Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 212336
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
435 PM MST Sun Jan 21 2018

.SHORT TERM...(This evening through Monday night)
Issued at 237 PM MST Sun Jan 21 2018

Moderate to heavy snow continues across the Nebraska Panhandle
this afternoon. Heaviest seems to be staying south across eastern
Colorado and extreme southeastern Nebraska/northwest Kansas. Have
been paring down warnings from west to east through the day today,
but still expecting impacts east across the Wyoming Plains and
nebraska Panhandle through remainder of the afternoon. Warnings
remain in place for these areas.

Winds are going to be an issue this evening into Monday. Snowpack
is comprised of very fine snow and is very light weight and non
compacting. By this evening, GFS showing 850mb winds out in the
Panhandle shifting to the northwest and increasing to 30-35kts.
Could see impacts from blowing snow this evening along and east of
the Laramie Range. Evening shift may want to consider a Blowing
Snow Advisory after current warnings expire.

A bigger issue for the South Laramie Range and Arlington tonight
through Monday. Craig to Casper 850/700mb gradients increasing to
around 50mtrs after 09Z tonight. Quality of the snow could create
very serious problems for travel on Interstate 80 over the Summit
and out by Arlington. Considered a Ground Blizzard Warning but
decided on issuing new Winter Storm Warnings for zones 110 and 116
(Arlington/I-80 Summit) Evening/overnight shifts may want to
upgrade once the new forecast run comes in later.

Another weak shortwave Monday evening may bring another shot of
snow out in the Snowy/Sierra Madre Ranges. Due to quick movement
of this feature, do not expect a lot of accumulation.

.LONG TERM...(Tuesday through Saturday)
Issued at 443 AM MST Sun Jan 21 2018

We note a modest warmup Wednesday into Thursday, then our next
chance at snow looks to be shaping up for Friday as an open upper
wave moves across the central Rockies. This next system does not
look to be as strong as the Colorado low we are dealing with
today.

&&

.AVIATION...(For the 00Z TAFS through Monday afternoon)

Improving conditions expected for KRWL, KCDR, and KBFF through late
this evening. Expect conditions to improve a bit further southeast
towards KCYS and KLAR, but IFR conditions may linger well through
late this evening or possibly until midnight. After the snow tapers
off, will have to monitor the blowing snow in these areas as well
for prolonged visibility reductions.

&&

.FIRE WEATHER...
Issued at 237 PM MST Sun Jan 21 2018

Minimal fire weather concerns expected next few days as widespread
snow in place from todays snow storm will remain. Cold temperatures
to keep humidity high and well above critical levels. Another cold
front and storm system will sweep across the region by the end of
the week, bringing the next chance of snow to the area.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Storm Warning until 6 PM MST this evening for WYZ107-108-
     117-118.

     Winter Storm Warning until 11 PM MST this evening for WYZ119.

     Winter Storm Warning from 11 PM this evening to 2 PM MST Monday
     for WYZ110-116.

NE...Winter Storm Warning until 6 PM MST this evening for NEZ002-003-
     019-095-096.

     Winter Storm Warning until 11 PM MST this evening for NEZ020-
021-     054-055.

&&

$$

SHORT TERM...GCC LONG TERM...JG AVIATION...TJT FIRE WEATHER...GCC



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