A subset of storm watchers, these are people who derive enjoyment from watching and being in storms that involve hail. The "clatter" is the sound of the hail hitting roofs and other metal or wooden objects.
NOAA predicted a big thunderstorm here. You know the clatterati are going to be coming out in droves!
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People who write online, be it blogs, comments on articles or other Internet writing. The style of writing is at once witty and informed. Clattering on the keyboard irreverently, yet still having a literati message of import. The word is a portmanteau of "clatter" and "literati".
Gloria would write amusing yet informative talkback comments on the newspaper's website, believing herself to be a distinguished member of the clatterati.