Typhoon Dolphin (2015)

From Wikipedia, the free encyclopedia
Jump to: navigation, search
This article is about the 2015 tropical cyclone. For other storms of the same name, see Typhoon Dolphin.
Typhoon Dolphin
Typhoon (JMA scale)
Category 5 (Saffir–Simpson scale)
Dolphin 2015-05-16 0530Z.png
Typhoon Dolphin just before peak intensity on May 16
Formed May 6, 2015
Dissipated May 24, 2015
(Extratropical after May 20)
Highest winds 10-minute sustained: 185 km/h (115 mph)
1-minute sustained: 260 km/h (160 mph)
Lowest pressure 925 mbar (hPa); 27.32 inHg
Fatalities None
Damage $10 million (2015 USD)
Areas affected Caroline Islands, Mariana Islands
Part of the 2015 Pacific typhoon season

Typhoon Dolphin was a powerful tropical cyclone that impacted the Mariana Islands, specifically Guam and the Northern Mariana Islands, in mid-May 2015. Forming as the eighth tropical depression of the annual typhoon season, Dolphin was first recognized as a tropical disturbance on May 3 over the eastern Caroline Islands. The system was upgraded to a tropical depression three days later, until it was classified as a named tropical system on May 9. Subsequently, the typhoon underwent rapid deepening to a Category 5 super typhoon. Afterwards, the typhoon began to weaken.

Meteorological history[edit]

Map plotting the track and intensity of the storm according to the Saffir–Simpson hurricane wind scale

Late on May 4, the Joint Typhoon Warning Center (JTWC) began monitoring an area of deep convection approximately 300 km (185 mi) southwest of Pohnpei.[1] Although the attendant low-level circulation was ill-defined, microwave imagery revealed several fragmented rainbands wrapping into the center of the disturbance, and environmental conditions were expected to favor further development over the coming days. Drifting east-northeastward, the disturbance steadily organized as shower and thunderstorm activity continued to coalesce about a broad area of low pressure, and the JTWC issued a Tropical Cyclone Formation Alert early on May 6 as a result.[2] At 12:00 UTC that same day, the Japan Meteorological Agency (JMA) highlighted the formation of a tropical depression approximately 300 km (185 mi) southwest of Pohnpei.[3] As low-level banding continued to become better defined, the JTWC initiated advisories on Tropical Depression Seven at 21:00 UTC.[4] Following formation, the depression turned eastward, steered by westerly flow along the equator. Deep convection continued to develop over the low-level circulation, albeit limited to the northwest quadrant due to persistent wind shear, prompting the JTWC to upgrade the system to a tropical storm at 15:00 UTC on May 8.[5] At 12:00 UTC the next morning, the JMA followed suit, designating the cyclone as Tropical Storm Dolphin.[6]

Upon being upgraded to a tropical storm, Dolphin executed a turn to the north-northwest under the influence of a building subtropical ridge to the cyclone's north.[7] Although moderate southeasterly wind shear initially hindered further organization, a track parallel to the shear vectors mitigated the unfavorable effects, allowing an eye feature to become visible on microwave imagery by early on May 11.[8] Upper-level outflow began to expand toward the north and south as upper-level winds slackened and a persistent central dense overcast feature developed over the low-level center.[9] At 00:00 UTC on May 12, the JMA upgraded Dolphin to a severe tropical storm,[10] while the JTWC upgraded the cyclone to a typhoon.[11] By 06:00 UTC on May 13, the JMA further upped Dolphin to a typhoon.[12] Amid a continued favorable environment, a pinhole eye approximately 10 km (6 mi) to 19 km (12 mi) in diameter became evident on satellite imagery, leading the JTWC to upgrade Dolphin to the equivalent of a Category 2 hurricane on the Saffir–Simpson hurricane wind scale (SSHWS) by 15:00 UTC.[13][14] Continuing on a general west-northwest to northwest track, the intensification trend was soon halted by a combination of moderate southerly wind shear and dry air from the west, causing the eye to become obscured on conventional satellite imagery.[15] On May 15, vertical wind shear once again lessened; tight low-level bands wrapped into a large 51 km (32 mi) eye, prompting the JTWC to upgrade Dolphin to an upper-end Category 3 equivalent on the SSHWS.[16] The overall structure of the cyclone continued to improve, and by 03:00 UTC on May 16, it harbored 1-minute sustained winds of 185 km/h (115 mph). This rapid deepening process continued, and 24 hours later, the JTWC upgraded Dolphin to a Category 5 super typhoon, the third super typhoon of the season. After maintaining that intensity for 12 hours, Dolphin weakened to a Category 4 super typhoon. Six hours later, it weakened to a Category 4 typhoon after maintaining super typhoon intensity for 30 hours. Over the next few days, Dolphin weakened further, until the JTWC issued its final warning on May 19. However, the JMA still tracked Dolphin as a tropical system until the following day, when Dolphin was declared to have become extratropical on May 20. Its extratropical remnants was then absorbed by another developing extratropical cyclone north of it on May 24.

