854
FXUS65 KCYS 030805
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
205 AM MDT Sun Aug 3 2025

.KEY MESSAGES...

- There is a Marginal Risk (Level 1 of 5) for severe weather for
  Sunday across western Nebraska. Primary hazards look to be
  damaging winds and isolated large hail.

- Another round of strong to severe storms possible on Monday
  with a small sliver of the Panhandle under a Marginal Risk for
  severe weather again.

- Drier and warmer conditions return mid-week and continue
  through late week.

&&

.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 204 AM MDT Sun Aug 3 2025

Quiet conditions once again tonight across the CWA, though some mid-
to high-level clouds remain overhead rather than the clear skies
seen in previous nights. Winds are light are variable for the most
part across the region with temperatures in the mid-40s to upper-50s
as of 07Z. The atmosphere remains quite stable tonight as
superrefraction and ducting is occurring from KCYS as the wind farm
south of Kimball, NE, in northern Colorado is easily visible on the
KCYS radar. Given the stability of the atmosphere at this time, no
weather is expected during the overnight hours or into the morning
hours.

Upper-level ridging attempts to move overhead today, undercutting a
stout ridge over Canada. An upper-level low moving southeast across
the Central Plains will act to stunt the propagation of the ridge
and weaken it significantly in the afternoon and evening hours.
Despite this, northwesterly flow is expected across the CWA today
which is a favorable flow pattern for multiple disturbances to push
through and initiate convection as they move through. Several
subtle, weak shortwaves will push through the 500mb flow, bringing
with them bursts of cyclonic vorticity advection and increasing
synoptic lift for much of the area east of the Laramie Range. 700mb
flow remains weak and generally northwesterly throughout the day,
keeping some of the heating expected under a ridge at bay as cooler
air from the northwest is advected into the region. Flow turns
easterly this afternoon and evening, leading to some additional
upslope flow along and east of the Laramie Range, favoring the
potential for a few storms to initiate off the Laramie Range.
Overall, the severe setup does not look as good as previous days,
hence only a Marginal Risk (Level 1 of 5) from the Storm Prediction
Center with the best threats being wind and hail. Forecast soundings
across the Panhandle look more indicative of a wind threat as dry
low-level and steep lapse rates throughout the lowest 3km favors
strong downburst winds. However, in this region hail can never
really be ruled out and some large hail is possible today. However,
relatively low MLCAPE, SBCAPE, and MUCAPE all suggest a significant
limitation of severe chance this afternoon as all values remain at
and below around 1000J. 0-6km bulk shear is very weak this
afternoon, less than 40kts for most locations east of the Laramie
Range. Temperatures are also progged to only warm into the low- to
upper-80s across the region today, which is likely acting to limit
the destabilization this morning into the early afternoon hours.
Overall, there is a chance for a few isolated storms this afternoon,
some of which may be severe, and have the threat of strong winds and
some large hail associated with these storms as well.

Monday looks similar to today, with an upper-level ridge attempting
to take over across the Intermountain West Monday morning into the
afternoon hours. Generally westerly upper-level flow is expected,
though a few disturbances within the flow may lead to temporarily
northwesterly flow overhead. A weak 500mb shortwave is progged to
develop and move through the crest of the ridge, giving the CWA
enough synoptic support to suggest the potential for some strong to
severe storms again in the afternoon hours. 700mb height gradients
are expected to increase throughout the late afternoon and evening
hours, leading to some semblance of a low-level jet across the
Panhandle Monday evening into the nighttime hours. This low-level
jet may further support convective development, but looks to arrive
a little too late to significantly impact convection. CAPE does look
to be stronger on Monday, along with much more shear in place across
the region as those 700mb gradients increase. However, a significant
forcing mechanism, such as a cold front, does not look to impact the
region, so storms will most likely be relying on upslope flow along
the terrain and potentially the terrain-induced dryline. Wind and
hail are the primary threats on Monday across western Nebraska, as
the Storm Prediction Center highlights this region in a Marginal
Risk once more.

Surface winds are expected to increase across the Panhandle and
southeast Wyoming, as the western portion of the region sees
tightening 700mb height gradients and increased winds. A jet around
40kts is progged to develop across the Laramie Range, which would be
strong enough to get some modest downslope flow across the region
along and east of the Laramie Range. In-house random forest guidance
is not favoring high winds at this time, nor does the pattern appear
to support high winds, but Monday evening into early Tuesday morning
will be quite gusty behind and convective development on Monday.
Temperatures will warm into the upper-80s to mid-90s east of the
Laramie Range and mid- to upper-80s west. Very dry conditions are
expected to develop west of the Laramie Range, so fire weather
headlines may be needed with future forecast updates.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Issued at 204 AM MDT Sun Aug 3 2025

Hot and dry conditions are expected to return to the region Tuesday
onwards as mostly zonal flow develops to the north of anupper-level
high over the southwestern CONUS. Subsidence from this ridge and
limited moisture fetches will prevent significant shower and
thunderstorm chances in the afternoon for the middle of the work
week. However, this also mean temperatures will rise once more.
Thursday remains to be the hottest day in the long term forecast
with the Panhandle returning to daytime highs in the 100s and
southeast Wyoming seeing highs in the low- to upper-90s. With these
hot and dry conditions, and breezier winds expected, fire weather
headlines look likely for much of the work week. The main fire
weather concerns will be west of the Laramie Range where dry
conditions have persisted for much longer than locations east of the
Laramie Range, though both will remain dry throughout much of the
week with limited precipitation chances. Next best precipitation
chance continues to be Friday into the weekend as an upper-level
trough encroaches on the region.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1105 PM MDT Sat Aug 2 2025

Quieter again tonight as some mid- to upper-level clouds slowly
clear out of southeast Wyoming and western Nebraska. Light and
variable winds overnight with lower chances of low stratus or
fog tonight. Winds pick back up after sunrise followed by
another round of strong to severe storms this afternoon.

&&

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

&&

$$

SHORT TERM...AM
LONG TERM...AM
AVIATION...AM