Texts Help US Park Police Beat Heat on the Fourth A new communications service is letting the U.S. Park Police send texts directly to visitors to Washington, D.C., this Fourth of July and warn them to take precautions to deal with the intense heat. A text sent through the new Nixle service Wednesday afternoon urges visitors to drink a lot, slather on the sunscreen and seek shade "to ensure a safe and healthy July 4 celebration." Officials say the temperature is one of their main concerns this year. The heat index on the National Mall was 100 degrees Wednesday afternoon. Thunderstorms threaten to disrupt the evening's Capitol Fourth Concert, but National Park Service spokesman William Line says it takes more than a drizzle to shut down the festivities.