Preparations and impact[edit]

Typhoon Dolphin approaching Guam on May 15

In preparation for the cyclone, schools, businesses, and public transit were closed on Guam.[17] The Federal Emergency Management Agency deployed approximately 15 representatives to the island to mitigate the response time in the wake of the storm.[18] Eight schools were opened as shelters, and more than 1,000 residents sought refuge during the height of the storm.[19] Additional shelters were opened on the islands Rota, Tinian, and Saipan in the Northern Mariana Islands, and nearly 200 people sought cover there. Airports and seaports between the three islands were shut down.[20]

On Guam, the Andersen Air Force Base recorded sustained winds of 135 km/h (84 mph), while gusts reached 171 km/h (106 mph). Rainfall amounts tallied to 236 mm (9.3 in) within a 12-hour period.[21] Wave heights offshore the island topped 6 m (20 ft).[22] Overall damage was estimated at nearly $10 million, prompting Governor Eddie Calvo to declare of state of emergency. On June 5, President Barack Obama signed a major disaster declaration for the territory, allowing for federal aid to be used.[23]

See also[edit]

References[edit]

  1. ^ "Significant Tropical Weather Advisory". Joint Typhoon Warning Center. May 5, 2015. Archived from the original on May 15, 2015. 
  2. ^ "Tropical Cyclone Formation Alert". Joint Typhoon Warning Center. May 6, 2015. Archived from the original on May 15, 2015. 
  3. ^ "Warning and Summary". Japan Meteorological Agency. May 6, 2015. Archived from the original on May 15, 2015. 
  4. ^ "Tropical Depression 07W (Seven) Warning NR 001". Joint Typhoon Warning Center. May 6, 2015. Archived from the original on May 15, 2015. 
  5. ^ "Tropical Storm 07W (Seven) Warning NR 008". Joint Typhoon Warning Center. May 6, 2015. Archived from the original on May 15, 2015. 
  6. ^ "RSMC Tropical Cyclone Advisory". Japan Meteorological Agency. May 6, 2015. Archived from the original on May 15, 2015. 
  7. ^ "Tropical Storm 07W (Seven) Warning NR 010". Joint Typhoon Warning Center. May 9, 2015. Archived from the original on May 15, 2015. 
  8. ^ "Tropical Storm 07W (Seven) Warning NR 020". Joint Typhoon Warning Center. May 11, 2015. Archived from the original on May 15, 2015. 
  9. ^ "Tropical Storm 07W (Seven) Warning NR 025". Joint Typhoon Warning Center. May 12, 2015. Archived from the original on May 15, 2015. 
  10. ^ "RSMC Tropical Cyclone Advisory". Japan Meteorological Agency. May 12, 2015. Archived from the original on May 15, 2015. 
  11. ^ "Typhoon 07W (Seven) Warning NR 026". Joint Typhoon Warning Center. May 12, 2015. Archived from the original on May 15, 2015. 
  12. ^ "RSMC Tropical Cyclone Advisory". Japan Meteorological Agency. May 13, 2015. Archived from the original on May 15, 2015. 
  13. ^ "Typhoon 07W (Seven) Warning NR 027". Joint Typhoon Warning Center. May 13, 2015. Archived from the original on May 15, 2015. 
  14. ^ "Typhoon 07W (Seven) Warning NR 028". Joint Typhoon Warning Center. May 13, 2015. Archived from the original on May 15, 2015. 
  15. ^ "Typhoon 07W (Seven) Warning NR 031". Joint Typhoon Warning Center. May 14, 2015. Archived from the original on May 15, 2015. 
  16. ^ "Typhoon 07W (Seven) Warning NR 037". Joint Typhoon Warning Center. May 15, 2015. Archived from the original on May 15, 2015. 
  17. ^ Staff writer (May 14, 2015). "Cancellations and Postponements due to the impending Typhoon Dolphin". KUAM news. Retrieved May 15, 2015. 
  18. ^ Betsy Brown (May 13, 2015). "FEMA representatives are helping GovGuam make preparations for Typhoon Dolphin". Pacific News Center. Retrieved May 15, 2015. 
  19. ^ Cameron Miculka (May 15, 2015). "1,000-plus fill shelters: Dolphin hits northern Guam with wind gusts over 100 mph". Pacific Daily News. Retrieved May 15, 2015. 
  20. ^ Shawn Raymundo (May 15, 2015). "CNMI prepares for brunt of Typhoon Dolphin". Pacific Daily News. Retrieved May 15, 2015. 
  21. ^ Jeff Masters (May 15, 2015). "Category 2 Typhoon Dolphin Hits Guam". Ann Arbor, Michigan: Weather Underground. Retrieved May 15, 2015. 
  22. ^ Angela Fritz (May 15, 2015). "Typhoon Dolphin threads the needle between Guam and Rota". The Washington Post. Retrieved May 15, 2015. 
  23. ^ Ken Quintanilla (June 8, 2015). "Major disaster declaration covers public assistance for Guam". KUAM News. Retrieved June 9, 2015. 

External links[edit]