Great Lakes-Atlantic Coast derecho

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Northeastern Ontario/Upper Midwest derecho/tornado event

Date of tornado outbreak:	July 17-21, 2006
Duration1:	~96 hours
Maximum rated tornado2:	F2; Derecho max. winds 180 km/h (110 mp/h+) non-tornadic tornado
Tornadoes caused:	10 confirmed (2 Ontario, 7 Missouri, 1 Iowa); 20 reported
Damages:	Not yet available
Fatalities:	0 + 14 non-tornadic (9 Missouri, 2 Ontario, 2 Pennsylvania, 1 Michigan)
Areas affected:	upper Midwest, Great Lakes, northeastern Ontario, southern Quebec, northeast US Atlantic coast
1Time from first tornado to last tornado 2Most severe tornado damage; see Fujita scale

The Great Lakes-Atlantic Coast derecho was a series of severe wind events associated with powerful thunderstorms, known as Derechos, that occurred between July 17 and July 21, 2006 across a wide swath of north-central and northeastern North America stretching from the Upper Midwest, through much of Ontario and into the northeastern United States. During the period over 2,000,000 people were left without power from the storms. Early evidence points to a classic 'Progressive Derecho' that struck parts of northern Michigan, northeastern Ontario and Quebec.

Contents 1 Northeastern Ontario derecho (July 17, 2006) 1.1 The Event 1.2 Aftermath 2 Central Great Lakes-Upper Midwest derecho (July 17, 2006) 2.1 Southern Ontario 2.2 Michigan 2.3 Wisconsin 2.4 Illinois 2.5 Iowa 3 Atlantic Coast derecho (July 18, 2006) 3.1 The event 3.2 Aftermath 4 St. Louis-Upper Mississippi River Derecho Events (July 19-21, 2006) 5 Heatwave 6 Near-derecho events related to the heat 7 See also 8 References 9 External links

[edit] Northeastern Ontario derecho (July 17, 2006)

[edit] The Event

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 south 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 mp/h) was recorded at the Killarney weather station on the north shore of Lake Huron. Tornado warnings were issued for the area and with the amount of damage reported there may been tornado touchdown(s), although unconfirmed as yet.

At about 3:30-4:00 PM EDT (1930-2000 UTC), the storm raced through Sudbury toppling hydro poles and trees. Highway 69, the major highway that links Sudbury to 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 5:30 PM EDT (2130 UTC), the storm affected North Bay, a city of over 50,000 and the surrounding Nipissing District. Numerous trees in the town were levelled and many buildings sustained heavy surface and some structural damage. Just south of the city, radio towers and a lighthouse were also demolished by the violent winds. At the nearby Airport, the wind measuring instrument snapped off before the peak gusts could be recorded, some estimates put them higher than 180km/h (111 mp/h). Tornado warnings were also in effect for the area and several were reported (or funnels observed) but none have 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.

At the same time, the storm affected the Algonquin Park region (mostly the northern portion) and killed at least one Michigan man 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.

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 in entered the Pontiac region of western Quebec. Also, the north-south oriented line became more disorganized at its southern end. Still, the storms carried a lot of lightning strikes 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 9 PM. Areas such as Chelsea, Cantley, La Peche, Notre-Dame-du-Laus and Kazabazua were hard hit. Spectacular lightning was seen from downtown Ottawa and when the storm was close enough, some pinkish color could have been seen in the northern sky. In the Upper Gatineau region north of the National Capital Region, several houses had damage, and scores of trees were snapped by winds in excess of 90 km/h (55 mph). Five more campers were injured by fallen trees while camping in Notre-Dame du Laus^[1]which was caused by a microburst. Meanwhile, in the Maniwaki area, a local radio station antenna suffered some 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.

During the rest of the late evening, the activity weakened as it travelled through southern Quebec and eastern Ontario, but still contained a fair amount of lightning when it crossed the Laurentians north of Montreal. The following day, the remnants of the derecho would re-fire over parts of New England including Maine, but were not as severe as the original cluster.

[edit] Aftermath

As a result of the storm at least one person died in the Algonquin Park region while another person was severely injured as a result of fallen tree. Several other injuries occurred in many areas hit by the storms. Also, two people were briefly missing at the La Vérendrye Wildlife Reserve northwest of Maniwaki, Quebec during the height of the storm.

Hydro One in Ontario reported that over 170,000 customers were left without power in the northeast part of the province and the 90% of the city of North Bay lost power. All of Manitoulin Island was without power. Many others areas including the Sudbury area and the Upper Ottawa Valley towns of Pembroke, Mattawa and Petawawa also had major power outages.^[2]. Major outages was also reported in several areas in Quebec particularly in the Outaouais region. 145,000 Hydro-Quebec customers lost power but separate storms in the Rouyn-Noranda, Val d'Or, Montreal, Trois-Rivieres and Quebec City areas contributed to the some of the outages.^[3]. However, if the storms would have move a few kilometres south, thus hitting directly populated areas in the city of Ottawa and downtown Gatineau, these numbers would have been much higher and property damage would have been greater.

