RALEIGH, N.C. (WNCN) — The coldest, most persistent Arctic air is moving into central NC this week. Highs won't get out of the 30s until Friday, with lows in the teens expected as well. Factoring in the wind chill, we could dip into the single digits on Wednesday morning.
This Siberian-originating air prompted the National Weather Service in Raleigh to issue a cold weather advisory for tonight into Tuesday morning. This was issued due to expected wind chills potentially dipping below 10°.
Cold weather advisories are a new kind of alert issued by local NWS offices. If it gets cold enough, extreme cold watches and warnings can also be issued. These three products replaced wind chill advisories, watches, and warnings.
Instead of needing a wind chill value to hit a certain value, now, even if there is no wind, cold weather alerts can be issued. If the actual air temperature or the wind chill value is forecast to hit a certain number, the NWS can issue the corresponding alerts.
The criteria for issuing the alerts varies by state, and even by county. Generally, the further north and west that you go, the lower the temperature or wind chill must be for alerts to be issued.
In the Triangle, the criteria for a cold weather advisory is 5°, meanwhile, in the Sandhills, it is 10°. For an extreme cold watch or warning, the criteria is -5° in the Triangle, and 0° in the Sandhills. Watches would be issued farther in advance than warnings would be, just like with hurricanes or tornadoes.