Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 200544
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1144 PM MDT Wed Apr 19 2017

.SHORT TERM...(This evening through Friday)
Issued at 250 PM MDT Wed Apr 19 2017

Upper low currently over western South Dakota with some showers
wrapping around the system and over parts of the CWA this
afternoon...mainly from northern Carbon county east into Platte
county. Expect these to fade out late this afternoon into early
this evening as the upper system moves farther east and weak
instability decreases...leaving a cool and quiet night across the
CWA.

Dry and mild across the CWA for much of the day Thursday as a
short upper ridge moves across then attention will focus on the
next shortwave that will drop southeast across the northern and
central Rocky Mtns late Thursday...developing an upper low that
will track across Colorado into Kansas Friday. Some diffluent
upper flow and favorable jet dynamics will allow for rain and
higher elevation snows to spread over much of the CWA Thursday
night...continuing Friday aided by surface upslope flow. Still
appears accumulating snows will remain confined to above about
7000 feet with the Snowys and the Sierra Madres looking to get
about 5-8 inches of snowfall by late Friday. Snow may fall into
the adjacent high plains by Friday morning but may have difficulty
sticking much. Cool on Friday given the pcpn with maxs likely
staying in the 40s over most areas outside of the mtns.

.LONG TERM...(Friday night through Wednesday)
Issued at 250 PM MDT Wed Apr 19 2017

Friday night/Saturday...With moist low and mid levels, and cyclonic
flow aloft, decent chance for showers Friday evening, decreasing
chances after midnight. On Saturday, low and mid levels being to dry
out as heights aloft rise ahead of the next shortwave ridge aloft,
thus decreasing chances for precipitation during the day on Saturday.

Sunday...Dry, breezy and much warmer day as the flow aloft turns
strong westerly, with moderating airmass and west downslope winds
warming up the low levels.

Monday...Next shortwave trough aloft and its associated cold front
move overhead, though with limited low and mid level moisture.
significant precipitation is not expected.

Tuesday...Next low amplitude shortwave trough aloft moves overhead
with a chance of afternoon showers, including over the Snowy and
Sierra Madre ranges, where orographics will dominate.

Wednesday...Next more potent shortwave trough aloft moves over
western Wyoming, with cyclonic flow over our forecast area, and with
adequate low and mid level moisture, will be scattered to numerous
showers develop.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1140 PM MDT Wed Apr 19 2017

Vfr conditions through early afternoon on Thursday. Clouds will be
on the increase by late Thursday afternoon into the evening,
especially across the southeast WY sites. Rain is expected to
develop at CYS/LAR by 00-06Z with MVFR cigs. Southeast winds will
also pick up by Thursday evening over southeast WY with gusts to
25-30 kts at LAR.

&&

.FIRE WEATHER...
Issued at 250 PM MDT Wed Apr 19 2017

Concerns expected to remain low for the rest of the week with
milder temperatures and sufficiently high min RHs mitigating
conditions. Wetting rains a good bet Thursday night through Friday
over much of the area.

&&

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

$$

SHORT TERM...RE
LONG TERM...RUBIN
AVIATION...ZF
FIRE WEATHER...RE



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