Flash Flood Warning 18, NWS Cheyenne, WY

146 
WGUS55 KCYS 142224
FFWCYS
NEC007-105-WYC015-021-150045-
/O.EXT.KCYS.FF.W.0018.000000T0000Z-260815T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Cheyenne WY
424 PM MDT Fri Aug 14 2026

The National Weather Service in Cheyenne has extended the

* Flash Flood Warning for...
  Banner County in the panhandle of Nebraska...
  Northwestern Kimball County in the panhandle of Nebraska...
  Southeastern Goshen County in southeastern Wyoming...
  East Central Laramie County in southeastern Wyoming...

* Until 645 PM MDT.

* At 424 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 3.5 and 4 inches of 
  rain have fallen. The expected rainfall rate is 1.5 to 2 inches in 
  1 hour. Additional rainfall amounts of 1 to 1.5 inches are 
  possible in the warned area. Flash flooding is ongoing or expected 
  to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Albin and Harrisburg.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 4170 10395 4170 10391 4170 10389 4170 10381
      4170 10378 4170 10375 4170 10372 4159 10359
      4137 10363 4136 10382 4133 10410 4150 10422
      4168 10403

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL RATE...1.5-2 INCHES IN 1 HOUR

$$

Brauer

554 
WGUS75 KCYS 150043
FFSCYS

Flash Flood Statement
National Weather Service Cheyenne WY
643 PM MDT Fri Aug 14 2026

NEC007-105-WYC015-021-150053-
/O.EXP.KCYS.FF.W.0018.000000T0000Z-260815T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Banner NE-Kimball NE-Goshen WY-Laramie WY-
643 PM MDT Fri Aug 14 2026

...FLASH FLOOD WARNING WILL EXPIRE AT 645 PM MDT THIS EVENING FOR 
BANNER, NORTHWESTERN KIMBALL, SOUTHEASTERN GOSHEN AND EAST CENTRAL 
LARAMIE COUNTIES...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

A Flood Watch remains in effect until 1000 PM MDT for portions of 
panhandle Nebraska and southeast Wyoming.

&&

LAT...LON 4170 10395 4170 10391 4170 10389 4170 10381
      4170 10378 4170 10375 4170 10372 4159 10359
      4137 10363 4136 10382 4133 10410 4150 10422
      4168 10403

$$

Brauer

Area Forecast Discussion
National Weather Service Cheyenne WY
1215 PM MDT Fri Aug 14 2026

.KEY MESSAGES...

- Temperatures warm a few degrees on Friday with isolated to
  scattered thunderstorms expected alongside a marginal risk of
  severe weather and a slight risk of excessive rainfall.

- Unsettled weather continues through at least Sunday, bringing
  cooler than average temperatures and daily chances for showers
  and thunderstorms.

- Isolated strong to severe storms and localized flash flooding
  will remain possible through Sunday.

- Drier weather and temperatures close to seasonal averages will
  return early next week.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 230 AM MDT Fri Aug 14 2026

Scattered showers and weakening thunderstorms are ongoing across
the CWA this morning, leftovers from yesterday's activity. These
showers should continue to weaken through sunrise, with
precipitation and cloud cover then expected to begin clearing
out through the afternoon in response to drier westerly flow at
the surface, allowing for a bit more daytime heating than
yesterday. Temperatures will rise back up in response to this,
with locations west of the Laramie Range generally still under
enough cloud cover that highs will only max in the upper 70's
for the day. East of the Laramie Range, we'll see the return of
the 80's, with a few spots in the Nebraska Panhandle possibly
even achieving the very low 90's again. As for our thunderstorm
chances, while not as widespread and heavy as the past couple of
days, we should see another round of activity form during the
early afternoon and continue into the evening, the strongest of
which should fire off of the high terrain and move across the
high plains into the evening. There will be some limitations to
the strength of this though, with the best instability along the
border of and into Colorado or further east into Nebraska. But
some guidance still produces decent low to mid level lapse
rates in the 8-9 C/km range, and bulk 0-6 km shear has pockets
in the 30-40 knot range, so a few storms along the I-80 corridor
from Cheyenne through the Panhandle could be strong to severe.
Also, our PWATs definitely aren't shabby, in the 1.2-1.4 inches
range, and a few pockets nearing 1.5 inches are showing up, so
any showers and storms could once again produce moderate to
heavy rainfall. And with soils now at least moist from multiple
rounds of precipitation, it may be easier again for localized
flooding to occur.

