Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 192333

Area Forecast Discussion
National Weather Service Cheyenne WY
533 PM MDT Thu Oct 19 2017

.SHORT TERM...(Today through Saturday)
Issued at 230 AM MDT Thu Oct 19 2017

Tonight...Southwest flow aloft strengthens with falling heights as
well. With a warm airmass already in place and decent low level
mixing, expect a relatively mild night for this time of year.

Friday...Heights aloft continue to decrease with strengthening
southwest flow and a quickly approaching cold front nearing our
western counties in the afternoon. Progged 700 mb temperatures near
7 Celsius yield maximum temperatures well into the 70s to lower 80s
east of Interstate 25 with mid to upper 60s west of I-25. The
atmosphere looks too dry for any precipitation except perhaps for
isolated afternoon showers over the Sierra Madre Range.

Friday night...A powerful shortwave trough aloft and its associated
strong cold front sweep quickly eastward across our counties in the
evening. Progged strong cold air advection and winds aloft suggest
winds may approach high wind criteria across our wind prone
locations, although forecast 700 mb Craig to Casper gradients still
look too low for widespread high winds, thus will hold off on a high
wind watch for now. Looks like enough moisture along the baroclinic
band for a chance of showers over our Snowy and Sierra Madre Ranges.

Saturday...Quite windy and much colder in the wake of the shortwave
trough aloft and cold frontal passage. 700 mb temperatures near -7
Celsius suggest high temperatures only from the mid 40s to mid 50s
at lower elevations. Downslope winds plus minimal low and mid level
moisture suggest a dry day.

.LONG TERM...(Saturday Night through Thursday)
Issued at 345 AM MDT Thu Oct 19 2017

Primary forecast concern will be high wind potential Saturday
night through Monday morning for southeast WY.

Deep upper trough will advance eastward from the Rockies into
the Great Plains through Saturday night. Shower activity over
the mountains will end by midday. It will be breezy and colder
Saturday with west-northwest winds gusting to 40 mph from the
southern Laramie Range east along the I-80 corridor. High
temperatures will be in the 40s and 50s, with 20s and 30s over
the mountains.


.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 522 PM MDT Thu Oct 19 2017

VFR conditions expected tonight through Friday with gusty
westerly winds this evening becoming light overnight. Very windy
conditions are expected by Friday afternoon with gusts over 45
knots possible at KRWL and KLAR. Gusts between 20 to 30 knots are
expected further east including the western Nebraska terminals.


Issued at 215 AM MDT Thu Oct 19 2017

Ongoing Red Flag Warning looks on track based on the
trends in the humidities and wind gusts. Although winds will
definitely be strong enough to increase concerns on Friday
afternoon, minimum humidities look slightly too high for a Fire
Weather Watch. Concerns will decrease on Saturday in the wake of a
strong cold frontal passage. Fire weather concerns may increase
again during next week with dry and mild weather on tap.






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