South Dakota Mesoscale Discussion

Areas affected…NE Panhandle…Western/Central NE…South-Central

Concerning…Severe potential…Tornado Watch likely

Valid 101925Z – 102130Z

Probability of Watch Issuance…80 percent

SUMMARY…Thunderstorm initiation is anticipated over north-central
NE/south-central SD later this afternoon. All severe hazards,
including tornadoes, are possible with the initial development.
Upscale growth into a strong, forward-propagating MCS anticipated

DISCUSSION…Recent surface analysis places a warm front from just
south of the YKN (in far southeast SD) west-southwestward across
north-central NE and into far southeast WY. Moist conditions exist
south of this front with dewpoints in the upper 60s/low 70s. These
moist conditions combined with steep mid-level lapse rates are
contributing to moderate to strong buoyancy. Additionally,
southeasterly surface winds beneath increasing southwesterly flow
results in a veering wind profile and strong deep layer shear.

Expectation is for storm to develop quickly along and near the front
once convective inhibition erodes this afternoon. An initially
discrete mode is anticipated but close storm proximity suggests
clustering could occur quickly. Even so, favorable low-level shear
profiles and ample low-level moisture suggest tornadoes are
possible. A forward-propagating MCS will likely develop out of the
storm cluster as cold pools amalgamate. Given the overall
environment, some significant wind gusts (i.e. 74 mph) are possible
within this MCS.

..Nauslar/Hart.. 09/10/2019

…Please see for graphic product…


LAT…LON 42370311 43190254 43550192 43670060 43579968 43129893
42139884 41460004 41370260 42370311

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