Anthony Phillips Department of Geography Virginia Tech

Reports of straight-line wind damage in Marion, VA might easily have been tornado damage. The supercell had… increasing reflectivities at all tilts, a well-defined inflow notch and shallow v-notch, strong low and mid-level circulation, an overhanging weak echo region (WER), and tightening of the mesocyclone as it passed near Marion.

From radar observations, the SPC meso analyses were correct in predicting the greatest amounts of shear to the north. Strong updrafts and rotation reached over 20 kft near Marion. Shear and rotation didn’t extend much above 10 kft with the Alleghany tornadoes.

A very good correlation exists between mesocyclone strength and tightening of rotation Even though the storm weakened while crossing the high country, it regained strength quickly before tornadogenesis occurred (conservation of potential vorticity) Consider extending Tornado Warnings even if the storm has weakened since: 1) it’s had a history of rotation, and 2) it may likely re-intensify.

Finally…storms could have been even more severe had additional CAPE been present.