757
FXUS65 KPIH 120757
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
157 AM MDT Wed Aug 12 2026

.KEY MESSAGES...

- Isolated to scattered thunderstorms this afternoon. Gusty
  outflow winds possible near storms.

- Threat for showers and thunderstorms increases Thursday
  through Saturday.

- Locally heavy rain possible with burn scars most vulnerable.

&&

.DISCUSSION...
Issued at 154 AM MDT Wed Aug 12 2026

Seeing some light (mainly virga) rain showers drifting through
the south Idaho this morning. Models point to additional
isoalted to scattered thunderstorms developing across the
southern highlands and portions of the central mountains east of
a line from Stanley to Ketchum. Expect a mix of wet and dry
storms today with strong gusty outflow winds possible near
storms today. Most of the activity should diminish tonight.

On Thursday, a low pressure system will eject out of California and
advance towards south Idaho. Models are showing a band of showers
with isolated to scattered thunderstorms within and around this band
of showers. This is expected to arrive Thursday afternoon with
models showing quite a bit of moisture across the eastern highlands
as this feature moves north. Potentially this could bring 0.25 to
0.50 inches of rain just Thursday afternoon. Confidence is moderate
to high of appreciable rain on the Big Rock fire east of Idaho
Falls. So have decided to issue a flood watch for the burn. While
other burn scars may need watches as well with this feature moving
north, this particular burn scar is the most likely to see heavy
rain assuming the track of the low doesn`t shift appreciably.

As we move into Friday, a secondary weaker trough will arrive from
the southwest and provide the trigger for additional convection. The
models seem to be favoring the central mountains into the upper
Snake River highlands for appreciable rainfall with over 0.10 inches
forecast Friday afternoon. So we may need additional flood watches
for burn scars and possibly for the Big Rock again. On Saturday, one
additional shortwave trough will move through the region resulting
in scattered showers and thunderstorms with the main focus once
again across the central mountains into the Island Park region. With
the monsoon air firmly in place, the threat for flash flooding on
these burn scars will likely continue. As we head into Sunday and
Monday, a ridge retrogrades from the east and and builds across the
area. This will shut down the "organized" thunderstorms. But the
monsoon moisture will remain in place. So we`ll probably keep
continued chances for isolated storms into early next week. The
forecast at this point could very well be too dry on pops with the
models assuming too strong of a cap in place.

From a temperature perspective, today is the last warm day with
cloud cover and showers providing cooler temperatures into the
weekend. As we head into next week, temperatures rebound into the
80s but not the extreme heat that we`ve been experiencing.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 154 AM MDT Wed Aug 12 2026

Main concern today involves isolated to scattered thunderstorms
this afternoon. Looking at 30% chance of storms on station or
outflow winds affecting the terminal at most locations. SUN is
probably the only location that models keep storms away from
this afternoon.

&&

.FIRE WEATHER...
Issued at 154 AM MDT Wed Aug 12 2026

Isolated to scattered thunderstorms is expected today as
monsoon moisture works into the region. A mix of wet and dry
storms is expected today with gusty outflow winds likely near
storms. A flood watch is in effect for the Big Rock fire for
Thursday afternoon. Widespread showers with isolated to
scattered thunderstorms is likely. Potentially, 0.25 to 0.50
inches are possible across much of east Idaho Thursday
afternoon. Isolated to scattered thunderstorms is expected
Thursday afternoon across central Idaho as well, but qpf amounts
are much less and the chances for wetting rains is much less.

&&

.PIH WATCHES/WARNINGS/ADVISORIES...

&&

$$

DISCUSSION...13
AVIATION...13
FIRE WEATHER...13