Chadron, Nebraska 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

104
FXUS65 KCYS 211944
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
144 PM MDT Sun Jun 21 2026

.KEY MESSAGES...

- A few isolated showers and storms are anticipated Sunday
  afternoon.

- Widely scattered strong to severe thunderstorms are possible
  again on Monday, with large hail and strong winds as the
  primary hazard.

- Daily chances for showers and thunderstorms will continue
  through much of the week ahead with temperatures near average
  west of I-25 and cooler than average east of I-25.

&&

.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 130 PM MDT Sun Jun 21 2026

Thunderstorms are getting an early start today. GOES visible
satellite imagery shows convective plumes developing already over
portion of the High Plains. Analysis of the environment early
this afternoon suggests that capping will not be a problem
today. On the large scale, we are now on the backside of the
shortwave trough with its upper level circulation apparent over
the Dakotas. The surface trough behind this feature has mostly
cleared the area. This is is showing up as a weak surface cool
front and a wind shift. Surface northwest winds have spread
across the entire area behind this boundary. Wind shear is
fairly weak as a result, with a little bit of backing flow in
the lowest 3-km or so mostly in the ballpark of 20 to 40 knots.
Fairly potent instability has developed where low- level
moisture remains abundant (north of a roughly Douglas to Sidney
line). Isolated to widely scattered storms are already
developing over the area, and should continue through the
afternoon. Overall, today will be an earlier show, with most of
the hazard expected to conclude by around 7PM or so. However,
forcing for ascent will shift west this evening as the surface
cool front pushes over the Laramie range and into Carbon/Albany
counties. Expect scattered showers and a few thunderstorms to
continue over our western zones late into the evening. Today`s
storms will have some limited potential to become strong to
severe, most likely in the southern/eastern panhandle where
vertical wind shear is the most prominent.

With strong moisture return overnight as the moisture and frontal
boundary surge west of the Laramie range, we will have another round
of patchy fog and low clouds developing over area Monday morning.
The highest probabilities for fog are around the Pine Ridge and the
northern Panhandle. Models are in fairly good agreement showing the
low clouds/fog burning off fairly quickly Monday. While we should
have some CIN present during the morning to early afternoon, it
appears the chance for this continuing all day (as yesterday) is a
bit lower. The surface high and associated moisture will retreat
back to the Laramie range Monday morning as dry, westerly flow
pushes back into Carbon and Albany counties. This will accentuate
the dryline along the terrain boundary, and thus provide a focus for
convective initiation around 1-3PM. Monday`s environment looks
fairly potent with ample instability and deep layer shear around 50
knots. Large hail and gusty winds will be the primary hazards
through most of the day. In the late afternoon, models suggest that
the low-level jet will start to ramp up, accelerating southerly flow
over the High Plains. This will enhance low-level shear and may
increase the tornado threat for a few hours. Hi-res models struggle
with what to do with the explicit convection tomorrow, especially
after about 6PM. An upper level low sitting to our north will
provide a little bit of synoptic scale lift through the evening and
overnight hours as a surface front pushes southward across the area.
Overrunning lift in place of continuing elevated instability may
allow for some nocturnal convection through much of the night. This
should be mostly isolated, but we may not have clear radar for much
of night. PoPs in the 20 to 40% range are maintained all through the
night along and north of a roughly Douglas to Alliance line, which
is the area closer to the forcing. Another round of patchy fog is
anticipated Monday night into Tuesday morning over the plains.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Issued at 130 PM MDT Sun Jun 21 2026

The long-term period will begin under zonal flow aloft underneath a
flat longwave ridge with numerous embedded vorticity maxima
propagating across SE Wyoming into Western Nebraska. High
temperatures on Tuesday will be cooler than the previous day thanks
to a cold frontal passage during the morning hours which will shift
our surface winds to NNE. Moist, post-frontal upslope flow will
increase our surface dewpoints across SE Wyoming and the Nebraska
Panhandle into the mid to upper 50s combined with 40-50 knot 500 mb
flow and an associated shear-induced vorticity maximum moving across
the area which will set the stage for convective initiation on
Tuesday afternoon. Forecast soundings continue to indicate effective
bulk shear values in excess of 45 knots, so there will be the
potential for a few severe thunderstorms with the addition of 500-
1000 J/Kg of MLCAPE confined to areas east of the I-25 corridor
where the greatest low-level moisture will exist. This lines up with
the Day 3 SPC Convective Outlook which places Cheyenne and other
locations along and south of the I-80 corridor in a marginal risk
for severe weather. Despite sufficient deep-layer shear for
supercells, low and mid-level flow is progged to be quite weak,
lower than 10-15 knots, yielding little to no low-level curvature in
the hodograph. This should limit the overall tornado threat with any
storms, leaving large hail and damaging winds as the main threats
with any supercells. With the cooler post-frontal air mass and
lingering low-level moisture, forecast highs on Tuesday are expected
to be near or slightly below climatology in the mid to upper 70s
mainly east of the Laramie Range, with upper 70s to low 80s to the
west.

The pattern remains active into Wednesday as another shortwave
trough embedded in the zonal flow regime progresses across our area,
providing another source for forcing for ascent. Surface winds turn
to more SE, which will allow for additional theta-e advection and
low-level moistening throughout the day. It is too far out to get
into specifics, but the combination of a lifting mechanism, progged
dewpoints in the mid 50s (resulting in surface-based instability),
and effective bulk shear values greater than 50 knots, there will be
a threat for severe weather on Wednesday as well. SPC has placed
much of SE Wyoming and the Panhandle in a Day 4 risk for severe
weather, so future forecasts will have to be monitored. High
temperatures will again be slightly below climatology mainly in the
low to mid 70s.

Much of the same for Thursday as embedded disturbances continue to
move across our region and consistent signals from ensemble guidance
that low-level moisture will remain in place east of the Laramie
Range. Forecast soundings and medium-range ensembles continue to
show sufficient deep-layer shear and flow aloft for organized
convection, with primary hazards to be ironed out in the coming
days. As we finish off the work week and head into the weekend, the
synoptic-scale flow pattern will become southwesterly downstream of
a rather high-amplitude trough centered over British Columbia and
the Pacific Northwest. PWAT is progged to be at or above the 80th
percentile on Friday, so there will be the possibility for an
additional round of late day afternoon showers and storms. Severe
potential looks low at this time given the lack of shear. A warming
trend will continue into the weekend with mostly dry conditions and
temperatures near or slightly above climatology.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1133 AM MDT Sun Jun 21 2026

An active TAF period, mainly for the Nebraska terminals as low-level
moisture remains in place, resulting in a chance (30-50%) of showers
and thunderstorms mainly before 02Z, hence the mention of VCTS and a
TEMPO group primarily for KAIA, KCDR, and KBFF where confidence is
highest. As winds calm during the evening hours and dewpoints are
progged to remain in the mid-50s, effective radiative cooling is
anticipated, which may lower CIGs to IFR for the aforementioned
terminals. Not enough confidence (<30%) at this time to include fog
in the TAFs, but lowered CIGs to IFR criteria after 04Z to convey
the possibility of low clouds. This will have to be monitored and
potentially included in the 00Z forecast depending on how today`s
convection evolves. Otherwise, expect VFR for the Wyoming terminals
with variable winds less than 10 knots after 02Z.

&&

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

&&

$$

SHORT TERM...MN
LONG TERM...NB
AVIATION...NB