808
FXUS65 KCYS 102107
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
307 PM MDT Thu Jul 10 2025

.KEY MESSAGES...

- There is a potential for isolated strong to severe storms this
  afternoon and evening for portions of southeast Wyoming and
  the southern Nebraska panhandle.

- A strong cold front will move south across the area Friday
  morning, with potential for strong storms and heavy rain
  Friday afternoon and evening near the higher terrain.

- Temperatures will be warming Saturday through Monday, before a
  potent cold front brings cooler temperatures for Tuesday and
  Wednesday, with another warming trend for Thursday. Shower and
  thunderstorm chances will be greatest for Tuesday and
  Wednesday.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 252 PM MDT Thu Jul 10 2025

Thunderstorms are becoming more widespread this afternoon as a
shortwave moves east overhead and a sfc trough slides southward
across the plains, backing westward into the higher terrain.
Satellite-derived TPW percent of normal shows values roughly in
the 120-150% range in advance of the shortwave with drier conditions
in its wake. Near the sfc, SPC mesoanalysis shows sfc-based CAPE
values in excess of 500 J/kg across most of the forecast area
with a tongue of 1500-2000 J/kg in the immediate wake of the sfc
trough and just to the lee of the Laramie Range. Much of this
area has minimal CIN with the relatively steep low- and mid-
level lapse rates. The exception is over Niobrara County eastward
into the northern NE panhandle where convective inhibition is
relatively strong. 0-6km bulk shear values are 30-40 kts east of
the Laramie Range as well. Thus, will have to keep a close eye
on strong to severe thunderstorm development over much of southeast
WY and the southern NE panhandle, with large hail ~1.00 diameter
and strong winds around 60 mph out of the strongest storms that
develop. With the high TPW values, expect many of these storms
to be efficient rain producers as well. Activity will diminish
through the evening as the shortwave slides east.

A strong cold front associated with an upper level trough over
the northern US will push south across the forecast area Friday
morning. The main focus for thunderstorms will be along the
Laramie Range and near the CO border in the afternoon and
evening where pooled moisture and strong surface forcing will
support development. There is a marginal threat for strong
winds and large hail out of storms that form in this area. In
addition, NAM and GFS forecast soundings show a fairly moist
profiles along and east of the Laramie Range, so expect moderate
rain rates and rainfall totals with showers and storms in this
area. WPC has the majority of the forecast area in a marginal
risk for excessive rain. Maintained POP values of 60-70 percent
in the vicinity of the southern Laramie Range to the WY/NE
border with this possibility of heavy rain. Upslope stratus and
fog will be the main concern for Friday night in the continued
moist regime.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Issued at 252 PM MDT Thu Jul 10 2025

Saturday...Northwest flow aloft continues, and temperatures will
slowly moderate as 700 mb temperatures rise to near 14 Celsius.
Looks like enough moisture along a low level convergence axis near
the Colorado state line to spark isolated to widely scattered
afternoon showers and thunderstorms from Laramie to Cheyenne to
Kimball.

Sunday...Ridging aloft builds overhead with 500 mb heights nearing
5920 meters. Warm temperatures aloft should limit convective chances
and produce a dry day. Decent warming trend with maximum
temperatures in the mid 80s to mid 90s with 700 mb temperatures near
17 Celsius.

Monday...Another hot day expected with 700 mb temperatures near 17
Celsius. Looks like enough low and mid level moisture for isolated
to widely scattered afternoon and evening showers and thunderstorms.

Tuesday...A progressive shortwave trough aloft moving across Montana
and North Dakota will send a fairly strong cold front southward
across our counties, dropping high temperatures into the mid 70s to
mid 80s. With decent low level upslope winds and plenty of low and
mid level moisture, we expect to see scattered afternoon and evening
showers and thunderstorms.

Wednesday...Another relatively cool day for mid July with low level
upslope, plenty of cloud cover and high temperatures only in the mid
60s to mid 70s. Adequate moisture for scattered afternoon and
evening showers and thunderstorms, most numerous near the Colorado
state line where the moisture will be the deepest.

Thursday...The atmosphere will slowly moderate with 700 mb
temperatures returning to near 15 Celsius, yielding high
temperatures in the upper 70s to mid 80s. Warm temperatures aloft
will limit convection, though still should see isolated to scattered
late day showers and thunderstorms.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1118 AM MDT Thu Jul 10 2025

Primarily VFR will continue through the forecast period for
southeast Wyo and western Neb terminals. The main aviation
weather concerns are scattered rain showers and thunderstorms
through this evening, along with gusty north winds. Gusts 25+
kts are likely near and outside any shower activity in Wyo this
afternoon and everywhere tomorrow morning. Stronger gusts will
accompany any storm this evening. An overnight lull with a brief
transition to south/southeast flow may contribute to a limited stratus
deck and/or fog from KCYS to KLAR. Low confidence and coverage
has precluded any mention in the TAF for now.

&&

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

&&

$$

SHORT TERM...RM
LONG TERM...RUBIN
AVIATION...DS