 Good morning, I'm Mark Lewis. Mike Chikaitis is our producer. The top story we're following, our extreme summer heat is not letting up. An excessive heat warning goes into effect today at noon for the immediate D.C. area. A heat advisory is in effect for the rest of the region. It'll once again feel like we're in the triple digits. We asked National Weather Service meteorologist Eric Taylor what that agency considers before issuing weather advisories and heat warnings.