While the Winter of 2010-2011 had a La Niña, it also saw anomalously negative NAO and AO throughout much of its entirety. Winter 2011-2012 has seen La Niña as well, only as anomalously negative as NAO and AO were last winter, this winter they have been as anomalously positive, and that pattern does not look to break any time soon.
As for the short term, a shortwave is moving through the area triggering some shower activity, albeit of a more scattered nature, and mainly in Tennessee.
Shower activity should continue throughout the day. A more organized and widespread event can be expected over the weekend. The 06Z run of the NAM and GFS have moved the arrival of this system to Saturday as opposed to Sunday, with the NAM being a bit more progressive at 84 hours out than the GFS. The GFS wants to keep the ridging intact with the NAM breaking the ridging down.
As observed on the 84 hour 1000-500mb Thickness/MSLP charts from the 06Z run, the NAM also is more aggressive with the precipitation, as well and has the system being better organized as well. One consensus of the models is that this will definitely be a rain event, as has been the recurring theme of many storm systems over the past several weeks.
