FXUS63 KUNR 261050
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
450 AM MDT Fri Apr 26 2024

.KEY MESSAGES...

- Patchy areas of fog may develop over the western SD plains this
  morning.

- Widespread rain expected today through much of the weekend.

- Warm and dry conditions move in early next week. 

&&

.DISCUSSION...(Today Through Thursday)
Issued at 159 AM MDT Fri Apr 26 2024

Current Water Vapor and upper air models show upper ridge over the
great lakes and midwest regions, while upper low sits over
northeastern CO this morning. At the surface, low pressure sits
over the MT/ND border, with cold front running southwest through
Wyoming. Skies are partly to mostly cloudy, with light winds.
Temperatures currently sit in the mid 40s to low 50s. Current
radar shows showers over much of south central SD. Ample moisture
coupled with light winds may allow for some areas of fog to
develop in the western SD plains this morning.

Active weather continues over the weekend, as multiple waves move
through the region. Upper low will swing into Nebraska today and
up towards MN early Saturday. Current modes have progged the track
a bit more east compared to previous runs. As such, higher QPF 
amounts have also shifted east. Northwesterly flow on the backside
of the flow will allow for some stronger downslope winds over the
central foothills today. The northwest flow coupled with cloud 
cover and moisture will make for a cooler day, with highs in the 
mid 50s to mid 60s. Wrap-around moisture allow showers/storms to 
fill into the region through this morning and afternoon. 24hr prob
of 1"+ rain for this first system sit around the 40 to 60% range 
for the Black Hills and foothills, while areas to the east along 
and south of I-90 climb into the 60 to 80% range. Cooler air moves
into the region for the rest of the weekend, with highs in the 
40s and 50s for Sat/Sun. Second system swings into the region from
the southwest later half of Saturday into Sunday, bringing 
another round of precipitation. Models show a bit less moisture 
with this second wave, and with a similar track to the first, the 
higher QPF amounts are progged in south central SD. The higher 
elevation Black Hills could see some very light snow Saturday 
night into Sunday, but little to no accumulations are expected. 

System exits the right late Sunday into Monday morning, and
quasi-zonal flow sets up over the region. Temps will rebound to 
above normal quickly, reaching back into the 60s Monday. Weaker
upper low treks across the Canada/US border Monday night into
Tuesday, brining chances for showers/storms across the Black Hills
and northwestern SD. Mild ridge builds into the Rockies and
northern plains behind this low, allowing for a dry Tues/Weds
before another system treks through the northern plains later next
week.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Saturday Morning)
Issued At 447 AM MDT Fri Apr 26 2024

Widespread MVFR/local IFR conditions expected through the day for
much of western South Dakota with numerous showers/scattered
thunderstorms. Areas of LIFR visibility in fog will also persist 
through the morning across northwestern South Dakota. Mainly VFR 
conditions expected over northeastern Wyoming.

&&

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

$$

DISCUSSION/KEY MESSAGES...Dye
AVIATION...7