Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 031727
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1027 AM MST Sat Dec 3 2016

.SHORT TERM...(Today through Monday)
Issued at 300 AM MST Sat Dec 3 2016

Winds are the primary forecast challenge in the short term
followed by snow chances Monday.

Two systems impacting our weather in the short term. One, a low
pressure system over southern Arizona and New Mexico this morning
will track east towards the southern Plains. THis one may
effectively cut off any low level moisture from the Gulf of Mexico
from getting up this way. The other system moving into the PACNW
this morning. Pretty strong gradient behind this system with very
cold air as evidenced by all the open cell CU observed behind the
front in the southeastern Gulf of Alaska.

For today, Craig to Casper gradients continue to increase this
morning. By 12Z, 850/700mb gradients are forecast to be near
60mtrs respectively on both the GFS and NAM High Wind Products.
GFS 700mb winds at 12Z forecast at 50kts across Carbon and Albany
Counties. Thinking the current High Wind Warning is looking in
good shape and will let it ride through the morning hours.

We see a slight decrease in winds by late afternoon and overnight
before gradients again begin to increase Sunday morning after 12Z.
This could a more prolonged strong wind event as gradients remain
high (60mtrs or greater into Monday. By 09Z Monday, 700mb
gradients off the GFS approaching 73mtrs that persist through
Monday morning. Went ahead with a High Wind Watch for Sunday
morning through Monday morning to alert customers of strong wind
potential after todays wind event.

Front finally moves into western Wyoming Monday morning and into
southeast Wyoming Monday afternoon. 700mb temperatures fall from
-4C at Cheyenne Monday morning to -16 to -18C Monday afternoon
with the passage of the front. Have to agree with the GFS that
there may not be a lot of low level moisture to work with this
system due to the southern low. Best chances for heavier snow
looks to be the Snowy and Sierra Madre Ranges with this system.

.LONG TERM...(Monday night through Friday)
Issued at 300 AM MST Sat Dec 3 2016

Monday night/Tuesday...Bitterly cold air will continue to filter
into the region from the north following an arctic cold frontal
passage on Monday. Light snow associated with a passing shortwave
will move from our central counties Monday night, to near and along
the Colorado state line on Tuesday assisted by upslope northeast
winds.

Wednesday...Snow will gradually end as the flow aloft becomes
northwest and drier air filters into the region, although bitterly
cold temperatures will persist as 700 mb temperatures plunge to -22
Celsius, yielding maximum temperatures in the single digits and
teens.

Thursday...A slow warming trend will begin under northwest flow
aloft. Continued dry with limited low and mid level moisture.

Friday...As the flow aloft backs to zonal, west to east, surface lee
troughing will become more established, helping to moderate the low
levels of the atmosphere, and most locations will climb above
freezing, at least into the upper 30s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday morning)
Issued at 1027 AM MST Sat Dec 3 2016

VFR expected overall through the period with some higher mtn
obscurement at times.  Gusty winds affecting mainly the se Wy
terminals this afternoon with gusts around 30kts.

&&

.FIRE WEATHER...
Issued at 300 AM MST Sat Dec 3 2016

Minimal fire weather concerns will continue through next week as
cold temperatures will remain over the area. Winds will increase
today and persist through Monday ahead of a low pressure system
that will track through the area. Accumulating snow is possible
with this system Tuesday into Wednesday next week.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning until 3 PM MST this afternoon for WYZ106-110.

     High Wind Watch from Sunday morning through Monday morning for
     WYZ106-110.

NE...None.
&&

$$

SHORT TERM...GCC
LONG TERM...RUBIN
AVIATION...RE
FIRE WEATHER...GCC


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