2011 North Atlantic Hurricane Season

I presented my 2011 North Atlantic Hurricane Season forecast at the 2011 Umass-Lowell student research symposium on April 25, 2011.  My forecast calls for 15 named storms, 9 hurricanes, and 6 major hurricanes.  That would mean less named storms and less hurricanes than 2010,  but more major hurricanes.  I also predict 3 to 5 hurricane landfalls in the United States.  Realizing this is a bold claim, here is why I believe in a high impact Hurricane season.

Analog's


First and foremost, what is an analog?  An analog is a past year with similar conditions to 2011.  I have identified  seven analog year's, 1950, 1955, 1985, 1989, 1996, 1999, and 2008.  These years, like 2011, featured a weakening La Nina.  La Nina occurs when the waters of the central Pacific Ocean cool a few degree's below average.  2010 featured a strengthening La Nina, just like 1949, 1954, 1984, 1988, 1995, 1998, and 2007.  2009 was an El Nino year, which is the warming of the equatorial Pacific waters (opposite of La Nina).  1948, 1953, 1983, 1987, 1994, 1997, and 2006 were also under the influence of El Nino.

To sum it up, there appears to be a connection between hurricane season's that go from El Nino, to strengthening La Nina, then to Weakening La Nina in a 3 year span.  Not all these analog's are equal however.  The Atlantic Ocean varies between a warm, or positive phase, and a cool, or negative phase.  The Atlantic Multidecadal Oscillation (AMO) was positive from 1925-1965, and 1995-present.  The AMO was negative 1966-1994.  Named Storms, Hurricanes, and Major Hurricanes all increase when the AMO is positive.  The Pacific Ocean has a similar pattern of sea surface temperature variability.  The Pacific Decadal Oscillation (PDO) was negative from 1947-1976, and 2007-pres.  The PDO stayed positive from 1977-2006.

El Nino's dominate in positive phases of the PDO, while La Nina's dominate in negative phases of the PDO.

Influence of La Nina/El Nino to North Atlantic Hurricanes


During an El Nino event, Hurricane activity in the Atlantic Ocean is suppressed as vertical wind shear (changes in wind speed with height) tends to dominate the tropical Atlantic.  Wind Shear tears apart thunderstorms and does not allow tropical cyclones to strengthen.  In a La Nina, these winds lessen and allow for deep tropic storm formation and activity is increased.  Many New England Hurricanes come from storms born in the deep tropics. 

Analyzing the Analog Seasons


1950- A record setting season, to say the least.  There were 13 named storms, a staggering 11 of which became Hurricanes, and an even more staggering 8 of those became major Hurricanes which is still the North Atlantic record for most Major Hurricanes in a single season.  Keep in mind satellites were not tracking storms yet, so its possible (probable) that  there were more storms of tropical storm strength missed by forecasters at the time.  Two hurricanes struck South Florida, both at major Hurricane strength.  New England was brushed by two Hurricanes, and one of them, Hurricane Dog killed 12 people and caused 2 million dollars (1950 USD, 18.2 million 2011 USD) in property damage.

1955- This featured 13 named storms, 11 hurricanes, and 6 major hurricanes.  Three hurricanes struck North Carolina causing millions of dollars in damage and rasing flood levels to near record levels.

1985- Though the AMO was negative, 11 named storms developed, with 7 becoming Hurricanes and 3 of those hurricanes were major.  What stands out about 1985, and why it is an analog of mine, is that six hurricanes struck the United States.  Hurricane Bob (not that Bob!) struck South Carolina, Hurricane Gloria struck North Carolina and then New England.  Central Massachusetts was on the strong side of Glorida as it passed to the west.  Four additional Hurricanes struck the Gulf coast.

1989- Much like 1985 in terms of activity, with 11 named storms, 7 hurricanes, 2 major hurricanes.  3 hurricanes struck the United, two hitting Texas and then the big daddy, Hurricane Hugo striking the South Carolina coast.  Hugo struck as a category 4 hurricane and was the costliest Hurricane in US history at the time (now 8th due to inflation, coastal population increases, and the AMO returning to its positive phase).

1996- 13 named storms, 9 hurricanes, 6 major Hurricanes.  Hurricanes Bertha and Fran each struck North Carolina.  Bertha continued all the way up the coast into New England, though it weakened to a tropical storm by the time it crossed into the region.  Hurricane Edouard threatened Cape Cod and is responsible for my interest in Hurricanes and the weather.

1999- 12 named storms, 8 hurricanes, 5 major Hurricanes.  Three Hurricanes struck the United States, one in  Texas, one in south Florida, and yes you guessed it, one in North Carolina.  Hurricane Floyd killed 57 people, mainly in North Carolina and brought epic rains and wind to New England as it continued up the coast and passed directly through Central Massachusetts.

2008- 16 named storms, 8 hurricanes, 5 major hurricanes.  Three hurricanes struck the United States, all in Texas/Louisiana.  Hurricane Hanna had a North Carolina/New England target, but it stalled over Hispaniola and affected the region as an intense tropical storm.  I remember being in college and playing volleyball outside during the storm late at night during the storm...but that's enough story telling.

Conclusion 


In averaging these numbers together, looking at the current set up in the world's ocean's, I believe a high impact Hurricane Season is on the way.  The western Gulf of Mexico region, south Florida,  the Carolina's, and yes New England are all in potential danger this year as they all were hit time after time in my analog seasons .  The weather in 2011 has been wild to begin with, with blizzards, floods, droughts, and tornadoes.  Remember, before the June 1 Springfield tornado the last major one was in 1953.  Our weather is continuing to show striking similarities to the 1950's.  Analog forecasting is not all that popular, but the results of my research are too much to ignore.

  • Texas-                                                            5     Hurricane Landfalls
  • South Florida                                                  4     Hurricane Landfalls
  • North Carolina/South Carolina                          9     Hurricane Landfalls
  • Rest                                                               3     Hurricane Landfalls

I'll have a detailed post on New England hurricanes in the near future, but the fact of the matter is the region is due for a direct hit from not only a hurricane, a major hurricane.

So here you have my forecast and my rational for an active Hurricane season.  Share my thoughts with anyone you know living along a coastline, its much better to make a plan now than 2 days before a major storm is barreling towards the coastline.  Thanks for reading and I know this is a long and may be hard to understand, so leave any questions or comments below and I'll do my best to answer them.

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