The Tropical Meteorology Project at Colorado State University released their initial outlook for the 2013 Atlantic basin hurricane season last Friday, providing four scenarios for how the season may unfurl.
The four scenarios are;
- THC circulation becomes unusually strong in 2013 and no El Nino event occurs (resulting in a seasonal average net tropical cyclone (NTC) activity of ~ 180) – 20% chance.
- THC continues in the above-average condition it has been in since 1995 and no El Nino develops (NTC ~ 140) – 40% chance.
- THC continues in above-average condition it has been in since 1995 with the development of a significant El Nino (NTC ~ 75) – 35% chance.
- THC becomes weaker and there is the development of a significant El Nino (NTC ~ 40) – 5% chance.
Typically, seasons with the above-listed NTC values have TC activity as follows:
- 180 NTC – 14-17 named storms, 9-11 hurricanes, 4-5 major hurricanes
- 140 NTC – 12-15 named storms, 7-9 hurricanes, 3-4 major hurricanes
- 75 NTC – 8-11 named storms, 3-5 hurricanes, 1-2 major hurricanes
- 40 NTC – 5-7 named storms, 2-3 hurricanes, 0-1 major hurricanes
“We have been in an active era for Atlantic basin tropical cyclones since 1995, and we expect positive Atlantic Multi-Decadal Oscillation (AMO) and strong thermohaline circulation (THC) conditions will continue,” said Phil Klotzbach, lead author of the forecast.
“One of the big challenges for 2013 is whether or not El Nino will develop for the 2013 hurricane season. Since El Nino never fully developed in 2012, and we have since returned to neutral conditions, there is the possibility that an El Nino event will develop next year.”
The team will release the first forecast on April 10 with predictions for the number of named storms, hurricanes, and major hurricanes expected for the Atlantic basin. The full initial outlook can be viewed here (pdf).