Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 211611

Area Forecast Discussion
National Weather Service Cheyenne WY
911 AM MST Wed Feb 21 2018

Issued at 910 AM MST Wed Feb 21 2018

Minor update to expire wind chill advy and make minor changes to


.SHORT TERM...(Today through Friday)
Issued at 340 AM MST Wed Feb 21 2018

Pretty quiet this morning compared to what we have been seeing
over the past week weatherwise. Clear skies over southeast WYoming
over into southern Idaho this morning. Pretty cold this morning,
Alliance down to -23, Chadron -13 and Scottsbluff -7 at 2AM this
morning. Winds are pretty light this morning, but any wind at all
will cause windchills to plummet. Because winds are light, will
keep the current Windchill Advisories going as they area. If winds
pick up any more, will then consider warnings for some areas.

Pretty nice day today as clear to mostly clear skies continue.
Temperatures are going to be a challenge with widespread snow pack
and light winds. But 700mb temperatures forecast to warm about 4C
over yesterday, so would expect slightly warmer temperatures over
yesterday. Generally followed guidance on temperatures today. Sure
the day shift will have to make an update or two based on observed

Start to see the effects of a low pressure system moving into
Colorado Thursday as guidance begins to paints some light QPF over
our western mountains. Did keep chance PoPs going for the SNowy
and Sierra Madre Ranges for much of the day Thursday. Not much of
a warm up seen for Thursday as 700mb temperatures remain around
-14 to -16C as well as increased cloud cover, so did not mess too
much with guidance highs.

Best chances in the short term for more snow appears to be late
Friday as upper level diffluence ahead of upper low over eastern
Utah begins to move into the area. Best chances will be out west
across Carbon and Albany Counties and the mountains.

.LONG TERM...(Friday night through Tuesday)
Issued at 340 AM MST Wed Feb 21 2018

Friday night/Saturday...Shortwave trough aloft moves eastward across
Colorado, producing a chance of snow across portions of our
counties, mainly in the evening, with decreasing chances after
midnight. Mostly dry and continued cold on Saturday in the wake of
the cold front and with 700 mb temperatures near -15 Celsius.

Sunday...Next fast moving shortwave trough aloft moves across our
counties, producing orographic snows over our Snowy and Sierra Madre
Ranges, with dry conditions elsewhere. Slightly warmer based on
thickness trends.

Monday...Windy and a bit warmer as the flow aloft turns westerly
with strengthening flow aloft and near the surface, and with 700 mb
temperatures rising to -8 Celsius.

Tuesday...Next Canadian cold front enters our counties and along
with a shortwave trough aloft, will see a chance of snow, mainly in
the afternoon over our Wyoming counties.


.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 448 AM MST Wed Feb 21 2018

VFR, except for occasional IFR at Alliance through 15Z today, and
occasional MVFR at Rawlins through 15Z today.


Issued at 300 AM MST Wed Feb 21 2018

Minimal fire weather concerns over the next several days with cold
temperatures, light winds and a widespread snowpack. Next chance
for snow looking like Thursday into Friday as a low pressure
system tracks across Colorado.




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