445
FXUS65 KCYS 011752
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1152 AM MDT Sat Jun 1 2024

.KEY MESSAGES...

- Isolated to scattered afternoon thunderstorms are expected
  both today and tomorrow. A few of these storms may become
  strong to severe east of I-25.

- Warm and dry weather is expected most of next week, aside from
  a few scattered showers/storms with a cold front on Tuesday.
  This front may also bring another round of late-season strong
  winds to the area.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 430 AM MDT Sat Jun 1 2024

It`s another active active early morning across the area with an
unstable environment in the central and northern NE panhandle
producing a few isolated severe thunderstorms. A weak wave
leading the main trough which is currently back in Nevada is
moving across sour area this morning. An associated area of
isentropic lift overrunning the frontal boundary is providing
enough lift to allow storms to tap into some elevated
instability. MUCAPE in excess of 1000 J/kg is collocated with
decent shear values in this area. These storms will be capable
of producing large hail through the early morning hours. The
shortwave providing the lift that is initiating these storms
should shift east in a few hours, so expect this threat to wane
after about 5-6AM.

After that, we`ll turn attention to this afternoon for another
round of isolated to scattered showers and thunderstorms with
some severe potential. As usual, the main uncertainty today will
be dryline position. Certain models such as the HRRR continue to
push this east fairly aggressively in the early afternoon hours,
which would dampen the organized severe chances. However, other
HiRes models keep the dryline near the WY/NE border or even as
far west as I-25 (NAM-Nest), which would allow for more
organized convection once it crosses into the more moist
environment. Most likely, it will end up somewhere in between
these extremes, which would still put a potent storm
environment in place over much of the NE panhandle. Overall
shower/storm coverage will be a bit higher than recent days
today thanks to added lift from another approaching vort-max.
West of the dryline, showers and storms will pose a risk for
gusty winds with deep inverted-v soundings in place, but the
more isolated organized severe threat will be focused further
east. Shower and storm activity may continue well into the
evening and early overnight hours, but it should be less
widespread after about 9PM.

We`ll do it all over again on Sunday as the axis of the main
upper level trough finally arrives. Recent guidance has
accelerated the timing of the surface cold front, now bringing
it through late morning or early afternoon, with low level
cool/dry air advection working in behind. This should nudge the
dryline to our far eastern zones. Lift with the upper level
trough should kick off another round of isolated to widely
scattered showers and thunderstorms during the afternoon, but
the probability of severe weather will be lower. Deep
inverted-v`s once again though will present a risk for gusty
winds, and can`t rule out an isolated hail threat.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 150 PM MDT Fri May 31 2024

The long term looks relatively uneventful with mostly dry and mild
conditions expected throughout next week. Quasi-zonal flow for the
first half of the work week will lead to breezy and windy conditions
across much of the CWA. A strong shortwave trough passing just to
the north of the CWA on Tuesday will lead to the greatest potential
for high winds across the southeast Wyoming wind prones. The GFS has
700 mb wind speeds of 50 to 60 kts, and elevated CAG to CPR 700 mb
height gradients. In-house guidance is also pinging the potential
for high winds around the wind prones. Cannot rule out some slight
precipitation chances with the passage of this shortwave either.
Cooler temperatures can also be expected on Tuesday as the shortwave
ushers in slightly cooler 700 mb air. By Wednesday, ridging begins
to build over western CONUS, leading to a warmer and drier airmass
infiltrating the CWA. Temperatures through Friday will gradually
increase, with most locations seeing highs in the 80s by Friday.
Minimal precipitation chances are expected during this time frame as
subsidence keeps conditions dry.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1152 AM MDT Sat Jun 1 2024

Main aviation concern for this TAF cycle will be scattered showers
and thunderstorms. A few isolated strong to severe storms could be
possible this afternoon and evening, mainly in the Nebraska
panhandle. Storms could contain strong, gusty, erratic winds and
some could contain large hail. Scattered showers and thunderstorms
will continue overnight, but with lesser coverage than the
afternoon. A weak low-level jet may also develop over the panhandle,
leading to some 30 kt wind gusts at western Nebraska terminals late
tonight.

&&

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

&&

$$

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