Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 212050

Area Forecast Discussion
National Weather Service Cheyenne WY
250 PM MDT TUE JUN 21 2016

.SHORT TERM...(This evening through Thursday night)
Issued at 249 PM MDT Tue Jun 21 2016

Hot across much of the CWA this afternoon with temps flirting with
100F over the panhandle. Cheyenne has equaled its record high for
the day at 95 so far. Some cumulus has developed over se WY but
warm mid level temps capping them off so far. Still could see a
few storms pop up later this afternoon into this evening in
association with a surface trough that will move east across the
plains through this evening. An upper low near the NW Montana
border will move east overnight and drive a cold front across the
CWA later this evening bringing cooler temps to the CWA for Weds
and Thursday. A little convection is possible mainly over the mtns
Thursday afternoon and evening otherwise a dry day expected.
Little change seen for Thursday except for some uptick in moisture
from the south as the upper ridge builds a bit to the east of the
area. Should see somewhat better coverage of convection in the
afternoon and evening as a weak impulse moves across the area.

.LONG TERM...(Friday through Monday Night)
Issued at 249 PM MDT Tue Jun 21 2016

Friday could be an active thunderstorm day as a shortwave trough
swings up from the southwest ahead of a stronger storm system
moving east across the PacNW. Looks mostly like a chance for high
based weak storms based on marginal instability and shear progged
by the models. Saturday will be a bit cooler and overall windier
than Friday behind a Pacific front attendant to the PacNW storm,
and Sunday looks similar albeit less wind. The upper ridge will
build back over the Rockies on Sunday night and Monday, although a
vort max looks to round the ridge and across Wyoming through the
day. Could see a return of afternoon convection as a result.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1157 AM MDT Tue Jun 21 2016

Main concern for this TAF cycle will be thunderstorms late this
afternoon and evening, and widespread gusty winds. Regarding
winds, WY terminals will see westerly winds gusting 25-35 kts
through the afternoon as a sfc trough shifts east across the
forecast area. Across the NE panhandle, south winds could get a
bit gusty as well ahead of the trough, with 20-25 kts possible
through the afternoon. The main chance for thunderstorms will be
across the WY/NE plains, particularly KCDR and KSNY, late this
afternoon through the evening. Erratic downdraft winds will be
the main threat with thunderstorms, and perhaps brief MVFR vsbys.
A cool front moving south across the plains tonight will shift
winds to the NNW, with breezy conditions likely through mid-
morning in the post-frontal environment.


Issued at 249 PM MDT Tue Jun 21 2016

Marginal/low end red flag conditions will end over the western
districts this evening as the air mass cools. Concerns then
expected to be low over the next couple days with lighter winds
and cooler temps behind a cool front that will pass across


.CYS Watches/Warnings/Advisories...
WY...Red Flag Warning until 9 PM MDT this evening for WYZ301-303-308.



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