Table 2. Comparison of the composite synoptic conditions between weak (F0 or F1) tornado events, significant (F2 or greater) tornado events, and outbreak (five or more F2 or greater) tornado events across the southern Appalachian region.

Weak Significant Outbreak
(156 total events) (94 total events) (8 total events)
Surface temperatures (0C) 18.5-20.5 16.5-18.5 18-20
Surface dewpoints (0C) 17-19 15-17 16-18
Surface winds (m s-1) SW 3.5-4.5 SW 5.5-6.5 SW 8.5-9.5
850 hPa temperatures (0C) 12.5-14 11-13 12-14
850 hPa dewpoints (0C) 9-10 8-9 10-12
850 hPa winds (m s-1) SW 10-11 SW 14-15 SW 18-20
500 hPa trough tilt neutral neutral positive
500 hPa winds (m s-1) SW 19-21 SW 26-28 SW 32.5-37.5
250 hPa jet quadrant none right exit right exit
Lifted index -3 -2 -2
Showalter index +3 +1 0

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