March 1st is just a few days away and with it the beginning of Meteorological Spring. Which runs from December 1st through February 28th. It certainly looks like mother nature has different plans for the eastern half of the country in particular the Southeast.
For the past week or so there have been hints of it and now it appears very likely winter is going out with a bang. The long-range guidance as well as the climate teleconnections all point to some of the coldest air of the season coupled with a very active storm track.
The first part of the equation is the Arctic Oscillation and the North Atlantic Oscillation. When these 2 indices are negative the east coast gets cold and stormy weathe
It’s not always full proof but combined with the long-range numerical models they hold more weight than normal here. Below is the ECMWF forecast along with the analyzed NAO. If this verifies this would be the lowers of the entire season. Below tat is the AO from the GFS model.
NAO North Atlantic Oscillation:
AO Artic Oscillation:
Why is the NAO important? It indicates high latitude blocking in the North Atlantic. Which is just a persistent high pressure area at about 500mb usually near Greenland. It forces cold air back into the lower 48 states east of the Rockies. It also promotes a trough over the East coast and the Southeast. This is basically your setup for low pressure to form in the Gulf of Mexico and move up the east coast.
This pattern is reflected in the numerical guidance or weather models quite well. Both the GFS and ECMWF show a huge dip in the Jetstream over the eastern U.S. by this weekend. In fact the 540 line(blue dashed line) or what is usually considered the rain/snow line is well down into the Gulf of Mexico.
The temperatures by this weekend into next week will be extremely cold for early March.
Plus it looks like this cold pattern maybe sticking around for a while. The long-range climate models show most of the Southeastern U.S. to have a month of March about 2-3° below average for the entire month. Below is the monthly temperature outlook for March 2013.
This is always the first question I get when posting about upcoming patterns. The honest answer is I’m not sure yet. All I can say is the pattern is very conducive for winter storms in the Southeast. You still need things to line up just right for some March snow. I should point out though early March snow is not that uncommon around here. In fact for Charlotte March is almost as snowy as December. So stay tuned!