Carbon County Wyoming Weather Forecast Discussion

775
FXUS65 KCYS 140009
AFDCYS
Area Forecast Discussion
National Weather Service Cheyenne WY
609 PM MDT Mon Oct 13 2025
.KEY MESSAGES...
- Gusty southerly winds will continue through this evening along
  with chances of scattered rain showers.
- Areas of locally dense fog may develop late tonight into
  tomorrow morning near the I-80 summit and over the High
  Plains.
- Another storm system will slowly move through the area late
  Wednesday through early Friday, bringing first showers and
  thunderstorms, following by chances of mountain snow and
  strong winds.
&&
.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 222 PM MDT Mon Oct 13 2025
Clouds are moving into the CWA and expect them to linger through
the overnight hours while rain showers are not too far behind.
Why did we cloud up today along with increased chances of rain
showers, well, a strong conveyor of monsoonal moisture is being
pumped into our CWA. This is due to a deep upper level trough
diving south into the California Coast and ridging amplifying to
our east, which is bringing southwest flow to our area.
Instability parameters are meager at best so thunderstorms are
unlikely, but can`t be totally ruled out, especially in Carbon
County where the best instability exists. All this activity
should end tonight, say about 9PM, with more energy moving in
late tonight through Tuesday afternoon. Carbon County may not
catch a break from precipitation as hi-res guidance indicates,
this along with a few other locations west of I-25. Winds are
the other big story as a tight pressure gradient has set up over
our CWA, producing strong southerly to southeasterly winds
which may gust in the 30 to 45 mph range. Laramie, being the
exception, may see gusts topping out to near 50 mph. The
gradient laxes a bit overnight; however, winds only weaken
slightly. As mentioned above, the southwest flow will also
result in higher dewpoint values which will help with fog
developing late tonight into tomorrow morning, especially over
the I-80 summit and portions of southeast Wyoming and the
Nebraska Panhandle. Expect more fog to develop Tuesday night
into Wednesday morning, which could be more widespread. Highs
today generally in the upper 50s to low 60s with slightly warmer
temps for Tuesday, while lows won`t dip down as low as we`ve
seen over the previous nights.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 222 PM MDT Mon Oct 13 2025
At the start of the long term, a pretty robust 500mb trough is
deep across the Western CONUS while ridging sits to our east
over the Central Plains. As we progress through the long term
period, the upper level trough will slide east into our CWA by
Thursday evening, continuing on a easterly track through the
weekend. So, what does all this mean for us, well, expect an
active pattern through mid-week with southwest flow pumping in
deep moisture. As the 500mb trough slips to our east by the
weekend, upper level flow will then become northwesterly. This
will bring in some changes, especially to the temperatures.
Initially, with the southwest flow, temperatures will warm
through Wednesday with highs approaching 5 to 15 degrees above
normal. The warmest temperatures for this short period will be
across the Nebraska Panhandle as highs top out in the low to mid
70s, with a few locations possibly hitting 80 degrees F. Lets
go down to 700mb where we see temps hitting 6 to 10 degrees C,
this along with clear skies will help achieve the temps
mentioned previously. All this will be short lived though,
because we will see increasing clouds and precipitation chances
late Wednesday into Thursday. As the 500 mb trough pushes east
of our CWA, a cold front will move through Thursday resulting in
a return of cooler temps. This too will be aided by the upper
level pattern as flow aloft becomes northwesterly. Expect cooler
temperatures Friday into the weekend. Also, as the cold front
passes, another high wind event may be possible Thursday into
Friday. At the tail end of the long term period, expect the
coldest temps over the weekend while moderating some on Monday
as ridging aloft builds in.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 608 PM MDT Mon Oct 13 2025
A few scattered light rain showers will linger this evening along
with gusty winds. Another round of precipitation will arrive early
Tuesday morning, bringing low stratus and potentially fog to areas
east of the Laramie Range. Low CIGs will lead to MVFR conditions.
Light rain could also lead to visibility reductions at times.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...RZ
LONG TERM...RZ
AVIATION...SF

NWS CYS Office Area Forecast Discussion