JULY 1995 DERECHO SERIES

Figure 1. Outline of areas affected by four derechos during the period from July 11, 1995 through July 15th, 1995. The area of an intense hot and humid "heat wave" is shown over much of the Midwest including the southern Great Lakes region. The derecho events are described in more detail below.

A tremendously hot and moist air mass resulted in a deadly "heat wave" in portions of the Midwest during mid July 1995. This very hot and moist air mass contributed to a series of progressive derechos along a nearly stationary east-west front to the north of the heat wave region (Fig 1).

Four derechos occurred over portions of the northern United States and southern Canada between the evening of July 11th and the morning of July 15th and the storm paths are shown as colored outlines on Fig. 1.

1. The first derecho (outlined in green) began in eastern Montana (MT) early on the evening of July 11th and ended over northern Wisconsin (WI) and Upper Michigan (MI) by mid morning on July 12th.

2. The second derecho (outlined in orange) began the next evening, July 12th, over eastern Montana (MT) and followed nearly the same track as the one the night before, reaching northern Wisconsin (WI) and Upper Michigan (MI) by mid morning on July 13th. However, unlike the previous day's derecho, this one continued through the remainder of the day and well into the evening hours of the 13th...turning southward across eastern Lower Michigan (MI) and a part of southern Ontario (ON) and reaching southern Ohio (OH) around midnight.

3. The third derecho (outlined in purple) began developing over western South Dakota (SD) during the late evening of July 13th as the second derecho was nearing its demise in Ohio (OH). This derecho moved northeastward reaching northeastern Minnesota (MN) before dying out near dawn on July 14th. For some residents of northern Minnesota (MN) this would be the third night in a row that a derecho roared through their area causing serious damage!

4. The fourth derecho (outlined in red) began in eastern Upper Michigan (MI) during the evening of July 14th. This derecho crossed southern Ontario (ON) and western and northern New York (NY) during the nighttime hours and moved off the coast of southern New England by mid morning on July 15th.

The second (orange) and the fourth (red) derechos were the most significant cases in the series and they are described in more detail below.

JULY 12-13, 1995 DERECHO

"The Right Turn Derecho"

Figure 2. Area affected by July 12-13, 1995 derecho event (outlined in blue). Curved purple lines represents the approximate locations of the "gust front" at three hourly intervals. "+" and "w" symbols indicate the locations of wind damage or wind gusts above severe limits (measured or estimated at 58 mph or greater).

During the late afternoon on Wednesday, July 12, 1995 thunderstorms developed over southeastern Montana (MT) and began producing winds that damaged homes and barns and blew over a mobile home. As the storm system moved eastward across North Dakota (ND) vehicles were overturned and a grain bin was destroyed. Measured winds reached 70 mph at Bismarck. As the system approached Fargo during the early morning hours on Thursday, July 13th, it became a well defined bow echo storm with measured winds reaching 91 mph at the Fargo airport. The derecho was now becoming a "high end" event.

The derecho was taking a track similar to one the night before (outlined in green on Fig. 1) producing significant damage for a second time from southeastern North Dakota eastward across Minnesota (MN) to western Lake Superior (LS) (Fig. 2). Damage was extreme across Minnesota with over 5 million trees blown down and many buildings damaged and some destroyed. Six campers were injured from the falling trees during the pre-dawn hours. Trucks with plows were needed to clear many of the roads. Some areas were out of power for a week. Damage totaled well over 30 million in 1995 dollars.

As the derecho continued eastward across extreme northern Wisconsin (WI) and Upper Michigan (MI) on the morning of July 13th, many more thousands of trees were blown down and another camper was injured by a falling tree. By early afternoon the derecho entered Lower Michigan (MI) and turned towards the south southeast (Fig. 2). Millions of dollars worth of damage, 3 deaths and several injuries occurred in northern and eastern portions Lower Michigan during the afternoon and early evening hours on July 13th. In Roscommon County alone 100,000 trees and 100 miles of power lines were blown down. In southeastern Lower Michigan over 400,000 of Detroit Edison's customers lost power. This was the largest power loss for Detroit Edison since the July 7, 1991 derecho event.

