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three consecutive years with a remarkable 19 named storms in the Atlantic
After three consecutive years with a remarkable 19 named storms in the Atlantic, expect another Atlantic hurricane season with similar levels of activity in 2013, says the hurricane forecasting team of Dr. Phil Klotzbach and Dr. Bill Gray of Colorado State University (CSU) in their latest seasonal forecast issued April 10. They call for an Atlantic hurricane season with 18 named storms, 9 hurricanes, 4 intense hurricanes, and an Accumulated Cyclone Energy (ACE) of 165.
The long-term averages for the past 63 years are 11 named storms, 6 hurricanes, 3 intense hurricanes, and an ACE of 103. The active hurricane period that began in 1995 has averaged 15 named storms, 8 hurricanes, and 4 major hurricanes.
The 2013 forecast calls for an above-average chance of a major hurricane hitting the U.S., both along the East Coast (48% chance, 31% chance is average) and the Gulf Coast (47% chance, 30% chance is average).
...
The CSU team cited two main reasons why this may be an active hurricane season:
1) Neutral El Niño conditions are expected during the August - September - October peak of hurricane season. Since the active hurricane period we are in began in 1995, neutral years have seen much above-average activity (remember the neutral El Niño year of 2005?) If El Niño conditions are present this fall, this will likely bring about a quiet Atlantic hurricane season due to increased upper-level winds over the tropical Atlantic creating wind shear that will tend to tear storms apart.
2) Sea surface temperatures (SSTs) in the Main Development Region (MDR) for hurricanes from the Caribbean to the coast of Africa between 10°N and 20°N were near-average in the western tropical Atlantic, but unusually warm in the eastern tropical Atlantic, in March 2013. Much of this unusual warming was due to a persistent negative phase of the North Atlantic Oscillation (NAO) since mid-February (which also brought an unusually cold March to the Eastern U.S. and Western Europe.) A negative phase of the NAO is associated with a weakened Bermuda-Azores High and slower trade winds across the tropical Atlantic. The slower winds allow the ocean to heat up more, due to less mixing of cool water to the surface. Virtually all African tropical waves originate in the MDR, and these tropical waves account for 85% of all Atlantic major hurricanes and 60% of all named storms. When SSTs in the MDR are much above average during hurricane season, a very active season typically results (if there is no El Niño event present.) Conversely, when MDR SSTs are cooler than average, a below-average Atlantic hurricane season is more likely.
http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2381
The long-term averages for the past 63 years are 11 named storms, 6 hurricanes, 3 intense hurricanes, and an ACE of 103. The active hurricane period that began in 1995 has averaged 15 named storms, 8 hurricanes, and 4 major hurricanes.
The 2013 forecast calls for an above-average chance of a major hurricane hitting the U.S., both along the East Coast (48% chance, 31% chance is average) and the Gulf Coast (47% chance, 30% chance is average).
...
The CSU team cited two main reasons why this may be an active hurricane season:
1) Neutral El Niño conditions are expected during the August - September - October peak of hurricane season. Since the active hurricane period we are in began in 1995, neutral years have seen much above-average activity (remember the neutral El Niño year of 2005?) If El Niño conditions are present this fall, this will likely bring about a quiet Atlantic hurricane season due to increased upper-level winds over the tropical Atlantic creating wind shear that will tend to tear storms apart.
2) Sea surface temperatures (SSTs) in the Main Development Region (MDR) for hurricanes from the Caribbean to the coast of Africa between 10°N and 20°N were near-average in the western tropical Atlantic, but unusually warm in the eastern tropical Atlantic, in March 2013. Much of this unusual warming was due to a persistent negative phase of the North Atlantic Oscillation (NAO) since mid-February (which also brought an unusually cold March to the Eastern U.S. and Western Europe.) A negative phase of the NAO is associated with a weakened Bermuda-Azores High and slower trade winds across the tropical Atlantic. The slower winds allow the ocean to heat up more, due to less mixing of cool water to the surface. Virtually all African tropical waves originate in the MDR, and these tropical waves account for 85% of all Atlantic major hurricanes and 60% of all named storms. When SSTs in the MDR are much above average during hurricane season, a very active season typically results (if there is no El Niño event present.) Conversely, when MDR SSTs are cooler than average, a below-average Atlantic hurricane season is more likely.
http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2381
