850
FXUS65 KCYS 010913
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
313 AM MDT Wed May 1 2024

.KEY MESSAGES...

- A series of weather disturbances will move across the
  forecast area Thursday and Friday, producing a chance of
  showers and thunderstorms mainly during the afternoons and
  evenings.

- Drier and warmer conditions are anticipated for the weekend.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 305 AM MDT Wed May 1 2024

Current KCYS radar loop early this morning shows isolated rain
showers, and a few embedded thundershowers, moving northeast
across the area with some light rainfall and mountain snow. This
activity is in response to WAA along the stalled frontal
boundary across Colorado. High res guidance shows this front
lifting northeast slowly as a warm front this morning with
increasing coverage of showers and maybe a thunderstorm or two
through noon. Further west, another progressive upper level
trough will push eastward across the Great Basin Region and into
Wyoming later today. Once this trough moves into Wyoming,
expect an increase in coverage of thunderstorms this afternoon,
mainly east of I-25 as low level instability and upper level
jet dynamics result in some low to midlevel forcing across the
high plains. Not sure how far west these thunderstorms will
develop, but kept POP between 50 to 80 percent for most of the
western Nebraska Panhandle and far southeast Wyoming. May see
some decent precip amounts with some of this activity into this
evening. With SBCAPE around 300 to 600 j/kg and dewpoints
struggling to reach 40 degrees this afternoon, not expecting any
strong to severe weather at this time. Otherwise, the airmass
associated with the upper level trough is notably colder
compared to yesterdays disturbance which brought strong winds to
the portions of the area. Models continue to show 700mb
temperatures lowering between -4c to -8c, which is still several
degrees warmer than what models were showing a few days ago.
Kept low temperatures tonight near freezing for most areas, and
well into the low to mid 20s west of the Laramie Range. Once the
cold air arrives tonight...most of the precipitation will
likely have already ended across the region with any snow
accumulations confined to the mountains. Will not issue any
winter headlines for the mountains with snow accumulations below
Advisory criteria.

For Thursday...similar conditions are expected compared to
Tuesday with a bit less wind, but cooler temperatures, as the
cold front settled across central and southern Colorado. It
should be mostly dry across the area with some shower activity
developing over the mountains in the afternoon. Increased high
temperatures slightly due to recent model trends and more
sunshine forecast through the day. Afternoon highs in the mid to
upper 40s west of the Laramie Range expected with 50s to near
60 across the eastern high plains. The next round of
precipitation is expected later Thursday night as the stationary
front to the south lifts northward as a warm front and another
progressive Pacific trough quickly moves eastward across the
Great Basin. This evolution is a little different than what
previous model runs were suggesting, but increased POP and cloud
cover after midnight Thursday into early Friday morning.


&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Issued at 215 AM MDT Wed May 1 2024

Friday...A secondary shortwave trough aloft is progged to move
across our counties near peak heating, and with adequate low and mid
level moisture and a cold frontal passage, we anticipate scattered
showers and some thunderstorms in the afternoon and evening.

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

Sunday...Continued dry as the flow aloft transitions to southwest
and there is limited 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 10 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.

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

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1146 PM MDT Tue Apr 30 2024

Southwest flow aloft will prevail, with a weather disturbance
moving across the terminals today producing some showers.

Wyoming TAFS...Ceilings will range from 5000 to 10000 feet with
showers in the vicinity of Laramie and Cheyenne from 08Z to 02Z.
Winds will gust to 25 knots at all terminals after 14Z.

Nebraska TAFS...Ceilings will vary from 4000 to 10000 feet with
occasional showers this morning through early evening reducing
visibilities to 5 miles at times. Winds will gust to 35 knots.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...

WY...None.
NE...None.

&&

$$

SHORT TERM...TJT
LONG TERM...RUBIN
AVIATION...RUBIN