Looking Ahead to Hurricane Season

Hurricane season runs from June 1 through November 30

Although the Atlantic hurricane season doesn’t begin until June 1, the discussion of the upcoming season is well underway.  Conversations of lessons learned the previous season, as well as seasonal outlooks, begins shortly after the previous season ends.  Hurricane seasons spans half the year through November 30.

While it’s uncommon for tropical storms and hurricanes to develop early or late in the season, there are exceptions.  Tropical systems can also develop outside the hurricane season as happened twice last year.  Hurricane Alex developed in January 2016 and Tropical Storm Bonnie late last May.  That helps illustrate the importance of year round preparation and awareness of tropical storm and/or hurricane development.

While NOAA hasn’t issued a forecast for the 2017 hurricane season yet, the esteemed team of meteorologists at Colorado State University, led by Dr. Phil Klotzbach, recently issued its April update.  The CSU forecast is for a total of 11 named tropical storms, 4 of which will become hurricanes, including two major hurricanes.  That’s slightly below the Atlantic’s 30-year average of 12 tropical storms, 6 hurricanes and 2 major hurricanes.  Unlike a “mid-latitude” system which is a cold core system that is energized by temperature contrasts, a “tropical cyclone” is a warm-core system that requires warm ocean water of sufficient depth to develop.

A tropical cyclone becomes a “tropical storm” when sustained winds reach 39 mph.  Once sustained winds reach 74 mph, the tropical storm is upgraded to hurricane status.  If maximum sustained winds reach 111 mph, than the hurricane becomes “major.”  Hurricane intensity is measured on the Saffir-Simpson Scale that ranges from Category 1 (sustained winds of 74 – 95 mph) to Category 5 (sustained winds of 156 mph or greater).

The overall number of tropical storms and hurricanes that develop in a given season is not significant.  What is important is whether or not any of the systems impact land.  For example, the active 2010 Atlantic hurricane season saw 19 tropical storms and 12 hurricanes but none impacted the United States.  However, the quieter than average 1992 and 1983 seasons saw devastating Hurricanes Andrew and Alicia, respectively.  All it takes is one storm to cause a lot of damage and injury.

NOAA data shows that only seven hurricanes impacted the United States during the ten-year period from 2006 – 2015, a record low.  It’s also interesting to note that no major hurricane has made landfall in the United States since Wilma did in 2005.  However, there have been damaging hurricanes like Matthew last fall, Irene in 2011 and Ike in 2008.  The first named storm of 2017 will be “Arlene.”  A future column will discuss some of the factors involved in seasonal hurricane forecasting.