JULY
4-5, 1999 DERECHO
"The Boundary Waters-Canadian Derecho"
Figure 1. Area affected by the July 4-5, 1999 derecho event (outlined in blue). Curved purple lines represent the approximate locations of the "gust front" at three hourly intervals. "+" symbols indicate the locations of wind damage or estimated wind gusts above severe limits (58 mph or greater). The other symbols are described in the text below.
During the pre-dawn hours on Sunday, July 4, 1999 thunderstorms were occurring over portions of the Dakotas. By 6 AM CDT some of the storms formed into a bow echo and began moving into the Fargo, North Dakota area with damaging winds. Thus, would begin the "Boundary Waters-Canadian Derecho" which would last for over 22 hours, travel over 1300 miles at an average speed almost 60 mph, and result in widespread devastation and many casualties in both Canada and the United States (Fig. 1). The following paragraphs describe what happened along the path of this long-lived international derecho.
...NORTH DAKOTA...
As the bow echo system developed over eastern North Dakota (ND) on the morning of July 4th, it quickly started producing very severe long-lasting winds. The storm winds reached Fargo's Hector Airport about 7:30 AM CDT, and winds in excess of 58 mph continued for 39 minutes with a maximum gust of 91 mph measured at 7:42 AM! Many planes at the airport were damaged or overturned and hangers were damaged as well. In the Fargo metropolitan area over 85 million 1999 U. S. dollars worth of damage was done. Many roofs were damaged or blown off and some buildings and garages were destroyed. Vehicles were damaged or overturned and many trees and power poles were blown down. About 40,000 customers were without electrical power and several people were injured.
To see the bow echo developing over eastern North Dakota and moving into Minnesota, click here. (Radar animation provided by NWS employees Peter S. Parke and Norvan J. Larson)
...MINNESOTA...
Severe wind damage continued to occur as the derecho moved across northern Minnesota (MN). The roof was blown off the public works building in Ada and many buildings, mobile homes, and vehicles were damaged by the derecho winds and falling trees in Clay, Norman, Hubbard, and Beltrami Counties. Damage in Cass, Itasca, and Aitkin Counties exceeded 3 million 1999 U. S. dollars and several campers were injured in the Walker-Leech Lake area. As the derecho entered St. Louis County, a wind gust of 81 mph was recorded at the Chisholm-Hibbing Airport and the terminal building and hanger suffered damage. A semi-trailer truck was blown over on U.S. Highway 53 near Canyon which is just northwest of Duluth.
As the derecho raced into the Arrowhead region of northeastern Minnesota during the early afternoon of July 4th, many casualties would occur despite the normally low population density of this heavily forested area. Since it was Independence Day weekend, many people had traveled to the Boundary Waters Canoe Area (BWCA) to enjoy canoeing and camping in the region. Winds estimated at 80 to 100 mph moved rapidly through the area causing serious damage to 600 square miles of forest in the Arrowhead region. Tens of millions of trees were blown down (Figs. 2 and 3). Sixty people in the BWCA were injured by falling trees, some seriously. Twenty of those injured were rescued by floatplanes flying to lakes within the forest that were near the victims.
Figure 2. Percentage of trees blown down in Superior National Forest in northeastern Minnesota on July 4, 1999. Scale: 1" = 15 miles. (Courtesy of USDA Forest Service, Superior National Forest)
Figure 3. Trail in the Boundary Waters Canoe Area blocked by fallen trees as far as the eye can see. (Courtesy of USDA Forest Service, Superior National Forest)
To see the derecho producing bow echo system as it was moving through the Arrowhead region, click here. (Radar animation provided by NWS employees Peter S. Parke and Norvan J. Larson)
Other interesting details (including photos, and a video) concerning the July 4-5, 1999 derecho and its affects on the Boundary Waters Canoe Area of northeastern Minnesota can be found on the following web pages:
"The
Boundary Waters Windstorm of July 4, 1999" .....Duluth, Minnesota NWS
Forecast Office
Video
Describing July 4, 1999 Derecho Event ...............American Museum of
Natural History
"A
Blowdown in the Border Forest"..................................Science
Museum of Minnesota
Boundary
Waters Blowdown Page....................................Minnesota Dept.
of Natural Resources
Blowdown
Storm Recovery Information..........................Superior National Forest,
USFS
...ONTARIO...
As the derecho entered Ontario (ON) during the early afternoon of July 4th, serious forest blowdowns continued with some of the worst damage extending from the southeastern corner of Quetico Provincial Park eastward to the area around Arrow Lake. As the derecho moved farther east it began affecting more of the northern portions of Lake Superior (LS). Environment Canada's automated weather station on Trowbridge Island near the southeast corner of Thunder Bay recorded a gust to 115 kph (71 mph) as the bow echo gust front moved into the area. However, the winds over the open waters of Thunder Bay and adjacent portions of Lake Superior were estimated to have been much stronger...possibly greater than 160 kph (100 mph). Many boaters in and near Thunder Bay ("T" on Fig. 1) were besieged by these intense derecho winds. In his book "Wake of the Green Storm", Marlin Bree describes his and other boaters close calls in surviving the fierce winds and huge waves as the storm roared through the area. One sailboat was overturned and two people were thrown into the cold water. Fortunately, a boater close by was able to rescue them before the cold water took its toll.
