Frigid winds have returned this winter, but the alerts Iowans receive about cold weather have changed.Starting this season, the National Weather Service will no longer issue wind chill warnings, watches or advisories. The agency will instead issue "extreme cold" watches or warnings and "cold weather advisories."Why the change?For years, the NWS has been trying to simplify the various weather alerts it issues. Remember sleet advisories? Blowing snow advisories? Freezing rain advisories? Those were all eventually lumped into the weather weather advisory.The same concept applies here. No more separate alerts for cold and calm vs. cold and windy.Will the temperature criteria be different?For most of Iowa, no. Until now, wind chill advisories were issued if feels-like temperatures were forecast to drop between -20 degrees and -29 degrees. Cold weather advisories will now be issued at that range. If feels-like temperatures will fall below -30 degrees, an extreme cold warning will now go out instead of a wind chill warning. The only exception is northern Iowa. Counties north of Highway 20 now have slightly colder thresholds than the rest of the state for cold weather advisories and extreme cold warnings. Cold weather advisories will be issued at -25 degrees. Extreme cold warnings will be issued at -35 degrees. The National Weather Service uses different warning criteria in various parts of the country. One of those dividing lines now happens to cross through Iowa.