MD 0380 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR PORTIONS OF FAR SOUTHEASTERN SD INTO IA…NORTHWESTERN IL…AND EXTREME NORTHEASTERN MO
Mesoscale Discussion 0380
NWS Storm Prediction Center Norman OK
0205 PM CDT Sun Apr 07 2024
Areas affected…Portions of far southeastern SD into IA…
northwestern IL…and extreme northeastern MO
Concerning…Severe potential…Watch unlikely
Valid 071905Z – 072130Z
Probability of Watch Issuance…5 percent
SUMMARY…An isolated threat for strong/gusty winds and perhaps a
brief tornado may exist with any low-topped thunderstorms that can
develop. Watch issuance is not expected.
DISCUSSION…Recent visible satellite imagery shows a cu field
gradually deepening across IA and vicinity along an occluded front
extending eastward from a deep surface low in northeastern NE.
Low-topped convection has recently developed in far southeastern SD,
in close proximity to the surface low. Boundary-layer moisture
remains modest across this region, with surface dewpoints generally
in the mid 40s to around 50. Still, filtered diurnal heating of this
airmass is contributing to around 75-125 J/kg of 0-3 km MLCAPE in a
narrow zone focused along the front per latest mesoanalysis
estimates. Near-surface vorticity is also likely maximized along
this boundary, with modest low-level shear present based on recent
VWPs from KDMX/KDVN.
Even with the moisture/instability limitations, there should be some
chance for ongoing low-topped thunderstorms to gradually increase in
coverage and intensity over the next few hours this afternoon into
IA and perhaps northwestern IL. Given steepened lapse rates through
the cloud-bearing layer, isolated strong/gusty winds appear possible
with the more robust cores. A brief tornado/landspout or two may
also occur, mainly focused along the occluded front where
near-surface vorticity overlaps with maximized 0-3 km CAPE and steep
boundary-layer lapse rates. However, the overall severe threat this
afternoon is expected to remain too isolated/marginal to justify
watch issuance.
..Gleason/Goss.. 04/07/2024
…Please see www.spc.noaa.gov for graphic product…
ATTN…WFO…DVN…DMX…FSD…
LAT…LON 41259366 41669477 42599600 43429738 43439631 42619311
42269227 41289055 40359085 40309160 40899231 41259366
