337
FXUS65 KCYS 081120
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
520 AM MDT Wed May 8 2024

.KEY MESSAGES...

- Strong winds continue this morning mainly for southeast
  Wyoming wind-prone areas before weakening, but still
  remaining breezy this afternoon.

- Precipitation chances increase later today and overnight with
  accumulating mountain snowfall expected.

- Warming trend likely headed into the weekend with the return
  of above normal temperatures for mid-May.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 243 AM MDT Wed May 8 2024

Winds across southeast WY have been relatively calm early this
morning compared to the past 48 hours, but still gusting 35 to
45 mph for wind-prone locations. Latest GOES WV imagery shows an
area of mid-level vorticity slowly sliding south with stronger
subsidence across the Laramie Range moving in behind with a
brief tightening of mslp gradients across the Laramie Range. Do
still expected another maximum in wind speeds to occur across
mainly wind-prone locations near daybreak before winds decrease
through late morning. High Wind Warnings will likely be able to
be dropped by midday Wednesday as height gradients begin to
improve quickly, but will continue to assess latest trends and
observations through the morning.

As the upper level low across the north-central CONUS continues to
weaken and slide south, weak and short-lived isentropic lift with
the remaining moisture on the backside of the upper level low will
be enough for snow showers across the mountains with accumulating
snowfall above 7500 ft elevation beginning later this morning.
Showers will become more numerous late this afternoon and evening as
a vort max pushes southwest with northerly flow out ahead. For lower
elevations, ptype will remain rain. But areas along and west of the
Laramie Range should see a switch over to snow this evening.
Overall, accumulations outside of the mountains should be light, but
north facing slopes could see slightly heavier precipitation with
upslope enhancements, including the Arlington and Elk Mountain areas
along I-80. Decided to issue a Winter Weather Advisory for the North
Laramie Range as 4-8 inches of snowfall will be possible, but will
need to monitor to determine if addition issuances will be necessary
near the mountains farther south.

Weak lift will continue Thursday with additional showers as the
final vort lobe slides to our southwest with a Rex Block setting up
across the western CONUS. Expecting below average temperatures once
again in the mid-40s to 50s before the expected gradual warm up
headed into the weekend.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 243 AM MDT Wed May 8 2024

Minimal changes made from the previous forecast. We are still
looking at a gradual warming trend as we transition into a
ridging pattern toward the end of the week.

While the closed low continues to circulate over the SW CONUS, upper-
level ridging moves into southeast Wyoming and western Nebraska,
increasing temperatures and drying conditions. Friday temperatures
are still cool, sitting right near normal. As a shortwave propagates
through the forecast area, some light showers/thunderstorms in
higher elevations along and west of the Laramie Range cannot be
ruled out, but impacts should be minimal if any. Saturday
temperatures warm up a few more degrees with additional chances for
showers in higher elevations, but due to limited dynamic support,
these showers/thunderstorms will likely not move off the higher
elevations. Sunday into Monday another shortwave embedded in the
flow ejects through the forecast area as the subtropical jet pushes
the closed low that was over the SW CONUS over out into Texas. This
additional dynamic support, as well as a few hundred J/kg of CAPE
and 20 to 40 knots of bulk shear, has the potential to kick off more
scattered showers and thunderstorms across far southeast Wyoming and
the Nebraska panhandle Sunday and Monday afternoons. Long range
models begin to diverge more in their solution as a stronger
shortwave trough drops south along the northern Rockies, dropping
temperatures once again and kicking off more precipitation
potential.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 516 AM MDT Wed May 8 2024

VFR conditions with gusty winds to start the 12Z TAF period. As
rain/snow showers begin to move in from the northwest this
evening, CIGS and potentially VIS will drop to MVFR and IFR.
Overall it should remain MVFR unless a shower moves directly
over a TAF terminal, then it may briefly drop to IFR. Showers
are most likely to impact KRWL, KLAR, KCDR, and KAIA, remaining
in the vicinity of KCYS and KBFF. Showers will begin to taper
off early Thursday morning between 09Z and 12Z.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Weather Advisory from 4 PM this afternoon to 6 AM MDT
     Thursday for WYZ103.
     High Wind Warning until 6 PM MDT this evening for WYZ106-110-
     116.
NE...None.

&&

$$

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