809
FXUS65 KPIH 032220
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
420 PM MDT Thu Sep 3 2026

.KEY MESSAGES...

- Showers and thunderstorms confined to the central mountains
  through Saturday

- Gusty winds across the rest of eastern Idaho will lead to
  near-critical fire conditions with humidity near 15%

- Best chance of showers and storms will be Sunday into Labor
  Day

&&

.DISCUSSION...
Issued at 1237 PM MDT Thu Sep 3 2026

The potential for showers and thunderstorms will remain anchored
over the central mountains through Saturday. There MIGHT be a
few shower or storms elsewhere on a given day, but the chance
right now is well under 10%. The best chance for appreciable
rain across the central mountains will later tonight and again
tomorrow night. For tonight, the potential is up to 0.40" across
the Frank Church and Stanley Basin including the Wapiti burn
scar. There is a 20-50% chance for over 0.50" tonight. For
tomorrow night. Up to 0.33" is possible over the same area, with
a a 5-15% chance for exceeding 0.50". Otherwise, the potential
for more than 0.10-0.15" in a given 12 hour period is low. We
will see a few thunderstorms, even during the overnight hours,
which is likely pushing the models toward some of the higher
rainfall amounts. Across the rest of eastern Idaho, expect
breezy conditions at times through Sunday morning. Ahead of a
boundary overnight, look for gusts of 25-35 mph (maybe 40 mph in
some spots) from the south and southwest. Similar speeds are
likely. Temperatures will rebound a bit through Sunday, with
highs return to lower 80s across the Snake Plain, Magic Valley,
and toward the Utah border.

The latest trends in the forecast for Sunday and Monday are
toward most of the moisture from Marie not making it into Idaho.
We will likely see some of this getting quickly pulled in as the
closed low along the coast swings inland, but the bulk of it is
directed through Utah and Wyoming. While we continue to see
some decent swings in terms of just how much rain may fall, the
trend in the past 24 hours has been to hold amounts down a bit
from the highest end of the range of forecasts. For the Snake
Plain, Magic Valley, and South Hills/Albion Mountains...the WPC-
based rainfall is 0.10-0.30". For the central mountains,
0.15-0.45" with locally higher amounts are expected. Across the
eastern and southeast highlands, the latest shows 0.30-0.70".
This is slightly above the "middle of the road" forecast from
the Blend of Models. The higher end still wants to push totals
over 1" across higher elevations, but the trend definitely lower
than yesterday in terms of where those amounts could happen.
Labor Day looks cool thanks to the rain and cloud cover, with
most valley locations in the 50s and 60s with some low 70s south
of the Snake River. The central mountains will see some highest
elevations temperatures stuck in the 40s. We do dry out briefly
before see more moisture trying to shift north for showers and
thunderstorms for the latter half of next week.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 420 PM MDT Thu Sep 3 2026

Winds should weaken for a time this evening. However we expect
winds to pick up overnight as a low pressure system slides
northward through the area. Then winds should diminish by late
morning once again. Rainfall with this system looks confined to
the central mountains and probably north of SUN, perhaps
encroaching upon SUN by 12z.

&&

.FIRE WEATHER...
Issued at 1237 PM MDT Thu Sep 3 2026

The pattern remains fairly locked in through Saturday across
central and eastern Idaho. Outside of a few random showers or
storms, the best chance will be across the central
mountains...especially Zones 422 and 475. Wetting rains in any
given 12 hour period will be low EXCEPT for tonight and tomorrow
night. There is the potential for up 0.40" tonight and 0.30"
tomorrow night, with low potential for amounts over 0.50". This
will likely be aided by a few overnight thunderstorms and
upslope into those zones. For the rest of eastern Idaho, look
for gusty winds and marginal afternoon humidity which will lead
to near-critical fire weather conditions at times. Through this
evening, we are looking at 410, 413, 425, and 427 for this
possibility. For Friday, mainly across 413, and for Saturday in
413 and 427. The best chance of showers and storms is still
Sunday and Labor Day, although the best moisture from Marie
looks to remain south and east of us. We will see a small amount
pulled into the closed as it swings across the area. Highest
amounts be across the higher elevations, especially Zones 411
and 413. Those areas may 0.40-0.70". For Zones 410, 425 and 427,
the latest shows 0.10-0.30"...and the central mountains
0.15-0.45". We briefly dry out Tuesday, but showers and storms
may return as soon as Wednesday as another area low pressure
sets up along the coast and we pull in moisture from the
southwest.

&&

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

&&

$$

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