138
FXUS65 KCYS 072013
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
213 PM MDT Mon Jul 7 2025

.KEY MESSAGES...

- There is an Slight Risk (Level 2 of 5) for severe weather
  today across portions of western Nebraska. All modes of severe
  weather are possible today: large hail, damaging winds, and an
  isolated tornado.

- Hot temperatures and dry conditions return Tuesday, limiting
  precipitation chances across the CWA.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 1230 PM MDT Mon Jul 7 2025

Visible satellite imagery remains fairly clear late this morning,
showing most of the cloud cover in South Dakota. There is a small
cumulus field north of the Pine Ridge in Sioux and Niobrara
Counties, which could be a potential area of development for storms
later this afternoon. Although, based off the lack of cloud cover
over the CWA now, storms could have a hard time developing this
afternoon. Model soundings do show a capping inversion, but this
looks to erode by early afternoon. However, there are several
boundaries at play which could help storms initiate this afternoon.
A weak shortwave moving across the area today as sent a front
through the Interstate 25 corridor in Wyoming, switching winds out
of the north. Dewpoints behind this front remain in the 50s which
will be favorable for storms. A dryline along the Laramie Range
could also be an area of initiation if clouds can develop.
Lastly, more south and east flow in the Nebraska panhandle could
lead to converging boundaries and areas of development.

Hi-Res models show a bit of disagreement with each other, making it
difficult to iron out a solution for today`s severe weather
potential. The HRRR appears to be the least aggressive, showing only
a few storms in the southern Nebraska panhandle. Other models like
the NAMNest, RRFS, and MPAS show storm development in northeast
Wyoming tracking southeastward into Niobrara County and the northern
Nebraska panhandle. The environment in Converse and Niobrara
Counties and the Nebraska panhandle are still favorable for severe
weather if storms can develop. MUCAPE values range anywhere from
1200 to 2000 J/kg. Effective shear values are a bit weaker today
compared to yesterday, however its still high enough to sustain
stronger storms with rotating updrafts. DCAPE values remain over
1200 J/kg as well. These factors will lead to both a damaging wind
and large hail threat for most areas east of the Laramie Range. Also
cannot rule out the potential for an isolated tornado threat, mainly
in the far eastern row of counties of the panhandle where MLCAPE
values are over 1300 J/kg. Mid-level lapse rates are also very steep
across the area which will help support deep convection if storms do
get going. Storms will dissipate and/or move out of the area later
this evening.

Upper-level ridging will stregthen on Tuesday, allowing conditions
to warm up and dry out. Temperatures will climb back up to above
average with highs in the upper 80s to mid 90s. Precipitation
concerns will be relatively low thanks to subsidence under the ridge
and dry surface conditions. Hi-Res guidance does show the potential
for a weak shower or thunderstorm to develop in the Interstate 80
corridor between Cheyenne and Sidney. Given the dry surface and
inverted-v soundings, gusty winds will be possible. Any storms will
dissipate by the evening hours, leading to a quiet overnight.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Issued at 205 PM MDT Mon Jul 7 2025

Water Vapor Imagery shows an active Pacific Ocean thats going to be
responsible for the multitude of shortwaves traversing The Pacific
Northwest and Intermountain West. Wednesday and Thursday will be our
break as the ridge axis moves over the intermountain West to keep
things dry over those two days. Temperatures look to soar into the
80`s and 90`s with a few isolated spots of 100 degrees. Friday
starts the return of troughs as an upper level low flattens out our
ridge to resurrect our storm chances. The 500mb and 700mb heights
show this compression resulting in increased winds for Friday as
those jets push through. The other result of these compressed
heights will be the synoptic support to help increase the storms
duration as well. Some cooler air will accompany this compression
dropping temperatures back down into the 70`s before another ridge
pushes through this weekend to turn the temperatures right back into
the 80`s.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1110 AM MDT Mon Jul 7 2025

The atmosphere is currently capped with delaying development
but, storms are still expected to initiate around 21z and
expected to move roughly southeast. some showers may start off
over KLAR and become a storm over KCYS. For KCDR if storms
develop to the north they are expected to drop south over KCDR
however if no storms develop then KCDR may just see some brief
showers to weak thunderstorms. The most favorable environment is
over KSNY as the CAPE looks to be the strongest in the southern
panhandle. Tomorrow as the ridge becomes more pronounced over
the area, light but possibly variable winds will be expected
through the morning.

&&

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

&&

$$

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