As the derecho was affecting Lower Michigan, it was also creating havoc in portions of southern Ontario (ON). In the town of Goderich on the eastern side of Lake Huron (LH) (green shaded circle on Fig. 2) hundreds of trees were blown down, some more than 100 years old. There was also damage to many buildings and vehicles and a state of emergency was declared. Farther south in Ontario winds reached 120 km/hr (75 mph) at London and Parkhill (indicated by "w" on Fig 2.)

Many boaters were on Lake Erie (LE) as the storm approached rapidly from the north. On the U.S. side of the lake, most were caught by surprise as the derecho winds moved out ahead of the bow echo storm. Dozens of boats were capsized or destroyed on rocks. One boater was badly injured when his boat was overturned near Lorain, Ohio and he later died. Nine other boaters suffered injuries. The U.S. Coast Guard received 152 calls for assistance and had to rescue many people. One couple spent almost 8 hours in the water after their boat capsized near Kelly Island.

As the derecho continued to move southward across Ohio (OH) during the evening hours, measured gusts reached 88 mph in Avon (Lorain County) and Tiffin (Seneca County) and 87 mph in Stow (Summit County). Hundreds of trees were blown down and many buildings were damaged. Three people were killed and 6 were injured from falling trees. The derecho finally met its demise as it reached the Ohio River near midnight EDT (Fig. 2).

Overall, "The Right Turn Derecho" traveled 1400 miles in 27 hours at an average speed of 52 mph. Many millions of 1995 dollars worth of damage was done, millions of trees were destroyed, 7 people were killed and nearly three dozen were injured.

JULY 14-15, 1995 DERECHO

"The Ontario-Adirondacks Derecho"

Figure 3. Area affected by July 14-15, 1995 derecho event (outlined in blue). Curved purple lines represents the approximate locations of the "gust front" at two hourly intervals. "+" symbols indicate the locations of wind damage or wind gusts above severe limits (measured or estimated at 58 mph or greater). The red dots represent tornado occurrences.

On the evening of Friday, July 14th, 1995 thunderstorms producing severe weather were occurring over Upper Michigan (MI) and adjacent portions of Ontario (ON) near Sault Saint Marie. By late evening the storms developed into a bowing line just northwest of the Mackinac Bridge. At 10:17 PM EDT the thunderstorm gust front hit the bridge and a gust to 90 mph was measured. Sustained winds above 80 mph continued on the bridge for 10 more minutes! Thus, began the intense "Ontario-Adirondacks Derecho" which would cause hundreds of millions of 1995 U.S. dollars worth of damage, several deaths, and many injuries as it raced southeastward from the northern Great Lakes region to the Atlantic coast (Fig. 3).

...ONTARIO..

As the bow echo system producing the derecho crossed northern Lake Huron (LH) and Georgian Bay (GB) it grew in scale and the derecho winds affected a large area of southern Ontario (ON) during the pre-dawn hours on Saturday, July 15th (Fig. 3). Some damage occurred in the Toronto metropolitan area near the southern edge of the derecho and a wind gust to 136 kph (85 mph) was measured at the Buttonville Airport just north of the city. However, the most severe damage, which was likely associated with wind gusts up to 160 kph (100 mph) or more, occurred along a band from the "cottage country" east of Georgian Bay to the northeastern corner of Lake Ontario (LO) and adjacent portions of the St. Lawrence River. This severe damage band was associated with the most rapidly moving portion of the bowed line as is depicted by this radar imagery loop from Environment Canada's King City, Ontario radar. While most of the damage was associated with intense straight-winds, there were several brief tornadoes reported with the bowed line. Most were weak, but a strong Fujita Scale F2 intensity tornado hit the town of Bridgenorth destroying a marina and damaging 20 homes.

Particularly hard hit by the July 14-15, 1995 derecho was that portion of south central Ontario east of Georgian Bay with some of the most severe damage around the towns of Huntsville, Bracebridge, Orillia, Minden, and Fenelon Falls. Between 1:30 and 3:30 AM EDT on July 15th, thousands of trees were blown down, with some blocking roadways, severing electrical lines, and damaging or destroying homes and automobiles. Many mobile homes were also overturned or blown away. One person was killed and numerous people were injured, typically receiving cuts, bruises, and/or broken bones. On Pigeon Lake north of Peterborough a house boat was overturned trapping eight people in the overturned boat for several hours until they were rescued after sunrise.

