Marine Thunderstorm Wind — Vermilion To Avon Point Oh, Lake Erie

2021-10-15 · Vermilion To Avon Point Oh, Lake Erie

Event narrative

The Lorain Harbor C-MAN Station (LORO1) recorded a peak convective gust of 39 mph from nearby outflow-dominant rain showers.

Wider weather episode

A stationary front extended northeastward from the Lower Ohio Valley to western and north-central Ohio, central and eastern Lake Erie, and western New York during the late morning through early evening of the 15th. Simultaneously, one low moved along the front from central Indiana to central Lake Erie. Increased surface convergence along the front, ahead of the aforementioned low, allowed an ongoing cluster of multicell thunderstorms and eventually a supercell to persist generally northeastward as the storms encountered moderate MUCAPE and effective bulk shear, respectively, in north-central Ohio and over central Lake Erie.

The surface front and associated horizontal wind shear were probably a rich source of surface-based vertical vorticity. Surface-based effective storm-relative helicity of 100 to about 150 meters squared per second squared and low mixed layer LCL heights near 750 meters AGL resided along the front. All these factors indicated a favorable environment for tornadoes. As the supercell paralleled the front over Lake Erie, it managed to produce several waterspouts as its updraft ingested preexisting surface-based vertical vorticity, stretched the surface-based vertical vorticity to tornado-strength via low-level convergence, and then advected the vorticity upward several times. Moderate DCAPE likely contributed to some storms producing gale-force peak wind gusts along the southern lakeshore.

Source: NOAA Storm Events Database, event_id 986033. Narrative written by the NWS forecast office that issued the report.