Saturday we will cool back down by a few degrees into the
widespread 70's and low 80's as a modest cold front drops across
the region, possibly aided by pockets of cloud cover lingering
from Friday's activity. But we are anticipating some fairly
decent destabilization on Saturday across the high plains, with
more widespread and favorable CAPE in the 1000-2000 J/kg range,
steep lapse rates, and more readily available bulk shear.
Because of this, a slight risk of severe weather is expected
from Cheyenne eastwards and across most of the Nebraska
Panhandle, with large hail and damaging wind gusts the most
likely hazards. PWAT values will generally mirror Friday's as
well, so any strong or training storms could easily produce
excessive rainfall once again. Likely scenario for this activity
will be storms consolidated into clusters or a linear segment
as they start moving out of the CWA towards the early evening,
with a few stragglers possible outside of this, but otherwise
not the widespread lingering precipitation from the last couple
of days.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Issued at 1150 AM MDT Thu Aug 13 2026

Saturday...Moist westerly flow aloft and a weak shortwave trough
aloft near peak heating will combine with deep atmospheric moisture
supply to produce scattered to numerous showers and scattered
thunderstorms in the afternoon and evening, with the greatest areal
coverage east of Interstate 25. Aiding in the lift will be low level
southeast winds adding the mechanical lift in addition to diurnal
heating. PWAT, Precipitable water values look decent for beneficial
rainfall. 700 mb temperatures yield highs in the 70s to lower 80s.

Sunday...Ridging becomes a bit more pronounced over Wyoming,
producing warmer temperatures aloft which will tend to limit areal
coverage of showers and thunderstorms, compared to Saturday.
Nevertheless though, the monsoonal moisture will stretch from
central Colorado through far eastern Wyoming and western Nebraska,
where scattered to numerous showers and thunderstorms will occur in
the afternoon and evening. Slightly warmer, but comfortable,
temperatures for this time in August.

Monday...A drier pattern ensues and is on tap as the flow aloft
turns west northwest and the precipitable water values decrease, due
to drying at low and mid levels and downslope southwest winds near
the surface. Thus, a much drier day when compared to the weekend. A
warming trend begins with more sunshine and warmer mid level
temperatures.

Tuesday...Brisk westerly flow aloft prevails, and with a decent
amount of low and mid level moisture availability, expect isolated
to widely scattered late day showers and thunderstorms, mainly east
of Interstate 25 and the Laramie Range. Similar maximum temperatures
to Monday based on 700 mb temperatures.

Wednesday...The synoptic pattern looks more like September and early
autumn with a deep shortwave trough aloft sweeping across western
Montana and Idaho, with west southwest flow aloft over our counties.
Right now, we have scattered late day showers and thunderstorms in
our gridded forecasts, though with a decent increase in precipitable
water values, the moist flow aloft, and low level upslope, along
with pattern recognition, believe our POPS and convective coverage
will likely need to be increased in the next few days.

Thursday...The high amplitude and progressive shortwave trough aloft
moves eastward from western Montana, to the Dakotas and western
Nebraska by evening, sending a decent Pacific origin cold front
across our counties. There may be enough moisture at low and mid
levels for isolated to widely scattered convective coverage, though
the biggest change will likely be a return to cooler temperatures
and windy downslope west winds, which will likely need to be
adjusted in the next few days, if model consistency remains for day
7. If you are looking for an early taste of fall weather, this may
be your day.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1129 AM MDT Fri Aug 14 2026

Inherited TAFS from our midnight shift Meteorologist were in
excellent shape, with only some minimal tweeks needed based on
recent observational data and model trends.