As the storm system continued on southeastward towards Lake Ontario and the St. Lawrence River, the severe damage continued. A roof was torn off a downtown building in Campbellford and fallen trees blocked roads. The severe winds reached the eastern towns of Picton, Kingston, and Brockville around 4 to 4:30 AM EDT and then crossed into northern New York.

Power outages along the severe damage band across south central Ontario would last from several days to a week in some areas. A report from the Insurance Bureau of Canada indicates that the July 14-15, 1995 derecho event resulted in 53 million in 1995 Canadian dollars of insurance damage claims in Ontario.

...NEW YORK...

As the Ontario-Adirondacks Derecho entered New York (NY) around 4 to 4:30 AM EDT, very severe wind damage continued to occur, especially along most bowed out portion of the line of thunderstorms. Winds estimated to be 100 mph or greater occurred at several points along a band from Jefferson and western St. Lawrence Counties through the Adirondack Mountain region. Of the five deaths and 11 injuries associated with the derecho event in New York, most were the result of trees falling on campers in the Adirondacks. Over 30 campers and hikers in the area had to be removed by helicopter since their paths out of the forest were blocked by thousands of fallen trees. According to the New York Dept. of Conservation about 900,000 acres of forest were damaged in the state and the value of the loss of timber was estimated to be over 200 million in 1995 U.S. dollars.

In the more populated areas of central and eastern New York almost 190 million in 1995 U.S. dollars in damage was done to structures and vehicles. Many mobile homes were overturned and numerous homes and businesses were damaged. Many vehicles were damaged or destroyed by falling trees. At the Syracuse Airport a wind gust of 76 mph was measured at 5:30 AM EDT as the storm gust front passed through and a parked Boeing 727 jet plane was blown into another commercial jet plane at the airport terminal. Less than an hour later a gust of 77 mph was recorded at the Albany airport. Several hundred thousands of people lost electrical power due to the powerful derecho winds.

Reflectivity imagery from the the Doppler radar at Rome, New York showing the bow echo entering northern New York can be found on the Albany, New York NWS Forecast Office web site by clicking here.

A radar loop from the NWS Doppler radar at Albany, New York (provided by NWS meteorologist Jeff Waldstreicher) showing the bow echo system as it is crossing the Adirondacks Mountains can be seen by clicking here.

...NEW ENGLAND...

The Ontario-Adirondacks Derecho entered western New England about 7 AM EDT on July 15th and passed offshore of Cape Cod by 9:30 AM EDT. Measured wind gusts in Massachusetts (MA) include 92 mph at Otis, 85 mph at Upton, 63 mph at Blue Hill Observatory, and 58 mph on Martha's Vineyard. Many roads were blocked by fallen trees and homes and cars were damaged. Fifty people were left homeless when the roof was blown off an apartment building in Holyoke. One person was killed and another injured by falling trees and power lines in western Massachusetts. Three others were injured in Deerfield when their hot air balloon was caught by the storm gust front and spun out of control for five miles before crashing into a tree.

...SUMMARY...

The Ontario-Adirondacks Derecho of July 14-15, 1995 was one of the most costly severe thunderstorm events to occur in eastern North American during the 20th century....creating almost one-half billion 1995 U.S. dollars in damage. The derecho raced across an 800 mile path in eastern North America in 12 hours at an average speed of 67 miles per hour! Seven people were killed and several dozen were injured. Many of these were hikers and campers visiting the forested regions of south central Ontario and the Adirondack Mountains in New York.

The series of four derechos that occurred from July 11th through July 15th, 1995 over central and eastern North America resulted in 14 deaths, nearly 100 injuries, and between one-half and one billion U. S. dollars worth of damage. It is certainly one of the more noteworthy series of derecho events occurring in North America during the last 50 years.

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Scientific data and other information concerning July 13th and July 15th, 1995 derechos in Ontario were provided by Environment Canada meteorologists Phil Chadwick, Mike Leduc, Peter Rodriquez, Sarah Scriver, and Dave Sills.

References: Bentley, 1997; Bosart et al., 1998; Cannon, et al., 1998; Storm Data for July 1995.

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