User:Mobius Gerig/2023 October mass cyclogenesis

Between October 17 to October 29, there has been several tropical cyclone formations, most of which strengthening into hurricane-strength storms. Due to the numerable cyclonic storms, this user page will document these occurrences. Along with this, every major tropical cyclone that occurs at this time will have its section from their respective article here.

Hurricane Tammy
On October 11, the NHC began monitoring a tropical wave located just offshore of west Africa. Showers and thunderstorms associated with the disturbance became more concentrated and better organized on October 14, but nearby dry air infiltrated the system, suppressing convection to some degree. Later, when environmental conditions became more conducive, thunderstorm activity within the disturbance was able to become more organized on October 17. The following afternoon, satellite imagery indicated a well-defined low-level surface circulation, prompting the NHC to designate the system as Tropical Storm Tammy. Despite having a sheared appearance due to light to moderate westerly vertical wind shear, hurricane hunter data indicated that Tammy was strengthening as it moved quickly westward through record-warm waters towards the Leeward Islands on October 19. The storm's inner core became better organized the following morning. Radar imagery showed that strong convection had quickly evolved into a curved band, and a closed eye. Meanwhile, aircraft data showed that its central pressure had fallen quickly, and sustained winds increased. As a result, the storm was upgraded to a Category 1 hurricane. Later, Tammy passed to the east-southeast of Guadeloupe, and then at 01:15 UTC on October 22, made landfall on Barbuda at its initial peak intensity of 85 mph. It pulled away from the Leeward Islands throughout the day, though heavy rains still impacted the islands. After weakening to a minimal hurricane while struggling against wind shear for a couple of days, Tammy began to strengthen on October 25 due to increasing upper-level divergence associated with a deep-layer trough. Later that day, it intensified into a Category 2 hurricane and reached its peak intensity with sustained winds of 105 mph. Shortly after peaking, Tammy then began to interact with a front to its north, which caused the hurricane to begin its transition to an extratropical cyclone. Tammy then merged with the front and transitioned into a strong extratropical cyclone early on October 26. The next day, however, Tammy became detached from the front, and redeveloped into a tropical storm. Not long afterward, environmental conditions began to deteriorate and strong vertical wind shear and dry air entrainment quickly stripped the storm of its convection and caused it to weaken. Tammy was then declared post-tropical again on October 29.

Barbuda and Antigua both received minimal damage, though blackouts occurred across both islands. At least two families on Barbuda had to be evacuated. Among the islands of Guadeloupe, only La Désirade experienced hurricane force winds. There were no reports of serious storm damage. Rainfall amounts across the Leeward Islands were between 4 and 8 in, and storm surge heights were between 1 and 3 ft. Bermuda was impacted with wind gusts of 40 mph.

Hurricane Norma
An area of low pressure formed south of the southern coast of Mexico on October 15, producing disorganized showers and thunderstorms. The showers and thunderstorms associated with the disturbance gradually became better organized as it moved parallel with the southwestern coast of Mexico, and by the afternoon of October 17, had developed enough to be classified as Tropical Storm Norma. Norma quickly intensified, and by the following morning was generating intense inner-core convection. Consequently, a ring of very cold cloud tops had formed around its center, within which a ragged eye had emerged. Norma then rapidly intensified from a high-end tropical storm to Category 4 hurricane by the next morning. During the 24hour period ending 15:00 UTC on October 19, its maximum sustained winds rose from 70 mph to 130 mph. Later, moderate wind shear caused the system to weaken below major hurricane strength as it approached the southern end of the Baja California peninsula on the morning of October 21. Shortly after 20:00 UTC, the storm made landfall with sustained winds of 80 mph about 15 mi west-northwest of Cabo San Lucas. Several hours later, after weakening to tropical storm strength, Norma moved offshore over the Gulf of California. There, strong wind shear enabled dry mid-level air to penetrate the circulation from the northwest, weakening the system to a tropical depression as it approached the coast of Sinaloa. The depression made a second landfall at about 16:30 UTC on October 23, near El Dorado, Sinaloa, and soon degenerated into a remnant low.

Norma brought large waves, flooding and high winds to Baja California Sur. Over 4 in of rain during its passage in some areas. Multiple wind gusts of more than 90 mph (with a peak gust of 107 mph) were recorded a weather station high in the hills surrounding Cabo San Lucas. Numerous streets and canals across La Paz flooded as the storm passed through. Also, the gusty winds blew down numerous trees damaged numerous sailboats along the city's coast. Resorts and hotels in Los Cabos Municipality suffered little damage from the storm. Due to the storm's impact on roads and other public infrastructure elsewhere, the governor of Baja California Sur issued a disaster declaration. Norma dumped heavy rains and caused widespread power outages in Sinaloa as it came ashore as a tropical depression. Three people died in the state, including two in vehicle-related accidents and a 3-year-old child due to electrocution. Broken glass, fallen trees and damage to homes and business was reported, mainly in the municipalities of Los Mochis, Ahome and Guasave.

