Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 252308
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
508 PM MDT Fri May 25 2018

.SHORT TERM...(This evening through Sunday)
Issued at 215 PM MDT Fri May 25 2018

Generally quiet weather expected over the next 36 to 48 hours as
an upper level ridge builds over the Front Range through early
Saturday. This ridge axis will then shift eastward by Saturday
afternoon bringing the warmest temperatures so far this spring.
For this afternoon and early this evening partly cloudy skies due
to daytime instability expected across the mountains and ridges
east of the Laramie Range. Can not rule out a few showers with
this activity since there is a convergence boundary setting up
just east of the Laramie Range early this afternoon. Overall, do
not expect the coverage to be anything like mid afternoon
yesterday due to drier air aloft and less boundary layer
instability. So kept minimal POP along and east of I-25.
Otherwise, skies will quickly become mostly clear tonight. Very
warm day on Saturday with highs in the mid 80`s to mid 90`s
(warmest across western Nebraska) before clouds increase late in
the day. Again, can not rule out a shower or a thunder shower late
in the afternoon and in the evening, mainly north of I-80.

For Sunday, models show the next Pacific system, currently along
the Calif coastline, moving east of the Great Basin region and
then stalling across Utah or far southwest Wyoming. Models
indicate a series of shortwave disturbances rapidly moving
northeast across Colorado and Wyoming through the day and into the
evening hours. With a llvl convergence boundary setting up near
the mountains along with ample jet energy, there appears to be a
good chance for strong thunderstorms, especially late in the day
given current model soundings. Believe models are too low on
llvl dewpoints since various ensembles are quite a bit higher.
Maintained 25 to 40 percent POP, especially Sunday evening. Some
severe thunderstorms are also possible, but it will depend on the
timing of the shortwave and jet activity since shear will be very
marginal earlier in the day. Although Sunday will be slightly
cooler, it was still be pleasant for most of the day with highs in
the mid 70s (west) to mid/upper 80s (east).

.LONG TERM...(Sunday night through Thursday)
Issued at 253 AM MDT Fri May 25 2018

Forecast guidance continues in good agreement with a slow moving
low moving through the area Monday and Tuesday. Monday still looks
pretty wet with likely rain showers and thunderstorms. Probably
need to start messaging a wet forecast for Memorial Day outdoor
activities.

Unsettled weather to continue with afternoon showers/thunderstorms
Tuesday as upper low slowly moves through. Upper low finally moves
east Tuesday night/Wednesday morning with warmer temperatures and
drier conditions returning.

&&

.AVIATION...(For 00Z TAFS through 00Z Saturday afternoon)
Issued at 505 PM MDT Fri May 25 2018

VFR. Scattered cumulus clouds early this evening will give way to
mostly clear skies tonight. Winds will be light and variable.

&&

.FIRE WEATHER...
Issued at 1258 PM MDT Fri May 25 2018

Minimal Fire Weather concerns this weekend and into next week with
green fuels and relative humidities above 20 percent east of the
I-25 corridor. Daytime humidities will drop to around 10 percent
on Saturday west of I-25, but due to recent green up, no impacts
are expected. Another Pacific storm system will move into the
region Sunday and Monday resulting in another chance of
thunderstorms and wetting rainfall.

&&

.HYDROLOGY...
Issued at 1258 PM MDT Fri May 25 2018

Mountain streams and creeks will likely respond to warm temperatures
this weekend and possibly early next week depending on how much
rainfall the region receives Sunday and Monday. Temperatures well
into the 70`s and even mid to upper 60`s across the higher peaks
will result in increasing snowmelt. No major impacts are anticipated
at this time, but streams and creeks from the Snowy Range and
northern Rockies will need to be watched, including the Laramie
River.

&&

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

$$

SHORT TERM...TJT
LONG TERM...GCC
AVIATION...MAJ
FIRE WEATHER...TJT
HYDROLOGY...TJT



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