Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 161807
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1107 AM MST Fri Feb 16 2018

.SHORT TERM...(Today and tonight)
Issued at 313 AM MST Fri Feb 16 2018

Going to be a busy few days upcoming for southeast Wyoming. Winds
are the primary concern initially, turning to colder temperatures
and widespread snowfall Sunday/Monday.

Currently...Pretty quiet right now with a 1052mb surface high over
central South Dakota. IR imagery showing mostly clear skies over
the CWFA. Winds are already up pretty high at Arlington where
gusts to 50 mph are being reported.

For today and tonight we are expected steadily increasing winds as
the day progresses. Craig to Casper 850/700mb height gradients
reach 45/62mtrs respectively by 21Z with both going above 60mtrs
this evening.

Had a predicament this morning with what to do with Arlington.
Recent snow out there reported on the morning CoCoRaHS
observations had anywhere from 3 to 4 inches of fresh snow from
Elk Mountain all the way to Laramie. Enough snow to be a concern
on what type of headline to issue. Opted to go with a Ground
Blizzard Warning for the Arlington zone. May need to add the
Laramie Valley into that warning as well depending on how the
webcams look tonight.

Winds become widespread this evening as Craig to Casper gradients
reach 67/75mtrs after midnight. Upgraded all watches to warnings
with the morning package. Also added Rawlins and the northern
Carbon/Albany County zones into a warning. MOS guidance showing
sustained winds of 33kts at Rawlins after midnight tonight.

.LONG TERM...(Saturday through Thursday)
Issued at 313 AM MST Fri Feb 16 2018

May get a little break in winds Saturday afternoon for a time as
700mb winds fall back to 35-40kts. But this will be short lived as
height gradients exceed 70mtrs saturday evening. NAM advertising
gradients up to 90mtrs Saturday evening.

Arctic front begins to impact the area Sunday afternoon as it
moves into Converse County. Very slow movement of the front will
create a widespread and prolonged snow event across the area.
Areas impacted the most will be along and north of a line from
Alliance to Guernsey to maybe Rawlins where the potential for 10
to 12 inches of snow is possible. Southern Panhandle and over to
Cheyenne may get shadowed by the Laramie Range as westerly winds
create downsloping conditions here.

Front finally clears the area Tuesday morning with snow ending
from north to south. We will definitely need some winter headlines
with this event once we get through the wind event.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1101 AM MST Fri Feb 16 2018

Strong winds will be the main theme over the Wyoming TAF sites
during the next 24hrs as jet energy pours in from the northwest.
Otherwise, VFR conditions will be the rule.

&&

.FIRE WEATHER...
Issued at 313 AM MST Fri Feb 16 2018

Widespread strong wind event to begin late this afternoon and
continue into Sunday morning. Much of southeast Wyoming expected
to see wind gusts in excess of 65 mph. An arctic front is
approaching from the north and is set to move into Converse County
Sunday afternoon as moves southeast. Along and behind the front,
we are looking at widespread moderate snow and very cold
temperatures through Tuesday morning.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning from 8 PM this evening to 5 AM MST Sunday for
     WYZ104>106-116-117.

     Winter Weather Advisory until 6 PM MST this evening for WYZ110.

     Blizzard Warning from 6 PM this evening to 5 AM MST Sunday for
     WYZ110.

     High Wind Warning from midnight tonight to 11 PM MST Saturday
     for WYZ107-109-115-118.

NE...None.
&&

$$

SHORT TERM...GCC
LONG TERM...GCC
AVIATION...REC
FIRE WEATHER...GCC



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