During mid-August, a huge tropical wave traversed the African Sahel, producing massive amounts of rain in west Africa. This impressive feature emerged over the Atlantic on August 15 and moved quickly westward. The system organized only slowly, hampered primarily by its own large size and competing regions of vorticity on the eastern and western edge of the disturbance. Ultimately, convective activity dissipated in the eastern blob and the western end won out. On August 19, the circulation became defined enough to designate the system Tropical Depression Thirteen.
By that time, the depression was moving rapidly west-northwestward and contending with a bit of dry air to the west. This kept development slow in an otherwise favorable environment with warm air and low shear. During the afternoon of August 20, it became evident that multiple low-level swirls existed in the system as one was ejected northwestward out around of the convective canopy. That swirl ultimately dissipated and the center was hard to locate overnight. Nevertheless, thunderstorm coverage increased some the next day as the depression approached the Leeward Islands. Aircraft reconnaissance found tropical storm force winds during the morning of the 21st, prompting an upgrade to Tropical Storm Laura. Laura was the new earliest "L" storm and surpassed the record of Hurricane Luis, which formed on August 28, 1995 (00:00 August 29 in UTC time).
Despite the upgrade, Laura was disheveled on satellite imagery as its bands brought rain to the northeasternmost Caribbean islands. Some improvement to its structure took place overnight and thunderstorm activity became much more widespread. On August 22, instead of no apparent center, there were two: a low-level one moving on a more southerly track south of Puerto Rico, and a mid-level one which crossed the island and ultimately emerged north of it that afternoon. This separation prevented Laura from strengthening quickly, but its winds nevertheless increased to 50 mph that day. On the other hand, the large-scale circulation of Laura was very vigorous and barely slowed down as it went directly across Hispaniola beginning that evening.
Torrential rainfall occurred in both Haiti and the Dominican Republic over the next day, leading to widespread flooding even though Laura was still moving around 20 mph toward the west-northwest. The cyclone deepened a bit more during the afternoon of August 23 as it emerged over water briefly and began to move close to eastern Cuba. A bit of wind shear out of the north pushed some drier land air into the northern semicircle as Laura passed over the waters between Cuba and Jamaica overnight. During the day of the 24th, the structure began to improve again. The storm moved back over land in western Cuba that evening, but it wasn't long until it emerged into the Gulf of Mexico. Even as it exited land, an inner core began to develop.
Steady strengthening commenced once Laura was over water; it became a hurricane the morning of the 25th. It was still moving west-northwest fairly quickly (though slower than before) and so the main difficulty was moistening the slightly drier air mass it was moving into. Thus the storm had the most difficulty closing an eyewall on the western side. Cold cloud tops eventually wrapped all the way around the center that afternoon. That evening, Laura began an extreme bout of rapid intensification. The storm's outflow became more pronounced and its banding more symmetric overnight as it strengthened to a category 2 hurricane. An eye appeared early on August 26 and Laura became the first major hurricane of the season. It also made a turn toward the northwest as it felt the influence of a trough to the north.
The eye cleared out and became more circular in the afternoon as the ring of cold cloud tops around it widened. Soon, the storm reached category 4 status and completed an increase in winds of 65 mph over a period of 24 hours. At the same time, outer bands swept across the Gulf coast of Louisiana and neighboring states, bringing strong winds and isolated tornadoes. Laura's intensity finally leveled out that evening just before landfall, with winds of 150 mph and a minimum central pressure near 938 mb. Just after midnight local time, the eye came ashore in southwestern Lousiana, bringing tremendous storm surge and wind. Its landfalling windspeed of 150 mph was the highest recorded for a Louisiana hurricane since 1856! Even Katrina had lower winds, though its pressure was lower and storm surge higher. In addition, the inundated area was primarily marshland and much less populated than the area Katrina had impacted 15 years prior.
Laura quickly weakened over land and lost hurricane status during the morning of August 27. Later that day, it moved northward into Arkansas. By this time, the radar presentation had degraded significantly. The system weakened to a tropical depression that evening and began a turn toward the east. It brought rain to Ohio Valley and ultimately the southern part of the mid-Atlantic, but impacts were minor. Laura became post-tropical early on August 29 and soon sped eastward into the open Atlantic.
The above image shows Laura at category 4 intensity on August 26.
Laura passed over nearly all of the Greater Antilles as a tropical storm without significant weakening. Once it was over warm waters, it became one of the fastest intensifying Gulf of Mexico hurricanes on record.
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