Negative EPO Fights Back

9:12 PM

The winter pattern is still lingering in the northern branch of the Polar jet stream as we continue to see the continuation of a back and forth game between the North Atlantic Oscillation and the Eastern Pacific Oscillation.  As the negative NAO begins to collapse once again early this coming week, the negative EPO (which had all but disappeared through the end of February and into early March) will make another return.  The latest stratospheric anomaly positions and upper tropospheric wind currents strongly suggest a return to the negative EPO pattern seen through much of the winter.  

While the southern branch of the jet stream will continue to strengthen going forward through March and the overall Polar jet stream begins to reposition northward, the return of the negative EPO pattern will keep a trough over eastern Canada and the northern half of the eastern United States.  

So what does this mean for March?  Well, while the winter storms are all but done for the forecast area given the moderating Polar air mass and the shifting of the Polar jet stream northward, the continuation of colder than normal air masses over the forecast area will remain.  This means that while moderation will slowly take over, especially in the middle of this coming week, the support for a trough in the East will keep the Southeast ridge positioned off the coast and send a parade of cold fronts through the forecast area.  

This pattern also will produce generally dry conditions over the East and limit the potential for strong low pressure systems to bring significant moisture into the forecast area.