Okay that's neat. It was interesting watching how the misery changes as the storms roll through watching something like DAL which is easy to see the effects. The cascade effect on cities without storms reminds me of how auto traffic slow downs from an accident continue to linger even though the blockage has cleared.
Most of the time the red fills in counter-clockwise. Until it is over 50%, then the red fills in clockwise.
Lots of the map circles actually represent MULTIPLE airports. But they still "represent" them with a three letter code. Sometimes by the largest airport (ORD, SFO), sometimes by a non-airport code (NYC), and sometimes by the second largest (DFW is larger that DAL).
Just as a fun fact, there are IATA airport codes that designate cities instead of airport for purposes like this. NYC is one of them. So is YTO (Toronto) or CHI (Chicago, which should probably replace ORD).
