Sean brushes Bermuda; largest wave ever surfed; Tipton tornado an EF-4

Tropical Storm Sean brushed by Bermuda this morning, bringing winds near tropical storm force to the island. Top sustained winds at the Bermuda airport were 37 mph this morning, and a gust of 56 mph occurred at 4:38 am AST. Dry air disrupted the circulation of Sean before it reached Bermuda, and the island picked up just 0.08" of rain as of 10 am AST today. Sean is headed northeastward, out to sea, and will cease to exist later today or on Saturday. Sean may not be the last storm of the season, however. The most recent runs of the GFS, NOGAPS, and ECMWF models all predict an extratropical storm capable of transitioning to a subtropical or tropical storm will form in the middle Atlantic late next week. If such a storm did form, it would be called Tammy, and would not threaten any land areas.


Figure 1. A wet, windy day in Bermuda: morning webcam image from the island. Image credit: freddiebda's webcam.

Largest wave ever surfed
A new world record was set this week for the largest wave ever surfed. On Tuesday, November 8, Hawaiian big wave rider Garrett McNamara caught a 90-foot (27 meter) wave during a tow-surfing session just offshore of the small fishing village of Nazare, Portugal. An undersea canyon 5000 meters deep runs very close to the shore, and the unique bathymetry is known to create unusually large waves when west-northwest swells affect the coast. On Tuesday, an approaching cold front extending southwards from a low pressure system centered just south of Iceland generated strong winds off the coast of Portugal, and a west-northwest swell of 8 meters (26'). The canyon generated three big waves in excess of 60 feet that day, and McNamara was able to catch the tallest, 90-foot wave. The previous record highest wave surfed was a 77-foot (23 meter) wave caught in 2008 at Cortes Bank off the coast of Southern California by Mike Parsons.


Video 1. Surfer Garrett McNamara rides a 90-foot wave off the coast of Portugal on November 8, 2011, setting a new world record for the largest wave ever riden.

November 7 Tipton, Oklahoma tornado rated an EF-4
The powerful tornado that hit Tipton, Oklahoma on November 7 has been rated an EF-4 by the National Weather Service. The Tipton tornado hit two Oklahoma Mesonet stations and destroyed them; the Tipton mesonet site measured winds of 86.4 mph and the Fort Cobb site measured winds of 91.4 mph before destruction. The tornado was one of a family of six spawned that day by the parent supercell thunderstorm. The Tipton tornado is the first November EF-4 tornado in Oklahoma's history, and one of only twenty EF-4 or stronger November tornadoes observed in the U.S. since 1950, according to the Tornado History Project. There have been twelve December EF-4 tornadoes and two December EF-5 tornadoes observed in the U.S. since 1950. The confirmed tornado count for 2011 is 1543, putting this year in third place so far for most tornadoes, behind the 1692 tornadoes observed in 2004 and 1817 tornadoes in 2008. By the time the year ends, 2011 should wind up with 1600 - 1700 confirmed tornadoes.


Figure 2. Time series showing the weather at the Fort Cobb, OK mesonet station during passage of the November 7, 2011 Tipton tornado. A wind gust of 91.4 mph and pressure spike down to 946 mb occurred during the tornado's passage. Image credit: NWS/Norman Oklahoma.

Have a great weekend, everyone, and I'll be back Monday with a new post.

Jeff Masters