Do sultry Gulf of Mexico waters mean trouble for hurricane season?
The Gulf of Mexico is getting a jump on summer, seeing its warmest start to the Atlantic hurricane season on record.
Water temperature near Tampa topped 90 F (32ºC) in the first week of June -- about 7 degrees warmer than average for this time of year, and outside even the 90th percentile for the record period.
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While these bathwater-like temperatures don't necessarily mean a potent hurricane season is ahead of us, they do correspond to what forecasters were expecting to see this summer, albeit a bit ahead of schedule.
Weak El Niño conditions in place over the Pacific correspond to a less-favourable environment for storms to form over the central and eastern Atlantic -- a zone known as the main development region (MDR). That lowers the risk for the kind of long-track hurricanes that slowly gain steam as they cross the Atlantic, heading for a Caribbean or North American landfall.
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At the same time, however, hurricane forecasters expected to see warmer coastal waters, and that's just what's playing out in the Gulf as we speak. With plenty of warm water to fuel storm development, this kind of set up does favour storms that rapidly strengthen close to land; so-called "homegrown" storms like last year's Hurricane Michael.
Temperatures at the Clearwater Beach gauge have since dropped down to more typical values and the rest of the Gulf remains several degrees cooler, but nearly the entire body of water has already exceeded the minimum value typically needed to fuel a tropical system (about 26ºC).
Gulf of Mexico sea surface temperatures observed by satellite. Image courtesy NOAA.
While Michael occurred late in the 2018 season, the other storm that took a similar track -- Alberto -- actually jumped the gun on the official start date. Taking advantage of warm gulf waters, Tropical Storm Alberto trekked from the Yucatan to the Gulf Coast in late May 2018. By late July last year, it wasn't just the Florida coast that was bathed in warm water; the central and western Gulf were nearly 2 degrees above average temperature, too.
It remains to be seen if the same will hold true for 2019, but this early temperature spike is not an encouraging sign. The good news is no tropical systems are expected to form through at least the next week. In fact, despite above-average temperatures in the Gulf of Mexico for the past few years, the majority of storms have still formed from August onward for the past 5 years, which corresponds to the average pattern for the season.