Tropical Storm Alberto was a damaging pre-season tropical cyclone that caused $125 million in damage to the Gulf Coast of the United States in late May 2018, the costliest for any pre-season tropical cyclone. The first storm of the 2018 Atlantic hurricane season, Alberto developed on May 25 near the Yucatán Peninsula as a subtropical cyclone. As it entered the Gulf of Mexico, Alberto intensified and transitioned into a tropical cyclone. Early on May 28, Alberto reached its peak intensity, with maximum sustained winds of 65 mph (100 km/h) and a minimum pressure of 990 mbar (hPa; 29.23 inHg). Afterward, however, dry air caused Alberto to weaken before it made landfall near Laguna Beach, Florida, with winds of 45 mph (75 km/h). Alberto maintained a compact area of thunderstorms as it progressed through the central United States, entering southern Michigan as a tropical depression on May 31. That day, Alberto weakened further and dissipated over Ontario.
Along its path, Alberto dropped heavy rainfall, mainly to the east of its storm path. In Cuba, storm flooding killed ten people, and also damaged houses, roads and crops. Floodwaters caused an oil spill in Cienfuegos Bay. In the United States, Alberto caused about $125 million (2018 USD) in damage, as well as eight deaths. Five fatalities occurred in North Carolina, three of which were a result of landslides, and the other two from fallen trees. Flooding was responsible for the deaths of three people in Virginia. The storm caused coastal flooding along the United States Gulf Coast, most significantly in Florida where it moved ashore.
Meteorological history
On May 12, a trough moved eastward from Mexico and stalled over the Gulf of Mexico and the Caribbean Sea. By May 20, the trough had rotated into a northwest–southeast orientation, which increased diffluence and contributed to the formation of a broad low pressure area over the northwest Caribbean. Early on May 21, the National Hurricane Center (NHC) first indicated the potential for the low to undergo future cyclonic development. On May 23, the low moved over the eastern Yucatán Peninsula, where its development was impeded due to strong wind shear and dry air. On May 25, the low moved back over the Caribbean Sea and developed a well-defined circulation. That day, the NHC designated the system as a subtropical depression while it was located about 80 mi (130 km) east-northeast of Chetumal, Quintana Roo. The subtropical designation was due to the depression's interaction with an upper-level low, as well as its broad wind field, with multiple low-level circulations evident.
With most of the convection located east of the center, the subtropical depression remained disorganized as it moved northward. On May 26, the center redeveloped under the primary area of convection in the Gulf of Mexico, northeast of the previous weak circulation in the Caribbean. Soon after this structural improvement, the depression intensified into a subtropical storm off the northwest tip of Cuba, and was named Alberto. Operationally, the NHC considered Alberto a subtropical storm from its first advisory in the Caribbean. As Alberto moved parallel to Florida's west coast, a large band of thunderstorms persisted to the east of the storm's center, extending from Florida to Cuba. The thunderstorms concentrated near the center and became more symmetrical, a sign that the storm was transitioning into a tropical cyclone. Alberto became fully tropical by 00:00 UTC on May 28 while nearing the Florida panhandle. Around that time, the Hurricane Hunters observed maximum sustained winds of 65 mph (100 km/h), which would be the storm's peak intensity.