fci wrote:Is it getting late for CV storms to develop?
It is getting late, but not too late for a reasonable chance for something to form. However, it is getting pretty late for one to form and later hit the lower 48 of the U.S. For the period 1851-2006, here are the exact dates of FORMATION (TD+) for the 45 CV storms* that later hit the lower 48:
7/5, 7/11, 7/15, 7/31, 8/3, 8/3, 8/5, 8/7, 8/7, 8/15, 8/15, 8/16, 8/16, 8/17, 8/17, 8/18, 8/19, 8/20, 8/20, 8/21, 8/23, 8/25, 8/25, 8/27, 8/28, 8/28, 8/29, 8/29, 9/2, 9/3, 9/4, 9/6, 9/6, 9/7, 9/8, 9/10, 9/10, 9/10, 9/10, 9/11, 9/15, 9/16,
9/21, 9/21, 9/25 *My def. of CV storm: tropical storm/hurricane that first became at least a TD E of 50W and S of 20N
So,
156 years of history clearly show a sharp peak on 9/10 and only three after 9/16.
Here are some stats for
9/15+ formations:
- From 1851-2006, there were 36 CV storms that formed within the interval of 9/15-9/25.
- Five later hit the lower 48 and all five were majors at some point along their trek. Here are their formation dates: 9/25/1893 (storm #9 hit SC), 9/21/1966 (Inez hit FL), 9/16/1985 (Gloria hit NC to NE), 9/15/1998 (Georges hit FL keys and MS), and 9/21/2002 (Lili hit LA)
- So,
five of 36 (13%) 1851-2006 CV storms that formed 9/15-9/25 later hit the U.S.
- This compares to ~19% for the entire hurricane season.
- So, the
chances for a lower 48 hit from any one CV storm that forms 9/15-25 are ~2/3 as high as they are for CV storms that form throughout the season as a whole. That makes sense since it is more difficult to make it across the Atlantic by this point in the season vs. earlier. But each still has about a 1 in 8 chance, a nontrivial chance of hitting the lower 48.
