For the central and eastern U.S., including the Gulf Coast, winter has been relatively mild thus far.
There have been some respectable intrusions of arctic air, but they have not been sustained or anomalous.
Taking a look at data from the High Plains Regional Climate Center (see figure 1), temperatures have actually been running above average. This is not all that surprising considering the U.S. just experienced its fifth warmest January on record.
The lack of sustained cold can be at least partially attributed to a strong positive phase of the Arctic Oscillation (AO).
According to a tweet from the Climate Prediction Center, the recent positive phase of the AO has been record breaking.
The most recently observed Arctic Oscillation is the highest daily value in our historical record (6.34), breaking the past record from February 26th, 1990 (5.91). #AO https://t.co/YWilD9lYGu pic.twitter.com/84Vc1pzSnH
— NWSCPC (@NWSCPC) February 10, 2020
When the AO is positive, cold air tends to get locked up in the polar regions.
Looking at the latest long-range model guidance, the AO should remain positive for the remainder of February, and possibly even longer.
This doesn’t mean winter is over. Quick shots of colder air can still be expected. However, a pattern that favors anomalously strong arctic air masses dropping southward into the U.S. is unlikely to evolve any time soon.
