Sidney, Nebraska Weather Forecast Discussion

124
FXUS65 KCYS 082301
AFDCYS
Area Forecast Discussion
National Weather Service Cheyenne WY
501 PM MDT Mon Sep 8 2025
.KEY MESSAGES...
- Daily chances for afternoon showers and thunderstorms with
  primary threats being small hail and gusty winds.
- A cold front will impact the area later this week with cooler
  temperatures and lowering precipitation chances for the
  weekend.
&&
.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 325 PM MDT Mon Sep 8 2025
A weak shortwave is producing some light showers over the mountains
currently. Low and Mid level water show moisture being advected in
the region ahead of the low pressure system pushing into the West
coast. While we have ample moisture the forcing is mostly synoptic
based developing weak showers with some embedded thunder possible.
CAPE values are rather low with the most modest amount being 300
joules. During the overnight hours the ridge will begin to amplify
creating a nocturnal inversion. There is a slight chance for some
fog development where showers develop, mainly in the southern
portion of Albany and Laramie county. Tuesday, another shortwave
disturbance will develop a little bit stronger thunderstorms.
However, once again CAPE values are progged to be very limited so
Severe thunderstorms aren`t expected but one or two can`t be ruled
out. Moisture is expected to be sufficient enough for storm
development as its still be advected in from the Pacific Northwest.
Heavier rainfall looks to occur with these storms compared to
today.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 325 PM MDT Mon Sep 8 2025
Primary forecast concern in the long range forecast will be the
upper level Pacific trough...currently near the northern Cali/Oregon
coastline. Models are in good agreement through the end of the week
as this system moves into the forecast area later this week and into
next weekend. For the next few days, all models show this system
slowly moving onshore and eventually moving into the Great Basin
region on Wednesday and Thursday. Increasing southwest flow aloft is
expected ahead of the trough across the Front Range , which
typically results in warmer than average temperatures this time of
the year along with a decent chance for rainfall and thunderstorms.
A quick glance at NAEFS show portions of the area, mainly north of I-
80, around the 90th to 95th percentile for PWATs Wednesday through
Thursday. Convective parameters look good with SBCAPE of 1000 to
2000 j/kg east of I-25, and even close to 3000 j/kg across the
southern Nebraska Panhandle Thursday evening. Shear is very marginal
based on most model runs and ensemble guidance with 0-6km shear
hovering around 20 to 25 knots. Strong to near-severe thunderstorms
are possible, especially on Thursday, with model soundings
suggesting linear growth as lines of thunderstorms propagate east or
southeast (individual storm motion will be northeast). However, we
are getting to the time of year where thunderstorm coverage is much
lower compared to mid-summer...so kept POP below 35 percent due to
expected widely scattered coverage. There is also a noticeable lack
of forcing ahead of the main system on Wednesday, with a decent
shortwave disturbance embedded in the mean southwesterly flow late
on Thursday. Pleasant weather is expected other than the
thunderstorm activity with highs in the upper 70s (west) to upper
80s and near 90 east. Warmest temperatures will be below elevations
of 4500 feet.
Best chance for precipitation appears to be Friday as a stronger
shortwave ejecting northeast out of the four corners region.
Surface and midlevel cold front are also expected to gradually
move across the forecast area later in the day with additional
forcing continuing into Friday night. Kept POP between 40 to 60
percent over most of the area, but especially over the mountains
and areas well north of I-80 into east central Wyoming. This
cold front will bring cooler temperatures for late Friday and
into the weekend with highs dropping into the upper 60s west of
I-25...and into the 70s/near 80 for the eastern plains which is
slightly below average. Thankfully, the upper level trough will
slowly move eastward well north of the forecast area across
Montana and northern Wyoming. This will result in a much drier
airmass over southeast Wyoming with shower and thunderstorm
coverage becoming very isolated this weekend.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 500 PM MDT Mon Sep 8 2025
Isolated showers are ongoing across this region this afternoon
and are expected to continue over the next 1 to 3 hours for the
terminals. Gusty winds will begin to subside in the next 1 to 2
hours, with calm and variable winds expected overnight at most
terminals. Mid-level cloud decks remain, around 12,000 to 15,000
feet overnight into the early morning hours. Showers and storms
return tomorrow afternoon.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...MM
LONG TERM...TJT
AVIATION...AM

NWS CYS Office Area Forecast Discussion