Final damage assessment from this destructive storm are fully unknown as yet, in part because of the remoteness of large portions of the affected area. It is also uncertain if there were not more injuries or deaths, again due to inaccessibility to parts of the region, especially with trees blocking so many remote roads. Environment Canada will investigate areas with heavy damage to ascertain whether tornadoes touched down, particularly on the Manitoulin Island and in Larder Lake, near Kirkland Lake. But at this stage, almost all damage reports are straight-line in nature and radar imagery also favors a classic 'progressive derecho storm' with winds of up to and possibly exceeding 200 km/h (120 mp/h) at its peak, possibly with embedded tornados.

Later that evening a powerful cool front crossed southern Ontario causing further storm damage in Ontario (see below).

[edit] Central Great Lakes-Upper Midwest derecho (July 17, 2006)

While the northern part of the system was producing severe damage only within Canada (northeast Ontario/southern Quebec), an associated cold front led to significant damage in the US Midwest and Southern Ontario. There were dozens of reports of significant wind and/or tornado damage, especially in Michigan but also in southern Ontario, Wisconsin, Illinois, Iowa and as far south as northern Missouri. The setup was similar along the long cold front, and the hot, humid air mass led to the damaging derecho, although the stronger derecho that affected areas well north of there formed much earlier that day in Upper Michigan just before noon local time. It had a clearly defined bow echo squall line formation, unlike these cells which were more fragmented.

[edit] Southern Ontario

Sweeping from west to east in the late-evening hours, the greatest concentration of damage was centred around Newmarket, Scugog Lake and the Kawartha Lakes region further to the east. Numerous trees and power lines were downed in those areas and one camper was killed when a tree crashed into a camping trailer at the Warsaw Caves Provincial Park 30 km (18 miles) northeast of Peterborough. Official wind gusts reached 98km/h (61 mp/h) at Pearson Airport near Toronto and 107 km/h (66 mp/h) at Peterborough Airport. Heavy storms also crossed Essex County in the southwest, associated with southward moving line that hit much of lower Michigan. At least 70,000 people lost power in the south, bringing in total at least 300,000 customers who lost power in Ontario that day. On July 19, 2006, Environment Canada confirmed two tornadoes hit a residential section of Newmarket. (See Tornadoes of 2006 article)

[edit] Michigan

The hardest-hit areas appear to be in northern and central lower Michigan, particularly in and around Oceana County. Several houses were severely damaged, and many others suffered varying degrees of damage. In addition, the Oceana County Fairgrounds lost at least one of its buildings due to the extreme winds. At least one person was injured in the county. Extensive damage was also reported in Benzie County. Wind speeds of 66 mph (106 km/h) were recorded in Saginaw.

Agricultural damage was severe;^[4] many grape and cherry crops were heavily damaged or destroyed, especially in Antrim, Grand Traverse and Leelanau Counties, which will likely have a devastating effect on farmers as the storm took place while they were at maturity stage.

One person was killed by a lightning strike in the Detroit area. In Michigan, over 270,000 people were without power at the storm's peak.^[5]

[edit] Wisconsin

Significant wind damage was also reported that afternoon in parts of Wisconsin, especially the northeastern part around Sheboygan. High winds knocked out power to at least 12,000 people and even knocked vehicles off Interstate 43. Winds were officially estimated to be at least 61 mph (97 km/h) but unofficial readings exceeded 75 mph (120 km/h) in Kohler. ^[6] Some thought it was a tornado that hit but it was later confirmed to have been straight-line winds like most of the derecho.

Significant damage was also reported in the city of Manitowoc, where hundreds of trees were blown down city-wide knocking out power to hundreds of households. Winds unofficially reached 60-65mph at the storms peak. No injuries were reported in the state.^[7]

[edit] Illinois

More damage was reported in extreme northern Illinois along the same line. Trees and power lines were knocked over all over the northernmost areas, some landing on power poles and buildings. The extreme heat also compounded the problem, forcing emergencies to be declared in several communities.

Over 110,000 people were without power at the peak of the storm in Illinois, from northern Chicagoland to the Mississippi River. Peak wind gusts as high as 70 mph (110 km/h) were recorded in Stephenson. Some of the hardest hit areas were Crystal Lake, Mundelein, Rockford, Lake Zurich and Buffalo Grove.^[8] Damage was reported even in the city of Chicago, particularly on the Northwest Side. Numerous houses even lost their roofs as a result of the severe winds. Several people were injured, some of which were due to lightning strikes.^[9]

[edit] Iowa

One tornado touched down at Tama, along with numerous other hail and high winds reports in the eastern part of the state.