Challenges include thunderstorm coverage, intensity, duration
and cessation, and secondarily, the likelihood of fog and low
cloud development later tonight along and east of the Laramie
Range.

Southwest flow aloft prevails, with a shortwave trough aloft,
moving up through northeast Colorado, far southeast Wyoming and
the southern Nebraska Panhandle later this afternoon and this
evening, producing scattered to numerous showers and scattered
thunderstorms to the southeast of a Laramie to Chadron line
through the evening hours, with far drier conditions elsewhere.

Wyoming TAFS...Using the 12Z NAM and the consistent runs of the
HRRR, including the latest HRRR runs, high confidence in the
development of scattered to numerous showers and scattered
thunderstorms this afternoon and early evening, to the southeast
of a Laramie to Torrington line, with enough signals to go with
a TEMPO wording for KCYS from 20Z to 24Z, with some storms
producing wind gusts up to 48 knots along with some MVFR
visibilities and low VFR ceilings. Felt confident enough to
include VCTS at Laramie from 20Z to 01Z, and will monitor
cumulonimbus development for later updates. Storms look to
remain well east of KRWL, thus no mention of thunderstorms
there.

Otherwise VFR prevails, with gradient and mix down winds
producing gusts to 35 knots at the TAF sites through sunset.

Nebraska TAFS...Using the consistent runs of the HRRR, including
the latest HRRR runs, as well as the 12Z NAM, there is high
confidence in the development of scattered to numerous showers
and scattered thunderstorms this afternoon and this evening, to
the east of a line from Laramie to Chadron, with enough signals
to go with a TEMPO wording for Scottsbluff and Sidney from 22Z
to 02Z and from 23Z to 03z, at Scottsbluff and Sidney,
respectively, Some storms at Scottsbluff and Sidney will produce
erratic winds and gusts to 45 to 50 knots, with high MVFR and
low VFR ceilings and visibilities and even some possible hail.

Locally heavy rain is anticipated across the southern half of
the Panhandle later this afternoon and evening from slow moving
thunderstorms. Using the HRRR runs, being consistent and all,
felt confident enough to include a PROB30 at KAIA from 23Z to
02Z, with MVFR visibilities and low VFR ceilings. No mention of
thunderstorms at KCDR.

Otherwise VFR prevails, with mix down winds and gradient winds
producing gusts to 25 knots at the sites. Based on expected
rainfall and boundary layer progs, and experience with these
types of synoptic and mesoscale setups, feel confident enough to
include IFR and low MVFR ceilings and visibilities in fog at
all sites from roughly 08Z to 15Z.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Flood Watch until 10 PM MDT this evening for WYZ117>119.
NE...Flood Watch until 10 PM MDT this evening for NEZ020-021-054-
     055.

&&

SHORT TERM...CG
LONG TERM...RUBIN
AVIATION...RUBIN

Special Weather Statement
National Weather Service Cheyenne WY
133 PM MDT Fri Aug 14 2026

NEZ019-020-WYZ108-119-142015-
Scotts Bluff NE-Banner NE-Goshen County WY-East Laramie County WY-
133 PM MDT Fri Aug 14 2026

...A STRONG THUNDERSTORM WILL IMPACT SOUTHWESTERN SCOTTS BLUFF...
WESTERN BANNER...SOUTHEASTERN GOSHEN AND EASTERN LARAMIE COUNTIES
THROUGH 215 PM MDT...

At 132 PM MDT, Doppler radar was tracking a strong thunderstorm 8
miles southeast of La Grange, or 29 miles southwest of Scottsbluff,
moving northeast at 15 mph.

HAZARD...Wind gusts up to 50 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Harrisburg.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4158 10419 4183 10400 4153 10364 4143 10404
TIME...MOT...LOC 1932Z 233DEG 13KT 4155 10404

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPH

Rubin