421
FXUS63 KUNR 062007
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
207 PM MDT Mon May 6 2024

.KEY MESSAGES...

-Deep low pressure system will bring numerous hazards through
 Tuesday.

-Severe thunderstorms possible this afternoon over eastern areas.

-Strong winds expected tonight northeast WY and most of western
 SD, with gusts to 70 mph possible.

-Heavy wet snow expected tonight above 6000 ft in the northern
 Black Hills.

-Heavy rain expected in portions of NE WY.

&&

.DISCUSSION...(This Evening Through Monday)
Issued at 207 PM MDT Mon May 6 2024

Vigorous low pressure system deepening and closing off across the
region this afternoon. The dry trough has already shifted across
most of the area with lingering thunderstorms and showers along
the trough from far NW SD through scentral SD. Severe threat will
wane this evening as the sfc trough shifts east. The main show
will then become strong winds across most of the region. LLJ core
on the south side of the sfc low will strengthen and mix down to
the sfc overnight tonight with winds becoming quite strong.
Expecting sustained winds of 30 to 45 mph with gusts in excess of
70 mph possible. In addition, terrain effects around the BH will
accentuate the flow with locally strong wind gusts possible, esp
along the northern foothills. Winds will be the strongest
overnight, across the west, with high winds slowly diminishing
through Tues, but remaining at warning or adv levels for most of
the day. The other main impact will be heavy deformation rains
across far NE WY into the northern Black Hills where 1-2 inches of
rain will possible through tonight. Temps will drop across the
higher elevations of the BH with rain changing to snow and
becoming quite heavy overnight. Snow amounts around foot are
possible above 6000 ft in the northern Black Hills, impacting
portions of highway 85 around the state line. Strong saturated
deep layer flow, extending into the dgz will help accentuate
snowfall rates overnight. Rain (and high elevation snow) will
taper off Tues morning with some lingering showers across the NW
half, mainly dry across the far south. Strong winds will slowly
diminish through the day, but remain breezy through Wed as the sfc
low pivots over the region. The next round of rain will push into
the region Tue night-Thur as the upper low moves slowly southeast
across the region. This will bring more scattered activity with
more instability type showers. There will also be some snow once
again in the higher elevations of the Black Hills, mainly Tue
night. Things will begin to dry out and warm back up this weekend
with semi-unsettled NW flow possibly supporting isolated
showers/storms at times.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Tuesday)
Issued At 1144 AM MDT Mon May 6 2024

Showers and storms are expected this afternoon and tonight over
much of the forecast area. MVFR/IFR conditions can be expected
with these showers and storms. Winds will shift out of the west-
northwest throughout the day, with gusts 35-50 knots possible by
early afternoon through the late evening hours. These strong winds
will persist through the overnight hours.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Wind Advisory until 6 PM MDT this evening for SDZ001-002-012-013-
     026-027-030-031-041-042-073>076-078.
     High Wind Warning from 6 PM this evening to 6 PM MDT Tuesday for
     SDZ001-012-013-025-072-073-078.
     Wind Advisory until 6 PM MDT /7 PM CDT/ Tuesday for SDZ014-032-
     043-044-046-047-049-077.
     High Wind Warning from 6 PM this evening to noon MDT Tuesday for
     SDZ024-026>031-041-042-074>076.
     Winter Storm Warning from 6 PM this evening to noon MDT Tuesday
     for SDZ024.
WY...High Wind Warning from 6 PM this evening to 6 PM MDT Tuesday for
     WYZ060.
     High Wind Warning from 6 PM this evening to noon MDT Tuesday for
     WYZ054>059.
     Winter Weather Advisory from 6 PM this evening to 9 AM MDT
     Tuesday for WYZ057.
&&

$$

DISCUSSION/KEY MESSAGES...JC
AVIATION...Dye