754
FXUS65 KCYS 040535
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1135 PM MDT Tue Jun 3 2025

.KEY MESSAGES...

- Patchy dense fog late tonight and early Wednesday morning along
  the Interstate 80 Summit between Laramie and Cheyenne.

- Cooler and wetter conditions expected through the end of the
  work week. Strong to marginally severe storms expected
  Thursday.

- Warming trend possible during the weekend with daily chances of
  showers and thunderstorms.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 200 PM MDT Tue Jun 3 2025

Radar currently shows light returns over the South Laramie Range
moving into the Cheyenne area. This was captured well by the HRRR so
decided to use HRRR for the PoP blend in the short term. According
to the HRRR, isolated showers will be possible throughout the
afternoon and evening hours, with some locations potentially
seeing rain overnight as well. Severe storms are not expected as
cooler air behind the cold front has lead to a much more stable
atmosphere.

Heading into Wednesday, a broad upper-level trough will still be
locked in place over most of CONUS. This trough will continue to
stay in place throughout much of the week leading to cooler and
wetter conditions both Wednesday and Thursday. 700 mb temperatures
will be in the single digits during this time, leading to high
temperatures in the 60s across most of the CWA. These temperatures
will be about 5 to 15 degrees below average for the beginning of
June. Precipitation chances will also be possible both days as two
weak shortwaves move overhead through the main trough. Rain looks
possible mainly during the morning and overnight on Wednesday. This
is when the best moisture will be present. Once again, model
soundings seem to be too stable for any severe weather, however 600
J/kg of MUCAPE could lead to small hail and gusty winds in some
storms. Stronger storms look more probable on Thursday as the
stronger of the two shortwaves moves across the area. Model
soundings from the GFS show up to 1000 J/kg of MUCAPE in the
Nebraska panhandle with decent shear. This environment could
support a marginally severe storm or two during the afternoon.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 354 PM MDT Tue Jun 3 2025

The unsettled weather pattern will transition into a warming and
drying trend through the weekend, before possibly becoming unsettled
once again next week.

Several disorganized shortwaves will continue to traverse through
the area Thursday night into Friday, which will keep cool and
showery conditions in place. This should lead into another round of
scattered PM thunderstorms on Friday with the highest probabilities
generally along the Laramie range and southern I-25 corridor. An
upper level ridge over the southwest CONUS will expand over our area
Saturday, nudging the shortwave trough storm track a little further
off to the northeast. Expect to see temperatures climb back to near
or slightly above average on Saturday with reduced thunderstorm
coverage. Sunday and Monday look overall quite similar, but about
25% of ensemble members show the upper level low over the northern
Plains sagging just far enough to the south and west to bring cooler
and wetter weather back into the area for both days. Most ensembles
show the southwest ridge shifting eastward into the central Plains
beginning around Tuesday of next week. This should return higher
confidence in warmer temperatures and a southwest flow regime aloft
along with increased chances for showers and thunderstorms during
the afternoon.

&&

.AVIATION /06Z TAFS THROUGH 12Z THURSDAY/...
Issued at 1135 PM MDT Tue Jun 3 2025

Cool and unsettled pattern will continue over southeast Wyoming and
western Nebraska tonight and into Wednesday. Periods of rain showers
and a few thunderstorms are possible, especially across the western
Nebraska Panhandle late tonight and into early Wednesday morning.

HAZARDS/WEATHER TRENDS: Low CIGS and MVFR expected at KLAR and KCYS
tonight with IFR CIGS possible as early as 10z Wednesday. Also,
there is a low end chance (~15%) of some fog at these locations late
tonight and early Wednesday morning, but timing is uncertain. CIGS
will lower for the western Nebraska terminals late tonight through
early Wednesday with scattered showers and a few thunderstorms
possible...especially for KCDR and KAIA. VFR conditions will
continue for KRWL.

CIGS will lift across all terminals after 18z Wednesday with VFR
conditions expected. Another round of showers and thunderstorms are
possible after 22z through Wednesday night for all SE Wyoming
terminals and KCDR.

&&

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

&&

$$

SHORT TERM...SF
LONG TERM...MN
AVIATION...TJT