A cold weather advisory was issued by the National Weather Service on Thursday at 1:11 p.m. valid for Friday between midnight and 10 a.m. for Suffolk and Nassau counties. The weather service states, "Very cold wind chills as low as 11 degrees below expected." "The cold wind chills could result in hypothermia if precautions are not taken," says the weather service. Understanding cold weather alertsCold weather advisory: Be Aware. A cold weather advisory is issued when seasonably cold air temperatures or wind chill values, but not extremely cold values, are expected or occurring.