Though model consensus is quite divergent over the next 120-240 hours, it looks almost certain that well-defined Tropical Disturbance 13 will become a depression and likely a tropical storm before it reaches the eastern Caribbean Islands over the next 24 hours. If the storm strengthens as expected, Depression 3 could become Tropical Storm Bertha by tomorrow afternoon (July 30).
Formation of Bertha would be slightly ahead of climatological average. Like Hurricane Arthur which developed on July 1, eight days ahead of seasonal averages, should Bertha form tomorrow it will be two days ahead of seasonal averages which lists Aug. 1, as the typical development date of the second named storm.
The storm had a drop-off in overall rain shower and thunderstorm activity overnight, and even flirted a bit with the Saharan dust—which can often put a kibosh on not only a single storm but on the entire season—but the disturbance is expected to push on. ImpactWeather’s TropicsWatch Meteorologist Derek Ortt gives the storm a 90% chance of reaching tropical storm status.
What next? The storm will eventually turn northwest and, after crossing the central or northern islands of the eastern Caribbean, likely move north and out to sea. Ortt is quick to point out two things. First, at this time of year the models tend to turn a storm northward too quickly. Meaning, when the models suggest crossing the the northern regions of the Caribbean Islands, the central islands should remain alert for a more southern track. Additionally, the long-range models suggest a location anywhere from east of the United States coastline, to east of Bermuda—a distance of potentially 800-1,000 miles. In terms of the long-range forecast, Ortt states that interests along the eastern coastline of the U.S. and even the eastern Gulf of Mexico should continue to monitor the progress of this developing storm.
Overall there have been no significant changes to the seasonal forecast for the Atlantic Basin. Early predictions were for a quiet season, or one with fewer named storms and hurricanes than is typical for an Atlantic storm season, and that remains the case. However, when interviewed for Houston Public Media’s News 88.7 FM yesterday (link), ImpactWeather’s TropicsWatch manager and lead hurricane forecaster, Chris Hebert, said, “The Gulf of Mexico is going to be one of those areas that’s a little bit more favorable for development this season because it’s going to be so unfavorable further south. We have to watch it: We could see two or three named storms form in the Gulf and maybe a hurricane or two in the Gulf of Mexico this year.”