I’m hearing rumblings out there that you can’t get sustained cold across Indiana without a negative Arctic Oscillation (AO) and/ or negative North Atlantic Oscillation (NAO). I would ask those with that belief to please explain the following:
January temperature anomalies month-to-date show widespread cold (even accounting for the January thaw the past week).
The first two weeks of the month were downright frigid and this was in the face of an AO that was not just positive, but strongly positive.
To take this a step farther, the recent relative warmth has come with a negative AO.
Bottom line is that a ton of drivers are trying to take the wheel this winter. Admittedly, that makes things incredibly difficult for forecasting- short-term or longer range. That said, coming out with a “blanket statement” that you can’t have sustained cold without a negative AO or NAO is a flat-out lie and we wanted to address it. Teleconnections can help many times with coming weather patterns, but not always. This winter is a prime example of that.
Quick note on the clipper system- all forecast models today have taken the primary impacts (at least from a snow standpoint) north of the immediate region (central Indiana). Heaviest snows are favored across the Great Lakes, extending down into northern IN. We’ll continue to keep a close eye on things…