Sidney, Nebraska 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

685
FXUS65 KCYS 251752
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1152 AM MDT Sat Apr 25 2026

.KEY MESSAGES...

- A messy pattern is anticipated today through much of the
  upcoming week, allowing for ongoing precipitation chances
  across the entire CWA. The best chance for precipitation will
  be Sunday, when a few rumbles of thunder will be possible.

- A Winter Weather Advisory has been issued for the Sierra Madre
  and Snowy Ranges from 6PM Saturday through 6AM Monday.

- Cool and wet weather is expected to continue into the work
  week. Possible dry spell come next weekend.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 345 AM MDT Sat Apr 25 2026

Active weather is progged to return to the region starting today and
continuing through much of next week. A messy pattern is currently
overhead and will continue throughout the weekend as an upper-level
low spinning over southern Canada meanders northward with little to
no eastward progression. A secondary trough is progged to develop
Sunday into Monday across the Pacific Northwest as the primary low
remains largely stationary. Model consensus is that this secondary
trough will deepen over the western CONUS and finally act to push
the stationary Canadian low off to the northeast by late Sunday
night into early Monday morning. Initially, with the stationary low,
an unsettled, moist pattern persists with continued weak synoptic
support. Looking down at 500mb, the vorticity advection associated
with the Canadian low is not favorable for propagation and will only
spin around the low without advecting it off to the east as wind
direction remains largely parallel to the 500mb vorticity maxima
surrounding the low. Luckily, as the primary vorticity maxima advects
around the west side of the low, the northerly flow induced by the
system itself will act to strengthen the vorticity advection,
allowing a 500mb shortwave to develop. The positive vorticity
advection on the leading edge of the developing shortwave will
enable the system to start its northeastward propagation Sunday
night into the early morning hours Monday. All the while, an upper-
and mid-level ridge developing off the western coast of the CONUS
will funnel westerly to southwesterly winds across central
California northeastward into the Intermountain West, allowing a
plume of Pacific moisture to impact western portions of the CWA as
early as midnight Sunday. With this Pacific moisture plume entering
the area, NAEFS Mean Integrated Water Vapor Transport suggesting
90th to 97.5th percentile IVT values combined with 90th percentile
Precipitable Water values across much of the region, further
showcasing the increasing moisture expected into the day Sunday.
Additionally, multiple lobes of 500mb vorticity will eject out ahead
of the developing trough across the Pacific Northwest, leading to
continued synoptic ascent across much of the CWA Sunday into Monday.

The 700mb low associated with the nearly-stationary upper-level low
over southern Canada will start to meander northeastward by early
Sunday morning, with the low itself weakening and becoming more
broad starting this morning and continuing through Sunday morning.
As a result, the CWA will see a break from elevated surface winds
across the region as 700mb flow remains quite weak without the
influence of the Canadian low. 700mb winds turn southwesterly by
Sunday morning and southerly east of the Laramie Range, further
supporting the advection of Pacific moisture into the CWA. Broad,
weak warm air advection at 700mb is expected this afternoon, with
the stronger WAA arriving Sunday morning into the afternoon hours.
WAA both today and tomorrow will act to support the overall synoptic
ascent across the region, with strong ascent expected Sunday with
the strong WAA. Strong WAA comes to an end early Monday morning as
the next cold front begins to sweep northwest to southeast across
the CWA. While the mid- and upper-level flow remains fairly messy,
it does not hold a candle to the surface flow expected today and
Sunday. For today, northerly surface flow behind a stationary front
that slowly meandered southward will flip to easterly by late
morning as a surface high develops downwind from the Black Hills of
South Dakota. As this high slowly move southeastward, easterly,
upslope flow continues across the CWA with a strong, reverse
pressure gradient expected along and east of the Laramie Range.
Surface pressure is progged to be around 1013mb near Pine Bluffs and
1006mb near the I-80 Summit, a 7mb change across approximately 80
miles. Therefore, the easterly upslope flow expected this afternoon
will be a bit stronger than typical easterly flow regimes, likely
around 15 to 20mph and gusting over 20mph. As the high continues to
propagate southeasterly, southeasterly flow will slowly return to
the Laramie Range by early afternoon. This flow will continue to
support upslope development along the Laramie Range, so there is
around a 35 to 45% chance for ongoing, light precipitation
throughout the afternoon hours today. For Sunday, surface flow east
of the Laramie Range remains largely south to southeasterly, with
southwesterly surface flow developing west of the Laramie Range.
With the 90th percentile PWs and IVT across the mountains,
significant snow is expected for both the Sierra Madre and Snowy
Ranges. With stronger WAA expected east of the Laramie Range,
widespread precipitation is anticipated Sunday with chances at and
above 80 to 90%. With WAA ongoing earlier in the day, precipitation
is expected to fall as primarily rain everywhere outside of the
mountains. However, behind the cold front, rain with transitioning
to rain/snow before switching over to all snow for everywhere west
of the Laramie Range and rain/snow mix east of the Laramie Range by
early Monday morning. Significant snow accumulation outside of the
mountains is not anticipated at this time, but the rain accumulation
should be quite decent, especially with 90th percentile PWs across
much of the area. Many locations could see up to and over 0.5 inches
of rain Sunday afternoon. West of the Laramie Range, the HRRR is
suggesting up to 500 J/kg of MUCAPE, which would enable a few
thunderstorms to develop across the region. These storms will put
down more precipitation, but over a smaller area. Severe weather is
not anticipated at this time. As for the mountains, 6 to 10 inches
of snow will be possible throughout the day Sunday, with the
potential for over 10 inches in the highest peaks. As a result, a
Winter Weather Advisory has been issued for the Sierra Madre and
Snowy Ranges from 6PM Saturday to 6AM Monday.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 345 AM MDT Sat Apr 25 2026

