063 
FXUS63 KUNR 240512
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1112 PM MDT Wed May 23 2018

.DISCUSSION...(This Evening Through Wednesday)
Issued at 155 PM MDT Wed May 23 2018

Latest analysis shows southwesterly flow aloft over the forecast 
area as an upper low/trough approaches from the west. A surface
trough continues to deepen along the eastern slopes of the
Rockies. The resulting southerly low level flow, combined with the
moisture from the rain last night has pushed dewpoints into the
mid-40s to lower 50s over northeastern Wyoming and into the 
mid-50s to mid-60s over much of western South Dakota. 
Temperatures over much of the area have already reached the 
mid-70s over most of the area with mid-80s over parts of south 
central South Dakota. SBCAPE ranges from 1000-2000J/KG at this 
time with eroding CIN. Shortwave energy moving up from the 
southwest has caused showers and thunderstorms to develop over 
southeastern Wyoming, which will move into northeastern Wyoming 
and southwestern South Dakota during the next few hours. May also 
see some convective development over south central SD late this 
aftn. With 0-6km bulk shear around 20m/s, there is the usual 
hail/wind threat into early evening, becoming more of a wind 
threat as an MCS develops and 0-3km shear profiles bulge into the 
evening hours. PWATs are relatively high, but storm movement is 
decent too. The thunderstorms, and the severe threat will shift 
eastward through the evening and are expected to be out of most of
the forecast area shortly after 06Z but may linger over parts of 
south central South Dakota into early Thursday morning.

From Thursday into Saturday, an upper ridge will build over the 
northern Plains as yet another upper trough dives southward across
the western CONUS. The thermal ridge is trending warmer, with 
forecast high temperatures around 20F warmer than average on the 
SD Plains. Isolated thunderstorms are possible.

Sunday into Tuesday, the upper trough/low will affect the northern
Plains bringing a period of active weather with good chances for 
TS. Mainly dry weather is expected on Wednesday.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Thursday Night)
Issued At 1110 PM MDT Wed May 23 2018

Scattered showers and thunderstorms moving into central South
Dakota with local MVFR/IFR conditions...will continue to move
east overnight. Otherwise, VFR conditions expected through 
Thursday evening. 

&&

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

$$

DISCUSSION...10
AVIATION...7