October 2021 nor'easter
The October 2021 nor'easter, which eventually became Tropical Storm Wanda, was an erratic nor'easter and tropical cyclone that struck the East Coast of the United States, and meandered across the northern Atlantic Ocean in early November 2021. The powerful extratropical cyclone affected much of the East Coast, causing significant flooding in areas which were previously affected by hurricanes Henri and Ida. As Wanda, the cyclone was the twenty-first and final tropical cyclone of the 2021 Atlantic hurricane season. The system originated from a non-tropical mid-level trough that moved across the Southern United States on October 24–25, and moved out into the Atlantic, where a well defined area of low pressure formed. This quickly became a bomb cyclone off the East Coast of the United States on October 27, causing flooding and bringing powerful gale-force winds to the region in the process. Then, on October 30, after weakening and moving eastward out into the Atlantic, the system acquired subtropical characteristics and was given the name Wanda. By 12:00 UTC on November 1, the system transitioned into a tropical storm. Over the next several days, Wanda meandering well west of the Azores, before curving southward and then accelerating northeastward, before degenerating into a post-tropical cyclone on November 7, several hours before merging with a frontal system.
The nor'easter caused over $200 million in damage in the Northeastern United States, and two storm-related deaths were reported. More than 600,000 customers across the region were without electrical power at the height of the storm. There were no reports of deaths from Wanda.
Meteorological history
On October 2425, a non-tropical mid-level trough moved across the Southern United States and out into the Atlantic, where a well defined area of low pressure formed. The National Hurricane Center began monitoring the disturbance on October 24, noting that it could potentially develop into a subtropical or tropical cyclone several days later. The extratropical low that produced the nor'easter formed on October 25, about southeast of Cape Fear, North Carolina, when the eastern part of the trough began interacting with the warm waters of the Gulf Stream. The following day, the low proceeded to move northeastward along the U.S. East Coast, ahead of another trough. There it deepened, and its structure improved, as it absorbed another extratropical low over the Northeastern United States, which was located to the west. The nor'easter became a bomb cyclone on October 2627, when its central barometric pressure dropped from to over a 24 hour period. During this time, at 00:00 UTC on October 27, the system also reached its peak strength with sustained winds of, while located about east-southeast of Nantucket, Massachusetts.The nor'easter was making a counterclockwise loop while rapidly intensifying, and when completed, it gradually weakened while moving out to sea. Embedded within a trough as it began moving eastward late on October 27, the NHC rated the five-day probability of it becoming subtropical as low. Late on October 29, the system began acquiring subtropical characteristics, following a flare-up of convection in its northern region. Then, at 12:00 UTC on October 30, Subtropical Storm Wanda formed about south-southeast of Cape Race, Newfoundland. That same day, Wanda's generally eastward movement came to an abrupt stop, and the sheer decreased, which provided an opportunity for it to gain strength. Consequently, it was able to reach its peak intensity with maximum sustained winds of and a minimum central pressure of at 12:00 UTC on October 31.
Though Wanda moved over slightly warmer waters on November 1, it was weakened somewhat due to renewed shear and entrainment of dry air. Nonetheless, the system transitioned into a fully-tropical storm at 12:00 UTC that day, about west-southwest of the Azores. After turning east, then northeast early on November 2, the storm produced a large burst of convection. Several hours later, however, Wanda entrained more dry air, which degraded the convection. On the next day, now following a northerly track, Wanda generated another burst of convection. This brought the storm over cooler waters, where its sustained winds fluctuated between into November 4. Even so, Wanda was able to maintain some convection around its center during this time. Wanda turned southward on November 5, due to a narrow, strengthening ridge to the northwest.
Late on November 6, Wanda began accelerating northeastward, as it began interacting with a larger extratropical cyclone approaching from the west over the northern Atlantic. The resulting wind shear stripped away Wanda's remaining convection, and it became a post-tropical cyclone by 12:00 UTC on November 7, while located about west-northwest of the Azores. Several hours later, the cyclone merged with an approaching frontal system and dissipated.