026
FXUS65 KCYS 212350
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
550 PM MDT Tue May 21 2024

.KEY MESSAGES...

- Much cooler temperatures with scattered to numerous showers
  and thunderstorms.

- Patchy frost is expected on Wednesday morning due to low
  temperatures hovering between 30 and 36 degrees. Recently
  planted vegetation may need to be covered to prevent any
  frost/freeze damage.

- Daily shower and thunderstorm chances continue through the
  long term. Elevated winds possible in wind prone areas
  Thursday.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 159 PM MDT Tue May 21 2024

As the next shortwave continues to move across Wyoming,
precipitation chances continue to increase through the afternoon and
evening across southeast Wyoming and western Nebraska. Precipitation
will mainly be rain showers with isolated thunder possible. While
gusty winds and lightning are likely in these storms, they are not
expected to be particularly strong or severe. Precipitation chances
taper off quickly between 8 PM and 11 PM tonight as a low amplitude
ridge pushes eastward across southeast Wyoming and western Nebraska
overnight. As the ridge pushes eastward and skies clear overnight
with generally light winds, radiational cooling will allow
temperatures to plummet overnight to near freezing. NBM is showing
greater than 50% probabilities of temperatures less than 32 degrees
tomorrow morning at elevations above 5000 feet. At elevations below
5000 feet, there are greater than 40% probabilities of temperatures
less than 36 degrees. As temperatures less than 36 degrees is
conducive to frost formation, areas of frost are likely across
southeast Wyoming and western Nebraska Wednesday morning. Due to the
brief ridging, afternoon high temperatures are expected to be in the
60s to low 70s with dry conditions and breezy winds.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Issued at 159 PM MDT Tue May 21 2024

Thursday will begin with generally zonal flow aloft with a compact
shortwave moving into western WY that looks to traverse northeast
across the state. Afternoon temperatures across the NE panhandle
will warm into the 70s, but CAA from the west will keep temperatures
cooler across much of Carbon Co and additional areas west of the
Laramie Range. Precipitation will be possible (20-30%) with the
frontal passage, however this will likely dry out before reaching
the I-25 corridor and the better lift associated with the system
will remain farther to the north of our CWA. With the upper level
low passing to the north, this could lead to a breezy day across
much of the CWA with 700mb flow increasing to 35-40 kt.

Friday will be on the cooler side with morning lows returning to the
30s and afternoon highs in the low-60s. Could see a few showers
develop late in the afternoon Friday near the CO/WY border with
northeast post-frontal upslope flow into the Front Range and a weak
shortwave passing in the westerly flow aloft. Expecting the active
pattern to continue into the weekend with daily chances for showers
and thunderstorms as multiple shortwave pass in the flow.
Temperatures will remain steady in the 60s to low-70s.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 550 PM MDT Tue May 21 2024

An upper level disturbance will continue tracking east across
eastern Wyoming and western Nebraska this evening, resulting in cool
temperatures and scattered rain showers with brief snowfall above
6500 feet mainly impacting KLAR and KRWL. A few rumbles of thunder
are possible until 04z, especially for the western Nebraska
terminals.

HAZARDS/WEATHER TRENDS: VFR conditions will prevail this evening and
tonight with gusty winds diminishing around sunset/02z. Brief MVFR
CIGS and VIS possible near the heaviest showers at KCDR, KAIA, and
KSNY. Probability of fog look to be very low (below 10%) tonight due
to dry surface conditions.
&&

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

&&

$$

SHORT TERM...LEG
LONG TERM...MB
AVIATION...TJT