Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 181730

Area Forecast Discussion
National Weather Service Cheyenne WY
1130 AM MDT Tue Oct 18 2016

.SHORT TERM...(Today through Thursday)
Issued at 222 AM MDT Tue Oct 18 2016

Today...Much less windy today with weaker gradients near the
surface. Fast westerly flow aloft continues with the next quickly
moving shortwave aloft moving into western Wyoming this afternoon,
spreading increasing cloudiness and isolated to scattered showers
across our Carbon county, and especially over the Snowy and Sierra
Madre Ranges. NAM and GFS MOS high temperatures close and have

Tonight...Shortwave aloft and its associated cold front and
baroclinic band pass overhead, producing scattered to numerous
showers, including snow showers over the mountains. Will need to
watch for accumulations over the I-80 summit, though fortunately,
the fast movement of the shortwave should limit snowfall

Wednesday...Cool, breezy and unsettled day with isolated to
scattered showers in the cyclonic flow aloft, with precipitation
north of a Rawlins to Kimball line. Relatively cool day and have
compromised between the NAM and GFS MOS maximum temperatures for

Wednesday night...Clearing skies and cold with sub freezing
temperatures areawide.

Thursday...Warming trend begins with brisk northwest flow aloft
overhead and lack of low and mid level moisture. Again, compromised
between the NAM and GFS MOS maximum temperatures.

.LONG TERM...(Thursday night through Monday)
Issued at 222 AM MDT Tue Oct 18 2016

A fairly benign synoptic pattern is setting up this weekend.

The models are in fairly good agreement with showing a weak upper
level ridge dominating the region with above normal temperatures.
Afternoon highs will generally be in the 60s west of the Laramie
Range with 70s east. Conditions will also continue to be dry with
the potential for critical fire weather conditions especially on
Saturday as a shortwave skirts across Northern Montana/Southern
Canada. This shortwave may create more breezy conditions during
the afternoon. The next chance of precipitation appears to be
around the middle of next week as more shortwave energy ejects
from the the trof in the Eastern Pacific.


.AVIATION...(For the 18Z TAFS through Wednesday morning)
Issued at 1128 AM MDT Tue Oct 18 2016

The main aviation concern continues to be the snow potential between
Laramie and Cheyenne this evening. VFR conditions are expected
through most of today with the potential for MVFR and IFR conditions
over KLAR and KCYS as a midlevel frontal boundary moves across the
area. Low confidence forecast for this evening and tonight as there
are indications that some moderate to heavy precipitation bands will
develop and lift northeast across the area between 23Z through 09Z
tonight. If this precip falls heavy enough...may see snowfall even
at KCYS late this evening. Although some precip is expected further
east across western Nebraska...precip type should be all rain for
these locations with CIGS above 4000 feet AGL.


Issued at 222 AM MDT Tue Oct 18 2016

Minimal concerns through Thursday based on projected
humidities. However, concerns increase again Friday and Saturday
with lowering humidities and gusty winds expected.




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