F/EF Scale Ratings By Time Of Day

Below is a graph showing tornado ratings by time of day for tornadoes from 1950-2010.  I've broken it down into six 4 hour time intervals for simplicity.  The graph is fairly self explanatory but there are a few things worth mentioning.  I decided to use Z time since Indiana lies in 2 time zones.  Secondly, this graph is only as accurate as the times given in the NCDC/SPC databases.  Thirdly, some tornadoes were not rated especially prior to the 1970's.  Those tornadoes are shown as "F?"  Finally, each tornado was grouped based on the START time of the tornado.  For example, a tornado starting at 1750z and ending at 1815z would be classified in the 1400z-1759z timeframe.





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Here are the same data as above in text form:


0200z-0559z:

F?:  6
F0/F1:  95
F2/F3:  64
F4/F5:  4

0600z-0959z:

F?:  0
F0/F1:  24
F2/F3:  28
F4/F5:  0

1000z-1359z:

F?:  3
F0/F1:  33
F2/F3:  19
F4/F5:  0

1400-1759z:

F?:  1
F0/F1:  63
F2/F3:  10
F4/F5:  0

1800z-2159z:

F?:  11
F0/F1:  223
F2/F3:  105
F4/F5:  13

2200z-0159z:

F?:  19
F0/F1:  370
F2/F3:  130
F4/F5:  15