003
FXUS65 KCYS 020444
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1044 PM MDT Sat Jun 1 2024

.KEY MESSAGES...

- A few strong to severe thunderstorms are expected late this
  afternoon through the early evening hours, mainly from far
  southeast Wyoming into the western Nebraska Panhandle. Large
  hail and damaging winds will be the primary hazards, although
  an isolated tornado cannot be entirely ruled out.

- Numerous showers and thunderstorms are expected across all of
  southeast Wyoming and the western Nebraska Panhandle on
  Sunday. Strong to locally damaging wind gusts will be the main
  convective hazard, mainly from late morning through late
  afternoon.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 220 PM MDT Sat Jun 1 2024

A few strong to severe thunderstorms will likely impact portions
of far southeast Wyoming and the western Nebraska Panhandle over
the next few hours, aided by modest upper-level support ahead of
a weak short wave disturbance and moisture convergence along the
surface dryline. Convective coverage should remain limited given
the modest forcing, but the main focus area should be across the
southern Nebraska Panhandle in the zone of weakest CIN and over-
all best low-level convergence. Dew points in the low to mid 50s
and steepening lapse rates are supporting MLCAPEs near 1500-2000
J/kg, while 40+ knots of 500-mb flow contributes to strong deep-
layer effective vertical shear of 35+ knots. As such, any storms
that develop will have the potential to become supercells w/ the
potential for large hail & damaging winds. Significant hail risk
will depend on whether storms can remain discrete, but expect to
see some additional development in the next few hours which will
have potential to disturb the inflow.

An active day is expected for Sunday beneath fast, active quasi-
zonal flow aloft. This mid-level energy will interact with a 700
millibar warm front, giving way to numerous showers and thunder-
storms by mid/late morning. Ample jet energy, coupled with shear
vectors oriented parallel to the warm frontal zone would suggest
potential for organized linear and bowing line segments, capable
of strong/damaging wind gusts in excess of 60 MPH with localized
potential for 75+ MPH, especially over the southern Panhandle as
a more organized MCS starts to become established to the east in
the deeper moisture. The latest SLGT/ENH risks from SPC are just
east of the CWA, but would not be surprised to see this nudged W
in future updates if high-res guidance continues to suggest this
type of storm mode.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 220 PM MDT Sat Jun 1 2024

Minimal changes made to the long term forecast. Still looks mostly
dry with a windier period possible through mid-next week and warmer
temperatures for the end of the week. Both the ECMWF and the GFS
show a shortwave trough moving across the CWA late Monday night into
Tuesday. With this trough, comes a cool front, which will lead to
cooler, but still mild temperatures on Tuesday. Aside from cooler
temperatures, this front will also bring breezy to windy conditions
across much of the CWA, with the potential for high winds for
the usual southeast Wyoming wind prone areas. Behind the front,
strong westerlies will exist with 700 mb winds between 50 and 60
kts over the Laramie Range and Arlington area. A decent MSLP
gradient will exist west of the Laramie Range with good
subsidence. This could bring some stronger winds down to the
surface and lead to high winds over Arlington and the South
Laramie Range on Tuesday. Continued elevated to high winds could
continue into Wednesday with strong westerlies. Even in-house
guidance shows 50 percent and greater probabilities for high
winds at Arlington and the South Laramie Range. By Thursday,
upper-level ridging begins to build over western CONUS, leading
to quiet, dry and warming temperatures through the end of the
work week.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 1044 PM MDT Sat Jun 1 2024

Primary aviation concern tonight will be thunderstorms moving out of
the area. Winds should be calm overnight, with ceilings expected to
remain VFR at all terminals. For tomorrow afternoon, thunderstorms
will become a concern once more, with KCYS, KBFF, KCDR, KSNY, and
KAIA all likely seeing some thunderstorms in their vicinity. Highest
confidence at this time is KSNY. KLAR and KRWL may see some
thunderstorms earlier in the afternoon, so be prepared for gusty and
erratic winds around any storms that develop in the afternoon.

&&

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

&&

$$

SHORT TERM...CLH
LONG TERM...SF
AVIATION...AM