Need help with SigWX symbol

[Pjsmith]

I probably should know this, but then the symbol probably should also be on the table of chart symbols...

What does the square box over the TS symbol mean?

I feel silly even asking.....

 

[MAKG1]

If it's actually a solid dot, it means rain or snow but not hail at time of observation. One would think that the "showers" symbol combined with it would give that information….

 

[Pjsmith]

OK, does the solid round dot then mean the same thing as the solid square? I can't believe that these guys would naturally use two symbols for the same thing.....