Riverside, Wyoming Weather Forecast Discussion

065
FXUS65 KCYS 282350
AFDCYS
Area Forecast Discussion
National Weather Service Cheyenne WY
550 PM MDT Sun Sep 28 2025
.KEY MESSAGES...
- Warm temperatures continue today, though isolated to scattered
  showers are possible across western portions of the region.
  Breezy conditions across the Panhandle today.
- Slightly cooler temperatures on Monday behind a departing
  upper- level trough. Isolated to scattered precipitation
  chances out west once again.
- Drier conditions return late week as another upper-level ridge
  moves overhead.
&&
.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 146 PM MDT Sun Sep 28 2025
Today, the upper level ridge breaks down and moves east as the upper
level low pushes into the four corners region. This will send a
shortwave to move through this afternoon and evening producing some
light rain showers and weak thunderstorms for our mountainous
regions west of I-25. Dry conditions across the Panhandle with
mostly drier mid-level will prevent any significant precipitation
potential for locations east of the Laramie Range. For Monday, The
upper level low is expected to lift through the Rocky mountains and
Intermountain West. This will develop showers mostly in the same
locations as Sunday however, there is a little bit more uncertainty
wil the panhandle as some of the models has a couple streams of
vorticity Monday evening traversing over the Panhandle. This may
lead to some measurable precipitation as the vorticity streams
enhance the lifting mechanisms capable of producing showers. Still a
little uncertain if this will be enough to produce strong enough
showers to punch through the dry layer over the Panhandle Monday.
Winds will be a little breezy as well Monday as the upper level low
pushes through the Intermountain West tightening the pressure
gradient at 700mb and lower.  Temperatures look to be in the 60`s
and 70`s west of I-25 and in the 70`s and 80`s east of I-25.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
Issued at 146 PM MDT Sun Sep 28 2025
Warm and largely dry weather is expected to prevail Tuesday through
Friday, but a pattern change is increasingly likely for the weekend.
The synoptic pattern for most of the work week will be dominated by
a broad ridge encompassing most of the central and eastern CONUS
with southwest flow over our area. Tuesday looks like a mild day
ahead of a weak shortwave trough moving through the flow aloft.
Highs will be generally between 5 and 10F above average for the time
of year. As the shortwave passes through, we may see a few showers
kick off in the late afternoon through the evening hours, mainly
concentrated near the higher terrain as usual. There won`t be much
of an impact from this system aside from a wind shift to westerly
for Wednesday and perhaps a decrease in maximum temperature by a few
degrees. This will carry into another warming trend through the end
of the week. Thursday looks like the warmest of the week with 700-mb
temperatures peaking around +10 to +12C in advance of a much
stronger trough slowing pushing inland from the Pacific Northwest.
This trough will be the main player for Friday into the weekend.
However, there is quite a bit of spread between model scenarios in
strength and timing of individual shortwave troughs ejecting out of
the broad longwave trough. While the overall trend over the last 24
hours has been towards a more organized system in the Friday to
Saturday time period, the details are still unclear. The ECMWF
ensemble system is generally clustered around a faster solution
which breezes through some light precipitation Friday night and
clears things out by Saturday morning. Other solutions, most notably
the GFS and a good chunk of GEFS members, show a slower but stronger
shortwave trough moving through about 12 to 24 hours later,
supporting more widespread moderate precipitation and stronger winds
on Saturday. Due to these timing discrepancies, the official
forecast includes low end PoPs for most of the Friday PM through
Sunday period. Regardless of the precipitation outcome, expect this
system to bring a decent cool down, knocking temperatures down to at
least seasonal averages, if not 5 to 10F below average. Expect the
weekend to feel much more like autumn than summer.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 550 PM MDT Sun Sep 28 2025
Isolated showers and thunderstorms will continue to impact KLAR and
KRWL this evening before dissipating by 02z. Otherwise, partly to
mostly cloudy skies expected through tonight as a weak upper level
disturbance slowly moves northeast over the region.
HAZARDS/WEATHER TRENDS: VFR conditions will prevail through Monday
with occasional south to southwesterly wind gusts up to 20-25 knots.
Another round of thunderstorms expected for KCYS and KLAR after 20z
Monday with brief MVFR VIS possible, added PROB30 TS for these two
locations. Lower chances (~15%) for KRWL and KBFF Monday afternoon.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...MM
LONG TERM...MN
AVIATION...TJT

NWS CYS Office Area Forecast Discussion