Typhoon Roke batters Japan; Ophelia forms in the Central Atlantic

Typhoon Roke hit Japan near Hamamatsu at 14:00 JST Wednesday as a Category 1 typhoon with 80 mph winds. Roke brought sustained winds of 62 mph, gusting to 83 mph to the Tokyo airport at 5:25 pm local time, and a wind gust of 89 mph was reported at Shizuhama Airbase. Roke has dumped heavy rains of 155 mm (6.20") at Hamamatsu and 125 mm (4.86") at Tokyo. Damage due to flooding from Roke's heavy rains will likely be the main problem from Roke, as the soils over much of Japan are saturated from the passage of Tropical Storm Talas during the first week of September. Talas was a very slow moving storm, and brought extreme rainfall amounts of over six feet to some portions of Japan. Roke brought winds less than 25 mph to the damaged Fukishima-Dai-Iche nuclear plant northeast of Tokyo, and heavy rains of 189 mm (7.50") to Hirono, located 8 miles south of the plant.


Figure 1. Radar image of Typhoon Roke as it made landfall at 14:00 JST on September 21, 2011. The typhoon brought a large area of rainfall of 50 mm/hr (2"/hr) to Japan. Image credit: Japan Meteorological Agency.


Figure 2. MODIS image of Typhoon Roke taken at 3:55 UTC on Wednesday, September 21, 2011. At the time, Roke was a Category 1 storm with 80 mph winds. Image credit: NASA.

Tropical Storm Ophelia forms in the Atlantic
Tropical Storm Ophelia formed last night in the Central Atlantic from the tropical wave (Invest 98L) we've been tracking this week. Satellite imagery shows that Ophelia is suffering the classic symptoms of high wind shear, with the low level center of circulation exposed to view, and the storm's heavy thunderstorms pushed to the northeast side of the center of circulation. An analysis of wind shear from the University of Wisconsin CIMMS group shows a high 20 - 30 knots of wind shear due to strong upper level west-southwesterly winds affecting Ophelia. We don't have any ship, buoy, or hurricane hunter observations of Ophelia's winds, but an ASCAT pass from 7:27 pm EDT last night found top winds of 45 mph in the northeast quadrant of the storm. Ophelia will be passing south of buoy 41041 late tonight. Water vapor satellite images show dry air to the the west of Ophelia, and the strong upper level west-southwesterly winds bringing high wind shear to the storm are also injecting dry air into the storm's core, interfering with development.


Figure 3. Morning satellite image of Ophelia showing the low-level center exposed to view, with all the storm's heavy thunderstorms pushed to the northeast side.

Forecast for Ophelia
The latest SHIPS model forecast predicts that Ophelia will experience moderate to high wind shear of 10 - 25 knots over the next five days, and will move into a region with drier air. The combination of shear and dry air should keep Ophelia from strengthening, and could dissipate the storm, as predicted by the ECMWF and HWRF models. The Northern Lesser Antilles could see some wind gusts of 30 - 40 mph and heavy rain squalls from Ophelia on Saturday and Sunday, but right now it looks unlikely that the islands would see sustained tropical storm force winds of 39+ mph, since they are likely to be on Ophelia's weaker (dry) side. At longer ranges, Bermuda will have to keep an eye on Ophelia, since a large cut-off low pressure system over the Eastern U.S. should turn Ophelia to the northwest and then north early next week. Ophelia may eventually be a threat to Canada, but it is too early to assess the odds of this happening.

Ophelia is the 15th named storm this year, putting 2011 in 10th place for the most number of named storms in a year. Ophelia's formation date of September 21 puts 2011 in 4th place for earliest date of arrival of the season's 15th storm. Only 2005, 1936, and 1933 had an earlier 15th storm. With only three of this year's fifteen storms reaching hurricane strength, though, this year has been near average for destructive potential. Atlantic hurricane records go back to 1851.

Jeff Masters