In Numbers 16:16 the main verb connected with מחר is היו which is Qatal:
ויאמר משה אל קרח
אתה וכל עדתך היו לפני יהוה
אתה והם ואהרן מחר.
Randall Buth responded:
Fact: Num 16.16 heyu היו 'be ye' is not the qatal.
the qatal would have been heyiytem 'you were' הייתם.
Why is היו not qatal? It does not require the waw for the meaning. It is the
main verb connected with מחר.
If you would want to insert הייתם in that verse, you would have to add a waw
("conversive" - pardon me...) והייתם and you would get:
ויאמר משה אל קרח
אתה וכל עדתך והייתם לפני יהוה
אתה והם ואהרן מחר.
that והייתם would be wayyiqtol - it makes no sense and has no example in the
Bible.
So, clauses with maHar 'tomorrow' never have wayyiqtol' as
the main verb, but they can have 'qatal' as in Num 16.16 heyu היו 'be ye'.