A cold and wet start looks to be in the cards for our Monday.
Temperatures start in the upper 20s to low 30s. Snow showers are
likely, that turns to mostly rain in the afternoon. The mountains
will hold on to freezing temperatures, therefore snow can be
expected there on the western upsloping faces. A general troughing
pattern will keep the area overcast for most of the day with a few
breaks in the afternoon east of the mountains. Some instability may
build to allow a few thunderstorms, yet MUCAPE is expected to be
limited to below 500 J/kg. Overnight, temperatures dip back down to
near freezing allowing another period for rain to transition to
snow. Amounts outside the mountains remain low, from a trace to
perhaps a half inch in a few overachieving spots in the northern
parts of our CWA. Tuesday looks much the same as Monday, however a
shortwave trough is set to pass over and give us a better chance of
widespread precipitation, particularly in the early morning hours.
Winds may increase during this timeframe, with an in-house machine
learning model highlighting wind gusts of 40 to 50 MPH being
possible in the wind prones. Yet again CAPE may be enough to promote
a few thunderstorms in the afternoon.

The shortwave quickly departs our area by Wednesday, giving an
opportunity for a weak upper level ridge axis to build in, reducing
ascent and widespread precip. Showers may still occur in the
afternoon and evening hours, but QPF outlooks not quite as high as
it was Tuesday. Another shortwave could make it`s way into our area
as a parting gift from the upper level trough that been in place to
our north for the better part of a week. Increasing PoPs will be
attributed to this disturbance Thursday and Friday, along with an
artic cold front passage. The outlook for the weekend is for a few
days of ridging which may allow high temperatures to increase into
the 60s and 70s.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1152 AM MDT Sat Apr 25 2026

For the Nebraska Panhandle terminals, easterly to southeasterly
winds are expected for the duration of the TAF period. This is
an upslope direction meaning that clouds heights are going to
fluctuate between 500ft and 2,500ft for the next 24hrs. Fog is
also a possibility in upslope flow for the early morning hours
probably between 08z-15z for my best guest. Rain showers are
expected to push through overnight but precip reaching the
surface isn`t really expected until around 12-15z tomorrow. KCYS
is the boundary for these low clouds and upslope flow so clouds
may bounce between MVFR/VFR as clouds moving in and out of the
area between 1,500ft and 3,000ft and clear. Showers look to
begin this evening into the overnight period for KRWL and KLAR
but again the best chances for rain to hit the ground is after
12z.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Weather Advisory from 6 PM this evening to 6 AM MDT
     Monday for WYZ112-114.
NE...None.

&&

$$

SHORT TERM...AM
LONG TERM...RV
AVIATION...MM