On Jan 1, 8:17*pm, (justme2)
wrote:

The gap isn't in the height between the threshold and the storm door, but
the depth between the threshold and the storm door. *It's like we need the
threshold to be extended outwards another inch.
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snip

"It's like we need the threshold to be extended outwards another
inch.

From where I'm typing I can't see how your threshold is constructed/
installed, but perhaps you could rip a piece of wood and tack it to
the front of the existing threshold (or riser below) the threshold to
fill the gap.

How did this happen anyway? Did the old storm door fit correctly? If
so why doesn't the new one?