Typhoon Ma-on (2011)

Typhoon Ma-on (Ineng)
Typhoon Ma-on near peak intensity on July 16
Meteorological history
FormedJuly 11, 2011
ExtratropicalJuly 24, 2011
DissipatedJuly 31, 2011
Very strong typhoon
10-minute sustained (JMA)
Highest winds175 km/h (110 mph)
Lowest pressure935 hPa (mbar); 27.61 inHg
Category 4-equivalent typhoon
1-minute sustained (SSHWS/JTWC)
Highest winds215 km/h (130 mph)
Lowest pressure937 hPa (mbar); 27.67 inHg
Overall effects
Fatalities5 total
Damage$50 million (2011 USD)
Areas affectedNorthern Mariana Islands, Japan
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Part of the 2011 Pacific typhoon season

Typhoon Ma-on, known in the Philippines as Typhoon Ineng, was a large and powerful typhoon that affected southern Japan in July 2011. It was the sixth named storm and second typhoon of the 2011 Pacific typhoon season. Originating from an area of low pressure near Wake Island on July 9, the precursor to Ma-on gradually developed as it moved westward. By July 11, it had become sufficiently organized to be declared a tropical depression, although the cyclone's circulation remained broad. Over the following days, Ma-on gradually intensified and attained typhoon status on July 14. Favorable environmental conditions allowed for additional strengthening, and the storm ultimately attained peak ten-minute sustained winds of 175 km/h (109 mph) on July 16. After turning northward in response to a weakening subtropical ridge, the typhoon underwent a series of eyewall replacement cycles that caused it to weaken. On July 19, Ma-on struck Shikoku before turning southeastward and moving back over water. Slow weakening continued as Ma-on succumbed to the effects of high wind shear. The system ultimately became extratropical on July 24, and was last noted by the Japan Meteorological Agency a week later near the Kamchatka Peninsula.

Initially, Ma-on posed a slight threat to the Mariana Islands and prompted the issuance of tropical storm warnings. However, the system remained far away from the area and only produced scattered rainfall. In Japan, hundreds of people evacuated from mudslide-prone areas. Torrential rains produced by the storm, estimated at more than 1,200 mm (47 in), led to widespread and damaging floods. Five people perished as a result of Ma-on, and damage reached ¥3.9 billion (2011 JPY, $50 million 2011 USD).