As rain swept Britain, only New Road and Edinburgh saw enough play for a team to force victory - and even those games were shortened significantly.
Hales smashed 72 from only 41 balls to ensure Notts, set a Duckworth-Lewis target of 127 in 16 overs, recorded their third win from as many games in the competition.
Gareth Andrew had earlier made an unbeaten 62 from 34 balls for the hosts, who scored 132 for five in a 16-over innings which was interrupted by a 75-minute rain delay.
The other Group A game, between Warwickshire and Sussex, was washed out without a ball bowled as were both games in Group C - Gloucestershire v Middlesex and Glamorgan against the Unicorns.
Essex comfortably beat Scotland by 59 runs in Group B, in a match reduced to 29 overs a side.
Openers Tom Westley (63) and Mark Pettini (47) put on 79, James Foster belted 29 from 15 balls and Sajid Mahmood 20 not out from just five to lift the visitors to 217 for seven in Edinburgh.
Scotland could not get close despite captain Preston Mommsen's unbeaten 70 and 64 from Freddie Coleman as Tim Phillips (three for 21) restricted them to 158 for four.
Only three overs were possible in the other game in the group at Derby, where the hosts reached 12 without loss against Lancashire.
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