User:Hurricane Noah/Tropical Storm Carlotta (2018)

Tropical Storm Carlotta was a tropical cyclone that caused flooding in southwestern Mexico. Carlotta formed as the result of a breakdown in the Intertropical Convergence Zone to the south of Mexico. On June 12, the National Hurricane Center (NHC) reported that a broad area of low pressure had formed several hundred miles south of southeastern Mexico. The NHC continued to track the disturbance over the next couple of days as it drifted northward. After having increased in organization, the system was designated as a tropical depression on June 14. Late on the next day, the system strengthened into a tropical storm, after which it was named Carlotta. On June 16, Carlotta slowed down and unexpectedly stalled within a favorable environment, which led to more intensification than originally anticipated. Early on June 17, Carlotta reached peak intensity with maximum sustained winds of 65 mph (100 km/h) and a minimum central pressure of 997 mbar (29.44 inHg). Soon after, Carlotta began to interact with land and experience wind shear, which resulted in the system weakening to tropical depression status later in the day. Carlotta weakened to a remnant low early on June 19 and dissipated several hours later.

Carlotta prompted the issuance of multiple watches and warnings for the southern coast of Mexico.

Meteorological history
Tropical Storm Carlotta formed as the result of a breakdown in the Intertropical Convergence Zone to the south of Mexico, however, a tropical wave that crossed over Central America around June 11 may have contributed to Carlotta's formation as well. On June 12, the National Hurricane Center (NHC) reported that a broad area of low pressure had formed several hundred miles south of southeastern Mexico. The NHC continued to monitor the disturbance over the next couple days as it drifted northward. Initially, strong upper-level winds prevented organization, but by the next day, conditions had become marginally conducive. The system thereafter increased in organization, resulting in the formation of a tropical depression by 18:00 UTC on June 14. Around that time, the NHC forecasted that a mid-level ridge over Mexico would break down on the next day, leaving the depression in an area of light steering currents. Despite being located in an environment with low-to-moderate wind shear and sea surface temperatures exceeding 30 C, the depression experienced minimal change in intensity over the next 18 hours. The NHC later reduced its intensity forecast as the system's center had reformed further north, decreasing the amount of time until landfall. Around 18:00 UTC on June 15, the system strengthened into a tropical storm, after which it was assigned the name Carlotta.

Early on June 16, Carlotta's forward motion began to fluctuate, changing from northeast to southeast in six hours. Carlotta began to intensify at 06:00 UTC as it stalled off the coast of Mexico. Twelve hours later, the cyclone began moving in a northerly direction. At 00:00 UTC on June 17, Carlotta reached peak intensity with maximum sustained winds of 65 mph (100 km/h) and a minimum central pressure of 997 mbar (29.44 inHg). Around that time, the NHC noted that the system's structure had improved significantly, with a contracting eye and more symmetric eyewall. Soon after, Carlotta began to weaken due to increasing interactions with land and northerly wind shear. Meanwhile, the system had begun tracking towards the northwest. Around 18:00 UTC, Carlotta weakened into a tropical depression after lacking organized deep convection for several hours. Over the next day, Carlotta continued to weaken before degenerating into a remnant low on June 19 at 00:00 UTC. In the NHC's last discussion on the Carlotta, it was noted that the system's upper-level circulation had decoupled entirely and was drifting towards the southwest. Carlotta's remnants dissipated approximately six hours later.

Preparations and impact
On June 14 at 21:00 UTC, a Tropical Storm Watch was issued for Tecpan de Galeana to Punta Maldonado. Six hours later, the watch was upgraded to a Tropical Storm Warning. On June 15 at 15:00 UTC, the Tropical Storm Warning was extended to Lagunas de Chacahua. Six hours later, the warning was discontinued for Tecpan de Galeana to west of Acapulco. On June 17 at 03:00 UTC, the warning was extended westward from Acapulco to Tecpan De Galeana and canceled to the east of Punta Maldonado. At 09:00 UTC, the warning was discontinued east of Tepac de Galeana and extended westward to Lazaro Cardenas. The Tropical Storm Warning was cancelled at 18:00 UTC, after Carlotta weakened into a tropical depression.

Tropical Storm Carlotta caused severe flooding in southwestern Mexico, with the states of Michoacán and Guerrero being impacted the most.

In Michoacán, multiple cities along the coast experienced severe flooding. In Melchor Ocampo, a peak rainfall total of 285.0 mm (11.22 in) was reported. Approximately 210.6 mm (8.29 in) of rain fell in La Villita, while 194.9 mm (7.67 in) was recorded in Presa La Villita.