457
FXUS65 KCYS 242142
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
342 PM MDT Sat May 24 2025

.KEY MESSAGES...

- Marginal Risk (Level 1 of 5) for portions of southeast Wyoming
  and western Nebraska continues today, with hail and winds the
  primary hazards, though a very isolated tornado cannot be
  ruled out primarily in Wyoming.

- Unsettled weather expected to continue this weekend through
  next week with daily chances for showers and thunderstorms.
  Temperatures will be near or slightly below average for late
  May.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 236 PM MDT Sat May 24 2025

Thunderstorms are ongoing across the CWA this afternoon in a
marginally favorable environment for stronger to severe weather.
Low-level stratus has helped to limit daytime heating, but
mesoanalysis of the region indicates bulk effective shear of
around 45-60 knots and MUCAPE of 500-1500 J/kg, allowing this
activity to remain fairly stout as it develops around the
Laramie Range. But with the clustery nature of this activity
alongside a lack of stronger and more discrete forcing, most of
this will continue to remain sub-severe through this evening
with weakening into the nighttime hours and becoming mostly
rainfall. On the note of rainfall, there is a marginal risk of
localized flooding as well as these storms train across the
region under an environment composed of PWAT values around
125-150% of normal. A flood advisory was already needed earlier
for Banner County, NE, and with the highest moisture values for
our CWA in the Nebraska Panhandle, this region will be the most
likely for continued risk of flooding.

Moving into Sunday, moisture remains elevated across the region
and another round of low ceilings and mist or fog will be
possible for the morning hours primarily along and east of the
I-25 corridor. Thunderstorms will be possible once again during
the day but any lingering severe potential will finally shift to
our south with another bout of widespread rainfall and general
thunderstorms expected for the day. This could once again
promote a flooding threat however, and two-day QPF totals are
sitting between 0.5-2.0 inches for areas along and east of the
Laramie Range with locally heavier amounts possible for
locations that receive training storms/rainfall. Once again
activity should wane and and move eastwards into Nebraska
through the nighttime hours, but ongoing showers, particularly
for the Nebraska Panhandle, will be possible as we begin
Memorial Day.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 236 PM MDT Sat May 24 2025

The long term remains active through the middle of the week as
daily showers and thunderstorms continue to impact the CWA. At
the upper levels, a broad trough will continue to slowly
progress eastwards through the period while a ridge of high
pressure will try and take control of the Western US through the
end of the period, though a weak low off the California coast
moving into the Baja Peninsula will limit the strength of this
ridge. At the surface, low pressure in the Southern Plains on
Monday will evolve eastwards through the weak, but a weak
lingering stalled boundary and some small disturbances will
continue to to move across our area all the way through the end
of the week. Under this pattern we should see moisture allowing
for daily precipitation through Wednesday before drier air
begins to move in and brings clearing to end the week. That
being said, don`t expect a significant warm-up yet, as without a
stronger feature such as a deeper ridge to bring more heating
and warmth, temperatures will only slowly bounce back into the
70`s to end the period. The environment should mostly promote
generic showers and thunderstorms each evening, though the
environment may be favorable for some stronger activity on
Tuesday. Otherwise, a cool week is anticipated to bring an end
to May before we move into the summer months.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1145 AM MDT Sat May 24 2025

Very messy TAF forecast as ongoing precipitation alongside new
convection going into the afternoon and low CIGs will make for
difficult forecasting across the region. Areas of thunderstorms
expected this afternoon through this evening with widespread
coverage of precipitation possible through tonight. All TAF
sites have a chance of thunderstorms, with Wyoming terminals
having the best cloud decks outside of KCYS. Otherwise KCYS and
all Nebraska terminals with continue to see mid to low ceilings
through the overnight creating IFR to LIFR conditions. Some
storms could be strong to possibly severe as well, with
localized enhancements to winds and hail possible. Overall wind
field otherwise should be manageable, with winds 10-20 knots
outside of any nearby thunderstorms.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.

&&

$$

SHORT TERM...CG
LONG TERM...CG
AVIATION...CG