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Tornado Threat from Hurricanes

00:00 Hurricanes Birthing Tornadoes The Weather Channel host Matt Sampson and Meteorologist Chris Dolce discuss how hurricanes can spawn tornadoes.

Tornadoes are one of several dangers that hurricanes, tropical storms and their remnants can unleash as they move inland. They are the smaller cyclones within the larger tropical cyclone.

Tornadoes from tropical systems make up an average of over 20 percent of all United States tornadoes during the month of August, and sometimes 50 percent or more of all tornadoes in September, said Dr. Greg Forbes, severe weather expert for The Weather Channel. Most of the tornadoes develop in bands of thunderstorms and intense showers outside of the eyewall about 50 to 250 miles from the hurricane or tropical storm center, he said.

"Unfortunately, hurricane-spawned tornadoes often develop rapidly and there may be little or no advance warning," Forbes said. "Often there is a tornado watch in effect, indicating that conditions are favorable for the development of this type of tornado. It's important to be very aware of the weather on these occasions."

(MORE: Tornado Safety Precautions)

The majority of the tornadoes spawned by tropical storms and hurricanes are short-lived and of the weaker EF0 or EF1 variety, but some can reach EF2 or EF3 intensity.

In the active 2004 and 2005 hurricane seasons, Forbes found that about 8.5 percent of the 558 total tornadoes spawned by tropical storms and hurricanes in those two seasons were rated F2 or F3 intensity. The remaining 91.5 percent were rated either F0 or F1.

(MORE: How Tornadoes are Rated)

Only two F4 tornadoes have been documented from hurricanes moving inland.

On Sept. 10, 1961, Hurricane Carla spawned an F4 tornado that killed eight people in Galveston, Texas. A few years later on Oct. 3, 1964, an F4 tornado from Hurricane Hilda killed 22 people in LaFourche Parish, La.

What hurricanes have produced the most tornadoes in recorded history? On the following pages we highlight the top five most tornadic hurricanes.

Next:NEXT> #5: A tornadic second landfall for this hurricane.