Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 302329
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
529 PM MDT Sun Apr 30 2017

.SHORT TERM...(This evening through Tuesday night)
Issued at 255 PM MDT Sun Apr 30 2017

Afternoon water vapor loop showed the intense low pressure system
spinning over the south central Plains. Visible images detected
the western edge of the higher clouds over the eastern NE panhandle,
with scattered mid and high clouds spreading southeast across the
western 2/3 of WY. A tight surface pressure gradient along and
east of the Laramie Range was generating windy conditions with
gusts of 35 to 45 mph from the northwest. Temperatures rebounded
quickly from sub-freezing morning lows to the 40s and 50s.

12Z model solutions in good agreement taking the central Plains
upper low pressure system northeastward across the middle/upper MS
valley and western Great lakes through Tuesday. Meanwhile, an active
northwest flow from southwest Canada across the northern Rockies
and Plains will bring a pair of shortwave troughs through early
this week. The first will bring scattered rain/snow showers tonight
and Monday across northern and western portions of the CWA. This
trough will steepen the pressure gradient resulting in gusty
northwest winds of 25 to 35 mph east of the Laramie Range.
Temperatures will cool slightly behind the wave with 30s and 40s,
while 50s prevail to the east.

There will be a lull in the showers Monday night before increasing
Tuesday morning ahead of the second shortwave trough. The SPC Day
3 outlook indicates a general risk of thunder. While a weak
thunderstorm or two is possible, coverage is too limited to mention
attm. Those areas that don/t receive measurable precipitation Monday
stand a better chance Tuesday. The pressure gradient with this
trough will be slightly weaker and displaced to the west. High
temperatures Tuesday will be identical to Monday. Showers will
taper off from northwest to southeast Tuesday night with subsidence
in the wake of the departing shortwave trough.

.LONG TERM...(Wednesday through Sunday)
Issued at 255 PM MDT Sun Apr 30 2017

Pleasant weather expected to return to the area as an amplifying
upper ridge over the western CONUS Weds moves slowly east and
over the Rocky mtn chain by late Friday. This will result in dry
and warming conditions for the CWA. Max temps look to warm into
the 70s over the plains Friday and even around 80 over much of the
Panhandle Saturday with the upper ridge remaining over the region.
Some changes then expected next weekend as an upper low develops
and cuts off over the far southwest part of the country. Weak
impulses along with some uptick in moisture may combine to bring
some showers to the CWA especially on Sunday with diffluent upper
flow over the area.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 527 PM MDT Sun Apr 30 2017

Wyoming TAFS...VFR, except for MVFR at Rawlins from 09Z to 15Z.
Wind gusts to 34 knots through 02Z, then wind gusts up to 30 knots
after 15Z Monday.

Nebraska TAFS...VFR. Wind gusts to 34 knots through 02Z, then wind
gusts to 35 knots after 15Z Monday.

&&

.FIRE WEATHER...
Issued at 255 PM MDT Sun Apr 30 2017

No fire weather concerns for the districts through mid-week due to
recent and forecast precipitation, minimum humidities above critical
thresholds, and cool temperatures. A couple of upper level low
pressure disturbances will produce rain and snow showers Monday
through Tuesday night. Drier and warmer weather will is expected
Thursday through Saturday with minimum humidities lowering to 20 to
30 percent.

&&

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

$$

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


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