page_title: Tropical Storm Ileana (2018)
section_title: Meteorological history
hierarchical_section_title: Tropical Storm Ileana (2018) / Meteorological history
caption_attribution_description: English: Track map of Tropical Storm Ileana of the 2018 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: Tropical Storm Ileana was a small tropical cyclone that affected western Mexico in early August 2018, causing multiple deaths and flooding. The eleventh tropical cyclone and ninth named storm of the 2018 Pacific hurricane season, Ileana originated from a tropical wave that the National Hurricane Center began monitoring on July 26 as the wave left the west coast of Africa. The wave traveled across the Atlantic Ocean with no thunderstorm activity, before crossing into the Eastern Pacific Ocean early on August 4. Rapidly developing, the disturbance organized into a tropical depression on the evening of the same day. Initially, the depression was well-defined, but it soon degraded due to northerly wind shear. Despite the unfavorable conditions, the system began to strengthen on August 5, becoming Tropical Storm Ileana. A day later, on August 6, Ileana began to develop an eyewall structure as it reached its peak intensity with winds of 65 mph and a pressure of 998 mbar. The storm gradually became intertwined with the nearby Hurricane John; over the next day, the circulation of John disrupted Ileana before ultimately absorbing it on August 7.
context_section_description: The origins of Ileana can be traced back to a tropical wave that departed from the west coast of Africa on July 26. The wave had virtually no convection as it crossed over the Atlantic. Once the wave entered the Eastern Pacific Ocean early on August 4, thunderstorm and convective activity rapidly increased. The National Hurricane Center (NHC) first noted the potential for development on August 3. After satellite imagery indicated that an area of low pressure had formed a few hundred miles south of the Gulf of Tehuantepec and was showing signs of organization, the NHC raised the system's two-day development chances to 50% around 17:00 UTC on August 4. Only an hour later, at 18:00 UTC, the system was designated as a tropical depression while located about 230 mi (370 km) south-southeast of Puerto Angel, Mexico. Around that time, the depression had a well-defined low-pressure center and a pronounced, arced band of deep convection. Six hours later, the structure of the depression had degraded due to northerly wind shear caused by the stronger disturbance that would later become Hurricane John. The low-level center of the depression had become exposed in the northwest as it moved out from under the edge of the convection; simultaneously, convection decreased in the east and south. The depression was traveling west-northwest under the influence of the aforementioned disturbance, which was located to the west, and a mid-level ridge located to the east. Despite the disruptive wind shear, the depression then began to strengthen, becoming Tropical Storm Ileana on August 5 at 12:00 UTC. At that time, Ileana had a fairly symmetrical structure and a central dense overcast-like feature.
  Ileana continued to strengthen over the next day after entering an area with warm sea surface temperatures of 86 to 88 °F (30 to 31 °C). Ileana reached peak intensity on August 6 at 12:00 UTC with maximum sustained winds of 65 mph (100 km/h) and a minimum central pressure of 998 mbar (29.47 inHg), while located approximately 115 mi (185 km) southwest of Acapulco. Around the same time, Ileana had strong deep convection with cloud temperatures of −121 to −130 °F (−85 to −90 °C). Soon after, microwave imagery and Acapulco radar showed the emergence of an eyewall structure at the mid-levels of the system. By 21:00 UTC on August 6, Ileana had become increasingly intertwined in the outer bands of Hurricane John to the west as the two systems began to experience the Fujiwhara effect. The nearby Sierra Madre Mountains further disrupted Ileana's circulation center. The storm was completely absorbed by John at 12:00 UTC on August 7, just west of Cabo Corrientes.
caption: Map plotting the track and the intensity of the storm, according to the Saffir–Simpson scale
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