Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 180923
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
323 AM MDT SUN SEP 18 2016

.SHORT TERM...(Today through Tuesday)
Issued at 306 AM MDT Sun Sep 18 2016

Upper level shortwave is progged to move from eastern Montana into
the northern plains over the course of the day. The llvl gradient
is increasing across southeast Wyoming with the 850 mb CAG-CPR
gradient up to around 45 meters. Have seen a few gusts to 40-45
mph in the Arlington area, which is expected to continue through
the morning. Models continue to show breezy to windy conditions
impacting much of the region through from late morning through the
afternoon. This is the result of good mixing and 25-35 kts at the
top of the boundary layer. Although min RH values will be
marginally critical (15-20 percent) this aftn, decided to upgrade
the Fire Weather Watch over the entire CWA due to the stronger
winds. Temperatures will warm into the mid 70s to mid 80s.

The gradient will slacken on Monday and heights aloft rise
slightly. Although min RH values will be slightly lower (near 15
percent), winds will be weaker and thus no critical fire weather
threat is anticipated. However cannot rule out elevated conditions
for areas to the west of the Laramie Range with gusts to 20-25
mph. Similar conditions will exist on Tuesday with an increase in
mid to high level clouds along the Colorado border by the aftn.

.LONG TERM...(Tuesday Night through Saturday)
Issued at 306 AM MDT Sun Sep 18 2016

Tuesday night/Wednesday...Weak shortwave over western Colorado will
be approaching our forecast area Tuesday night, with perhaps some
middle and high cloudiness across our counties. Slightly cooler
though still dry on Wednesday with limited low and mid level
moisture and minimal lift.

Thursday...Flow aloft increases and backs to southwest in advance of
approaching trough aloft. With low and mid level moisture increasing
and increasing southeast upslope, will see isolated to scattered
afternoon and evening showers and thunderstorms most numerous across
our western and northern counties.

Friday...Powerhouse upper trough moves into western Wyoming with a
cold frontal passage across our counties making for a cooler day. It
looks windy based on the low and mid level gradients. With cyclonic
curvature aloft and progged low and mid level moisture, expect
isolated to scattered showers and thunderstorms.

Saturday...As the upper trough moves into the western Dakotas, we
should see our showers and thunderstorms coming to an end, though it
will be a windy and cool day with deep unidirectional northwest
winds and cold air advection.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1130 PM MDT Sat Sep 17 2016

Wyoming TAFS...VFR. Scattered to broken clouds at or above
12000 feet AGL. At Rawlins, gusts to 23 knots through 14Z, then
gusts up to 33 knots. At Laramie and Cheyenne, gusts up to 32
knots from 14Z to 04Z.

Nebraska TAFS...VFR. Scattered to broken clouds at or above
11000 feet AGL. Gusts up to 27 knots from 15Z to 03Z.

&&

.FIRE WEATHER...
Issued at 306 AM MDT Sun Sep 18 2016

Breezy to windy conditions will develop over much of the area by
late this morning and continue through the early evening.  These
gusty winds will combine with minimum afternoon humidity values
from 15-20 percent to produce critical fire weather conditions.
Winds will be weaker early next week, however minimum afternoon
humidity values will still fall to near 15 percent over lower
elevations of southeast Wyoming. No precipitation is expected
through Wednesday.

&&

.CYS Watches/Warnings/Advisories...
WY...Red Flag Warning from 10 AM this morning to 8 PM MDT this
     evening for WYZ301>310.

NE...Red Flag Warning from 10 AM this morning to 8 PM MDT this
     evening for NEZ311>313.

&&

$$

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



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