Area Forecast Discussion
Issued by NWS Rapid City, SD
FXUS63 KUNR 300954
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
254 AM MST Wed Nov 30 2016
.SHORT TERM...(Today Through Thursday Night)
Issued at 251 AM MST Wed Nov 30 2016
09z surface analysis had stacked low over eastern MN and western
WI. Weak lift and moisture continue to wrap around low across the
Dakotas. Slug of moisture earlier this morning produced another
burst of upslope snow for 2-4 hours, but this has waned per latest
KUNR WSR-88D reflectivity loops. However, moisture upstream and
Froude numbers above one through 15z; cannot rule out additional
upslope enhancement. Best lift is over with gusty winds slowly
subsiding this morning. Looking at latest observations, satellite,
and web cam trends, feel worst of storm will be over by 15z.
Additional accumulation over current warning areas will be minor
and wind speed peak has passed. Will convert warnings to
advisories with all headlines ending at 15z. Temperatures will be
5-10F below normal today given snow cover and chilly lower
troposphere. Exception will be over southwest South Dakota where
snow cover is virtually nil.
Tonight, shortwave upper ridge moves brings a quiet night and chilly
temperatures. Readings will be near to slightly below guidance.
Thursday, fast moving shortwave moves from the northern Rockies into
eastern UT. Lift and moisture ahead of system weak, but low level
winds remain upslope. As slug of low level moisture moves through
with Froude number rising above one again, suspect we`ll see a brief
period of upslope snow over the northern Black Hills Thursday night.
Have raised pops with some accumulation possible. Temperatures will
be near guidance.
.LONG TERM...(Friday Through Tuesday)
Issued at 251 AM MST Wed Nov 30 2016
Dry weather is expected across much of the forecast area for
Friday and the weekend. The exception will be across far northeast
WY and the Black Hills, where a few snow showers are possible
Friday and Saturday as weak energy moves across in west-northwest
flow aloft. Highs will be in the mid 20s to mid 30s Friday, with a
slight warmup to the mid 30s to mid 40s by Sunday as a weak ridge
quickly passes over the region.
Medium range models still point to a surge of arctic air early next
week as a large scale upper trof develops over the western US,
allowing an arctic front to slide through the Northern Plains in the
Monday/Monday night timeframe. Some light snow looks possible late
Sunday night into Monday from northeast WY to northwest SD, but
better chances may stay north of the forecast area. Models become
very inconsistent beyond this time, with additional upper level
energy within the trof possibly bringing chances for snow to some
areas through midweek, but confidence is low at this time.
Temperatures look to be well below average Tuesday and Wednesday,
with highs in the teens and 20s and lows in the single digits to
.AVIATION...(For the 12Z TAFS Through 12Z Thursday Morning)
Issued At 251 AM MST Wed Nov 30 2016
MVFR conditions will continue across portions of far northeast WY
and much of the western SD plains early this morning, with areas
of IFR conditions over the northern Black Hills. Snow will taper
off over the northern hills. Conditions will slowly improve from
west to east across the western SD plains today as areas of light
snow shift slowly east. Northwest winds of 15 to 25 kts with gusts
to around 30 kts can be expected across the SD plains today,
diminishing in the late afternoon and evening.
SD...Winter Weather Advisory until 8 AM MST /9 AM CST/ this morning
WY...Winter Weather Advisory until 8 AM MST this morning for WYZ057-