Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 221143
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
443 AM MST Thu Feb 22 2018

.SHORT TERM...(Today through Saturday)
Issued at 355 AM MST Thu Feb 22 2018

Today...Temperature and dewpoint spreads narrowing over far eastern
Wyoming and western Nebraska, thus have added patchy freezing fog
through mid morning there. Moist southwest flow aloft continues with
perhaps one or two weak shortwave troughs aloft moving overhead and
producing a chance of snow over and near our Snowy, Sierra Madre and
southern Laramie Ranges as well as over our far eastern counties of
the Nebraska panhandle. Continued cold with abundant cloud cover and
700 mb temperatures near -11 Celsius.

Tonight...Orographic type snows continue over and near our western
mountains on moist southwest flow aloft. Dry elsewhere.

Friday...Increasing snow chances across our western half of counties
as another shortwave trough aloft approaches from the main upper
trough over Utah. Best chances will be over the mountains due to
orographics. Continued cold with plentiful cloud cover and 700 mb
temperatures near -11 Celsius.

Friday night...Primary trough aloft moves overhead, with the
greatest snow chances in the evening, then decreasing after midnight
in the wake of the trough.

Saturday...Other than a chance of orographic snow showers over and
near the Snowy and Sierra Madre Ranges in moist northwest flow
aloft, it will be dry due to lack of other lift. A bit warmer east
of I-25 due to more warming downslope west winds.

.LONG TERM...(Saturday Night through Wednesday)
Issued at 355 AM MST Thu Feb 22 2018

Extensive upper-level troughing is expected to dominate the large-
scale weather pattern across much of the CONUS early in the medium
to long range. Low-level height gradients look to remain strong on
Sunday/Monday as numerous waves & associated areas of sfc pressure
falls spread across the northern high plains. That said, windy may
be the best word to describe the general outlook through Monday. A
bit of snow may fall over the mountains, but a general lack of mid
and high level moisture should limit amounts. Temperatures look to
remain generally on the cooler side of seasonal normals, given the
fairly unsettled upper-level pattern advertised by both the GFS/EC
suggesting multiple opportunities for re-inforcing shots of cooler
air.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 435 AM MST Thu Feb 22 2018

In general, VFR prevails today for those terminals not impacted by
snow shower activity. Periods of MVFR to IFR ceilings/visibilities
can be expected over the high plains, mainly impacting KSNY during
the morning hours and possibly impacting KCYS after 21z. Expect to
see some fog developing over the northern NE Panhandle between 06z
and 12z Friday, with locally MVFR/IFR conditions possible at KCDR/
KAIA late in the TAF cycle.

&&

.FIRE WEATHER...
Issued at 355 AM MST Thu Feb 22 2018

No concerns based on projected winds and humidities.

&&

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

$$

SHORT TERM...RUBIN
LONG TERM...CLH
AVIATION...CLH
FIRE WEATHER...RUBIN



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