It's kind of funny, in a sad way, that some JWs are going to the kind of extreme emergency preparedness measures that you mention.
I suppose, in the wake of Hurricane Katrina, the Indonesian tsunami, major earthquakes, etc., that JWs are readying for the Great Tribulation™ - the WTS has always focused on the Composite Sign™ as pointing to The End™ being near.
I've never heard of it all happening in the space of 3 days though. That seems really strange to me - only 3 days of supplies, like water and food?? A 72-hour kit is what Emergency Preparedness organizations recommend, but for The Great Tribulation™?? Really??