Note that two the storms you're referring to (Iselle and Julio) may have similar predicted paths, but they currently 1000 miles away from each other, and will definitely not merge. Iselle is already impacting Hawaii, while Julio will not approach for several days (assuming the current forecast verifies).
Both FTDNA and Ancestry sponsor groups or projects where people in the same haplogroup can exchange information and maybe even find an ancient connection. But Y-DNA and mtDNA are intended to check ancient bloodlines, 10,000-50,000 or so years ago. They are not generally useful by themselves for genealogy.
Subgroups have a numeric name which follows the haplogroup name. For example, haplogroup E has two subgroups called E1 and E2. There is also a subgroup E* which belongs to haplogroup E but not either of the defined subgroups. Y-DNA haplogroup is defined as all of the male descendants of the single person who first showed a particular SNP mutation. More information about SNPs at FTDNA. FTDNA also offers Deep Clade tests to confirm your haplogroup assignment and determine where your lineage fits within that haplogroupâs tree.