931
FXUS65 KCYS 022006
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
206 PM MDT Thu May 2 2024

.KEY MESSAGES...

- A cold front will move through the region on Friday with
  another round of shower activity in the mountains and isolated
  thunderstorms over the southern Nebraska panhandle. Snow
  levels will remain above 6500 feet.

- Mainly dry and warmer conditions are anticipated for the
  weekend.

- Breezy to windy, and cooler weather expected for Monday
  through Wednesday, with isolated to scattered late day showers
  and thunderstorms.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 125 PM MDT Thu May 2 2024

Afternoon satellite imagery and mesoanalysis reveals a stream
of fast mid-level flow over southeast Wyoming evidenced by
several mountain wave structures in both visible and Water vapor
imagery. Surface gusts reflect this signal and have remained
elevated in the 20-30 knot range today over much of the region.
With a deeply mixed and dry boundary layer present, borderline
critical fire weather conditions are possible for a few hours
this afternoon before solar heating diminishes toward sunset.
Expect surface flow east of I-25 to quickly diminish through the
evening before switching to southeasterly upslope ahead of our
next storm system. By early Friday morning, most guidance
remains in good agreement showing a band of moisture stretching
across central and southern Wyoming as a vort max approaches
from the west. HREF ensemble guidance is in tight agreement
depicting a surface cold front moving southward through
southeast Wyoming and western Nebraska through the morning and
early afternoon hours on Friday. Precipitation should remain
generally confined to areas west of the Laramie range. Medium
range and global guidance has continued the trend of slight
increases in QPF today, with up to 6 inches expected in the
higher elevations of the Snowy and Sierra Madre ranges. Given
that this precipitation will fall mostly after sunrise on
Friday, have opted to keep these areas out of headlines for now
given the expected very low impact nature of this event. Snow
showers are possible in lower elevations on Friday as well in
Carbon, Albany, and far western Laramie and Platte Counties.
However, impacts will remain quite low with warm ground
temperatures and partly sunny skies during the afternoon.
Farther east, the frontal boundary will not quite clear the
southwest Nebraska Panhandle before convective initiation
commences. With upper-30s to near 40 dewpoints in place with
southeast flow, wind and moisture profiles favor a few isolated
convective cells possibly affecting Cheyenne and Morrill
Counties from 1pm through about 4pm. Briefly gusty winds and
perhaps some sub-severe hail would be the greatest threat from
any storms. Behind this system, expect a reinforcing shot of
cold air with temperatures in the 20s or lower in all zones by
Friday night. Forecast guidance is in generally good agreement
with high confidence through the short-term period.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Issued at 220 AM MDT Thu May 2 2024

Saturday...Warming and drying expected as a transitory low amplitude
shortwave ridge aloft builds overhead. 700 mb temperatures near
2 Celsius will yield maximum temperatures in the lower to mid 60s.

Sunday...Continued mainly dry, though with isolated showers and
thunderstorms, as the flow aloft transitions to southwest and there
is minimal low and mid level moisture. This day looks like the
warmest day of the period as a low level thermal ridge develops with
700 mb temperatures near 9 Celsius yielding maximum temperatures
mainly in the 70s.

Monday...Cooler temperatures expected as the next progressive
shortwave trough aloft moves across the region. It looks like there
will be adequate low and mid level moisture to produce scattered
afternoon and evening showers, and a few thunderstorms.

Tuesday...Looks like a windy and mild day as a wound up trough aloft
and its associated surface low pressure pivots across eastern
Montana, producing decent low level pressure gradients for our
forecast area. With cyclonic curvature aloft and some low and mid
level moisture, we anticipate isolated to scattered afternoon
showers and a few thunderstorms despite the drying westerly low
level downslope winds.

Wednesday...The trough aloft pivots across the Dakotas, keeping
cyclonic northwest flow aloft over our counties, and with adequate
low and mid level moisture, we anticipate isolated late day showers.
Continued breezy with decent low level pressure gradients and low
level winds.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 1049 AM MDT Thu May 2 2024

VFR expected to dominate at all terminals through the entire
afternoon and evening. Expect gusty westerly winds in the 20 to
35 knot range at most terminals. Winds will diminish this
evening with partly cloudy skies overnight at all terminals.

&&

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

&&

$$

SHORT TERM...MAC
LONG TERM...RUBIN
AVIATION...MAC