Damaging Winds in Wyoming, May 24, 2026

Area Forecast Discussion
National Weather Service Riverton WY
1240 PM MDT Sun May 24 2026

.KEY MESSAGES...

- Warm today, with highs in the 70s to low-80s. There is a
  chance (15 to 35 percent) of showers and thunderstorms
  through a little after sunset today, with the main hazard
  being gusty outflow winds 30 to 50 mph.

- Warm temperatures continue for Monday and Tuesday, along with shower
  and thunderstorm chances (15 to 45 percent). Best chances
  occur along and west of the Continental Divide.

- Daily shower and thunderstorm chances continue through the
  rest of the week. The areas with the best chances changes day-
  to-day.

&&

.UPDATE...
Issued at 1238 PM MDT Sun May 24 2026

Not much change to the forecast for today. Showers, and some
thunderstorms, will be fairly widespread across the area today,
at least in coverage, but specific locations only have a 15 to
40 percent chance of actually getting convection over them. The
main hazard with this will be gusty outflow winds. Given dew
point depressions around 50 degrees, would expect outflow gusts
up to 55 mph being a possibility, with a 30 to 50 mph range
being the most likely. Otherwise, temperatures climb again
today, each the 70s for most locations, with low-to-mid-80s for
the Bighorn Basin and Johnson County. Convection should quickly
diminish after sunset, with the last few showers waning between
10pm and midnight.

&&

.DISCUSSION...
Issued at 100 AM MDT Sun May 24 2026

As with most things with forecasting the weather, there are some
things we know, and some things we don't know. And, there is no
exception to this as I write this early on Sunday morning. I am
listening to hair metal this morning, and the song Dirty Love just
came on. And this ties into the main hazard over the next several
days. The above mentioned song is by a British hard rock band called
Thunder (they were a thing for a brief time in the early 90s). We
will have daily chances of thunder for the next several days. That
is the part we know. The part we don't know, especially a few days
out, are the coverage and placement of the storms.

We currently have a few showers out there, largely in southwestern
Wyoming. Little if any of the precipitation is reaching the ground
though. The main driver of the thunder today will be a shortwave
moving in from the west and some increasing moisture from the
southwest. This should increase coverage of showers and storms this
afternoon and evening. There is good model agreement of having the
highest coverage (about a 2 in 5 chance) across the southwest with
tapering chances further to the north and east. Precipitable water
values are about 50 percent higher than yesterday. However, model
soundings continue to show Inverted Vs along with high cloud bases.
Dew point depressions are also over 40 degrees in many locations
once again.  What this means is that although there is a better
chance for some rain to reach the ground, there will still be a lot
of virga showers and possibly dry thunderstorms. And this means that
we have the potential of strong wind gusts from any shower or
thunderstorm. Most convection again looks diurnal and should decrease
after sunset.

Memorial Day may end up being a bit drier than today, as heights
rise by around 40 decameters and precipitable water values fall by
around 25 percent. Most guidance is fairly consistent with this.
Most guidance is also in decent agreement in most of the showers and
storms remaining West of the Divide with less than a 1 out of 5
chance East of the Divide. With the southwest flow, temperatures
should average 5 to 10 degrees above normal through the holiday
weekend.

The uncertainty really increases as we head into Tuesday and the
rest of the week. And what happens is dependent on the position of
two features. One, is a strong ridge that will be found across the
midwest. The second, which has more impact on us, is one of the
features that leads many meteorologists to early hair loss. It is a
stacked upper level low that will move onshore in the Pacific
Northwest Monday night and Tuesday and drift toward the Great Basin
for the middle of the week. It looks like it will cut off from
the main low and sit for a few days, but exactly where will be
the determining factor for our weather. Ensemble guidance is all
over the place. With the deterministic models, the GFS, which
has been flip-flopping more than a fish out of water, now keeps
the low west of Wyoming before opening it up into a trough for
the end of the week. The European model has been more
consistent, keeping the low a but further south during the
middle of the week before moving it northward about 24 hours
later, again West of Wyoming. As for the forecast, the low will
continue to feed moisture into the area, and as a result there
should be some showers and thunderstorms around each day.
However, the moisture may be more of the mid and high level
variety. Model soundings at this time show largely inverted Vs
which would imply more high based showers and storms. But a lot
depends on the ultimate path of the low, and cut off lows are
one of the most difficult things to forecast. If it moves
further east, we have a better chance of some still needed rain.
And as far as placement and timing of the showers and storms, a
lot depends on shortwaves rotating around it and these are
difficult to time this far out. For now, we kept the forecast
largely broadbrushed with more POPs in the mountains and western
Wyoming and precipitation largely diurnal. Temperatures look to
be near to slightly above normal through the period.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1124 AM MDT Sun May 24 2026

VFR conditions prevail at all terminals through 18Z/Monday. Ongoing
light showers are indicative of existing atmospheric instability
over the region. Afternoon heating, particularly over southwest
and central Wyoming, will lead to a more robust round of
convection beginning around 19Z/Sunday. Scattered showers and a
few thunderstorms persist until 01Z-03Z/Monday. The main
aviation hazard will be gusty outflow wind from even weak
convection. Inverted-V profiles support frequent outflow wind
gusts of 30-40kts, with localized gusts around 45kts. Westerly
surface winds increase between 18Z-20Z/Sunday to 10-15kts with
gusts 18-25kts. These winds fade early Sunday evening and cloud
cover gradually dissipates early Monday morning.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for
the latest information on icing and turbulence forecasts.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
None.

&&

UPDATE...Wittmann
DISCUSSION...Hattings
AVIATION...CNJ