Tornado and Hail in South Dakota, June 7, 2021

Area Forecast Discussion
National Weather Service Aberdeen SD
245 PM CDT Mon Jun 7 2021

.SHORT TERM...(This Evening through Tuesday Night)
Issued at 244 PM CDT Mon Jun 7 2021

Thunderstorms, some strong to severe, are possible primarily
across north central South Dakota this evening. The main forcing
mechanism will be a warm front, which extends east of an area of low
pressure across west central South Dakota, and is currently tracking
northward across central and northeastern South Dakota. Dewpoints
south of the front are in the mid to upper 60s, and CAPE is
plentiful. By about 00z (when CAMs suggest convection is most likely
to first get started), the warm front should be positioned roughly
from Stanley to McPherson Counties. The majority of CAMs develop
thunderstorms in this area, but coverage is not a consensus -
updrafts will have to battle warm air aloft, and the warm air could
largely win out considering the lack of good upper-level support
(strongest flow aloft resides and will stay further northwest, as
evident by stable billow clouds on GOES-16 north of Bismarck since
about 18z). Nonetheless, all svr hazards are possible with initial
convection. Will there be enough deep-layer shear to support
supercells? It's possible considering the up to ~35kts of effective
bulk shear near the ND/SD border. However, the bulk of the best
shear shifts progressively further north after 00z, and CIN
increases thereafter as well. Thus, the tornado across our CWA may
be greatest (though still small) if relatively discrete storms can
develop on the warm front prior to 00z, particularly if LCL
heights can become lowered a bit by any prior convection. If the
window for supercells is missed, a more messy multicell storm mode
is favored. Regardless of storm mode, wind will be a threat given
the steep low (>7.5 C/km) and mid (>8 C/km) level lapse rates,
and strong DCAPE of 1200-1500 J/kg. In time, activity will
progress east-northeastward, maintaining mainly a wind threat, and
should exit the CWA by about 09z.

On Tuesday, high temperatures will climb back into 90s, as little
changes in the upper-levels. A shortwave does track north-northeast
across the Rockies through the day however, and this feature will
help to initiate additional convection. While the majority of this
activity will west of the CWA, thunderstorms may line out and pose
primarily a wind threat across the western CWA during the
evening/overnight.

.LONG TERM...(Wednesday through Monday)
Issued at 244 PM CDT Mon Jun 7 2021

A persistent upper ridge will keep temperatures well above normal
in the extended other than a brief break on Friday as an upper
trough collapses the ridge Thursday night/Friday.

Shower and thunderstorm chances will linger on Wednesday across
central SD as a sfc low stalls over the Dakotas. The low will weaken
during the afternoon, but moist southerly flow and an llj will set
up through early Thursday evening allowing the showers to shift
farther east. A more potent low with better upper level support will
move through the region Thursday night. Chances for severe storms
will likely increase for this time period as it nears if the model
trends remain consistent.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon)
Issued at 1236 PM CDT Mon Jun 7 2021

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are anticipated through the period, with the
possible exception being during times of potential thunderstorm
activity this early evening at PIR and MBG as an area of low
pressure moves in from the west. Southerly winds will continue to
be breezy through the afternoon.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&

SHORT TERM...Lueck
LONG TERM...Wise
AVIATION...Lueck

Hazardous Weather Outlook
National Weather Service Aberdeen SD
453 AM CDT Mon Jun 7 2021

SDZ003>006-009-010-015>017-033>037-045-048-051-081000-
Corson-Campbell-McPherson-Brown-Walworth-Edmunds-Dewey-Potter-Faulk-
Stanley-Sully-Hughes-Hyde-Hand-Jones-Lyman-Buffalo-
453 AM CDT Mon Jun 7 2021 /353 AM MDT Mon Jun 7 2021/

This Hazardous Weather Outlook is for central South Dakota, north
central South Dakota and northeast South Dakota.

.DAY ONE...Today and tonight.

Strong storms will be possible late this afternoon and into the
overnight, especially for central and north central South Dakota.
Some storms could produce severe winds and hail. There is a low
probability for tornadoes.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

A few strong storms will be possible Tuesday night, mainly for
locations west of the James River valley. Damaging winds should be
the main severe threat.

Additional storms are possible Wednesday through Wednesday night.

Another round of potentially strong to severe storms appears
possible Thursday night into Friday morning. Damaging wind could be
the main threat, as well as severe hail.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed late this afternoon.

MNZ039-046-SDZ007-008-011-018>023-081000-
Traverse-Big Stone-Marshall-Roberts-Day-Spink-Clark-Codington-Grant-
Hamlin-Deuel-
453 AM CDT Mon Jun 7 2021

This Hazardous Weather Outlook is for west central Minnesota and
northeast South Dakota.

.DAY ONE...Today and tonight.

A few thunderstorms could be possible late tonight. Severe storms are
not expected at this time.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Additional thunderstorms are possible Tuesday through Thursday,
mainly during the afternoon through early overnight hours.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

SD