30 September 2010

A New Hurricane Record?

Gary Padgett, writing to a tropical storm list-serv I am on, provides an interesting factoid, which I reproduce here with his permission (emphasis added):
We’re now at the first of October, and there’ve been no Category 3 or higher hurricanes (IH) to make landfall in the U. S. so far this season. The chances of a U. S. landfalling IH decrease significantly after 1 October. Over the past half-century, the only IHs to make landfall in the U. S. after 1 October were Hilda (1964), Opal (1995), and Wilma (2005). Hilda and Opal were already named tropical storms on the map as September ended—the only case forming in the month of October was Wilma.

If an IH does not make landfall in the U. S. during the remainder of this season, this will make five consecutive seasons without an IH landfall in the U. S. The last such instance of this (based upon the current HURDAT file) was 1910 – 1914. However, that being said, some caveats are in order.

(1) The current Saffir/Simpson classification of historical U. S. hurricanes was made by Hebert and Taylor in 1975. The parameter used to classify most of these was central pressure (CP), based on the older nominal CP ranges associated with each category. Nowadays, the S/S classification is based strictly upon the MSW at landfall.

(2) There are several cases, especially in the late 1930s, 1940s, and early 1950s, for which the assigned S/S category does not match the Best Track winds, so when they are eventually re-analyzed, the landfalling category could be adjusted up or down.

(3) Hurricanes Gustav and Ike of 2008 both made their U. S. landfall with an estimated MSW of 95 kts, and with CPs of 957 and 952 mb, respectively. Had these storms occurred in the early 20th century, they would have been classified as Category 3 hurricanes, and barring any reliable wind measurements (which would have been unlikely) would have probably remained classified as such during the re-analysis. Similarly, though not within the past five years, Hurricanes Floyd and Isabel, which made landfall with an estimated MSW of 90 kts and CP around 956 mb, would have been classified as Category 3 hurricanes based on the CP.
Even with the caveats, the US has had a remarkable streak of luck with respect to hurricanes -- or maybe, it's climate change! ;-)

7 comments:

  1. Go back another decade to the '50s. 1954...the only Cat 4 known to hit NC occurred Oct 15th of that year...and went on to kill people all the way north to Ontario Canada. 1954 was an unusual year when drought gripped much of the east coast states and temperatures soared into the 90s in NC through the first week of October.

    ReplyDelete
  2. Heh. I know this drives some people nuts but what does 1910-1914 share with this current time period? Extremely low sunspot activity. Just another coincidence, I'm sure.

    ReplyDelete
  3. When global warming was redefined to climate change, every drought became positive proof. So now we're having a drought of hurricanes? Yep, that's climate change. If extremes are expected, then moderation must be part of change.

    When you go down the road of sophistry, logic drives you to embarrassing dead ends.

    ReplyDelete
  4. re Tornado season:

    Was it {January/February}, this year - the first tornado-free month recorded Stateside?

    Meanwhile, here in Central America, heavy rains are pushing Costa Rica´s solid and other wastes to the Pacific, and landslides left open one route West from the Central Valley. la Nacion website offers coverage.

    ReplyDelete
  5. Mark B - We're not having a drought of hurricanes in the Atlantic. They just aren't hitting the US. Mexico has had it fairly bad, but mostly they got steered to the central Atlantic.

    ReplyDelete
  6. I'm surprised no one has speculated that hurricanes are avoiding the Gulf due to the BP oil spill.

    ReplyDelete
  7. Yet AGW promoters are still out there claiming that storms are in fact increasing.

    ReplyDelete