Mike Umscheid
EF4
Assuming of course that the HPC map was based on some computer projection.
The chart that Rob posted is an un-official collaboration product produced by the HPC winter weather desk (hidden behind a password protected directory for internal collaboration among HPC and local WFOs). It is typically generated by some blending schemes of various models -- more or less as a baseline "thinking"... I'm not sure how much hand-editing is done to that graphic. The OFFICIAL HPC winter weather forecast products are the probabilistic graphics that are on the main HPC winter weather desk page.