649
FXUS65 KCYS 180838
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
238 AM MDT Sat Oct 18 2025

.KEY MESSAGES...

- High Wind Warnings remain in effect through 6 AM for the wind
  prone regions of southeast Wyoming.

- A strong cold front will move through Saturday leading to
  freezing temperatures across the entire region Saturday night
  into Sunday morning. Freeze Watches have been upgraded to
  Freeze Warnings.

- Strong winds look to return Sunday afternoon into early next
  week. High Wind Watches have been hoisted for the Bordeaux and
  Arlington wind prone zones. Breezy pattern expected to
  continue through Monday.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 237 AM MDT Sat Oct 18 2025

Very gusty conditions overnight tonight in many of the wind prone
regions of southeast Wyoming. The Bordeaux wind prone along I-25 has
gusted to 80 mph overnight with current gusts dropping back towards
60 mph. The Arlington/Elk Mountain wind prone zone has seen
consistent gusts overnight in the 60 to 66 mph range. Winds will
begin to decrease this morning, dropping below high wind criteria by
6 AM. The approaching cold front is currently over northeastern
Wyoming and western South Dakota, making its trek towards the CWA.
Expecting this front to be in Converse and Niobrara Counties within
the next hour. Winds behind the cold front are currently gusting ti
around 40mph, which is expected to continue into the CWA as the
front passes. The frontal passage will signal the end to the high
winds, but very gusty winds will continue behind the front.

Forecast remains largely unchanged as the upper-level trough
continue to push through the region today and an attendant cold
front dives north to south across the CWA. The cold front is
currently progged to reach northern portions of the CWA by 09Z, with
Chadron seeing a cold frontal passage closer to 10Z. The cold front
is expected to be through the region by 14Z this morning. 700mb
temperatures will tank into the -9 to -6C range today, leading to
daytime highs in the 40s and low-50s. Gusty winds behind the cold
front will make today feel much colder, with apparent temperatures
in the 20s and 30s this morning. High Winds in the typical wind
prone region of southeast Wyoming will see an abrupt end to high
wind criteria winds as the cold front pushes through and wind
directions turn northwesterly, an unfavorable direction for high
winds. Expecting winds to gust in the 40mph range for much of
morning and afternoon hours for the entire region behind the
departing cold front. There is a chance for precipitation with the
passing front, however, the biggest uncertainty remains whether this
precipitation will reach the surface. Downsloping winds yesterday
and early this morning have lead to very dry conditions east of the
Laramie Range, with dewpoints in the 20s and 30s, not overly
favorable for significant precipitation, especially not rain. Some
of this precipitation reaching the ground cannot be ruled out, so
increased PoPs over the southern CWA to around 20%. Northern
portions of the CWA are the most likely to see precipitation, as
downsloping winds have not impacted the moisture as much in these
locations. Rain, changing to a rain/snow mix, then light snow is
expected across Niobrara and Converse Counties, with a rain
transitioning to rain/snow mix expected across southern portions of
the region. With how warms its been the past few days, accumulation
is not expected outside of the mountains, as most snow that reaches
the ground will melt on contact. However, it is still possible to
see some flakes flying early this morning into the late morning
hours.

Clearing skies are expected behind the cold front and departing
upper-level trough as an upper-level ridge starts to build in.
Temperatures behind the front will remain fairly cool, as the
warmest air from the upper-level ridge does not arrive until Sunday
morning. With clear skies, radiational cooling will quickly tank
temperatures into the 20s and 30s across the entire CWA. As a
result, the Freeze Watches for the remaining counties has been
upgraded to a Freeze Warning for Saturday night into early Sunday
morning.

Temperatures will rebound quickly Sunday afternoon, with highs
returning to the 60 and 70s once more. As is typical with cool
season systems, the upper-level ridge will flatten out over the CWA
with increasing height gradients at 700mb as a 700mb low develops
over southern Canada. The 700mb jet will once again strengthen to
around 50 to 55 kts. Lapse rates are favorable for these strong
winds to mix down to the surface in the wind prone regions of
southeast Wyoming. As a result, a High Wind Watch has been hoisted
from 3am Sunday to 6pm Sunday for the Arlington/Elk Mountain and
Bordeaux wind prone zones. A period of weaker winds is expected 6pm
Sunday onwards, before 700mb height gradients strengthen once more
early Monday morning with a secondary developing 700mb low and a 55
to 60kt jet develops. The break between wind events looks to be long
enough to not warrant the Sunday High Wind Watch to continue into
Monday, but future model runs may decrease this time frame.
Therefore, the High Wind Watches may need to be extended in time or
a second set of Watches may be need for the Monday event. Will leave
this decision to day crew as newer model runs come in.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 313 PM MDT Fri Oct 17 2025

The long term remains active as we start the period in between
systems with a calm Sunday to end the weekend before another
system moves in to bring more high winds, precipitation, and
cold morning lows on Monday. On Tuesday, a flat ridge should
allow for us to warm on through Wednesday, with a slight chance
at some precipitation grazing us on Wednesday due to a weak low
passing to our south, with further ridging holding on to end
the long term on Thursday. Under this pattern, the primary
hazard we can expect will be another round of strong winds,
continuing from this weekend into Monday before finally
lessening during the evening. Based on ensembles and in house
guidance, high wind warnings are likely once again through the
start of the week for our wind prone regions. Meanwhile this
system should bring a quick shot of precipitation early Monday,
but the bulk of this should occur in the high terrain and
overall QPF will be limited at best. Into Tuesday morning skies
will clear, and with a cooler airmass in place behind this
system, a widespread freeze is likely with some locations that
haven`t quite seen a hard freeze below 30 degrees for the
morning. Warming should occur after that however, and highs will
bounce back into the upper 50`s to upper 60`s through the end
of the forecast period. The aforementioned weak system passing
just to our south on Wednesday may bring a glancing shot of
precipitation, but this will be overall weak and impacts will be
minimal to nil at best, with another seasonably warm and clear
day on Thursday to usher in the end of the work week.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1100 PM MDT Fri Oct 17 2025

Gusty conditions will continue overnight across the Southeast
Wyoming terminals and continue through much of the 06Z TAF
period. A brief lull in gusty winds across western Nebraska is
ongoing and will continue into the early morning hours until a
cold front begins to push north to south through the Panhandle
from 10Z at KCDR until 13Z at KSNY. This cold front, and the
associated wind shift, will be the primary aviation concern for
the 06Z TAFs. Front should push into KCYS between 14 and 15Z.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning until 6 AM MDT early this morning for WYZ106-
     107-110-116-117.
     High Wind Watch from late tonight through Sunday afternoon for
     WYZ106-110.
NE...Freeze Warning from midnight tonight to 7 AM MDT Sunday for
     NEZ019-021-055.

&&

$$

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