Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 200511
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1011 PM MST Mon Feb 19 2018

.UPDATE...
Issued at 900 PM MST Mon Feb 19 2018

Snow ending across northeast Wyoming and the Black Hills as main
snow band shifts into south central South Dakota. Adjustments made
to snowfall for the remainder of the night. Have dropped some
headlines with the update.

&&

.DISCUSSION...(This Evening Through Monday)
Issued at 208 PM MST Mon Feb 19 2018

Deep upper trough continues to slowly cross the western CONUS with
active southwesterly flow across the northern Plains. A series of
strong upper waves are crossing Wyoming into far western SD at this
time, with reinforcing shots of snow over the area. KUDX radar shows
bands of snow across the Black Hills area into central SD especially
along Interstate 90. More bands are approaching from east central
Wyoming as well. These bands will continue to affect the area
through the evening hours as heavier snow transitions toward south
central SD. Snow across south central will then continue through
early Tuesday morning, as snow over northeast Wyoming/the Black
Hills area weakens. Overnight snow totals across northeast Wyoming
the much of western SD will be in the 1-3" range while south central
SD is expected to get 4 to 7 inches by sunrise. Will continue with
ongoing headlines as timing still seems to be working out well.

Snow will end across the CWA by midday Tuesday. Morning lows will
reach zero to 15 below, with wind chills dropping to 25 below to 35
below. Highs Tuesday will be similar to today. Center of surface
high will cross the area late Tuesday into Tuesday night, with
return flow setting up Wednesday morning as it shifts to the east.
With early Wednesday morning temps again well below zero and a
developing southerly winds, wind chills are likely going to again
drop into the 25 below to 35 below range. Dry weather and warm air
advection is expected through the second half of the week. Highs
will gradually rise daily, reaching the upper 20s/30s by the
weekend. A passing shortwave Thursday may bring light snow
accumulations to south central South Dakota. Otherwise dry weather
is expected through the weekend.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Tuesday Night)
Issued At 1010 PM MST Mon Feb 19 2018

Widespread IFR conditions will continue through the night across
portions of southwest and south central South Dakota...with
conditions improving for those areas Tuesday morning. Elsewhere,
local MVFR conditions will be found across the area tonight, with
VFR conditions on Tuesday.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Storm Warning until 5 AM MST Tuesday for SDZ013-014-
     030>032-041>044-073.

     Winter Storm Warning until 9 AM CST Tuesday for SDZ046-047-049.

     Winter Weather Advisory until 11 PM MST this evening for SDZ002.

     Winter Storm Warning until 11 PM MST this evening for SDZ026-027-
     072-074.

WY...None.
&&

$$

Update...7
DISCUSSION...13
AVIATION...7



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