SPC Mesoscale Discussion: Tornado Watch 507…

SUMMARY…A brief tornado or two will remain possible through the evening hours with the stronger outer rain-bands/cells associated with weakening Tropical Depression Barry. Given the localized and brief nature of the tornado threat, a Tornado Watch re-issuance is not currently expected.

DISCUSSION…Tropical Depression Barry continues to slowly track northward across the Mid-South, and is expected to gradually weaken with time. Barrys wind fields remain structurally asymmetric, with a belt of stronger 925-700 mb flow established across western/central MS. Optimal kinematic and thermodynamic fields are decoupled, with relatively richer low-level moisture and subsequent buoyancy residing east of the stronger low-level flow. Even so, widespread cloud cover and the gradual loss of daytime heating suggest further weakening of the 0-3km lapse rates and associated CAPE, which is otherwise necessary to promote robust stretching of any low-level streamwise vorticity for TC rain-band tornadogenesis. In addition, the lack of a more favorable buoyancy/shear overlap suggests that any of the more intense cells/rain bands that can become established will likely struggle to obtain strong, sustained low-level rotation. As a few cells/bands may acquire brief, transient low-level rotation at least a few times through the evening hours, a brief tornado or two cannot be completely ruled out. Nonetheless, the expected brief and localized nature of any tornado threat that materializes precludes the re-issuance of an additional Tornado Watch.

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