Hurricane Otis
On October 18, a broad area of low pressure formed south of the Gulf of Tehuantepec. It drifted there for a few days before becoming a tropical depression on the morning of October 22. Then, that afternoon, it strengthened into Tropical Storm Otis about 500 mi (805 km) south-southeast of Acapulco, Guerrero. This was followed by a period of explosive intensification on October 24, during which Otis unexpectedly grew into a powerful 160 mph Category 5 hurricane. Otis strengthened slightly more, and at 06:25 UTC on October 25, made landfall near Acapulco at peak intensity with winds of 165 mph and a central pressure of 923 mb. Otis quickly weakened inland, becoming a tropical storm by 18:00 UTC and dissipating soon thereafter.

The hurricane caused at least 49 deaths and left 26 others missing. Total damage from Otis was estimated to be billions of dollars (2023 USD), with several agencies estimating more than 10 billion USD. Coparmex estimated that repairs would cost between $11.5–17.2 billion ($200–300 billion MXN), which would make it the costliest tropical cyclone (Atlantic or Pacific) on record for Mexico. According to Reuters, Mexican business groups estimate damage at $16 billion as of November 17, 2023.

Extremely Severe Cyclonic Storm Tej
On 16 October 2023, the India Meteorological Department (IMD) began monitoring the potential for a formation of a cyclonic circulation in the Arabian Sea. In Arabian Sea, the relatively higher sea surface temperature, pointing to positive Indian Ocean Dipole, created the favourable condition for the formation of cyclogenesis. A cyclonic circulation formed over the Arabian Sea on 16 October. A low-pressure area formed as a result of the cyclonic circulation on morning of 18 October. It intensified into Depression on 21 October. At the same day, the system intensified into Cyclonic Storm, received the name Tej. As it moves northwestward, Tej was in warm waters of Arabian Sea, rapidly intensified into a Category-3 tropical cyclone on October 22. The storm later weakened and made landfall over Al Mahrah Governorate of Yemen between 23 and Oct 24, 2023, bringing significant rainfall and flooding across the eastern half of the country and western parts of Oman.

Torrential rain on Saturday caused flooding on the island of Socotra as the cyclone made landfall. The flooding led to some roads in the governorate's capital city of Hadibu being cut, along with other areas in the archipelago. The Socotra Airport recorded 13 mm of rain, with wind speeds reaching 25 knot and gusts exceeding 25 knot.

Very Severe Cyclonic Storm Hamoon
On October 21, Tropical Depression 06B formed in the Bay of Bengal. It was upgraded to a Cyclonic Storm on October 23, receiving the name Hamoon. On October 24, Hamoon intensified into a category 2-equivalent cyclone, reaching its peak intensity on October 24, with sustained winds of 120km/h (75 mph) and gusts of 140 km/h (85 mph).

As the system lashed the country, five people were killed in total as Hamoon crossed the Cox's Bazar and Chittagong coasts. Hundreds were left homeless as their homes were severely damaged, while trees were uprooted, and electric poles are down.

In India, several districts of Tamil Nadu are expected to experience heavy rainfall for the next two days as cyclonic storm Hamoon is anticipated to further intensify. A yellow warning has been issued for six districts in the state.

Severe Tropical Cyclone Lola
On October 19, the Fiji Meteorological Service (FMS) reported that Tropical Disturbance 01F had developed out of an area of low pressure, about 700 nmi to the northeast of Honiara in the Solomon Islands. At this time the system located in an area favourable for further development, with warm sea-surface temperatures of 30-31 C and low to moderate vertical windshear. Over the next couple of days, the system gradually moved southwestward before the FMS classified it as a tropical depression. The cyclone drifted southward until an upper-level ridge forced the storm to the south. During the next day, it intensified into a Category 1 tropical cyclone, with the FMS naming it as Lola. Lola rapidly intensified into a Category 4 intensity was reached by 12:00 UTC that day, with Lola exhibiting maximum ten-minute sustained winds of 95 kn. With convective rain bands wrapping into the circulation, the JTWC assessed Lola as having one-minute sustained winds of 115 kn. At the same time, the FMS followed suit and upgraded the system to a Category 5 severe tropical cyclone. Lola's eye quickly disappeared, signaling a phase of rapid weakening. Lola made landfall in Sowan, at around 03:00 UTC on October 25. During October 26, Lola degenerated into a tropical depression, before it was last noted the next day and the JTWC issued their final advisory on the storm.

Tropical Cyclone Lola was the third severe tropical cyclone to impact Vanuatu during 2023, after Cyclones Judy and Kevin impacted the island nation during March 2023. Vanuatu Prime Minister Charlot Salwai took a Royal Australian Air Force to inspect the early damage. At least 10,000 households have been affected by the storm. Additionally, the New Zealand, Australian, and French defense forces will provide further aid and assess damages. In Solomon Islands, the Solomon Islands National Disaster Management Office (NDMO) reported that Cyclone Lola had severe impacts on Tikopia.