Sidney, Nebraska 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

659
FXUS65 KCYS 261202
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
600 AM MDT Tue May 26 2026

.KEY MESSAGES...

- A stormier weather pattern will setup Tuesday and Wednesday
  and continue into the weekend with daily chances for PM
  showers and thunderstorms.

- Increasing potential for strong to severe thunderstorms is
  being monitored late in the week and during the weekend.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 230 AM MDT Tue May 26 2026

Not many changes made to the previous forecast package for the
middle of the week. Quiet weather early this morning as the last
few rain showers are dissipating over the eastern plains.
Remaining at least partly cloudy through sunrise, which should
keep low temperatures mostly in the 50s, with mid to upper 40s
along and west of I-25. For today, models continue to show a
broad upper level trough/disturbance lifting northeast out of
Arizona and across the four corners region by midday today. A
strong Pacific storm system will continue to dig south and
parallel the Oregon coastline earlier today before it
redevelops across the western Great Basin region late tonight.
The disturbance across Arizona is therefore expected to
accelerate northward ahead of the main upper level low to the
west, with increasing coverage of showers and thunderstorms
today. However, this activity should be mainly confined along
and west of the I-25 corridor for much of the day since the main
vort axis and upper level jet dynamics will mainly be located
across Carbon and Albany counties through much of the day.
Further east, some outflow boundary initiation and/or terrain
influence is possible for convection initiation, but the best
coverage should be west of the Laramie Range. High res models
continue to show heavy rain showers and scattered thunderstorms
lifting north across southeast Wyoming between noon and
midnight tonight. Multiple bands are expected with NAEFS
continuing to show PWAT over the 90 to 95 percentile (today and
Wednesday). As for strong to severe weather, it appears highly
unlikely at this time due to MLCAPE below 400 j/kg and quick
initiation and multiple bands through the day. There is some
threat of strong gusty winds though, with high res guidance
showing some decent outflow near the first several bands this
afternoon. Will need to monitor any heavy rainfall in the
mountains with recent heavy snow pack (2 to 3 feet in some
areas) observed with the last storm system for rapid runoff/local
flooding concerns (low confidence/low areal coverage).
Remaining warm today, but noticeably cooler west of the Laramie
Range with highs in the upper 60s to low 70s.

For Wednesday, models show the best chance for showers and
thunderstorms shifting east into far eastern Wyoming. There is a
little uncertainty starting to creep into the forecast for
Wednesday, with models now showing the disturbance over Texas
retrograding westward a bit into Colorado and drifting northward
through Wednesday night. This is in response to the expected
Rex block taking shape over the central plains. Increased POP
through the late evening hours towards Thursday morning. Again,
convective parameters are subpar for severe weather since we`ll
have little 0-6km shear over the region and limited CAPE.
Moisture shouldn`t be a problem with dewpoints climbing into the
low 50s and PWAT climbing over the 97th percentile for this
time of the year. There is some upper level forcing, so kept POP
above 50 percent for most of southeast Wyoming and southwest
Nebraska. It will be a few degrees cooler compared to Tuesday
with highs in the upper 60s to mid 70s for most of the forecast
area, and in the low to mid 80s across east central Wyoming and
the northern Nebraska Panhandle.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Issued at 1250 PM MDT Mon May 25 2026

For mid to late week, eastern Wyo and western Neb sit between the
large closed low anchored near the Great Basin and the amplified
ridge over the Great Plains. Low level and upper flow will primarily
be south/southeasterly through the extended period for the forecast
area. This pattern will maintain near to slightly above normal
temperatures (highs in the 70s and 80s) and periodic precipitation
chances. While the near surface flow will not be uninhibited from
the Gulf, dew points will remain around 50F east of I-25 through the
workweek, which can be sufficient for thunderstorm activity. The
core of the upper dynamics remain west of the immediate region, but
large scale ascent should extend downstream from the main low and
influence the southern Wyo ranges and adjacent areas. Perhaps the
greatest potential for widespread moisture comes Wednesday as a mid-
level shortwave traverses the High Plains. Thunderstorm activity
should increase through the afternoon, taking advantage of elevated
instability/lift and a ribbon of moisture. Thunder parameters don`t
appear to support severe weather at this time, as overall CAPE is
limited and deep layer shear is weak. Friday could be a different
story, however. The upper jet swings a bit to the east, placing the
panhandle in the sweet spot for increased lift. A surface low also
emerges from the northern Rockies, along with a notable change in
low level moisture flux over the Plains. Early indications reveal
very steep lapse rates (~9C/km) and sufficient CAPE (1000+ MU j/kg)
over the panhandle. Will need to continue to monitor later forecast
trends regarding severe potential during the afternoon and evening.
Some mechanisms remain in place over the weekend, so will hold
status quo for chance PoP and seasonable temps.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 600 AM MDT Tue May 26 2026

An upper level disturbance will accelerate as it moves northward
today into central Colorado and Wyoming. This disturbance will bring
numerous showers and scattered thunderstorms to mainly southeast
Wyoming today and into tonight. Gusty south to southeast winds are
expected for most terminals between 15z this morning and 04z
Wednesday.

HAZARDS/WEATHER TRENDS: Gusty winds out of the south will begin over
the next few hours with gusts up to 40 knots likely for all
terminals after 18z, with the exception of KRWL. Showers and
thunderstorms will develop across the mountains and move northward
into KLAR and KRWL after 18z. KCYS may see some of this activity
later in the afternoon and evening hours. MVFR CIGS and VIS possible
with these thunderstorms along with erratic gusty winds.

&&

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

&&

$$

SHORT TERM...TJT
LONG TERM...MM
AVIATION...TJT