As the Summer of COVID draws to a close, many experts fear an even bleaker fall and suggest that American families should start planning for Thanksgiving by Zoom. Because of the many uncertainties, public health scientists say it’s easier to forecast the weather on Thanksgiving Day than to predict how the U.S. coronavirus crisis will play out this autumn. But school reopenings, holiday travel and more indoor activity because of colder weather could all separately increase transmission of the virus and combine in ways that could multiply the threat, they say.