page_title: Hurricane Marty (2015)
section_title: Meteorological history
hierarchical_section_title: Hurricane Marty (2015) / Meteorological history
caption_attribution_description: English: Track map of Hurricane Marty of the 2015 Pacific hurricane season. The points show the location of the storm at 6-hour intervals. The colour represents the storm's maximum sustained wind speeds as classified in the Saffir–Simpson scale (see below), and the shape of the data points represent the nature of the storm, according to the legend below. Saffir–Simpson scale Tropical depression≤38 mph≤62 km/h Category 3111–129 mph178–208 km/h Tropical storm39–73 mph63–118 km/h Category 4130–156 mph209–251 km/h Category 174–95 mph119–153 km/h Category 5≥157 mph≥252 km/h Category 296–110 mph154–177 km/h Unknown Storm type Tropical cyclone Subtropical cyclone Extratropical cyclone / Remnant low / Tropical disturbance / Monsoon depression
context_page_description: Hurricane Marty was a tropical cyclone that produced heavy rains and flooding in several states in Southwestern and Western Mexico. The twentieth named storm and twelfth hurricane of the annual hurricane season, Marty developed from a tropical wave on September 26, 2015 to the southwest of Acapulco, Guerrero, in Mexico. Initially a tropical depression, the system strengthened into a tropical storm early on the following day. Due to favorable atmospheric conditions, Marty continued to intensify, but wind shear sharply increased as the storm approached a large mid- to upper-level trough. Despite this, the cyclone deepened further, becoming a hurricane on September 28 and peaking with sustained winds of 80 mph shortly thereafter. Wind shear quickly took its toll on the hurricane, weakening it to a tropical storm early on September 29. About 24 hours later, Marty degenerated into a post-tropical low pressure area offshore Guerrero. The low further degenerated into a trough later on September 30, and eventually dissipated on October 4.
  In anticipation of the storm, tropical cyclone warnings and watches were issued in the states of Guerrero and Michoacán.
context_section_description: A tropical wave emerged into the Atlantic Ocean from the west coast of Africa on September 10. Tracking westward, the wave split into two portions, with the slower-moving northern portion ultimately developing into Atlantic Tropical Depression Nine on September 16. The southern portion crossed Venezuela and Colombia and emerged into the Pacific, where a large area of deep convection began to form. A well-defined low pressure area developed on September 26, and organized into a tropical depression by 18:00 UTC (1 p.m. CDT) the same day while situated about 335 mi (540 km) southwest of Acapulco, Guerrero. Six hours later, after banding features became more defined and intensity estimates using the Dvorak technique showed a slight increase in intensity, the depression was classified as a tropical storm and was accordingly named Marty by the National Hurricane Center (NHC). At the time, the storm was moving slowly northward due to the influence of a large mid- to upper-level trough.
  Located in a favorable environment of sea surface temperatures around 86 °F (30 °C) and low vertical wind shear, Marty strengthened steadily. Early on September 27, the NHC noted that rapid intensification was possible. However, as Marty neared the base of the trough, westerly vertical wind shear increased rapidly, causing the low-level circulation center to be partially exposed. Despite the hostile wind shear, the cyclone reformed a central dense overcast and intensified into a hurricane by 12:00 UTC (7 a.m. CDT) on September 28, as a mid-level eye feature was seen in microwave satellite imagery. Operationally, the NHC upgraded Marty to a hurricane nine hours later, after a reconnaissance aircraft flight observed hurricane-force winds. At 18:00 UTC, Marty attained its peak intensity with maximum sustained winds of 80 mph (130 km/h) and a minimum barometric pressure of 987 mbar (hPa; 29.15 inHg). Computer forecast models indicated that the storm would pass within just 25 mi (40 km) of the Southwestern Mexican coast on September 29 or September 30.
  Turning north and northeast while under the influence of the aforementioned trough, Marty began to weaken soon after peak intensity as deep convection was displaced to the east due to the strong westerly shear; the low-level circulation center became fully exposed in a span of three hours late on September 28. Upwelling of cooler waters further decayed the deep convection, prompting the NHC to downgrade Marty to a tropical storm at 06:00 UTC (1 a.m. CDT) on September 29. Continuing to steadily weaken, Marty degenerated into a post-tropical low a day later about 140 mi (225 km) west-southwest of Acapulco, while still producing gale-force winds. The shallow system turned westwards in the low-level flow and eventually opened up into a trough twelve hours later about 195 mi (315 km) west of Acapulco. The low became closed once again on October 1, however, it failed to produce sufficient organized deep convection to re-qualify as a tropical cyclone. It turned north-northeastwards towards the southern Gulf of California, however it dissipated before reaching the coast of Western Mexico. The remnant moisture continued into Northwestern Mexico and caused flooding in Sonora.
caption: Map plotting the track and intensity of the storm according to the Saffir–Simpson hurricane wind scale
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