Despite continued struggles against wind shear over the past 24 hours, Tropical Storm Earl appears to be gathering steam as it begins its anticipated turn northward some 100 miles north of Puerto Rico and the U.S. Virgin Islands this morning.
An impressive flare up of thunderstorm activity around Earl’s developing core – evident on both satellite and land-based radar from the islands – may signal an attempt by the storm to reorganize farther northeast in the face of blistering wind shear from the southeast. The exact orientation of upper-level winds around the base of a nearby jet stream dip will determine whether Earl will be able to maintain or extend the morning burst of activity. A pivot of upper-winds one way or the other may either act as exhaust for organizing thunderstorms or tear at the reorganizing center.
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Regardless, for Puerto Rico and the U.S. Virgin Islands, Earl is at its closest point of approach today and beginning to feel the pull northward thanks to the previously mentioned jet stream dip. This will turn Earl sharply northward today and tomorrow and keep the core from directly impacting the northern Caribbean islands or Bahamas.
Since the worst of Earl’s weather is north and east of its center, the primary threat to Puerto Rico and the U.S. Virgin Islands will be from trailing rainbands and a tail of moisture from the south, leading to locally heavy rainfall, isolated flash flooding, and the potential for mudslides along steeper terrain, especially early in the week.
Otherwise in the far north Atlantic, Danielle regained hurricane strength yesterday as it meanders over open waters. Some strengthening is possible over the next day or two before it accelerates over the cooler waters of the north Atlantic graveyard.
As we approach the climatological peak of hurricane season this week – what typically marks the height of tropical activity in the Atlantic – the only other system we’re tracking is a tropical wave just off the coast of Africa with a low chance of development for now.
Although the peak of the season occurs around September 10th, strong hurricanes are still quite common afterwards. Of the 37 Category 5 hurricanes on record since 1851 (of 946 total hurricanes), more than half occurred after Sept. 10. And as we’ve discussed in previous newsletters, South Florida’s greatest risk for a hurricane impact comes in October, so we’ll stay vigilant, especially over the next four to six weeks.