Northern Michigan and Northeastern Ontario The derecho originated from a severe thunderstorm that was forming across portions of the
Upper Peninsula and the northernmost parts of the lower Peninsula of
Michigan in the early afternoon hours of July 17. It crossed the
North Channel into
Northeastern Ontario near
Sault Ste. Marie, where it quickly developed into a
derecho line. As it crossed
Manitoulin Island just southeast of Sault Ste. Marie in
Lake Huron, numerous trees were uprooted and some homes sustained heavy damage. An official wind gust of 128 km/h (80 mph) was recorded at the
Killarney weather station on the north shore of Lake Huron.
Tornado warnings were issued for the area, but damage was consistent with severe straight-line winds. At about 15:30-16:00
EDT (19:30-20:00
UTC), the storm raced through
Sudbury, toppling hydro poles and trees.
Highway 69, the major highway linking Sudbury and
Toronto, had to be shut down because electrical wires blocked the highway. At that point, the storm system started to take the form of a comma signature of a fast-moving
progressive derecho. At about 17:30 EDT (21:30 UTC), the storm gathered further intensity before striking
North Bay, a city of over 50,000, and the surrounding
Nipissing District. Numerous trees were uprooted or snapped off and many buildings sustained heavy surface and some structural damage. Just south of the city,
radio towers and a
lighthouse were demolished by the violent winds. At the nearby
Jack Garland Airport, the
wind measuring instrument snapped off before the peak gusts could be recorded; some estimates put them higher than 180 km/h (111 mph).
Tornado warnings were in effect for the area and several funnels were reported but none has been confirmed. Within the district, the communities of
West Nipissing,
Callander,
East Ferris and
Mattawa, all about five hours north of Toronto, declared states of emergency in the wake of the storm as roadways in the area were blocked by felled trees and power was out throughout the region. The town of Mattawa and rural areas in West Nipissing were particularly hard hit as
storage siloes were torn apart, roofs were torn from buildings, utility poles were snapped in two and roads were entirely impassable from the debris strewn across them, in some cases for weeks after the storm. At the same time, the storm affected the
Algonquin Park region (mostly the northern portion) and fallen trees killed at least one man from Michigan and injured another, also from Michigan, who were on a canoe trip near
Kiosk, a small community located at the northern end of the park.
Ottawa Valley, Eastern Ontario and Southwestern Quebec Through the next two hours the storm entered the Upper
Ottawa Valley affecting places in
Renfrew County such as
Barry's Bay,
Deep River,
Cobden,
Petawawa and
Pembroke. There were numerous reports of damage, particularly blown-off or damaged roofs. After crossing the Pembroke area, the derecho started to lose some steam. At times, the storm moved at a forward speed of 100–120 km/h (65-75 mph) but had slowed down somewhat when it entered the
Pontiac region of western Quebec. Also, the north–south oriented line became more disorganized at its southern end. Still, the storm carried a lot of
lightning and damaging wind as it crossed portions of the
Outaouais region, the city of
Gatineau and extreme northern portions of the city of
Ottawa, primarily closer to the
Ottawa River, at around 21:00 EDT. Areas such as
Chelsea,
Cantley,
La Peche,
Notre-Dame-du-Laus and
Kazabazua were hit hard. Spectacular lightning was seen from downtown Ottawa and, when the storm was close enough, some pinkish colour was seen in the northern sky. In the Upper Gatineau north of the
National Capital Region, several houses and cottages were damaged and scores of trees were snapped by winds in excess of 90 km/h (55 mph). Five campers were injured by fallen trees, caused by a
microburst, while camping in Notre-Dame du Laus. Meanwhile, in the
Maniwaki area, a local radio station antenna suffered extensive damage. Northwest of that town in
Grand-Remous, several trailers in a park were heavily damaged or destroyed by the force of the winds but no injuries were reported there. Additional damage was reported in the
Papineau region further east as well as in
Mont-Laurier and the popular tourist village of
Mont-Tremblant in the Upper
Laurentians. The cities of Ottawa and Gatineau were brushed by the storm but escaped the worst of the effects.
Southern Quebec During the rest of the late evening, the storm weakened as it travelled through southern Quebec and eastern Ontario, but still brought lightning to the
Laurentians north of
Montreal. The following day, the remnants of the derecho reformed over parts of New England, including
Maine, with effects less severe than the original cluster. == Aftermath ==