Category 3 Typhoon Sanba hitting Okinawa

The winds are rising and heavy rain is lashing Okinawa, Japan where Category 3 Typhoon Sanba is expected to make landfall early Sunday morning local time (early this afternoon U.S. EDT.) Radar loops show that the large 35-mile diameter eye of Sanba is on a track that will bring it across the southern part of Okinawa, and heavy rains and wind gusts of 59 mph and 66 mph have been reported at Naha Airport and Kadena Air Force Base, respectively, over the past few hours. Moderate wind shear of 10 - 20 knots has weakened Sanba below its Category 5 peak on Friday morning, and satellite loops show that Sanba is weakening, with the cloud tops warming and the eyewall getting eroded on the west side, but Sanba should be able to maintain Category 3 strength as it crosses Okinawa today. Sanba will continue to weaken as it encounters cooler waters and higher wind shear between Okinawa and South Korea Saturday night and Sunday, and is likely to be at Category 1 strength at landfall in South Korea near 18 UTC on Sunday.


Figure 1. Radar image of Typhoon Sanba approaching Okinawa. Image credit: Japan Meteorological Agency.

Sanba: the strongest tropical cyclone of 2012
The most powerful tropical cyclone of 2012 is Typhoon Sanba. Sanba formed as a tropical depression over the western Pacific Ocean on September 10. The storm rapidly strengthened from a Category 1 to a Category 5 storm over very warm waters of 30°C (86°F) in just 24 hours beginning on September 13, and became Category 5 Super Typhoon with 175 mph winds for an 18-hour period ending at 12 UTC Friday, September 14. Sanba is Earth's only Category 5 tropical cyclone so far in 2012; the planet had two such 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.

Links for Sanba
Radar loop from Okinawa
Live traffic with audio and video of Typhoon Sanba approaching.is available from ustream.tv.
Current conditions from Naha Airport, Okinawa, Japan
Current conditions from Kadena Air Force Base, Okinawa, Japan

Atlantic tropical update
Hurricane Nadine is recurving to the northeast on a track that may bring the storm close to the Azores Islands in 4 - 5 days. Steering currents for Nadine are expected to collapse in about 5 days, and the storm will likely wander for many days in the Central Atlantic.

A tropical wave about 600 miles east of the Lesser Antilles Islands is moving west at 15 mph, and will spread heavy rain showers and gusty winds over the islands on Sunday. 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 increased some this afternoon, though. The 12Z run of the NOGAPS model predicts the wave could approach tropical depression strength by Wednesday, when it will be near the Dominican Republic. However, none of the other reliable models develop the system, and the wave doesn't have much spin at present, as seen on an 11:14 am EDT ASCAT pass.. In their 2 pm EDT Tropical Weather Outlook, NHC gave the wave a 20% of developing into a tropical depression by Monday afternoon. A hurricane hunter aircraft is on call for Monday afternoon to investigate the storm, just in case.

Jeff Masters