page_title: Tropical Storm Luke (1991)
section_title: Meteorological history
hierarchical_section_title: Tropical Storm Luke (1991) / Meteorological history
caption_attribution_description: Saffir-Simpson Hurricane ScaleTDTS12345 English: Tropical Storm Luke 1991 track. Uses the color scheme from the Saffir-Simpson Hurricane Scale.
context_page_description: Tropical Storm Luke, known in the Philippines as Tropical Storm Pepang, was a short-lived tropical storm that brushed Japan during September 1991. Tropical Storm Luke formed from a disturbance that moved through the Northern Marianas and became a tropical depression on September 14 just to the west of the islands. The depression began to slowly intensify as it moved towards the west-northwest and Tropical Storm Luke was named on September 15. Luke reached peak intensity prior to recurving to the northeast and weakening due to increased shear. Tropical Storm Luke then paralleled the southeastern Japan coastline before transitioning into an extratropical cyclone. Overall, 12 people were killed and 23 others were injured. A total of 225 houses were destroyed while 52,662 others were flooded. There were reports of 644 landslides and roads were damaged at 418 locations. Rivers crested at 18 spots and six bridges were washed away. Greater than 40 domestic flights were cancelled. A total of 103 bullet trains were cancelled and 160 others delayed between Tokyo and Osaka, which left 315,000 people stranded.
context_section_description: An area of disturbed weather that would later become Tropical Storm Luke was first noted by the Joint Typhoon Warning Center (JTWC) early on September 13. The disturbance was upgraded into a tropical depression by the Japan Meteorological Agency (JMA) the following morning. As the disturbance tracked west-northwestward, passing near Saipan, improved upper-level anticyclonic outflow and falling surface pressures led to the issuance of a Tropical Cyclone Formation Alert at 11:30 UTC on September 14. At 18:00 UTC, the JTWC designated the system Tropical Depression 20W, based on synoptic data that indicated the disturbance developed a closed surface circulation. At the time of the upgrade, the depression's structure resembled that of a monsoon depression, with a ring of 55 km/h (35 mph) winds surrounding a large area of light and variable winds, indicating a broad and ill-defined circulation. Early on September 15, the JTWC upgraded the depression into Tropical Storm Luke, with the JMA following suit six hours later.
  The cyclone continued to slowly intensity over the next 48 hours as it tracked west-northwestward. On September 17, satellite imagery indicated that the circulation had become less defined and the overall system had lost organization. Despite this, the JTWC increased the intensity of the storm to 95 km/h (60 mph), its peak intensity. Meanwhile, the JMA upgraded Luke into a severe tropical storm. At 18:00 UTC, the JMA estimated that Luke reached its peak intensity of 105 km/h (65 mph). Luke turned north-northwestward, only to make a turn to the east as a midtropospheric trough caused the subtropical ridge, which had been holding the system to a westward track, to recede eastward. Meanwhile, the vertical wind shear caused by westerlies increased, causing Luke to transition into an extratropical cyclone. The JTWC issued its final warning at noon on September 19, with the JMA declaring Luke extratropical that evening. It was last noted late on September 21.
caption: Map plotting the track and the intensity of the storm, according to the Saffir–Simpson scale
exif: {}