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000
FXUS65 KCYS 212352
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
552 PM MDT Sun Apr 21 2024

.KEY MESSAGES...

- Elevated to high winds possible for areas west of the Laramie
  Range Monday afternoon.

- Relatively mild temperatures are expected for Wednesday and Thursday
  along with a chance of late day showers and thunderstorms.

- Cooler and unsettled weather is likely for Friday and the
  weekend.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 220 PM MDT Sun Apr 21 2024

Current Visible Satellite loop shows mostly sunny skies across
southeast Wyoming and western Nebraska after 3 straight days of
overcast skies for a good portion of the area late last week.
Shortwave upper level ridge axis has pushed east across the
state with 700mb temperatures climbing over 0c and towards 5c
late this afternoon. Surface temperatures have responded in most
locations with readings in the 50s to mid 60s. However, a
persistent southerly wind has kept the west to east facing
ridges in the mid to upper 40s for most of the day. Expect winds
to gradually shift into the southwest and west later today, but
locations such as Cheyenne, Kimball, Harrison, Lusk, and Sidney
may struggle to reach the upper 50s to low 60s this afternoon.
Not as cold tonight with increasing high clouds and increase
winds ahead of the next cold front, with lows mainly in the 30s
to near 40.

Main forecast concern will likely be winds for Monday, but
impacts should be confined to southeast Wyoming with minor
impacts at best. All models show 700mb winds increasing between
45 to 55 knots by early Monday morning and remaining elevated
through most of the day. Pacific cold front should be quick to
push into the eastern plains through the afternoon, so expect
the warmest temperatures to be across southern Wyoming and the
southern Nebraska Panhandle where highs in the 60s to around 70
degrees are expected...along and south of the I-80 corridor.
With the lack of a west to east pressure gradient, due to the
progressive nature of the front, low level gradients are lacking
for a widespread wind event. However, will have to watch some of
the wind prone areas for gusts of 55 to 60 MPH early Monday
morning through late Monday afternoon. Some of the zones near
the wind prone areas may receive some of these higher gusts due
to mountain wave activity, but confidence with timing and
location(s) are low. Boundary layer subsidence isn`t all that
impressive, but it does peak in the late morning/early afternoon
on Monday in the lee of the Snowy Range and across the foothills
of the southern Laramie Range. Expect these locations to have
the best chance at seeing wind gusts around 55 to 60 MPH.

Other than winds, not much else to discuss for the weather early
this week. Tuesday will be slightly cooler after FROPA with
highs in the mid 50s to mid 60s, seasonable for this time of the
year. Increased POP across southeast Wyoming later on Tuesday
since the remnants of the cold front will provide low level
convergence along and west of the Laramie Range with easterly
winds along/east of I-25, and winds shifting into the northwest
along and west of the front. Expect showers and some rumbles of
thunder to return to the forecast area as early as Tuesday
evening.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 135 PM MDT Sun Apr 21 2024

Wednesday...Ridging aloft builds across the region which will
produce a decent warming trend as 700 mb temperatures rise to near 5
Celsius, yielding maximum temperatures in the upper 60s and lower
70s. Looks like there may be enough low and mid level moisture
combined with easterly upslope winds to spark isolated to scattered
afternoon showers and thunderstorms.

Thursday...The next progressive shortwave trough aloft moves across
Wyoming and Colorado, helping to produce scattered afternoon and
evening showers and thunderstorms. Continued relatively mild based
on the projected 700 mb temperatures.

Friday...In the wake of the passing shortwave trough aloft and its
associated cold front, cooler and unsettled weather expected with
adequate low and mid level moisture. Looks like scattered to
numerous showers, along with isolated thunderstorms.

Saturday...Cool and unsettled weather looks to continue as another
potent shortwave trough aloft approaches Wyoming near peak heating.
With abundant low and mid level moisture, combined with decent
upslope and low level convergence and dynamic lift, we anticipate
scattered to numerous afternoon and evening showers, along with
scattered thunderstorms. Relatively cool temperatures due to all the
cloud and precipitation coverage.

Sunday...Although the shortwave trough aloft will be located in the
Dakotas, it looks like there will be adequate low and mid level
moisture over our counties along with cyclonic curvature aloft, to
produce scattered afternoon and evening showers, along with isolated
thunderstorms.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 545 PM MDT Sun Apr 21 2024

VFR conditions expected across area terminals through the
forecast period. High clouds continue to spread over the area
late this afternoon with gusty winds continuing through 01-02z.
A cold front will drop south out of MT tonight turning surface
winds northwest early Monday morning for terminals east of the
Laramie Range. Additionally, low ceilings will be possible for
portions of east-central WY, but looks to stay away from TAF
sites. Stronger west winds are expected for terminals west of
the Laramie Range Monday with gusts up to 40 kt possible at KRWL
and KLAR. Could also see scattered light showers develop late
Monday afternoon near the CO/WY border, but have decide to hold
off with including specifics and timing with this TAF issuance.

&&

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

&&

$$

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