Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 280403
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
903 PM MST Sun Nov 27 2016

.UPDATE...
Issued at 851 PM MST Sun Nov 27 2016

Upgraded the winter storm watch to a warning over the northern
black hills. Very strong upslope snow signature continues to be
advertised in forecast models Monday night through Tues. Ample
deep layer moisture will be available monday night trough tues to
support heavy snow in the northern black hills, esp in the
sundance-four corners-lead areas. Latest lift/moisture progs
suggest 8 to 15 inches will be possible in the aforementioned
area, with generally 6 to 12 inches in the rest of the northern
black hills. in addition, gusty nw winds will support areas of
blowing and drifting snow. added the sturgis foothills zone to the
watch for potential carry over into the sturgis/tilford area from
steep lapse rates and high froude number. current forecast progs
suggest up to 6 inches possible in this area, with an inch or
less from Piedmont to black hawk given a sharp cut off.

&&

.SHORT TERM...(This Evening Through Monday Night)
Issued at 157 PM MST Sun Nov 27 2016

Water vapor shows upper low beginning to take shape over cntrl NE,
with sfc analysis showing deepening low near the same area. Radar
returns over sctrnl SD, with little pcpn reaching the ground due
to very dry low layers.

Tonight...nearly stacked low will continue to deepen as it lifts
slowly newd through ern SD. While there may be some light -shrasn
over our ern zones, the biggest effect will be the strengthening
winds with 850mb winds increasing to 40-55kts over the SD plains.
Have issued a wind advisory for the usual windy areas or nwrn SD
beginning at 09z.

Monday...Stacked low drifts very slowly nwd into ern ND by late
aftn. Very gusty nw winds will continue with best chances for any
-shrasn again over our ern zones.

Monday night...Stacked low remains stationary over ern ND with
trowal wrapping back into the cwfa, with accumulating snow likely
across much of the cwfa. Upslope snow will get going in the nrn
Blkhls with a downslope hole likely in the srn Blkhls to about
Rapid City.

As far as highlights, will continue with the wind advisory for
west central SD through Tuesday evening. Will keep the winter
storm watch in place for the nrn Blkhls, while issuing a winter
storm watch for parts of nern WY into far nwrn SD where a
combination of snow and strong winds may create very hazardous
travel conditions. It`s possible that some sort of winter
highlights will become necessary on the SD plains at a later time.

.LONG TERM...(Tuesday Through Sunday)
Issued at 157 PM MST Sun Nov 27 2016

Stacked low pressure system will be positioned over far eastern
SD and west-central MN Tuesday morning, very slowly moving east
into Wisconsin by Wednesday. Bands of wrap-around precipitation
will slide south across a good portion of the CWA during this
time, gradually diminishing on Wednesday. Gusty winds across the
plains will produce some areas of blowing snow. Snowfall totals of
6 to 12 inches are likely over much of the northern Black Hills by
the time the snow tapers off, with locally higher amounts
possible. Portions of far northeast WY into northwest SD will see
up to a few inches of accumulation, as well as along the Pine
Ridge. The Rapid City area, the southern Black Hills, and far
southwest SD will likely see little in the way of snowfall with
dry downsloping flow in place.

Conditions will improve in most areas by Wednesday afternoon, with
lingering areas of light snow or flurries possible in some areas. A
drier, but colder, pattern is then expected through the rest of the
week. The next west coast system is progged by most models to slide
south into the southwest US late in the week, keeping our area in
drier and weaker northern stream flow. Highs will mostly be in the
upper 20s and 30s through the end of the week.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Monday Evening)
Issued At 421 PM MST Sun Nov 27 2016

VFR conditions are generally expected over most of the fa through
the period. There is a chance for rain or snow showers over the
far east through tonight, shifting west through the SD plains Mon.
Areas of MVFR/IFR conditions are expected tonight generally along
and east of a line from 2WX to ICR. Gusty northwesterly winds
will develop from west to east across the forecast area this
evening behind a passing area of low pressure. Widespread
northwest winds of 20 to 35 knots are expected by early Monday
morning. Snow and blowing snow with IFR/LIFR visibilities will
develop across most of the area late on Monday.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Storm Warning from 5 PM Monday to 5 AM MST Wednesday for
     SDZ024-025-028.

     Winter Storm Watch from Monday afternoon through late Tuesday
     night for SDZ001-002-012-072.

     Wind Advisory from 2 AM to 5 PM MST Monday for SDZ001-002-012-
     072.

     Wind Advisory from 2 AM Monday to 11 PM MST Tuesday for SDZ013-
     014-026-030>032-073-074.

WY...Winter Storm Warning from 5 PM Monday to 5 AM MST Wednesday for
     WYZ057.

     Winter Storm Watch from Monday afternoon through late Tuesday
     night for WYZ054-056-071.

&&

$$

Update...JC
SHORT TERM...Johnson
LONG TERM...15
AVIATION...JC



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