Wednesday, September 11, 2013

Season's First Hurricane Misses Record by Hours

Early this morning, Hurricane Humberto formed far out in the Atlantic Ocean.  All weather watchers in Florida were keeping track of whether we'd set a new record for the latest first Atlantic hurricane.  The record holder, Gustav, formed on September 11th, 2002.  Humberto formed about 3 hours earlier in the morning.

Prior to Gustav, Diana formed on September 10, 1984.   The average date for the season's first hurricane is August 10th, based on 1966-2009 averages.  And for the first MAJOR hurricane (Cat 3 or higher), it's September 4th.    Another data point average is that the third hurricane of the season typically develops by September 9th.

Before we get too excited, we need to point to the Weather Channel's data that shows the lack of hurricanes through August does not necessarily mean we're in the clear or will see less storms than predicted.

And as they point out, an  "average" Atlantic hurricane season (1981-2010) would still deliver the following after September 7th and include:
  • 7 more named storms
  • 4 hurricanes
  • 2 major hurricanes
Put another way, 61% of all Atlantic named storms form from September through the end of the season.

And as a disclaimer, the National Hurricane Center chimes in from their Facebook page:

As a number of folks know, we are approaching a record for the latest formation of the season's first hurricane, 
at least in the satellite era. Since 1967, the latest formation of the season's first hurricane was 8 am ET September 11th (Gustav in 2002). As it happens, Humberto is approaching hurricane strength with 8 am on the 11th also just around the corner (to mix a space-time metaphor). So this might be a good time to remind folks that NHC always conducts a post-storm analysis of each tropical cyclone. We usually adjust the final positions and intensities a little bit in this analysis, and sometimes we make substantial adjustments, based on information that we might not have had in real time. 

The point being that regardless of when Humberto might become a hurricane in our advisories, the final final call on whether or not we actually set a record will not be determined until the post-storm analysis is complete, several weeks or perhaps even a couple months from now

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