Last June, Mother Nature threw open the doors to her hurricane season only to find guests would have arrival times diverging so far off traditional paths as to rival the most ardent cocktail party-attending Hollywood diva. With nine named storms already on the books, including the most recent, Tropical Storm Ingrid moving into Mexico and Hurricane Humberto (now Tropical Storm Humberto) in the Atlantic, you would think we’re on track to have an above average season. However, many of us are still pondering the absence of major hurricanes making landfall.
Just shy of setting a new record for the latest hurricane development in a season (the record holder is Hurricane Gustav which formed at 7 a.m. CDT on Sept. 11, 2002), Hurricane Humberto will miss the United States completely as it turns toward the northern Atlantic Ocean. It has since been downgraded to Tropical Storm status. Even on the heels of Tropical Storm Humberto, we are still asking the question: why haven’t we seen more hurricanes?
According to ImpactWeather’s recent State of the Tropics webinar from our Lead Hurricane Forecaster Chris Hebert, the Atlantic season was on track to being above normal with a slightly cooler Pacific Ocean, warmer water in the deep tropics and lower air pressure in the main development region, which are all ingredients to create the perfect recipe for an active hurricane season.
So, what happened? Hebert says that very dry and dusty air across the tropics could be the culprit. Early in the season, the Saharan Air Layer (SAL), which originates in the Sahara Desert in North Africa, pushed above-normal levels of dry air out over the ocean, dampening the possibility of any major tropical storm developments. This summer, the Northern Hemisphere also experienced a band of very dry air in the mid-levels of the atmosphere. Both of these dry air developments combined and created a fool-proof plan to slow down our hurricane season.
Despite the late arrival of hurricanes this year, it’s not time to pack away your hurricane preparedness kit just yet. The amount of dusty, dry air has declined in the past two weeks, meaning development in the second half of hurricane season could kick up and return to normal with additional hurricane formations.
That said, it just takes one storm to put business operations in jeopardy. As we mentioned previously, in 1992, meteorologists foreshadowed a relatively calm season. That year, the first hurricane of the season, Hurricane Andrew, hit in August and caused massive levels of death and destruction throughout the Gulf Coast and Southern Florida.
While history gives us reasons why this season is abnormal, it also gives us a warning to not let our guard down just yet.