SPC Mesoscale Discussion: Severe Potential… Watch Unlikely

SUMMARY…Low-topped supercells may produce isolated damaging winds and a brief, weak tornado. A watch issuance is unlikely given the marginal, isolated severe threat.

DISCUSSION…Remnants of Barry have moved up the Mississippi Valley and into the Ohio Valley. Weak disturbance(s) are rotating around the base of the now open shortwave trough per satellite imagery. A warm, moist environment is in place characterized by surface dewpoints of 70+ F and mean mixing ratios of 15+ g/kg. Moderate buoyancy of 1000-1500 J/kg of MLCAPE is aiding isolated low-topped supercell development (effective SCP of 1-4 across the MCD) with a brief, weak tornado possible with these storms given 0-1 km SRH of 100+ m2/s2. A few rotating storms have been detected via KNQA, KGWX, KPAH, and KVWX, but maximum Vrot estimates are only 15-20 knots. Isolated damaging wind gusts are also possible with water-loaded downdrafts, especially in areas that have had more insolation helping to steepen low-level lapse rates. Given the overall isolated, marginal severe threat, a watch issuance is unlikely.

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