It appears that they just said, "anything west of the Susquehanna gets a watch, anything east doesn't". I guess it's just the DMZ for this storm. I mean, it seems a bit lazy to me. Take Shamokin Dam and Sunbury, or Harrisburg and Enola for example. Both areas are in the 3-6 range and are practially neighbors divided by the river. Shamokin Dam (Enola) has a WSW and Sunbury (Harrisburg) do not.