583
FXUS65 KCYS 112339
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
539 PM MDT Sat May 11 2024

.KEY MESSAGES...

- Trending warmer through Monday, but remaining unsettled with
  daily chances for showers and storms. Severe weather is not
  expected.

- A cold frontal passage is expected on Wednesday, with much of
  the region returning to below-normal temperatures and
  increased chances for rain and high-elevation snow.

&&

.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 215 PM MDT Sat May 11 2024

A warming trend should persist across southeast WY & the western
NE Panhandle as thermal profiles warm in response to weak upper-
level ridging extending along the northern periphery of a closed
low drifting eastward from the Four Corners into the central and
southern plains over the next several days. Daytime highs should
climb into the lower to middle 70s across much of the CWA Monday
as 700-mb temperatures climb to near +8C by 00z Tuesday. Despite
the warming trend, an unsettled pattern will likely persist with
daily chances for showers & perhaps a few rumbles of thunder for
some locales as multiple pieces of mid-level energy continuously
pivot around the north side of the aforementioned low. Given the
very modest moisture profiles & dry sub-cloud layer suggested by
forecast soundings, potential rainfall amounts look to be fairly
limited w/ most areas not seeing anything measurable, perhaps up
to a few hundredths of an inch. Weak CAPEs under 500 J/kg, along
with modest deep layer vertical shear will preclude any risk for
strong to severe storms.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Issued at 215 PM MDT Sat May 11 2024

The long term forecast will start off active as numerous showers and
thunderstorms look possible mid-week. The weather will quiet down
towards the end of the week as a ridging pattern takes hold of
western CONUS.

A shortwave digging down from the Pacific Northwest on Tuesday will
likely spark widely scattered showers and thunderstorms during the
afternoon and into the overnight hours. A vorticity max over the
CWA, as well as a weaker 250 mb 85 kt jet streak just north of the
CWA will provide some of the ingredients needed to get
thunderstorms. Location of the jet streak puts the CWA in the right
entrance region, which is favorable for lift and the development of
potentially stronger storms. GFS soundings from Tuesday afternoon
into Tuesday evening do show areas of instability, with over 1000
J/kg of MUCAPE in parts of the CWA. There are even some impressive
effective shear values over the northern tier of the CWA, with both
Douglas and Chadron showing 35 kts EBWD. Because of this, cannot
rule a few marginally severe to severe thunderstorms. Based on
current sounding profiles, the main concern would likely be the
potential for severe hail. This would mainly be in the northern tier
of the CWA, as well as the Nebraska panhandle.

Showers will likely become more numerous Tuesday night as the
shortwave pushes into Wyoming, bringing with it more mid-level
moisture. Showers will continue into the day Wednesday with the
shortwave passing over the CWA. Cooler temperatures are expected
with this shortwave which will lead to a more stable environment
with less of a chance of thunderstorms developing. Could still hear
a rumble of thunder or two, but it will predominately be rain
showers across the area.

With the shortwave pushing off to the east Wednesday night, expect a
warmer and drier end to the week as an upper-level ridge builds over
western CONUS. Temperatures will warm up above average across the
CWA on Thursday and Friday, with minimal chances for precipitation
both days.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 536 PM MDT Sat May 11 2024

VFR conditions expected for the forecast period. A few slow
moving showers have developed along the I-80 corridor, and may
bring a brief shower and some gusty winds to KLAR, KCYS, and
KSNY through the evening hours. While a few rumbles of thunder
are possible, don`t have the confidence to add TSRA.

Mainly quiet conditions after midnight or so, although there is
a slight chance for some fog or low CIGs at KSNY early Sunday
morning. The probability is too low at this time, but worth
keeping in mind. By mid-morning, expect northeast winds to take
over at all terminals, followed by shower and thunderstorm
activity in the early afternoon. These showers will have the
potential to produce gusty and erratic winds.

&&

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

&&

$$

SHORT TERM...CLH
LONG TERM...SF
AVIATION...MN