354 
FXUS63 KUNR 220532
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1032 PM MST Sat Jan 21 2017

.SHORT TERM...(This Evening Through Sunday Night)
Issued at 223 PM MST Sat Jan 21 2017

Weak ridging to neutral flow will persist through the period with
dry wx. Moist BL will promote some patchy fog tonight on the
plains, esp across NW SD. Otherwise, temperatures will be similar
to today on Sunday, given neutral temp adv. Western CONUS
troughing will promote local ridging Sunday night, with gusty sw
flow developing over NE WY and portions of the Black Hills. This
will support mild overnight lows in portions of the eastern BH
foothills Sunday night. Weak impulse may spread some light
snow/flurries into NE WY late Sunday night. However, very dry low
levels will likely limit any activity.

.LONG TERM...(Monday Through Saturday)
Issued at 223 PM MST Sat Jan 21 2017

Weak upper level ridge shifts east of the area Monday as trough
over the west coast moves into the Rockies. Shortwave energy in
southwest flow ahead of the trough could bring some light snow to
parts of northeast WY and northwest SD Monday afternoon. Highs
will mostly be near average, with above average temps over south
central SD.

Upper trough is progged by most models to move across the Rockies
Monday night and into the central high plains Tuesday morning. 12z
medium range models in a little better agreement with the GFS having
the mid level low moving along the Nebraska/SD border, and the EC
having it slide through central Nebraska. Models still differ on how
quickly the system strengthens once it crosses the rockies. The GFS
develops the mid level low quicker across far eastern WY, while the
EC doesn't deepen the low until it moves into eastern Nebraska. Will
continue to use the blended models with regard to pcpn and snowfall
amounts at this point, which come in about the same as yesterday for
most areas, in the 2 to 5 inch range for most areas. Brisk winds
Tuesday into Tuesday night could produce some areas of blowing snow
as well.

Snow will taper off and end from west to east Tuesday night, with
northwest flow aloft in place for the rest of the week. This will
keep temps below average, with breezy conditions at times. Weak
energy passing over the northern Black Hills and Bear Lodge Mts
could produce a few snow showers at times Wednesday into Thursday.  

&&

.AVIATION...(For the 06Z TAFS Through 06Z Sunday Night)
Issued At 1030 PM MST Sat Jan 21 2017

A mix of VFR and IFR conditions are expected through Sunday
morning. Most likely location for IFR ST/FG will be over the
southwest side of the Black Hills and adjacent plains of northeast
WY and southwest SD - and, along and east of a line from K2WX to
KICR. VFR conditions will redevelop most areas by Sunday
afternoon.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&

$$

SHORT TERM...JC
LONG TERM...15
AVIATION...Helgeson