Chadron, Nebraska 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

828
FXUS65 KCYS 171711
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1111 AM MDT Thu Sep 17 2026

.KEY MESSAGES...

- A wet pattern is expected through the end of the week and into
  early next week, with daily chances for showers and
  thunderstorms.

- There is a Slight Chance of Excessive Rainfall and flooding
  issues on Thursday as a stronger than average late-season
  monsoon with tropical moisture moves into the region.

- Seasonably cool temperatures with highs ranging from the
  middle 60s to middle 70s through Monday. Friday will be the
  warmest day with low to middle 80s possible across the lower
  elevations.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 250 AM MDT Thu Sep 17 2026

Active over the next several days with a late-season monsoon
pattern setting up. Short term forecast through Friday night
looks on track with excessive rainfall and flooding remaining
the primary concern this afternoon through late this evening.
High res CAMs are starting to come into better agreement
regarding which area(s) have the best chance of seeing
persistent heavy rainfall, in addition to a low-end severe
weather threat across the eastern plains.

Current IR Satellite loop shows the potent shortwave trough, of
tropical origin, lifting north across Arizona at this hour.
Surface analysis shows the cold front has pretty much pushed
through the area and is now becoming stationary near the
mountains. Low to midlevel forcing appears to be in play later
today, with heavy showers and thunderstorms possibly beginning
as early as sunrise over the I-80 corridor as the shortwave
trough axis lifts north into the forecast area. Still expected
periods of very heavy rainfall, mostly across the eastern
plains...but can`t rule it out over Carbon and Albany counties
either. Model soundings continue to show 600-1200 j/kg of CAPE
with PWATs between 1.25 to 1.50 inches, and as high as 1.75
inches based on current model soundings. In addition, there is
also a risk for some locally strong gusty winds as convective
lines propagate southeast and then potentially redevelop
up-shear. SPC has introduced a Marginal Risk for strong to severe
thunderstorms, mainly for a strong wind threat. Large hail is
not expected at this time due to the tropical nature of this
event and long-skinny CAPE profiles on model soundings.

High res CAMs are finally coming into better agreement showing
most of the training storms and persistent rainfall over far
east-central Wyoming, South Dakota, and portions of the
northern and central Nebraska Panhandle this afternoon through
late this evening. Again, can`t rule out heavy rainfall across
other areas, but this appears the most likely region (generally
north of US Highway 26) to see a flood threat with the most
likely area(s) centered in southern South Dakota as the surface
low pressure system intensifies and stalls across central
Nebraska. Since our northeast zones are on the fringe of the
heaviest rainfall, decided to not issue a Flood Watch at this
time even though confidence has increased a bit. Current QPF is
still a little low to justify a Flood Watch based on current
flash flood guidance with limited areal coverage. Would also
like to see a bit more jet dynamics as the area of max
diffluence peaks over South Dakota and far northern Nebraska
this evening. With all this in mind, things may change and we
may end up issuing a Watch at a later time. Otherwise, kept
heavy rain wording in the forecast and will message accordingly
this morning. Expect high temperatures in the 70s to low 80s to
occur late in the morning or early in the afternoon before
temperatures fall into the 60s with the onset of precipitation.

For Friday, all models show the slow moving upper level trough,
currently across northern California, slowly nudging eastward
into the northern Great Basin Region and western Wyoming. With
low to midlevel moisture remaining over the area and a potent
midlevel shortwave ejecting northeast ahead of the main trough,
expect another day of scattered to numerous showers and thunderstorms.
This will be mostly over southeast Wyoming since the boundary
layer in western Nebraska will be pretty worked-over from the
previous night`s activity. Although we lose some of our CAPE,
heavy rainfall looks likely again on Friday with a Marginal Risk
of Excessive rainfall. It will be a little warmer with highs
back into the low to mid 80s below 6000 feet, and closer to the
middle 70s for Carbon, Albany, and western Laramie Counties.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Issued at 240 PM MDT Wed Sep 16 2026

Heading into Saturday, ensemble guidance has backed off on shunting
off our supply of monsoonal moisture as the closed low to our
northwest begins to lift to the north and east. While not as
impressive as the previous couple of days, PWAT values are still
expected to range between the 85th and 95th percentiles relative to
climatology, keeping additional shower and thunderstorm chances in
the forecast. The bulk of the forcing for ascent looks to be from
late Saturday evening into the overnight hours, with an additional
chance for some much needed rainfall. As it stands, ensemble
guidance has 55-65% chances of all areas east of the I-25 corridor
seeing at least 0.1" of rain from midnight to noon on Sunday, with
the highest values across the Nebraska Panhandle. However the spread
remains rather large, with the 25th percentile QPF being essentially
0.01"-0.05", which wouldn`t exactly do much to help our drought
conditions. Forecast soundings across the Panhandle show skinny CAPE
profiles throughout the troposphere, PWAT values around the 70th
percentile, and warm cloud layers up to ~3 km, so any showers and
storms are expected to be rather efficient rainfall producers.
Unsurprisingly, high temperatures on Sunday will be rather cool
(although not terribly far below average) in the 60s for SE Wyoming,
and low 70s in the Panhandle.

Heading into the work week, a warming trend is expected as flow is
more out of the WNW, resulting in drier conditions as another ridge
builds to our west over the Great Basin. Expect temperatures to be
around or slightly above seasonal values on Monday and Tuesday in the
upper 60s to mid 70s (warmest temps across the Panhandle), and
little to no chances for precipitation.

On Wednesday, ensemble guidance hints at the ridge building and
shifting east, placing SE Wyoming and W Nebraska in more WSW flow
aloft, allowing for some return of monsoonal moisture. At this time,
any monsoonal moisture surge doesn`t look nearly as impressive as
the one in the short/medium range, but low precipitation chances look
to return come mid next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1110 AM MDT Thu Sep 17 2026

A variety of hazards today across SE Wyoming and the Nebraska
Panhandle today, as numerous rounds of showers and thunderstorms are
expected this afternoon and evening. Primarily VFR conditions this
afternoon outside of any of the heavier showers and thunderstorms,
where MVFR cigs and vis will be in place. Any thunderstorms in the
vicinity of the terminals will be capable of producing gusty and
erratic winds, however the exact placement of these stronger storms
is highly uncertain, and future amendments will be necessary if one
of these storms happens to be in the proximity, with the highest
confidence being in the Nebraska Panhandle. Moderate confidence in
IFR cigs this evening and overnight for the Nebraska terminals, as
low clouds and stratus are expected to hang on given light winds and
low-level moisture. Can expect brief vis drops down to 2SM in/around
showers and thunderstorms.

&&

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

&&

$$

SHORT TERM...TJT
LONG TERM...NB
AVIATION...NB