Area Forecast Discussion
Issued by NWS Cheyenne, WY

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091
FXUS65 KCYS 192123
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
323 PM MDT Tue Sep 19 2017

.SHORT TERM...(This evening through Thursday Night)
Issued at 305 PM MDT Tue Sep 19 2017

Cold front moving into the plains currently and will move across
the Panhandle by early this evening. Expect area of rain and some
light snow to continue out west for the rest of the afternoon then
break up this evening as a shortwave lifts north away from the
area. Skies gradually clearing later tonight.

Dry and mild conditions on tap for Weds with breezy conditions
over the plains in the afternoon as decent mid level flow mixes
down. mainly clear Weds night and Thursday as the upper flow turns
southwesterly and advects some drier air over the region. Warmer
Thursday ahead of significant upper trough digging over the
western CONUS.

.LONG TERM...(Friday through Monday)
Issued at 305 PM MDT Tue Sep 19 2017

Models are in rather good agreement at showing a cool and unsettled
period from Friday into early next week.  Unseasonably deep upper
trough will be centered across the Great Basin on Friday.  Little
movement is forecasted through Saturday, and then the trough will
shift eastward slowly into early next week.  This will keep the CWA
in an area of good upper level divergence and large scale lift from
Friday evening into Monday morning, with an extended period of
elevated precip chances.  Wet bulb zero heights and snow levels will
generally remain above 10000 ft through Saturday and then fall by
Sunday night to Monday to around 8000 ft as the colder air aloft
moves overhead.  Current thinking is that lower elevations will be
mostly rain through early next week, with the higher terrain of the
Sierra Madre and Snowy Ranges potentially seeing more significant
accumulations.  Highs will struggle to get out of the low 50s by
Monday, which is 15-20 degrees below normal for late September.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1154 AM MDT Tue Sep 19 2017

Mostly vfr conditions through the taf period. Rain showers will be
possible through the afternoon for sites to the west of Laramie
Range (RWL/LAR), with brief MVFR cigs at RWL. A cold front will
push across the region through 00Z with winds becoming west to
northwest. Gusts to 30-35 kts will be common behind the front
through 03Z.

&&

.FIRE WEATHER...
Issued at 305 PM MDT Tue Sep 19 2017

Cold front will sweep across the area late this afternoon into
early this evening bringing much cooler air and a period of gusty
winds behind it. There will be areas of rain and snow over mainly
western districts into this evening before ending. It will be a
little cooler Wednesday. Some elevated fire weather concerns are
expected over the plains Wednesday afternoon as humidities look to
fall to about 15 to 20 percent and winds gust close to 25 mph.
Warm temperatures will occur Thursday then an approaching low
pressure system will bring cooler and wetter conditions by the
weekend.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Red Flag Warning until 5 PM MDT this afternoon for WYZ309-310.

NE...None.
&&

$$

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



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