SKYWARN™ Recognition Day (SRD) will take place this year on Saturday, December 2 from 0000Z until 2400Z (starts on the evening of Friday, December 1, in US time zones). During the SKYWARN Special Event, hams will set up stations at National Weather Service (NWS) offices and contact other radio amateurs around the world.
Participating Amateur Radio stations will exchange a brief description of their current weather (rainy, windy, partially cloudy, etc.) with as many NWS-based stations as possible on 80, 40, 20, 15, 10, 6, and 2 meters plus 70 centimeters. Contacts via repeaters are permitted.
From The ARES E-Letter for November 15, 2017