Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 281131
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
531 AM MDT Fri Apr 28 2017

.DISCUSSION...(Today Through Thursday)
Issued at 401 AM MDT Fri Apr 28 2017

Upper level analysis has weak cutoff low remaining over eastern
Wyoming, with strong jet rounding the base of the main trof into
the central Plains. Skies are cloudy or mostly cloudy across
northeast WY and southwest SD, with a steady stream of moisture
moving northwestward into the area. Temps are mostly in the 30s,
with some upper 20s over the higher Black Hills.

Today...Storm system will continue to spin over eastern WY
today, then track southeast into northeast CO late this afternoon
before getting swallowed up by stronger trof and low developing
across the Great Basin and Four Corners area. Latest medium range
models still showing some differences with regard to the eastern
and northern extent of pcpn shield across western South Dakota.
Will lean more towards the majority of models that have the main
precip band sinking south by late this afternoon. SREF is the
outlier with precip much further north than most. The heaviest
snow still looks to fall over southern Campbell County, with snow
gradually taper off in the afternoon. Snowfall amounts in southern
Campbell County look to mostly be in the 5 to 10 inch range, with
areas south and west of Wright possibly seeing higher amounts.
The advisory area should see 2 to 6 inches of snow, with locally
higher amounts possible, especially the further south and west
across those areas. Up to 2 or 3 inches of snow is possible across
the rest of the Black Hills into portions of far northeast WY and
toward portions of Oglala Lakota County. With the sharp gradient
in precip, temperatures will range widely from the mid 30s across
parts of Northeast Wyoming, to the lower 50s across northwest
South Dakota.

Snow will finally diminish across Northeast Wyoming this evening
with mostly cloudy skies remaining across much of the area.
Temperatures will fall into the mid 20s to lower 30s.

The weekend looks to be dry, but cool, as main trough and low
pressure system move east-northeast across the central and southern
plains and into the upper MS valley by Monday morning. A few showers
could clip far south central SD on the back side of the system
Sunday night. Highs will be in the mid 40s to mid 50s Saturday,
50s to around 60 on Sunday. The first half of next week still
looks to be unsettled with temps slightly below average. Daily
chances for showers are expected, especially for the afternoon and
evening hours, as a series of weak disturbances pass through on
the back side of the exiting trough. Latest longer range models
showing a nice warmup for late week, possibly into the first half
of the weekend as well, as a ridge finally moves over the area.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Saturday Morning)
Issued At 529 AM MDT Fri Apr 28 2017

Area of snow across northeastern Wyoming, the Black Hills area
and southwestern South Dakota will continue through into this
afternoon. Widespread IFR conds will continue in those areas
through this morning...gradually improving to MVFR conditions
this afternoon. Further across most of the rest of western SD,
conds will vary from IFR near the Black Hills, to low end VFR/high
end MVFR as dry air fights lower CIGS/precip.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Weather Advisory until 6 PM MDT this evening for
     SDZ027>029-041.

WY...Winter Storm Warning until 6 PM MDT this evening for WYZ055.

     Winter Weather Advisory until 6 PM MDT this evening for WYZ054-
     058.

&&

$$

DISCUSSION...15
AVIATION...10


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