#10 Postby MiamiensisWx » Fri Apr 04, 2008 2:30 pm
I definitely agree that the SE coast (including the Carolinas) faces greater probabilities of strikes during La Nina seasons. The large number of landfalling tropical cyclones in North Carolina likely indicates higher ACE and more Cape Verde development further east; therefore, this offers greater chances of recurvature depending on the setup as a TC approaches the Southeast. It is not because of a weaker Bermuda ridge; studies have demonstrated that the SE ridge tends to be stronger and further west, especially in moderate or strong -ENSO (Nina) seasons. A negative (-) NAO can also result in a displaced westward Bermuda ridge during the season. The Carolinas are vulnerable because 1) they "stick out" like FL and other regions; and 2) TC cyclogenesis often occurs further east in Nina seasons. Reduced temperature inversions reduces subsidence, allowing convective formation across the basin in multi-year moderate/strong La Ninas.
Your premise that Florida (or any other region) in Nina seasons features a lower risk versus another area is fundamentally flawed. Studies of past Ninas indicate a large percentage of Florida strikes originate from the south and southwest. Caribbean strikes on the state are very common.
Here are some examples from Nina seasons.
1. Isbell 1964 - Cat 2
2. Cleo 1964 - Cat 2
3. Storm #18 (1933) - Brush
4. Irene 1999 - Cat 1
5. Storm #10 (1909) - Cat 3
6. King (1950) - Cat 3
There are many additional cases, too. Storms have also struck FL from the east in La Nina years. 1933 and 1949 (two Jupiter hurricanes) immediately come to the mind.
A strong, west placed Bermuda ridge is a prominent feature in several multi-year moderate/strong Ninas. Why is it "abnormal"? If it didn't exist, storms would recurve long before reaching the Carolinas or Southeast coast.
I think it all depends on the timing and pattern when a TC approaches the coast. Personally, I think FL and the Carolinas are "at risk" this season, in addition to the CONUS from Maine to Brownsville. An above average season (NS) automatically guarantees higher probabilities along the entire Atlantic and Gulf Coasts.
Last edited by MiamiensisWx on Fri Apr 04, 2008 2:56 pm, edited 1 time in total.
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