Tropical Depression Nineteen-E (2018)

Tropical Depression Nineteen-E
Tropical depression (SSHWS/NWS)
19E 2018-09-19 1830Z.jpg
Nineteen-E making landfall in Baja California Sur on September 19
FormedSeptember 19, 2018
DissipatedSeptember 20, 2018
Highest winds1-minute sustained: 35 mph (55 km/h)
Lowest pressure1002 mbar (hPa); 29.59 inHg
Fatalities12 direct, 2 indirect
Damage> $296 million (2018 USD)
Areas affectedBaja California Sur, Northwestern Mexico, Arizona, New Mexico, Texas, Oklahoma, Arkansas
Part of the 2018 Pacific hurricane season

Tropical Depression Nineteen-E was a weak yet very costly tropical cyclone that caused significant flooding throughout Northwestern Mexico and several states within the United States in September 2018. The storm was also the first known tropical cyclone to form over the Gulf of California. Nineteen-E originated from a tropical wave that left the west coast of Africa on August 29 to 30. It continued westward, crossed over Central America, and entered the northeastern Pacific Ocean by September 7. It then meandered to the southwest of Mexico for the next several days as it interacted with a mid-to-upper level trough. The National Hurricane Center (NHC) continued to track the disturbance for the next several days as it traveled northward. A surface trough developed over the Baja California peninsula on September 18. Despite disorganization and having close proximity to land, the disturbance developed into a tropical depression in the Gulf of California on September 19, after having developed a circulation center and more concentrated convection. The system peaked with maximum sustained winds of 35 mph (55 km/h) and a minimum central pressure of 1002 mbar (29.59 inHg).

One day after forming, the depression quickly deteriorated and dissipated after making landfall in Sonora. Overall, the depression affected eleven Mexican states, with torrential rainfall and flooding ensuing in Baja California Sur, Sinaloa, and Sonora. Thirteen individuals were killed in Chihuahua, Sinaloa, and Sonora, and over $40 million USD in agricultural losses were recorded. Excessive rainfall led to the inundation of at least 300,000 structures in Sinaloa. Flood damage there is estimated to be in the hundreds of millions (USD). Remnant moisture from Nineteen-E led to severe flooding within the U.S. states of Arizona, Texas, Oklahoma, and Arkansas and the death of one person. Damage estimates totaled about $250 million (USD) in the aforementioned states. Minor damage was also reported in New Mexico.

Meteorological history

Map plotting the track and the intensity of the storm, according to the Saffir–Simpson scale

Tropical Depression Nineteen-E's origins can be traced back to a tropical wave that departed from the west coast of Africa in between August 29 and 30. On August 31, it generated Tropical Depression Six, which would later become Hurricane Florence.[1] The wave continued to track westward at low latitudes, leaving Florence behind in the far eastern tropical Atlantic Ocean. The wave eventually moved over Central America and crossed into the far northeastern Pacific Ocean by September 7. The wave then slowed down and leisurely moved westward, south of Mexico for the next week or so. Meanwhile, a mid-level shortwave trough dropped southward from the United States, entering Mexico on September 9. The trough continued to track southward for the next few days and a low- to mid-level low developed just south of the southern tip of the Baja California peninsula on September 12.[1] Around that time, the NHC noted the system had potential for future tropical development.[2] The low moved southwestward for the next several days. The trough and a plume of moisture rushed northward towards the Baja California peninsula just as the tropical wave was arriving. An area of low pressure formed several hundred miles south of the southern coast of Mexico on September 14 at 12:00 UTC.[3] A surface trough with a north-to-south orientation developed over Baja California Sur on September 18 with thunderstorms having developed from the deep tropics to the Gulf of California.[4][1]

The disturbance moved into the Gulf of California on September 19.[5] A circulation center and more concentrated convection formed along the trough. Despite stronger wind shear and its proximity to land, the disturbance consolidated into a tropical depression around 12:00 UTC. The genesis of Nineteen-E was unexpected, having occurred after the NHC had downgraded the 5-day formation chance to low. The NHC stated that Nineteen-E was the first tropical cyclone to have formed over the Gulf of California based on records dating back to 1949.[1] Six hours later, the depression's maximum sustained winds peaked at 35 mph (55 km/h).[1] Around that time, the NHC noted that banding features had become slightly more defined and an area of strong convection was present in the eastern semicircle.[6] At 00:00 UTC on September 20, the depression's minimum central pressure decreased to 1002 mbar (29.59 inHg). Around 03:00 UTC, Nineteen-E made landfall between the cities of Ciudad Obregón and Guaymas in Sonora.[1] After moving ashore, the rugged terrain of Sonora quickly weakened the depression. Six hours after landfall, the NHC noted that the depression's convection had taken on a more linear look and that it had lost its closed surface circulation.[7] The NHC reported that Nineteen-E dissipated around 12:00 UTC that day.[1] Nineteen-E's remnants continued to travel northward, while causing severe flooding in Mexico. After entering the United States, the remnants tracked eastward and drew in moisture from the Gulf of Mexico, causing flash flooding in several states.[8]

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