Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 181040

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
340 AM MST Sat Feb 18 2017

.SHORT TERM...(Today Through Sunday Night)
Issued at 340 AM MST Sat Feb 18 2017

Current surface analysis shows frontal boundary just south and
west of the forecast area, with weak low pressure over central WY.
Upper level analysis shows trough just off the west coast, with
southwest flow extending across the western US into the Northern
Plains. Cutoff low is drifting slowly east across the Southern
Plains into the southeast US. Weak energy aloft is bring mid and
high clouds across our area this morning. Some weak returns are
noted on radar across northeast WY into far western SD, with a few
sprinkles or flurries possibly reaching the ground. Temps are
mostly in the 30s and lower 40s.

Very mild weather will continue through the weekend as the frontal
boundary lifts slowly north and east as a warm front today and
tonight. Highs today will be in the 50s to mid 60s, generally
warmest over southern portions of the forecast area that are free of
snow cover. A good deal of cloud cover early this morning will give
way to some sunshine into the afternoon. South to southwest winds
will be breezy across northeast WY and portions of the Black Hills
this morning, with southerly winds developing elsewhere through the
day. Mild conditions tonight as warm front lifts north of the area
overnight, mid 30s to upper 40s for lows.

Partly cloudy skies can be expected through much of Sunday, with
some increasing clouds later in the day. Highs will range from the
50s over parts of northwest SD and the higher Black Hills to around
70 from parts of west central to south central SD. Record high
Sunday at Rapid City is 69 at airport and 68 in town, both of which
could be broken. Shortwave trough ejecting out of west coast system
will bring a good chance for showers to the area Sunday night into
early Monday. Low pressure at the surface looks to pass north of the
area, keeping milder air in place for mostly rainfall Sunday night.
However, it could get cold enough in the higher Black Hills and
parts of northeast WY for a mix or change over to snow late Sunday
night, with some accumulation possible, especially across the higher
Black Hills.

.LONG TERM...(Monday Through Friday)
Issued at 340 AM MST Sat Feb 18 2017

Shortwave moves north and east of the area Monday, with showers
ending from west to east during the morning. Some cooler air will
push in behind the exiting system, but temps will remain well
above average, upper 40s to around 60. Shortwave ridge on Tuesday
will bring another warm day, with near record highs possible in
some areas again. Ridge shifts east midweek, with some cooler
temps and increasing clouds on Wednesday.

Large scale trough along the west coast Wednesday is progged to move
quickly east across the Rockies Wednesday night and into the high
plains on Thursday. Medium range models continue to be in pretty
good agreement this far out on main feature, with some differences
on evolution, timing, and track of the system as it moves into our
region, as would be expected with a system 5+ days out. However,
GFS, EC, and GEM all continue to show good potential for snowfall
and at least some potential for significant snowfall across portions
of the region from late Wednesday night through Thursday night.
Still a lot of uncertainty at this point, with latest 06Z GFS run
more progressive, weaker, and further south with bulk of pcpn. Will
keep high pops in place from late Wednesday night through early


.AVIATION...(For the 12Z TAFS Through 12Z Sunday Morning)
Issued At 340 AM MST Sat Feb 18 2017

VFR conditions are expected through the forecast period.
Breezy south to southwest winds will persist over portions of
northeast WY and the Black Hills this morning, then gradually
decrease into the afternoon.




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