903
FXUS65 KCYS 041113
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
513 AM MDT Mon Aug 4 2025

.KEY MESSAGES...

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

- Red Flag Warnings and Fire Weather Watches are in effect
  Monday afternoon through Friday.

- Hot and dry conditions remain on track, with Thursday being
  the warmest day of the week.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 221 AM MDT Mon Aug 4 2025

Quiet conditions tonight as skies remain mostly clear across the
region. Some showers and storms are moving across northeast Wyoming
and into western South Dakota at this time. One of this storms may
briefly clip Dawes County, but no significant chance for
precipitation is expected tonight. Winds are light and variable
tonight, though generally with some southerly component.
Temperatures are mild in the 50s and 60s.

Northwesterly flow will return to the region today bringing with it
several chances for strong to severe storms in the afternoons. Mid-
level ridging across the southwestern CONUS will act to funnel some
Pacific moisture into the CWA this afternoon, leading to increasing
dewpoints throughout the day. Multiple lobes of 500mb vorticity
maxima will push through the flow, allowing for increasing synoptic
lift east of the Laramie Range, while most westerly flow across the
western zones will lead to hot and dry conditions. One major
difference for this afternoon is that a fairly stout 700mb jet is
progged to develop across western Nebraska, acting to fuel storms
throughout the evening hours and increase surface winds. In addition
to this, surface pressure gradients will strengthen across western
Nebraska this evening, further promoting very gusty environmental
winds this evening and through most of the overnight hours. A
surface low attempting to develop across north central Wyoming this
afternoon will be the primary forcing mechanism for storms this
afternoon, as well as upslope flow from easterly to southeasterly
winds east of the Laramie Range. MLCAPE values rise into the 1300 to
1800J range this afternoon, with forecast RAP soundings suggesting
dry low-levels, typical of downburst winds across this region.
Despite this, ample CAPE in the hail growth layer combined with
decently high MLCAPE values and bulk shear values will increase the
large hail potential this afternoon across the Panhandle. RAP
soundings also suggest decent low-level turning across the
Panhandle, with strong surface to 3km SRH values, increasing
tornadic potential across the Panhandle. However, 0 to 1km SRH
values are not overly supportive or tornadic development this
afternoon. Bulk shear will be much more favorable today, in the 45
to 50 kt range. Storms look to initially start as discrete before
combining into a more linear feature through the evening hours. As a
result, the Storm Prediction Center has highlight western Nebraska
in a Slight Risk (Level 2 of 5) for severe weather this afternoon.

West of the Laramie Range will be a completely different story, as
Fire Weather Watches and Red Flag Warnings have been hoisted for
western zones. Overall, flow across the western portions of the CWA
appears to be more westerly throughout the day, which is favoring
very dry conditions this afternoon and evening. Relative humidity
values are progged to drop into the single digits across the
furthest west zones this afternoon with winds gusting 25 to 35 mph.
A Red Flag Warning has been issued for these zones and is in effect
until Friday. Poor overnight humidity recoveries are expected in
this region, leading to very high fire danger and increasing the
ease at which any fire will start and spread. Slightly closer to the
Laramie Range is under a Fire Weather Watch through Friday. These
zones will occasionally have some time where they meet Red Flag
criteria and will be upgraded accordingly before falling back into a
Watch. The first Red Flag for these zones starts noon on Tuesday and
continues through 6 PM. After this, these zones will return to a
Fire Weather Watch as conditions still remain favorable for
increased fire weather concerns.

Much quieter weather is expected Tuesday as subsidence across the
region increasing with a flattening of the ridge over the
southwestern CONUS and westerly flow aloft developing. Very hot and
dry conditions are expected once again, so fire weather headlines
will continue through the week. Temperature Tuesday will be in the
low- to upper-90s for areas east of the Laramie Range and mid- to
upper-80s west of the Laramie Range. Afternoon relative humidity
values will drop significantly in the afternoon for most of the
region. However, most locations will not see winds strong enough for
fire weather headlines with the dry conditions. Instead, strong
winds will remain confined to areas west of the Laramie Range, as a
pattern usually indicative of very strong winds sets up across
western zones.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Issued at 221 AM MDT Mon Aug 4 2025

Hot and dry conditions continue through the week as fire weather
headlines remain in place through Friday. Upper-level ridging will
increase subsidence across the area and decrease shower and storm
chances most afternoons. Some afternoon showers and storms cannot be
completely ruled out as a few disturbances will pass through the
upper-level flow and promote convective development in the afternoon
hours. However, these storms are not expected to be severe at this
time. Winds remain breezy through the week, especially west of the
Laramie Range. It appears these winds want to remind the region of
the approaching wind season. However, winds are expected to remain
below high wind criteria at this time. Thursday remains the hottest
day of the week with highs in the mid-90s to low-100s east of the
Laramie Range and upper-80s to low-90s west of the Laramie Range.
Luckily, the dry weather will be firmly in place across the region,
so humid heat is not expected and apparent temperatures are progged
to be cooler than the actual temperatures.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 511 AM MDT Mon Aug 4 2025

Aviation forecast remains mostly on track with mostly clear
skies across southeast Wyoming and western Nebraska. Some mid-
to high-level clouds are drifting across the region and will
slowly clear through the morning hours. There is a slight chance
of some lower clouds moving into the Nebraska terminals, so kept
the TEMPO in for most terminals for FEW010. Isolated showers and
storms are possible this afternoon, mainly across western
Nebraska. Gusty winds return late this morning and continue into
the overnight hours.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Red Flag Warning from noon to 6 PM MDT Tuesday for WYZ420-421-
     427>429.
     Fire Weather Watch from Tuesday evening through Friday
     afternoon for WYZ420-421-427>429.
     Red Flag Warning from noon today to 6 PM MDT Friday for
     WYZ422>426.
NE...None.

&&

$$

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