Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 201415
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
715 AM MST Fri Jan 20 2017

.UPDATE...
Issued at 712 AM MST Fri Jan 20 2017

Made a quick update to the forecast this morning with a band of
light snow moving south and east along and east of I25 this
morning. The snow associated with this band is sticking on the
roads this morning with some icy conditions expected.
Thankfully...it should warm up a bit after sunrise which should
limit impacts. Updated forecast to increase POP along and east of
the Laramie Range through this afternoon. Believe it will be warm
enough for the snow to mix with rain by this afternoon across
western Nebraska.

&&

.SHORT TERM...(Today through Sunday)
Issued at 240 AM MST Fri Jan 20 2017

Fairly quiet weather expected across the CWA through this weekend.
An upper trough will pass across the region today with the bulk of
its energy passing south across Colorado. It should produce some
higher mtn snows with more isolated rain/snow showers elsewhere
across the CWA today and over the Panhandle this evening. Mainly
dry Saturday and Saturday night as the upper flow becomes
northwesterly on the top side of an upper ridge that will move
across the desert southwest. Orographics may help to produce a
few snow showers over the higher mtns late Saturday into Saturday
night then mainly dry Sunday as the ridge axis moves by the area.
Temperatures cool but seasonable across the CWA through the
weekend.

.LONG TERM...(Sunday night through Thursday)
Issued at 240 AM MST Fri Jan 20 2017

Models continue to show some agreement in the extended with the
development of the low pressure system over the plains Monday night-
Tuesday. Still plenty of uncertainty tho in the details, and models
are weaker and more progressive with the system than previous runs.
Went with a persistence forecast during this timeframe, maintaining
a good chance for snow over the mountains starting Sunday night as
the 150+kt jet moves overhead, then steadily spreading east into the
plains Monday night through Tuesday as the low strengthens. With the
progressive nature of the system, should be a relatively quick shot
of widespread light to moderate snow. Sfc winds will shift to the
north and strengthen as leeside cyclogenesis occurs in eastern
CO/western KS early Tuesday morning, so could be dealing with
impacts due to both snow and blowing snow. Temperatures will drop in
the wake of this system as northerly flow aloft advects a cold
Canadian airmass into the western CONUS. Slightly below normal
readings are expected Tuesday night through Thursday, however
wouldn`t be surprised if temps go even colder with a fresh snow pack
in place. A few midlevel disturbances in this flow pattern could
maintain light snow showers here and there across the forecast area.
However, models differ quite a bit with details in the 500mb
vorticity, so kept PoPs low overall and just highlighted the
mountains for now.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 456 AM MST Fri Jan 20 2017

Light snow continues to slowly progress eastward across the
forecast area, with snow expected to begin at KLAR before sunrise
and perhaps later this afternoon/evening across the Nebraska
panhandle. Will continue to see IFR conditions this morning at
KRWL in moist southwest flow with conditions improving by 16Z as
breezy winds mix out the llvl moisture. Winds may be a bit breezy
at times at most terminals today, but should diminish this
evening.

&&

.FIRE WEATHER...
Issued at 240 AM MST Fri Jan 20 2017

Minimal concerns seen through the weekend with non-critical fuels
and weather conditions remaining on the cool side. Some light pcpn
expected over many areas today into this evening then mainly dry
over the weekend.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&

$$

UPDATE...TJT
SHORT TERM...RE
LONG TERM...RJM
AVIATION...RJM
FIRE WEATHER...RE



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