Tropical Storm Dorian intensified into the second hurricane of the 2019 Atlantic hurricane season Wednesday afternoon after multiple reports of hurricane-force winds were reported in St. Thomas. Dorian is likely to continue to intensify, perhaps rapidly, over the next few days and could threaten the southeastern United States, especially Florida, as a very dangerous major hurricane. The exact track remains uncertain, but Florida appears to be at the highest risk right now.

Dorian becoming a major concern, especially for Florida

As of 2:00 p.m. Wednesday, Hurricane Dorian was centered near 18.3°N 65.0°W, and was moving northwestward at 13 mph. Maximum sustained winds were 65 knots (75 mph), with an estimated minimum pressure of 997 mb. Dorian has been tracking east of previously predicted, largely as a result of a center reformation on Tuesday that allowed Dorian’s circulation to avoid significant disruption by Hispaniola or Puerto Rico. Dorian has developed an open eyewall, but a reconnaissance aircraft has yet to observe a significant pressure fall, indicating that Dorian has not begun to deepen rapidly yet. The eye feature has been intermittently visible on satellite imagery.

While Puerto Rico and Hispaniola were likely spared of the worst of Dorian, Dorian is currently battering the U.S. Virgin Islands and is becoming a major threat to the United States. The SHIPS model predicts that Dorian will be traversing over warm waters above 29°C (84.2°F), light wind shear (less than 15 knots), and mid-level relative humidity values expected to increase to above 60% in about 48 hours. This is a nearly ideal environment for intensification, and rapid intensification is likely with Dorian at some point over the next three days. While the National Hurricane Center’s official forecast predicts that Dorian will peak as a Category 3 hurricane, it remains a distinct possibility Dorian could even attain Category 4 strength. With a building high pressure ridge to the north of Dorian, Dorian should turn more to the west on Saturday, possibly passing through the northern Bahamas as a major hurricane. Florida is at the greatest risk for a hurricane threat at the moment, but the exact landfall location remains highly uncertain and it is still not out of the question Dorian could turn to the north either inland or offshore. Wednesday’s 12z GFS model showed a more northern solution, with Dorian making landfall in northeastern Florida. The ECMWF model showed a more southern solution, with landfall in southern Florida and Dorian emerging into the Gulf of Mexico thereafter. It should be noted that landfalls in northeastern Florida are relatively rare, so that may give more support to the ECMWF solution. However, it should be stressed the exact track remains quite uncertain at this range. Interests in the Southeastern United States from Florida all the way to the Carolinas should closely monitor Dorian. Residents along the northern Gulf Coast should also monitor Dorian in case it tracks into the Gulf of Mexico.

Erin weakens to a tropical depression

Tropical Storm Erin, the fifth named storm of the season, has weakened to a tropical depression and is no threat to land. As of 11:00 a.m. Wednesday, Tropical Storm Erin was centered near 33.6°N 72.8°W, and was moving north-northwestward at about 13 mph. Maximum sustained winds were 30 knots (35 mph), with an estimated minimum pressure of 1008 mb. Erin should dissipate or become post-tropical very soon due to strong wind shear.