[edit] Atlantic Coast derecho (July 18, 2006)

The same system refired on July 18 over the Northeastern United States. It produced similar damage over a large swath of New England and the Mid-Atlantic states.

[edit] The event

Like the system in Ontario, but unlike the squall line of the upper Midwest, this was a continuous series of storms that produced widespread damage along its path.

The most significant line began in western Maryland, then tracked north-northeastward into southeastern Pennsylvania, northern New Jersey and the northern suburbs of New York City before tracking eastward into southern New England.

They generally moved in an eastward direction, with new cells popping up farther north as old cells dissipated. The first cells affected the southernmost part of Pennsylvania and western New Jersey. A new cell took over in northern New Jersey, crossing southern New York and southern New England.

Tree and power line damage was widespread throughout the entire affected area. A few people were injured, and several other people barely escaped injuries as a result of trees falling onto houses and cars. Some of the most spectacular footage came out of Providence Harbor where a tanker caught in the winds exploded in the harbor while unloading gasoline. Fortunately, it moved away from the dock, preventing severe damage in the harbor.^[10]

Two people were killed by fallen trees, both in Chester County, Pennsylvania.^[11]

No tornadoes were reported in the region.

[edit] Aftermath

There were hundreds of thousands of people left without power all across the region. In the Philadelphia area alone, over 500,000 people were left without power at the peak of the storm, according to PECO and PSE&G.^[12] Many customers will be without power until the weekend at least. It took place just after PECO had set record highs for electricity usage as a result of the preceding extreme heat wave. Power crews from as far away as Chicago were called in to help restore power, after fixing up their damage from the previous day's storms.^[13] A state of emergency was also declared in Bucks County, Pennsylvania as a result of the storm.^[14]

In northern New Jersey, about 110,000 people were without power at the peak of the storm.^[15]

In New England, the damage was just as severe. Over 22,000 customers lost power in Connecticut at its peak. In Rhode Island, that number was 30,000.^[16]

Railroad service was also badly affected, with several lines in northern New Jersey and southern New York completely blocked by debris and their electric trains disrupted by power outages on several lines.^[17]

The wind graphic from the SPC shows an extensive trail of wind damage, with over 100 reports in the region.

[edit] St. Louis-Upper Mississippi River Derecho Events (July 19-21, 2006)

Two powerful derechos about 36 hours apart made direct hits on St. Louis. The first occurred on the evening of July 19 and the second occurred during the mid-day hours on July 21. In all 9 storm related deaths were reported with 7 confirmed tornadoes.

The first storm cut power to over 590,000 customers in the St. Louis metropolitan area and injured 30 baseball fans at Busch Stadium. Ameren reported that it was the worst outage in their 100 year history. It also hit an extensive swath of the Upper Mississippi River valley including sections of Illinois. A wind gust of 92 mp/h (146 km/h) was recorded in Macoupin County. Also affected were parts of Iowa, southern Wisconsin and southern Minnesota.

The second storm struck after power had been restored to 375,000 customers. With 80 mp/h winds the storm battered the same areas that had been affected previously. Ameren estimated that the total number of power outages from both storms exceeded 1 million.^[18]

[edit] Heatwave

Main article: 2006 North American heat wave

The derecho that crossed into Ontario and Quebec was the result of a warm and very humid airmass that had plagued much of Central and Eastern Canada and the vast majority of the continental U.S. Temperatures in Toronto, Ottawa, Windsor and Montreal were approaching 35°C (95°F) for a few days including the day of the storms, while Heat Index values were exceeding well over 40°C (104°F) in some areas. Temperatures hit 100°F (38°C) at LaGuardia Airport in New York on July 18th and in St. Louis, Missouri on July 19th, before storms pummeled those metropolitan areas. This heat wave was somewhat similar in structure but less deadly than the 1995 Heat Wave which had also spawned several destructive derechos across the Great Lakes.

[edit] Near-derecho events related to the heat

Other near-derecho events occurred on August 1 in southern Quebec from the upper Laurentians to the Eastern Townships and on August 2 from eastern Michigan to southeastern Ontario. Again, the intense heat and humidity was responsible for these storms which look quite similar to the July 17 events. However, damage was less widespread but there were several tornadoes reported, most of them from supercells.

[edit] See also

• Derecho
• List of notable derecho events
• Tornadoes of 2006

[edit] References

[edit] External links

• Northern Michigan storm reports (Gaylord NWS office)