In our current weather pattern, a ridge of high pressure is dominating in the western US, while a persistent trough of low pressure is in place over the East. While this pattern is in place, the Southeast is experiencing waves of storms moving into the area from the northwest, bringing cold air and the potential for wintry weather. How do we know when the pattern will change?
Here’s a website (GEFS: 35-day North American Regimes | Simon Lee (simonleewx.com)) that is new to me showing the chance of four different patterns in North American weather. Whatever pattern we are in will help determine what kind of weather we have. These are probabilistic forecasts, so one of the less likely patterns does have a chance of occurring, and long-range forecasts are always somewhat uncertain, but this forecast does show that most of the long-range models agree the change is coming. The 35-day projections on this site indicate that our current pattern of an Alaskan ridge is expected to exit by the first week of February and is most likely to be replaced by an Arctic low for most of February. This pattern has low pressure in the western US and high pressure in the East.
If the most likely pattern occurs, that means a return of warmer and moister air to our region for most of February is likely. This could mean trouble for the fruit farmers in areas that received sufficient chill hours because the warm conditions are likely to bring on blooms so early that a frost later in the season is still likely and the crop could be threatened.