LGA Loc31 Approach

[JHNA57]

Can anybody tell me why this approach only seems to be used after a major weather front has moved through the area?
I usually see it after major snowstorms, and even saw it in use yesterday afternoon when the sky was begining to clear.

[AirtrafficController]

Usually this approach is used during the winter time. When there are strong winds from the NW that make the Expressway visual to 31 too difficult, the use the LOC 31 approach. This of course forces Kennedy onto all 31s operations as the LOC 31 intrudes its NE airspace for 22s or 4s runway configurations.