581
ACUS11 KWNS 272321
SWOMCD
SPC MCD 272321
NDZ000-SDZ000-280045-

Mesoscale Discussion 1453
NWS Storm Prediction Center Norman OK
0621 PM CDT Thu Jun 27 2024

Areas affected...portions of central North Dakota into central South
Dakota

Concerning...Severe potential...Severe Thunderstorm Watch likely

Valid 272321Z - 280045Z

Probability of Watch Issuance...95 percent

SUMMARY...The severe threat is increasing across portions of central
ND into central SD as strong to potentially severe storms approach
from the west. Severe gusts are the main threat, though some
instances of severe hail and perhaps a tornado also may occur. A
Severe Thunderstorm Watch issuance will be needed within the hour.

DISCUSSION...Multicells and discrete supercells are moving across
western SD/ND and are approaching the eastern bounds of Severe
Thunderstorm Watch 475 and Tornado Watch 476. Meanwhile, a mature
MCS continues to rapidly propagate eastward into ND from MT, and is
poised to reach central ND in the next few hours. As these storms
merge and approach central SD/ND, severe gusts will become likely as
the storms move into a strongly unstable airmass (characterized by
up to 3500 J/kg MLCAPE per 23Z mesoanalysis). Furthermore, the
strengthening of the southerly LLJ (to 40+ kts), beneath increasing
westerly 500 mb flow with the ejection of a mid-level vort max, will
support effective bulk shear values well over 50 kts. Regional VADs
and short-term RUC forecasts show enlarged and curved low-level
hodographs with modest mid-level elongation. As such, any storms
that remain surface based as they move into the central Dakotas
should be accompanied by a severe threat. The eastward moving MCS
should produce at least some severe wind, which is expected to be
the predominant severe hazard. However, embedded mesovortices may be
accompanied by an isolated tornado threat.

A Severe Thunderstorm Watch will be issued within the hour to
address the impending severe threat.

..Squitieri/Smith.. 06/27/2024

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...FGF...ABR...BIS...UNR...

LAT...LON   45990189 48440204 48960169 48660054 47669954 46719939
            45259904 44219928 43919977 43950084 45990189