I think it's useful. It gives you a quick recap.
Heck, I wonder if they could incorporate it so that when you mouseover the matrix, it shows the forecast?
This is maybe just excessive, but perhaps they could also include a little tiny box below each severe/fire day to indicate how far through the forecast cycle it is or such. A tiny little 2 pixel high meter that goes from totally white (just issued) to totally black (time for a outlook). It could be done in percentage of time elapsed since the standard time that the prior outlook was for until the next one. That would really make things great there, as you could quickly see if a new outlook had been issued.