480
FXUS65 KPIH 021929
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
129 PM MDT Tue Sep 2 2025

.KEY MESSAGES...

- Patchy smoke will remain, especially northern areas, but
  conditions will gradually improve through week and especially
  the weekend

- Warmer temperatures persist through midweek

- Showers and storms return later in the week

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY/...
Issued at 112 PM MDT Tue Sep 2 2025

We still expect warmer than average temperatures to continue
through Thursday, although we should a very slow drop (1-2
degrees per day) as the ridge breaks down. We continue to see
limited moisture working north and providing at least some
afternoon/evening mid level clouds. The potential for anything
other than a sprinkle and stronger downburst winds due to virga
is 10-15% at best, and is represented in the forecast. We will
need to watch for daily trends in moisture and the higher
resolution models to see if we need to push shower/storm
potential to 15% or higher...which is the threshold for an
actual mention in the text forecast. Outside of any potential
for virga, winds look pretty light with gusts not really pushing
higher than 15-20 mph.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Issued at 112 PM MDT Tue Sep 2 2025

The long term forecast features a gradual cooling trend and overall
wetter conditions. In the second half of this week, the ridge of
high pressure currently over our area begins to break down a bit as
a shortwave is ejected off an area of low pressure off the coast of
British Columbia. This will allow for an influx in monsoon moisture
to begin moving into Eastern Idaho on Friday, especially for
Saturday, and lingering into Sunday and Monday of next week. This
will help cool us down a few degrees with highs falling from the low
90s on Thursday to the mid 80s on Friday and then into the mid and
upper 70s for Saturday and Sunday. We will begin to dry out next
Monday and Tuesday as the ridge of high pressure builds back in over
the area, but temperatures will hold steady right around 80 degrees
for most. At this point, the NBM shows a widespread 30 to 50 percent
chance of at least a tenth of an inch of QPF for all of Eastern
Idaho in the 24 hours from Saturday morning to Sunday morning.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1031 AM MDT Tue Sep 2 2025

Look for VFR conditions in the next 24 hours. SUN and BYI will
still be sitting on the eastern edge of constant mid level
moisture streaming north into Idaho. There is still nothing
expected other than potential virga issues, but even then...the
risk of gusty downburst winds is VERY,VERY LOW.

&&

.FIRE WEATHER...
Issued at 112 PM MDT Tue Sep 2 2025

A ridge of high pressure remains over much of Idaho through the
middle of this week keeping us hot and mostly dry. Afternoon RHs
will remain critical or near-critical on either side of the 15
percent mark through Thursday. While some monsoon moisture does its
best to lift northwards into parts of the Central Mountains and
South Hills, it is so dry at the surface that this more likely
materializes as virga. Wind with this virga doesn`t look like much
of an issue, though an isolated gust around 35 mph isn`t totally out
of the question in the afternoons. Everywhere else, afternoon wind
gusts will be around 20 mph, so even through RHs are at or near-
critical, we don`t quite have the wind component to push us towards
any Red Flag Warnings. The high pressure ridge begins to break down
a bit as we end the weekend and head into the weekend as a shortwave
passes through the area. This means increasing isolated thunderstorm
chances beginning on Thursday with a better increase in moisture to
the area with min RHs generally 20 to 30 percent area wide by Friday
afternoon and then 40 to 60 percent for Saturday afternoon. Given
the influx of moisture for the weekend, the chance of wetting rain
will be higher area-wide for the weekend, so Friday could be the
more impactful day for any lightning starts before the better
moisture arrives with Saturday storms. This will help cool down
temperatures a bit for the weekend and early next week, even as high
pressure begins to build back in over the area. Long range models
are hinting at a stronger, wetter system towards the end of next
week.

&&

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

&&

$$

SHORT TERM...Keyes
LONG TERM...AMM
AVIATION...Keyes
FIRE WEATHER...AMM