Category 2 Sanba closes in on Korea; 92L enters the Lesser Antilles

Dr. Jeff Masters' WunderBlog - Sunday, September 16, 2012, 9:40

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The winds are rising in Busan, South Korea, and heavy rain is lashing the Korean Peninsula and Southern Japan as Category 2 Typhoon Sanba steams northwards at 22 mph. Sanba pounded Okinawa, Japan early Sunday morning local time as a Category 3 storm with 120 mph winds, but no casualties or heavy damage has been reported thus far. Radar loops show that the large 35-mile diameter eye of Sanba passed over the northern part of Okinawa. Oku, on the northern tip of the island, experienced the eyewall, and recorded a gust of 124 mph (55.3 m/s). At Kadena Air Force Base, the eye of Sanba missed, passing just to the north. The winds peaked at 56 mph, gusting to 77 mph, at 8:30 am local time, after the eye passed to the northeast, and the base received 6.30″ of rain. High wind shear of 25 – 35 knots is now affecting Sanba, and satellite loops show that the typhoon is weakening, with the cloud tops warming and dry air wrapping into the core. Radar out of Korea shows that heavy rains from Sanba cover most of the Korean Peninsula, and heavy rain is likely to be the main threat from Sanba in Korea. Sanba will continue to weaken as it encounters cooler waters and higher wind shear today, and is likely to be at Category 1 strength at landfall in South Korea near 22 UTC on Sunday.

Figure 1. Radar image of Typhoon Sanba over Okinawa at 6:25 am local time Sunday September 16, 2012. Image credit: Japan Meteorological Agency.

Video 1. Raw video of Typhoon Sanba hitting Okinawa, taken by storm chaser James Reynolds.

Sanba: the strongest tropical cyclone of 2012
Sanba became a Category 5 Super Typhoon with 175 mph winds for an 18-hour period ending at 12 UTC Friday, September 14, making it Earth’s only Category 5 tropical cyclone so far in 2012 (there were two Category 5 storms in 2011, both in the Western Pacific.) The previous strongest tropical cyclone of 2012 was Super Typhoon Guchol, a Category 4 storm with top winds of 150 mph east of the Philippines in June. Sanba is the strongest typhoon in the Western Pacific since October 2010, when Super Typhoon Megi’s sustained winds hit 180 mph.

Figure 2. Super Typhoon Sanba at peak strength, as seen at 04:50 UTC September 13, 2012, by the MODIS instrument on NASA’s Aqua satellite. At the time, Sanba was a Super Typhoon with sustained winds of 175 mph and gusts to 205 mph. The spectacular eye of Super Typhoon Sanba featured two counter-rotating eddies at the surface. Image credit: NASA. NOAA’s Environmental Visualization Laboratory has a spectacular large-scale image of Sanba at Category 5 strength.

Invest 92L entering the Lesser Antilles
A tropical wave (Invest 92L) entering the Lesser Antilles Islands is moving west at 15 mph, and is bringing heavy rain showers and gusty winds to the islands today. The wave is under a moderate 10 – 20 knots of wind shear, and has only a small amount of heavy thunderstorm activity, due to a large area of dry air surrounding the system. The amount of heavy thunderstorm activity has decreased since Saturday. The latest SHIPS model forecast predicts shear will fall to the 10 – 15 knot range Monday through Wednesday, which will favor development. However, the atmosphere over the Caribbean is unusually dry and stable, and this will make it difficult for 92L to organize quickly. 92L will bring heavy rain showers to the Dominican Republic and Haiti on Wednesday, Jamaica and eastern Cuba on Thursday, the Cayman Islands and Central Cuba on Friday, and Mexico’s Yucatan Peninsula and Western Cuba on Saturday. The 06Z run of the NOGAPS models indicates some weak development of 92L once it reaches the Western Caribbean, but none of the other reliable models develop the system. In their 8 am EDT Tropical Weather Outlook, NHC gave the wave a 20% of developing into a tropical depression by Tuesday morning. A hurricane hunter aircraft is on call for Monday afternoon to investigate the storm, if necessary.

Figure 3. Morning satellite image of Invest 92L.

Hurricane Nadine headed towards the Azores Islands
Hurricane Nadine is heading eastward on a track that may bring the storm close to the Azores Islands on Wednesday. However, steering currents for Nadine are expected to collapse by Wednesday, and the storm will likely wander for many days in the Central Atlantic.

Category 2 Sanba closes in on Korea; 92L enters the Lesser Antilles

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