210
FXUS65 KCYS 280740
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
140 AM MDT Thu Aug 28 2025

.KEY MESSAGES...

- Scattered precipitation chances continue for Friday and
  Saturday, though drier conditions are expected to return this
  weekend.

- Warming trend starts Sunday onwards, with fire weather
  concerns slowly creeping up to start the work week.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 139 AM MDT Thu Aug 28 2025

Mostly quiet tonight as low stratus and fog drifts across eastern
portions of the CWA. Radar has slowly cleared over the past few
hours with no showers currently visible on radar. Clearing skies out
west will allow temperatures to drop quicker west of the Laramie
Range, while east of the Laramie Range is expected to remain socked
in with clouds and fog throughout the night and into the morning
hours. Temperatures are mild east of the Laramie Range, in the mid-
50s to low-60s, while temperatures out west are in the low- to mid-
50s. Light, variable winds are ongoing across much of the area and
expected to continue into the morning hours.

Upper-level ridging continues for the next several days as the upper-
level ridge remains fixed in place across southern portions of the
Intermountain West. With this positioning, westerly flow will
continue aloft as the CWA remains under the northern edge of the
ridge through Saturday morning. Multiple 500mb vorticity maxima will
push through the region today and Saturday, leading to continued
daily precipitation chances. With continued monsoonal moisture
advection into the region, excessive rainfall threats continue with
both Friday and Saturday featuring a Marginal Risk from the Weather
Prediction Center. 700mb winds will be fairly light, leading to
mostly light surface winds today and tomorrow, though an approaching
trough may lead to wind increases in western portions of the region
by Saturday afternoon into Sunday. A very diffuse cold front pushes
through today, dropping 700mb temperatures a degree or two, but
mainly acting as additional forcing for showers and storms this
afternoon. Severe weather is not expected at this time, though
isolated to scattered showers will bring decent rainfall to impacted
regions. Coverage will be less widespread today compared to
Thursday, though many locations will still likely see precipitation.
A warming trend is expected to start Saturday into Sunday, though
temperatures Friday and Saturday will remain in the low-70s to low-
80s in the warmest locations.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Issued at 234 PM MDT Wed Aug 27 2025

Friday...Weak northwest flow aloft prevail, and with slightly warmer
temperatures as 700 mb temperatures rise to near 11 Celsius. Looks
like adequate low and mid level moisture for scattered afternoon and
evening showers and thunderstorms.

Saturday...For the penultimate day of August, northwest flow aloft
continues, and with plenty of low and mid level moisture available,
we expect scattered to numerous afternoon and evening showers and
thunderstorms. Cooler temperatures due to an increase in cloud cover
and precipitation coverage.

Sunday...Ridging aloft builds over western Wyoming, and with
atmospheric moisture decreasing and temperatures aloft increasing,
this day looks dry, with warmer temperatures compared to Saturday.

Monday...The ridge aloft continues amplified, which will effectively
keep it dry. The warming trend continues with 700 mb temperatures
near 14 Celsius.

Tuesday...Ridging aloft breaks down slightly as a shortwave trough
aloft moves across the region, and with a slight increase in low and
mid level moisture, we expect isolated to scattered late day showers
and thunderstorms.

Wednesday...Cooler temperatures expected after a cold frontal
passage. Looks like adequate low and mid level moisture to produce
scattered late day showers and thunderstorms.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1040 PM MDT Wed Aug 27 2025

Another round of showers and thunderstorms Thursday as a weak
stationary front develops near the Laramie Range. Primary forecast
challenge tonight and early Thursday morning will be fog and low
stratus across the eastern plains.

HAZARDS/WEATHER TRENDS: Persistent rainfall is coming to an end
tonight for most terminals. May see light rain continuing for KAIA
and KCYS over the next hour or two, but this activity should
dissipate shortly after 06z. Low confidence Aviation forecast for
KCYS, KBFF, KSNY, and KAIA through 15z Thursday with VFR conditions
expected to continue for KRWL, KLAR, and KCDR. Mixed signals for fog
tonight with weak upslope flow...at best, mid to high cloud cover,
but plentiful rainfall for far SE Wyoming and the central/southern
NE panhandle. Probabilities for fog have trended lower (20% to 30%)
compared to the last few hours , but can`t rule it out between 08z
and 14z Thursday...especially for KBFF, KAIA, and KSNY. Regardless,
still expect IFR CIGS at most of these terminals after 08z.

Afternoon thunderstorms will mainly impact KLAR and KCYS Thursday
afternoon, with a lower chance at KBFF and KRWL. Added PROB30 groups
for the most likely timing.

&&

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

&&

$$

SHORT TERM...AM
LONG TERM...RUBIN
AVIATION...TJT