Hurricane Karen was the eleventh named storm and the sixth hurricane of the 2001 Atlantic hurricane season. Karen formed on October 12 (tropical-wise; it was extratropical before that) in the Atlantic Ocean well east of any landmasses along the East Coast of the United States. Karen formed from the interaction of a cold front and an upper-level trough on October 10 to the south of Bermuda. Karen intensified quickly as an extratropical cyclone. Karen bypassed Bermuda on October 12, bringing hurricane-force winds to the island. It then became a subtropical cyclone later on October 12, followed by a tropical cyclone on October 13. Karen peaked as an 80 mph Category 1 hurricane. It made landfall in Nova Scotia as a tropical storm, then rapidly became an extratropical cyclone again.
Karen caused $1.4 million (2001 USD) in damage but caused no fatalities.
|Formation||October 12, 2001|
|Dissipation||October 15, 2001|
|Highest winds||80 mph|
|Lowest pressure||982 mbar|
|Damages||$1.4 million (2001 USD)|
|Areas affected||Bermuda, Atlantic Canada|
On October 10, a cold front stalled a couple hundred miles southeast of Bermuda. That same day, a strong upper-level trough moved southeastward off of the East Coast of the United States. Due to several factors, including upward motion and strong diffluence, the area became baroclinically unstable. This caused the interaction between the cold front and the trough to develop into an extratropical cyclone about 345 miles southeast of Bermuda on October 11. The low moved north, then northwest, strengthening at a rapid pace due to the instability that was available in the atmosphere. Late on October 11, the system slowed, and the upper-level circulation became aligned with the low-level circulation. Late on October 11, the extratropical low began to develop tropical characteristics, which included surface temperatures warmer than the surrounding environment, and also the vertical wind characteristics of a tropical cyclone. Based on the organization, it is estimated that the low became Subtropical Storm One early on October 12, while located about 35 miles south of Bermuda. After forming, the cyclone maintained winds of 70 mph, with gusts exceeding 100 mph on Bermuda. After becoming disconnected from the westerlies, the cyclone turned northward and began to develop convection near its center. In addition, the frontal characteristics that the subtropical cyclone possessed gradually weakened. On October 13, based on an Advanced Microwave Sounding Unit observation that stated that a warm core was present throughout the system, it is estimated that the subtropical cyclone became Tropical Storm Karen, while located about 200 miles north of Bermuda.
Karen strengthened over the warm waters of the Gulf Stream. Late on October 13, Karen became a hurricane. Convection continued to develop near Karen's center of circulation, and it organized into a ring around the eye as Karen became a Category 1 hurricane with winds of 80 mph. Karen reached this intensity on October 14, while located about 400 miles south of Halifax, Nova Scotia. Karen quickly weakened as it moved over cooler waters, and late on October 14, Karen weakened to a tropical storm as it accelerated to the north. Karen's convection gradually decreased, and it made landfall in southwestern Nova Scotia on October 15 with winds of 45 mph. Karen maintained its tropical characteristics upon making landfall and after making landfall, based on a research flight out of Halifax intended to study the early stages of extratropical transition. The flight reported arced bands and a warm-core system transitioning into a more typical mid-latitude system. Under the influence of a mid-latitude system, Karen turned to the northeast and it became extratropical shortly after landfall. Karen continued quickly northward, quickly weakened, and dissipated as it became absorbed by a larger extratropical low over the Gulf of Saint Lawrence on October 15.
Tropical Storm Karen shortly after its landfall in Nova Scotia.
The Bermuda Weather Service issued a gale warning and later a storm warning for the island on October 10, as the precursor extratropical cyclone was forming. It was expected that at least 50 to 60 mph winds would impact the island. In addition, several radio interviews and television stations issued information on the expected storm. Also, many residents believed that they were insufficiently warned, although it is acknowledged that emergency managers and citizens pay less attention to gale warnings than they do tropical storm or hurricane warnings. On October 12, as the storm was passing south of the island, officials closed all schools and government offices. In addition, many private businesses were closed.
At the time Karen made its landfall in the country, gale warnings were issued for coastal areas. In addition, inland wind warnings were issued for Cape Breton. Also, heavy rain warnings were issued for large portions of the country, including Halifax, southeastern New Brunswick, Fundy National Park, and Prince Edward Island.
While passing to the south of Bermuda, the pressure gradient between the precursor extratropical cyclone and the high pressures resulted in strong winds on the island. At Fort George, sustained hurricane-force winds were reported. The highest official wind gust reported on the island was 100 mph at Devonshire. Also, a cruise ship anchored at harbor reported a wind gust as high as 118 mph. However, this wind could have been caused by a downdraft, rather than the winds from the pressure gradient. Because the extratropical cyclone developed quickly, beach erosion was minimal. The strong winds caused by the storm left considerable tree damage and power line damage. During the height of the storm, 23,000 of the island's 30,000 residents were without electricity. Total damage to power lines is estimated at $385,000 (2001 USD). The strong winds caused considerable damage to vegetation. At Saint George Harbor, three cruise ships rode out the storm. There, the strong winds ripped out a post and snapped a mooring line, leaving a ship drifting in the harbor. In addition, one crew member was minorly injured. Over a dozen boats broke free from their moorings, resulting in them running aground or sinking. A total of 87 boats were affected to some degree by the storm, with marine damage reaching about $665,000 (2001 USD).
The strong winds also caused minor property damage to 175 properties on the island, primarily to houses. Total damage to houses totaled to $425,000 (2001 USD). Total damage on the island was moderate, totaling to $1.4 million (2001 USD). Thankfully, no fatalities were reported, although a few injuries did occur.
The precursor extratropical storm near Bermuda.
In Nova Scotia, Karen produced light to moderate winds, peaking at 47 mph with a gust of 64 mph in Cape George in Antigonish County. Also, a report of 26 mph winds occured in Charlottetown on Prince Edward Island. In addition, Karen's outer rainbands produced light rainfall of up to 1.8 inches in Yarmouth, as well as 1.4 inches in St. John, New Brunswick, most of which fell in a short amount of time. Skewed to the left side of the transitioning storm, the rainfall was beneficial for the drought-stricken areas of Nova Scotia and New Brunswick. Because Karen moved through fast, most areas only received a half inch of rain. A buoy in Halifax Harbor reported waves of 16.7 feet, causing breaking waves at docks as well as white caps in the ocean. Total damage in Nova Scotia was minor, limited to an uprooted tree in New Glasgow and several other trees with damaged branches. No fatalities or injuries occured in Atlantic Canada from Karen.