I don't know what a "level 4" storm is, but apparently, they expect one tonight in #GA. Actually, I do have an idea: The #NOAA / #NWS / #SPC Storm Prediction Center has sent out #tornado watches in parts of #MS, #AL, #TN, AR, #LA ... so their alerts in Georgia are probably an extension of the same severe #t-storm system. S probably means that an EF4 tornado is possible.

https://www.spc.noaa.gov/