CSU Qualitative Discussion on the 2014 Atlantic hurricane season

[TropicalAnalystwx13]

Abstract:

 

We are providing a qualitative discussion of features likely to impact the 2014
Atlantic basin hurricane season rather than a specific numbers forecast. This outlook for
2014 will give our assessment of the probability of four potential scenarios for Net
Tropical Cyclone (NTC) activity.

We have developed a new way of assessing next year’s activity in terms of two
primary physical parameters:

1. the strength of the Atlantic thermohaline circulation (THC)
2. the phase of ENSO

We have been in an active era for Atlantic basin tropical cyclones since 1995
(despite the quiet season that occurred in 2013), and we expect that typical conditions
associated with a positive Atlantic Multi-Decadal Oscillation (AMO) and strong
thermohaline circulation (THC) will continue. One of the big challenges for 2014 is
whether or not El Niño will develop for the 2014 hurricane season. Since El Niño has not
occurred since 2009, the odds of an El Niño this year are fairly high. In addition, many
of the global models are hinting at the possibility of El Niño developing next year. While
we saw a significant weakening of the Atlantic Multidecadal Oscillation (AMO) and
thermohaline circulation (THC) during the summer of 2013, North Atlantic SST and sea
level pressure patterns have since rebounded to conditions characteristic of an active era.
We anticipate that the 2014 Atlantic basin hurricane season will be primarily determined
by the strength of the THC/AMO and by the state of ENSO.

 

For the 2014 hurricane season, we anticipate four possible scenarios with the

probability of each as indicated on the next page:
 

1. THC circulation becomes unusually strong in 2014 and no El Niño event occurs
(resulting in a seasonal average net tropical cyclone (NTC) activity of ~ 180) –
15% chance.

2. THC continues in the above-average condition it has been in since 1995 and no El
Niño develops (NTC ~ 140) – 35% chance.

3. THC continues in above-average condition it has been in since 1995 with the
development of a significant El Niño (NTC ~ 75) – 40% chance.

4. THC becomes weaker and there is the development of a significant El Niño (NTC
~ 40) – 10% 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

 

http://typhoon.atmos.colostate.edu/Forecasts/2013/dec2013/dec2013.pdf