The Associated Press
A National Weather Service official said Thursday it was too early to tell for sure whether a massive swath of storms that sprawled across northern Indiana overnight had spawned the destructive derecho that had worried meteorologists across the Midwest.
A derecho is a storm of strong straight-line winds spanning at least 240 miles. The systems are distinctive and take on a comma or bow shape, and usually have a large area of very cold cloud tops not typically seen in an ordinary thunderstorm.
“A derecho is based more on research,” said Evan Bentley, a meteorologist at the weather service office for northern Indiana, “How much damage, how widespread it was.” It could take days to determine whether the storms met the criteria for a derecho, he said.
Derecho or not, the storms left a trail of damage from strong winds and golf ball-sized hail from Iowa through the Appalachians before it fizzled out.
“It was definitely strong,” Bentley said.
In Indiana, the heaviest damage came near Wabash, about 40 miles southwest of Fort Wayne, where weather service investigators found extensive tree damage and three farm structures destroyed by winds estimated at 90 to 100 mph.
“The guys who came back said they were some of the strongest straight line winds they’ve ever seen,” Bentley said.
At one point Wednesday night, utility poles and trees downed by the storms had cut power to about 44,000 customers of Northern Indiana Public Service Company, the region’s largest utility. The biggest concentration of outages was in northwestern Indiana’s Lake County.
NIPSCO said it had restored power to all but about 4,500 homes and businesses by mid-day Thursday. The utility said it expected to restore power for most of its remaining customers by late Friday night.
At one point Wednesday night, the mass of storms spanned the state from Gary to Fort Wayne.
Bill Bunting of the National Weather Service’s Storm Prediction Center in Norman, Okla. said thunderstorms took longer than expected to merge into a large line that could cause widespread damage. The merger also happened farther east than expected, which limited the potential for widespread damage in Illinois and Indiana, though those states still had pockets of severe weather.
Still, overall, the storms appear to have caused less wind damage than was feared, Bunting said.