750
FXUS63 KUNR 190823
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
223 AM MDT Sun May 19 2024

.KEY MESSAGES...

- Warmer today. Strong to severe thunderstorms this afternoon and
  evening across western South Dakota.

- Widespread showers/thunderstorms late Monday/Monday night.
  Locally heavy rain south central South Dakota

- Active pattern continues through the end of the week into the
  weekend.

&&

.DISCUSSION...(Today Through Saturday)
Issued at 219 AM MDT Sun May 19 2024

Current surface map places high across the eastern Dakotas with
weak low across Wyoming. Scattered showers/isolated thunderstorms
continue in area of theta-e advection across far northwestern
South Dakota. This activity shifts eastward by daybreak, with
potential for second area of development early this morning
across south central South Dakota. Focus turns to thunderstorm
development this afternoon/evening. Lead impulse ejects from upper
trough over the Rockies...tracking through the Northern Plains
this afternoon into this evening. Surface low deepens over the
Central Plains with inverted trough into western South Dakota. Low
level moisture and steep mid level lapse rates result in MLCAPE
0f 1000-2000J/KG across western South Dakota. Scattered
thunderstorms will develop around the Black Hills early this
afternoon and spread eastward this afternoon/evening. Sufficient
shear for a few supercells with large hail threat. Storms should
become more linear with severe wind threat increasing.

Stronger shortwave exits upper trough late Monday/Monday night,
moving through Nebraska into eastern South Dakota/Southern
Minnesota. This will bring widespread showers/scattered
thunderstorms to the southern half of the forecast area. Locally
heavy rain possible across south central South Dakota with LREF
60-80% probability of rainfall amounts >1.00" and 30-40%
probability of amounts >2.00".

Active pattern continues through the remainder of the week series
of troughs move through the Rockies into the Northern/Central
Plains.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Sunday Night)
Issued At 1023 PM MDT Sat May 18 2024

VFR conditions are expected through most of the TAF period.
Isolated late night high based showers and thunderstorms will be
possible toward central SD. Otherwise, another low pressure system
will cross the region Sunday and support breezy winds and
scattered afternoon showers and thunderstorms, mainly across SD.
Local MVFR conds and gusty winds will be possible INVOF TS. A cold
front will move through the region Sunday afternoon, with gusty
NW winds developing behind the front.

&&

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

$$

DISCUSSION/KEY MESSAGES...7
AVIATION...JC