Meteorology student at the University of Oklahoma. Tyler Stanfield is pursuing a career in Tropical Meteorology and Atmospheric Sciences.
By: TylerStanfield , 6:51 AM GMT on February 16, 2014
With the 2014 hurricane season approaching fast, It's that time once again for weather enthusiasts such as myself to assess, and interpret what the 2014 hurricane season may bring this Summer.
Each variable below will have the ability to hinder or enhance the season shown by the following ratings:
Very Favorable, Favorable, Fair, Unfavorable, Very Unfavorable
El Nino Southern Oscillation (ENSO)-
The ENSO is the biggest factor in forecasting a hurricane season. This oscillation is based on the measurement of equatorial Pacific waters, and the conditions of El Nino and La Nina are based on whether the waters in this region are above average (El Nino) or below average (La Nina). As of February 2014, the ENSO was in a slightly below average state (cool neutral), though this is forecasted to flip as many changes are beginning to take shape in the atmosphere that will likely allow the ENSO to be replaced by a warm neutral or El Nino event by the peak of hurricane season. The Pacific Decadal Oscillation (PDO) and Southern Oscillation Index (SOI) are leading the way for the atmospheric changes as both are headed in states that favor El Nino. The PDO has flipped to a positive state for the first time since April of 2010. The symptoms of a positive PDO are above average sea surface temperatures along the southwestern United States coast and Baja peninsula of Mexico. These above average sea surface temperatures aid in developing El Nino events.
Figure 1. Global sea surface temperature anomaly map based on 1982-2010 climatology. Note the cool tongue of below average waters in the equatorial pacific showing the cool neutral in place currently.
If, and this a big IF, this comes to fruition, the El Nino conditions in the Atlantic (Increased shear, dry stable air, and increased trade winds in the deep tropics) would likely result in a complete shutdown of the Atlantic hurricane season in 2014. But if the El Nino manages to be kept at bay, we may see the Atlantic light up with activity at times.
Rating: Very Unfavorable (El Nino)
Much like the past three hurricane seasons, instability is expected to remain below average during the hurricane season. Low instability in the tropics is a large burden for storms as it causes the storm to struggle developing deep convection, and sustaining it. Without deep convection, storms are more susceptible to unfavorable conditions such as dry air and wind shear, which limit the storm's ability to strengthen. With low instability in the forecast for the 2014 season, this will limit the number of named storms, as well as limit the ability of storms that do form to develop into hurricanes and major hurricanes.
Figure 2. Chart of the vertical instability in the tropical Atlantic since the start of the new year.
Wind shear is the winds that occur in the upper levels of the atmosphere. This condition is crucial for storm formation because if upper level winds are too strong, a storm will never be able to build and grow in height because the cloud tops get sheared off and can sometimes result in the complete dissipation of the storm. Though wind shear is difficult to forecast far in advance, especially 3 months and greater, the ENSO has a large impact on how these upper level winds develop through increased convectional outflow from thunderstorms that fire up in this region because of warmer than average waters. If an El Nino were to develop, these stronger upper level winds would prevail in a large way across the tropical Atlantic, while a neutral event would be more lenient. With the rising likelihood of an El Nino event, it also means there is a higher likelihood of strong upper level winds zipping across the Atlantic which will greatly impact the ability for storms to form and strengthen in the tropical Atlantic.
Rating: Unfavorable (El Nino)
Taking the likelihood of an El Nino event occurring, the trade winds will be enhanced and will want to move much faster under a stronger Azores High. If this were to happen, many storms, much like we saw last season, will have issues getting going in the deep tropics of the central and eastern Atlantic because of the trade winds pushing the storm faster than the speed of the mid and upper level winds around the storm, resulting in the circulation of the storm tending to become lopsided and stretched. This will likely cause for storms to dissipate, remain weak and prevent strengthening for many storms that face the trades.
Sea Surface Temperatures in the Atlantic
The Atlantic basin has cooled off significantly since the end of 2013, with the Main Development Region (MDR) fluctuating right at average. This is much different from the past few seasons where the MDR has been above average. With temperatures at average, this will limit the amount of ocean that will be able to sustain a hurricane. Along with the cooling of the deep tropics, the subtropics have significantly warmed. This warming, though it is beneficial for higher latitude storms, disrupts storms that try to develop in the deep tropics because the storm is having to compete with energy to the North where waters are warmer than usual.
Figure 3. Map of Atlantic ocean SST anomalies, and the chart of the MDR SST anomalies.
Overview of the 2014 Season
With the increasing odds of an El Nino event developing by the peak of the 2014 hurricane season, unfavorable conditions will likely plague the storms of the Atlantic basin from start to finish. This will cause a limited amount of hurricanes and major hurricanes to develop during the season and decrease the likelihood of a hurricane landfall. Along with the anticipation of a quieter, below average season, the overall lack of above average surface temperatures in the deep tropics, increased trade winds, and low instability will likely be a large factor in less storms being capable of intensifying and becoming hurricanes and major hurricanes.
That said, you should not keep your guard down. An inactive hurricane season can just as easily have a major hurricane make landfall as much as any other season, and this forecast should not be taken as a reason to write off the season. It only takes one to make a quiet season, a bad season.
My Numbers for the 2014 Hurricane Season
For the upcoming season I foresee nine to twelve named storms, three to six hurricanes, and zero to two major hurricanes. My targeted numbers are ten named storms, three hurricanes, and 1 major hurricane.
9-12 Named Storms (10 Named Storms)
3-6 Hurricanes (3 Hurricanes)
0-3 Major Hurricanes (1 Major Hurricane)
Thanks for reading my February issue of my outlook for the 2014 Hurricane Season. Comments and questions are encouraged!
I will have a new issue of my outlook of the 2014 hurricane season in May.
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