859
FXUS65 KCYS 151742
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1142 AM MDT Mon Jul 15 2024

.KEY MESSAGES...

- Hot temperatures will continue through this afternoon for a
  majority of the area today before tapering off temporarily
  through mid-week.

- Increased precipitation chances and cooler temperatures are
  expected this afternoon through Wednesday.

- Isolated severe thunderstorms are expected today and Tuesday.
  The primary hazards are lightning, brief heavy rainfall, and
  strong winds to 60mph.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 300 AM MDT Mon Jul 15 2024

Warm temperatures remain entrenched across the area as we are
still under the influence of a dominant upper level ridge
pattern. Overnight temperatures are much above average, with
observations in the 60 and 70s, with even a few 80+ temperatures
at 9Z. Dry air is also present, which has been a common theme
the past several day as well. Expect the morning sunshine to
assist with temperatures surging quickly again this morning.
However, we will have shortwave disturbances embedded within
northwest flow at H5 today, and there will be a surge of monsoon
moisture as the day presses on. Daytime highs in the 80s and
90s, with the warmest temperatures remaining across the NE
Panhandle once again today, will allow for atmospheric
instability to build. Hi-res models depict a wide variety of
solutions for convective initiation. Highest confidence exists
for towering cumulus to develop into more organized thunderstorm
activity as it rolls off the foothills of the Laramie Range this
afternoon. Discrete convection will likely become more of a line
segment as it conglomerates in the western NE Panhandle. This is
where the highest confidence of strong to isolated severe wind
gusts near or above 60mph may occur, but is also possible across
southeast WY this afternoon.

We will have a temporary break from the hot temperatures on
Tuesday and Wednesday, with daytime highs in the upper 70s to
low 90s, instead of upper 80s to low 100s. This is also when we
will have multiple opportunities for showers and thunderstorms
to become present as the continued impulses of monsoon moisture
makes its trek toward our cwa. Isolated severe thunderstorms are
possible both Tuesday and Wednesday afternoon and early evening.
The main hazards will be lightning, strong wind gusts, and large
hail. This will certainly be something to pay attention to in
the event that organized convection impacts communities in the
cwa. There could be some potential for localized heavy
rainfall/flooding if we have any training thunderstorms. The
summer-like weather is not atypical for this time of year, but
always recommend individuals be situationally aware for rapidly
changing weather conditions. In the meantime, enjoy the warmer
temperatures for the region.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Issued at 300 AM MDT Mon Jul 15 2024

Lee troughing Thursday will continue to support southeasterly
moisture advection ahead of another shortwave rounding the top of
the upper level ridge across the southwest CONUS. Afternoon
temperatures will reach the upper 80s to low 90s before scattered
storm development in the late afternoon continuing into Thursday
evening. Storm chances on Friday will highly depend on the placement
and timing of the shortwave moving southeast across SD and its
associated frontal passage. Portions of the NE panhandle could see
enough instability and for a few strong storms with MLCAPE around
600-800 J/kg and bulk shear around 40 kt. However, southerly
moisture advection Friday morning ahead of the front looks to be
positioned along the eastern CWA border and extending into central
NE. Farther west, low level moisture will be limited, but daytime
heating and destabilization will lead to elevated storms with gusty
winds, especially along the higher terrain of southeast WY.

Headed into the weekend, 500mb height rises across much of the
western CONUS will lead to warming temperatures and drier
conditions. However, much of the CWA looks to be just on the eastern
side of the upper level ridge that has led to retaining daily
chances for precipitation (25-35%) with generally weak forcing and
instability. Looking at cluster analysis, model solutions begin to
diverge headed later in the weekend, but ~25% of GEFS and EC members
show a slightly more expansive ridge over the Intermountain-West
with warmer temperatures possibly returning to the 90s across much of
the NE panhandle.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1137 AM MDT Mon Jul 15 2024

VFR conditions heading into the early afternoon hours with some
mid-level cloud cover lingering and gusty northwest winds at
KLAR and KCYS. Showers and thunderstorms are expected to
develop over Wyoming around 19z and then expand and coverage and
spread eastward through the evening hours. This will move into
NE around 21-22z, and dissipate after about 04-06z. Storms will
have the potential to produce lightning, brief MVFR visibility,
and strong, gusty, and erratic outflow winds as they move
through. TEMPO groups have been added to capture the most likely
timing for each terminal, but multiple rounds of storms are
possible.

&&

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

&&

$$

SHORT TERM...BW
LONG TERM...BW
AVIATION...MN