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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS65 KCYS 222045
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
245 PM MDT Mon Apr 22 2024

.KEY MESSAGES...

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

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

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

.SHORT TERM /THROUGH WEDNESDAY/...
-- Changed Discussion --
Issued at 245 PM MDT Mon Apr 22 2024

Locally strong gusty winds and isolated critical fire weather
are the primary concerns this afternoon and this evening.
Recently, WYDOT observations between Elk Mountain and Laramie
show a few gusts between 58 and 65 MPH early this afternoon.
Winds have remained elevated across this area over the last half
hour, so decided to issue short-fused High Wind Warning for the
Arlington area until 7 PM this evening. Will keep the SPS out
for the I-80 Summit for now, but a few sites have seen gusts of
50+ near Buford and Vedauwoo...so will need to keep an eye on
this area as well. Any fire weather concerns are pretty much
isolated to the Laramie Valley where fuels are still critical
and gusts over 50 MPH have been observed. Winds are expected to
diminish around sunset.

Other than these localized winds, quiet weather is expected for
the rest of southeast Wyoming and western Nebraska through at
least Tuesday night. Tuesday will be slightly cooler after
a Pacific cold front slowly slides south into northern Colorado
late tonight and early Tuesday morning. A few showers are
possible, but expect little of this precipitation to reach the
ground due to dewpoints in the teens and low 20s across the
region. Kept POP around 10 to 15 percent through this evening
and into early Tuesday morning. Models show this front lifting
northeast later on Tuesday as a warm front. Kept POP between 30
to 45 percent for most of southeast Wyoming and the southern
Nebraska Panhandle due to some WAA aloft/overrunning and low
level convergence along the front. Added a slight chance of
thunderstorms along the I-80 corridor where the best lift will
be located, but coverage should be pretty isolated. This shower
activity will likely linger through Tuesday night across the
eastern plains.

For Wednesday, all models show the warming trend continuing as a
ridge axis amplifies slightly across the Intermountain West and
the central Front Range. Expect high temperatures to return to
the upper 60s to mid 70s across the whole forecast area, including
the high valleys west of the Laramie Range. Previous model runs
showed a decent chance at some shower and thunderstorm activity
across most of southeast Wyoming and western Nebraska Wednesday
afternoon; but the 12z runs have kind of backed off on the
coverage due to the upper level ridge being a little stronger
and overall less boundary layer moisture west of the Nebraska
Panhandle. MLCAPE is only around 200 to 400 j/kg during the
afternoon from Cheyenne eastward to Scottsbluff and Sidney.
Lowered POP a bit, but kept a solid "chance" for scattered
coverage (30 to 45 percent).
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&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
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Issued at 202 PM MDT Mon Apr 22 2024

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 negatively tilted 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
Nebraska and Kansas in the afternoon, 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. Continued cool
temperatures with all the cloud and precipitation coverage.

Monday...As the flow aloft turns zonal, west to east, surface lee
troughing will develop along with a warming trend. With 700 mb
temperatures rising to near 5 Celsius, maximum temperatures will
reach the 60s to lower 70s at lower elevations. It looks like there
will be adequate low and mid level moisture for isolated afternoon
rain showers, with some snow showers for the higher mountain
locations.
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&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1125 AM MDT Mon Apr 22 2024

Strong northwest flow aloft will continue as a cold front moves
across the terminals, along with surface high pressure building
across the area tonight.

Scattered to broken clouds near 15000 feet will occur. Winds
will gust up to 40 knots at Rawlins and Laramie until 02Z, and
up to 25 knots at Cheyenne, Alliance and Sidney until 01Z.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...

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WY...High Wind Warning until 7 PM MDT this evening for WYZ110.
     Red Flag Warning until 7 PM MDT this evening for WYZ428.

NE...None.
-- End Changed Discussion --

&&

$$

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