Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 061818

Area Forecast Discussion
National Weather Service Cheyenne WY
1118 AM MST Wed Dec 6 2017

Issued at 1117 AM MST Wed Dec 6 2017

Gridded forecasts updated for this afternoon to boost maximum
temperatures a few degrees at some locations, and also to raise
wind speeds.


.SHORT TERM...(Today through Friday)
Issued at 300 AM MST Wed Dec 6 2017

Rather chilly conditions will hold over the CWA today through
Thursday as the area remains under northerly upper flow between a
positively tilted upper trough from the Great Lakes area
southwestward and a narrow upper ridge over the far western CONUS.
A few impulses will drop south out of Canada down the northern
and central Plains today through Thursday and bring some snow
showers or flurries to the area. One impulse evident on satellite
moving into the northern plains will clip the area through this
evening, with another minor impulse passing by late Thursday. A
reinforcing push of colder air will build in over the plains today
in association with the initial impulse, with rather blustery
northerly winds this afternoon. Continued cool Thursday then
warmer temperatures return Friday as the western upper ridge edges
eastward toward the CWA and downslope flow sets up. Breezy to windy
conditions through Friday, especially in the afternoons with mixing
of relatively fast mid level flow.

.LONG TERM...(Friday night through Tuesday)
Issued at 300 AM MST Wed Dec 6 2017

00Z medium range numerical model/ensemble guidance maintain the
highly amplified large scale flow with upper ridge over the western
1/3 CONUS and long wave upper trough over eastern 2/3 CONUS. This
pattern will favor periodic shortwave passages in the north-northwest
flow aloft. The lack of low/mid level moisture will preclude
precipitation through the long term. A fairly tight low/mid level
height/pressure gradient will promote breezy to windy periods each
day. Downsloping northwest winds will provide milder than normal
temperatures east of the Laramie Range this weekend. A cold frontal
passage Monday will lower high temperatures 5-10 degrees, followed
by slightly warmer temperatures Tuesday.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1029 AM MST Wed Dec 6 2017

In general, VFR prevails this afternoon. Light snow showers can be
expected over the western Nebraska Panhandle this afternoon. There
is potential for a period of IFR conditions at KCDR/KAIA in the 20
to 00z time frame in snow with visibilities around 1SM. Otherwise,
expect ceilings to lower today and tonight over the eastern plains
behind an arctic cold front. MVFR conditions are possible over the
Panhandle, and could spread into KCYS as well after 06z. Winds are
expected to be gusty across all of southeast WY and the western NE
Panhandle this afternoon, with gusts 30-40 knots common.


Issued at 300 AM MST Wed Dec 6 2017

Fire weather concerns will remain quite low for the rest of the week
with cool to mild temperatures and minimum humidities remaining well
above critical levels. There will be some breezy to windy periods
over the next few days, with some snow showers or flurries mainly
Today and Thursday.




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