&

$$

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