There exist some notable differences between these two disparate types of la nina events. Here are a couple of schematics outlining these differences:
Differences between east-based La Nina's & central-based La Nina's
Figure A is east-based. Figure B is central-based
DJF 500mb for East-based years:
DJF Temps
Ironically in east-based years JFM is colder than Dec. Dec is typically the warmest month in the
east-based years, which runs counter to typical cold ENSO climo.
JFM 500mb east-based years
JFM Temps
Compare all of that to central-based La Nina years:
DJF 500mb
DJF Temps
December is the coldest month for central-based Nina's.
One thing worth noting is not all East-based Nina's are frigid, as there is variability due to the relatively weak
ocean-atmosphere coupling. This is because many east-based events, as is the case with modoki el nino events, are
weaker. You can have warmth, especially if the event is weaker, and one such case is 2005-2006.
Likewise, there were some weak modoki events that were fairly cold across the eastern US, such as 2000-20001.