656
FXUS65 KCYS 221935
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
135 PM MDT Wed Jul 22 2026

.KEY MESSAGES...

- Widespread showers and storms are expected over the next
  several days. Monsoon moisture will lead to heavy rain with
  the potential for flash flooding. Isolated severe storms will
  also be possible.

- A drier and warmer airmass will spread across the region for
  Friday, with even hotter conditions for Saturday through
  Monday and possible Heat Advisories over the weekend and on
  Monday. Some cooling is anticipated for Tuesday and Wednesday.



&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 133 PM MDT Wed Jul 22 2026

Today, The core of central high pressure remains over the Oklahoma
panhandle and NW Texas area. The synoptic forcing is a little bit
stronger today with stronger vorticity lobes and Warm air advection
as well as pockets of MUCAPE ranging between 1000-1500 joules.
Looking at this mornings model runs NAEFS increased the IVT signal
and placed a maxed value over Goshen county while the rest of the
forecast area is blanketed in 90 to 99.7th percentile values
indicating a stronger moisture transport from the tropical Pacific
(Baja California) into the Intermountain West. Storm Coverage was
also slightly upgraded from a numerous scheme to a more widespread/
training thunderstorm pattern this afternoon and evening. With the
increased moisture advection and training storm signal a Flood watch
was issued for the Forecast area with two different start times
corresponding to when storms are expected and method of flooding.
The flood watch went into effect at noon today and will expire at
midnight Thursday for Southeast Wyoming. The main threat for the
higher terrain will be mostly excessive runoff collecting and
flooding low lying areas in the valleys. Our streams and river may
also run a little bit higher as the runoff increases in the evening
but with the lack of rain leading to lower stream and river levels,
The runoff is expected to be contained in the banks of the rivers
and streams. For areas east of I-25 and the Nebraska Panhandle, the
most likely flooding threat remains the same. Our Dry soils with
develop this initial Hydrophobic effect when the rain hits the
ground leading to increased runoff before soaking into the soil.
Training thunderstorms with torrential rainfall will increase this
effect possibly flooding irrigation canals and flow over low lying
roadways and farmland. In urban areas some roadways may be come
flooded as the drainage systems may temporarily overwhelmed but
eventually the water is expected to clear itself out. WPC has issued
a Slight risk for the higher terrain in Southeast Wyoming and a
Marginal risk for areas East of I-25 for excessive rainfall. SPC
also drew a Marginal Risk for Severe thunderstorms today for Eastern
Laramie County and majority of the Southern Panhandle for wind gusts
between 60 to 65 mph. These wind gusts are expected to be isolated
and caused from collapsing updrafts from dying or cycling
thunderstorms creating a brief but strong microburst type wind
gusts. Thunderstorms are expected to linger overnight as they
gradually push east. The flood watch ends Midnight Thursday as
storms with torrential rainfall are expected once more but the good
news is the coverage may not be as widespread so there is a chance
the flood watch may be cancelled a little early but we shall see on
that. MUCAPE is about the same as today with pockets of 2,000 to
possibly 3,000 joules collocated with the saturated layer but the
upper level ridge still puts a damper on shear so robust severe
storms aren`t expected tomorrow as well. Tomorrow also has a little
bit more isentropic ascent so its not really out of the realm of
possibility to have another afternoon of heavy rainmakers in the
lower elevations. Temperatures are expected to be in the 80`s with
some areas possibly reaching 90 to 93 this afternoon but as cloud
cover starts to increase, temperatures should drop into the 70`s and
80`s tomorrow afternoon. However, the cloud cover will act as a thin
blanket overnight leaving the intermountain west as little warmer
with temperatures in the 60`s for overnight lows.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Issued at 133 PM MDT Wed Jul 22 2026

Friday...Will see an abrupt cutoff to the low and mid level moisture
supply as drier air at low and mid levels advects into our counties
as the dominant ridge over Colorado and southern Wyoming reasserts
itself. Thus dry and hotter.

Saturday through Wednesday...Isolated to scattered afternoon and
evening showers and thunderstorms expected, with areal coverage
increasing each day due to increased mid level moisture.
Fortunately, more beneficial rains expected concentrated over and
near our Snowy, Sierra Madre and Southern Laramie Ranges, with the
best chances for convection on Monday through Wednesday. Typical
weak northwest flow aloft on the northeast periphery of the ridge
aloft will aid in occasional passing shortwave troughs aloft near
peak heating resulting in increasing convective potential each
day.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1144 AM MDT Wed Jul 22 2026

An active convective afternoon and overnight are expected as a
moist and unstable airmass and moist low level upslope combine
to produce numerous to widespread showers and scattered
thunderstorms across southeast Wyoming, with scattered evening
showers and thunderstorms across the Nebraska Panhandle. Another
shortwave trough aloft will affect southeast Wyoming late
tonight, which will likely produce additional showers and
thunderstorms that may affect Carbon County and KRWL towards
daybreak, and Converse and Niobrara Counties after daybreak
Thursday.

Wyoming TAFS...Numerous to widespread showers and scattered
thunderstorms will affect KLAR and KCYS from mid afternoon
through late evening, producing erratic winds and gusts to 45
knots from the strongest storms, along with occasional MVFR.
Lesser coverage at Rawlins, though still confident enough based
on the NAM and HRRR to include PROB30 from mid afternoon through
early evening, with some gusts to 40 knots and brief MVFR. Due
to moist low levels, will likely see MVFR ceilings and
visibilities in fog and low clouds late tonight until shortly
after daybreak Thursday. Typical gusty gradient winds until
sunset.

Nebraska TAFS...Isolated to scattered showers and some
thunderstorms will affect the terminals from mid afternoon
through early evening, with the most areal coverage at
Scottsbluff and Sidney, where confidence is high enough to
include PROB30 and TEMPO at Scottsbluff and Sidney,
respectively. Lesser coverage of storms at Chadron and Alliance,
where belief is that VCTS will suffice during the evening
hours. The strongest thunderstorms will produce wind gusts to 40
knots along with occasional MVFR at Scottsbluff and SIdney.
Moist low levels will likely produce MVFR ceilings and
visibilities in fog and low clouds at Sidney after midnight
until near daybreak. Typical gusty winds of 25 to 35 knots
expected until sunset.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Flood Watch through Thursday evening for WYZ101>111-113-
     115>119.
NE...Flood Watch from 6 PM MDT this evening through Thursday
     evening for NEZ002-003-019>021-054-055-095-096.

&&

$$

SHORT TERM...MM
LONG TERM...RUBIN
AVIATION...RUBIN