721
FXUS65 KCYS 120528
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1128 PM MDT Wed Jun 11 2025

.KEY MESSAGES...

- A few strong to severe thunderstorms are possible Wednesday
  and Thursday. Severe storms are more likely Friday.

- Above average temperatures are expected to persist through the
  upcoming weekend.

- Daily chances for afternoon showers and thunderstorms will
  continue through early next week.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 1150 AM MDT Wed Jun 11 2025

A warm summer day exists across the CWA late this morning with
temperatures already in the 70s and 80s as weak riding sits over the
Rockies. As with many summer patterns, storm chances are expected
once again this afternoon and evening. An upper-level shortwave
incoming from the west will provide some of the forcing needed to
kick off thunderstorm activity. Storms will likely initiate off
of the high terrain, with the dryline just east of the Laramie
Range as indicated by the 40 and 50 degree dewpoints along and
east of the Interstate 25 corridor. These higher dewpoints will
help fuel moisture and instability needed for stronger storms
this afternoon. Model soundings also show healthy profiles for
strong to marginally severe storms across much of the CWA. Most
areas east of the Laramie Range show over 1200 J/kg of MUCAPE
with effective shear of 20 to 30 kts. This could support an
isolated severe hail threat. However, a backdoor cold front
overnight has lead to a bit of a cap and some CIN to erode in
the Nebraska panhandle this afternoon. However, newer Hi-Res
guidance seems to be able overcome this and allow a storm or two
to develop in the panhandle. Areas west of the Laramie Range
show a much drier surface, leading to deep inverted-v soundings.
This will lead to primarily a wind threat in these areas as
DCAPE values exceed 1000 J/kg. Most of the CWA shows fairly
elevated DCAPE values which will lead to widespread strong winds
in storms. The more clustery nature of storms as portrayed by
most CAMs also lend itself to more of a wind threat with some
isolated hail. Storms will dissipate late this evening, but a
stray shower or storm will still be possible overnight.

Thursday will be almost a carbon copy of Wednesday as the upper-
level pattern remains largely the same. The ridge will still be in
place over the Rockies which will lead to similar high temperatures
in the 80s, and a weak disturbance aloft will lead to another round
of afternoon storms. Model soundings from the Nebraska panhandle
show a favorable environment for strong to marginally severe storms.
MUCAPE values of 1000 to 1800 J/kg and effective shear of 30 to 35
kts could support severe hail in some storms. GFS soundings also
point to a drier surface in the panhandle tomorrow, with inverted-v
profiles. This will lead to a wind threat with DCAPE values over
1000 J/kg. Storms will initiate over the high terrain earlier
in the afternoon and track eastward into Nebraska by mid-
afternoon. Most storms will move out of the area during the
evening, leaving a few isolated storms around the CWA through
midnight.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 203 PM MDT Wed Jun 11 2025

Low amplitude ridging with a multitude of shortwaves
creates daily thunderstorm chances in the long term period. Friday,
a weak trough pushes through the Intermountain west in the afternoon
and a frontal passage in the evening. Dewpoints are Friday are
progged to be in the 50`s and 60`s with the higher dewpoints in the
Nebraska Panhandle. CAPE values look to peak around 2,000-2,500 in
the NE corner of the Panhandle near Chadron, and values near 1,500
east of I-25 in Wyoming. Looking at the NAM4K thunderstorms dont
look to really develop until the late afternoon and early evening
then push east into the overnight hours. However, There doesn`t look
to be enough shear for prolonged supercells and look to be more
pulsy. The main threats with these storms looks to be wind and hail
with hail sized up to a golfball look to be possible in the
Panhandle. The UH tracks depict a stronger hail threat than tornado
threat. Model hodographs show more of a straight line than a
pronounced curved sickle shape indicating a bit crosswise vorticity
(hail city) as opposed to streamwise vorticity that would indicate a
TOR threat. SPC has also placed a slight risk for us for Friday. As
we get closer to Friday more Hi-res guidance will be able to resolve
the finer details and a clearer picture will be presented then.

This weekend, more shortwaves look to kick off some thunderstorms in
the afternoon. There fortunately wont be as much CAPE as Friday but
the other dynamics remain the same as weak troughs push through with
limited shear to sustain consistent energy levels from the storms.
Ensembles show high temperatures in the 80`s with dewpoints ranging
from 30 to 50 over the next week. The environment looks to be
persistent enough to support daily storm development. The severity
of these storms are yet to be determined. However, persistent
forecasting would suggest hail and wind will be threats to consider
with any of these storms.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1121 PM MDT Wed Jun 11 2025

Zonal flow aloft will continue. A passing weather disturbance
and adequate moisture will help produce isolated to scattered
late day thunderstorms on Thursday.

Wyoming TAFS...Scattered to broken clouds from 8000 to
15000 feet will prevail. Thunderstorms will be in the vicinity
of Laramie and Cheyenne from 19Z to 02Z, with showers in the
vicinity of Rawlins from 21Z to 01Z. Winds will gust to 23 knots
at Rawlins from 15Z to 01Z, and to 20 knots at Cheyenne from
20Z to 02Z.

Nebraska TAFS...Scattered to broken clouds from 5000 to
15000 feet will prevail. Occasional thunderstorms will occur at
Chadron and Alliance until 08Z, producing gusts to 30 knots at
Alliance and ceilings near 3500 feet. Thunderstorms will be in
the vicinity of all terminals from 22Z to 03Z.

&&

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

&&

$$

SHORT TERM...SF
LONG TERM...MM
AVIATION...RUBIN