Category:Typhoon Sonca (2011)

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Early on September 13, a low pressure area formed northeast of the Northern Mariana Islands.[1] The system gradually drifted north and steadily intensified until the next day when the JMA upgraded the system to a tropical depression.[2] Later on September 14, the JTWC issued a Tropical Cyclone Formation Alert (TCFA) on the system reporting that the system could intensify into a tropical storm within 24 hours from then.[3] Convection rapidly consolidated the center with persistent, deep convection around the north-eastern periphery, prompting the JTWC to initiate advisories on the system, designating it with 19W.[4] Soon, the JMA also initiated advisories on the systen, upgrading it to Tropical Storm Sonca.[5] In the begging, Sonca seemed to have intensified rapidly since formation, however, soon the storm weakened back to a minimal tropical storm because of dry air entering the LLCC that caused it to elongate and weaken.[6] However, that was not for too long as vigorous convection persisted over the well defined LLCC with tightly curved banding wrapped in, Sonca continued to strengthen gradually and the JTWC reported winds of at-least 50 knots (93 km/h; 58 mph) near the center.[7] As Sonca continued to strengthen, and the JMA upgraded it to a severe tropical storm on September 17.[8] Later that day, Sonca developed a large 10 nautical miles (19 km; 12 mi) ragged eye with deep convective banding tightly wrapped into it.[9] As a result, Sonca strengthened more rapidly and by early the next day, it became a typhoon.[10] On September 18, Sonca reached a peak intensity of 85 knots (157 km/h; 98 mph) (1-min mean) and 70 knots (130 km/h; 81 mph) (10-min mean) and soon the convection around the northern periphery started weakening.[11]


  1. JTWC - Tropical Cyclone Warning 130000 - Tropical Depression 28. Joint Typhoon Warning Center. Retrieved on 14 September 2011.
  2. JMA - Tropical Cyclone Warning 140000 - Tropical Depressions 28 & 29. Japan Meteorological Agency. Retrieved on 14 September 2011.
  3. JTWC - Tropical Cyclone Formation Alert - Tropical Depression 28. Joint Typhoon Warning Center. Retrieved on 15 September 2011.
  4. JTWC - Tropical Cyclone Advisory 01 - Tropical Depression 19W. Joint Typhoon Warning Center. Retrieved on 15 September 2011.
  5. JMA - Tropical Cyclone Advisory 150600 - Tropical Storm Sonca. Japan Meteorological Agency. Retrieved on 15 September 2011.
  6. JTWC - Tropical Cyclone Advisory 04 - Tropical Storm Sonca. Joint Typhoon Warning Center. Retrieved on 15 September 2011.
  7. JTWC - Tropical Cyclone Advisory 08 - Tropical Storm Sonca. Joint Typhoon Warning Center. Retrieved on 17 September 2011.
  8. JMA - Tropical Cyclone Advisory 170600 - Tropical Storm Sonca. Japan Meteorological Agency. Retrieved on 17 September 2011.
  9. JTWC - Tropical Cyclone Advisory 12 - Typhoon Sonca. Joint Typhoon Warning Center. Retrieved on 18 September 2011.
  10. JMA - Tropical Cyclone Advisory 180600 - Typhoon Sonca. Japan Meteorological Agency. Retrieved on 18 September 2011.
  11. JTWC - Tropical Cyclone Advisory 17 - Typhoon Sonca. Joint Typhoon Warning Center. Retrieved on 19 September 2011.

Media in category "Typhoon Sonca (2011)"

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