South Dakota Mesoscale Discussion

Areas affected…Parts of northeastern South Dakota and adjacent
portions of southeastern North Dakota and western Minnesota

Concerning…Severe potential…Watch possible

Valid 092341Z – 100115Z

Probability of Watch Issuance…40 percent

SUMMARY…A period of rapid thunderstorm intensification appears
possible this evening, which may include the development of isolated
supercells into and through the 8-10 PM CDT time frame. Due to the
somewhat isolated and possibly short-lived nature of the threat, a
severe weather watch issuance is not certain, but trends are being

DISCUSSION…Sustained thunderstorm activity appears in the process
of initiating near/southwest through east of Aberdeen. This is
focused to the northeast of a modest surface low, within a zone of
strong low-level warm advection along a frontal zone, as the axis of
a low amplitude mid-level short wave trough overspreads the region.
With increasing inflow of moist boundary layer air characterized by
CAPE of 1000-2000 J/kg, a period of rapid intensification appears
likely, in the presence of strong deep-layer shear beneath a 40 kt
westerly 500 mb jet. This may include the evolution of at least an
isolated supercell or two into and through the 01-03Z time frame,
which probably will pose at least a risk for severe hail and locally
strong surface gusts. Although the primary low-level jet appears
well to the east and southeast of the region, low-level hodographs
may still be favorably large and clockwise curved to support some
tornado potential.

As the stronger mid-level support rapidly shifts to the northeast of
the warm front, it remains unclear how long activity will maintain
intensity this evening.

..Kerr/Thompson.. 09/09/2019

…Please see for graphic product…


LAT…LON 45709920 46289790 45649522 44809577 44589701 45169928

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