From the northeast shores of Lake Superior (LS) to the western border of Quebec (QC) the derecho continued to topple many trees as it raced across the heavily forested and sparsely populated region of northern Ontario at a speed of almost 60 mph during the evening hours of July 4th. The main line of the Canadian Pacific Railroad was shut down between White River and Chapleau (dashed line on Fig. 1) because of fallen trees blocking the tracks. In nearby Chapeau Park Game Reserve many trees were blown down at a resort on Lake Wabatongushi ("R" on Fig. 1) with the severe derecho winds lasting for 20 minutes. Forest blowdowns were also reported in areas south of Timmins ("F" symbols on Fig. 1).
...QUEBEC...
[The description of the derechos effect in Quebec was obtained from Environment Canada, Technical Note, Quebec Region, 99N-04 by Serge Mainville. The radar and satellite imagery (Figs. 4 and 5 and the movie loops) have been provided by McGill University and Environment Canada meteorologist Pierre Vaillancourt.]
The derecho producing bow echo system, racing east southeastward at a speed of nearly 100 kph (62 mph), entered the Temiscamingue region of Quebec (QC) by late Sunday evening on July 4th (Fig 4). A gust of 100 kph (62 mph) was measured at Temiscaming and a gust of 105 kph (65 mph) was measured at Angliers with electrical power outages occurring within the region. There was also a tremendous amount of cloud to ground lightning associated with the bow echo thunderstorms....up to 6000 strikes per hour!
Figure 4. Radar imagery (reflectivity in bright colors) and satellite imagery (storm system cloud tops in shades of gray) showing the derecho producing bow echo system entering southwestern Quebec at 10:45 PM EDT on Sunday, July 4, 1999. Click here to see animated reflectivity imagery of the bow echo system moving across Quebec and into northern New England. Fig. 4 has also been modified to show the symbols for provinces and states (in green) and the locations of towns and cities discussed below (in orange).
As the derecho tracked across southern Quebec during the early morning hours of Monday, July 5th, farm buildings were damaged and many trees uprooted from the Maniwaki area to Mt-Tremblant Park and areas to the south. At Val-des-Lacs near St-Jovite (orange "V" on Fig. 4) falling trees killed a camper and injured a woman by crushing her car.
The derecho gust front with wind speeds ranging from 85 to 120 kph (55 to 75 mph) moved into Montreal (orange "M" on Fig. 4) and the surrounding region around 2 to 3 AM EDT. In the Montreal metropolitan area falling trees damaged cars and roofs. At the St. Lawrence River docks in Pointe-Claire fifteen boats were overturned. East of Montreal farm buildings were damaged in Vaudreuil-Soulanges and Beloeil. In St-Hyacinthe roofs were damaged and windows were blown out in the upper stories of a hotel.
Figure 5 shows the Doppler wind speeds as measured by the McGill radar at 2:45 AM EDT when the derecho gust front was located just east of Montreal. The radar (black "R" on Fig. 5) is located about 20 kilometers (12 miles) west southwest of downtown Montreal. The derecho gust front is located near the leading edge of the curved purple band. The strongest wind speeds, moving directly away from the radar, are in dark purple which represents speeds of 30 to 40 meters per second (110-145 kph or 65-90 mph) range.
Figure 5. Doppler wind speeds recorded by the McGill radar (black "R" at center of the rings) at 2:46 AM EDT on July 5, 1999. Winds blowing towards the radar are in shades of green and blue. Winds blowing away from the radar are in shades of yellow, orange, red, and purple. As one advances away from the radar location the wind measurements become higher above the ground. Additional information from the McGill radar concerning the derecho producing bow echo system's characteristics can be seen by clicking here .
The derecho roared through the Eastern Townships between 3 and 4 AM EDT with measured gusts to 105 kph (65 mph) at Lennoxville and 114 kph (71 mph) at the Sherbrooke Airport. In the city of Sherbrooke (orange "S" on Fig. 4) numerous trees were uprooted (Fig. 6) and numerous roofs and cars were damaged by falling trees. Also, St. Andrew Church in downtown Sherbrooke was badly damaged with a part of the roof destroyed and one of the brick walls collapsed (Fig. 7). Southeast of Sherbrooke in the Sawyerville, Martinville, and Johnville communities farm buildings were damaged and one tree farm had most of its 2000-3000 trees destroyed. Hydro-Quebec reported that from the Montreal area into the Eastern Townships 600,000 customers lost electrical power, some for over a week.
Figure 6. One of the 200 year old trees uprooted in the old north town part of Sherbrooke, Quebec (facing south) (From Mainville 1999)
Figure 7. East side of damaged St. Andrew church in downtown Sherbrooke, Quebec, with remains of brick wall downwind. (From Mainville 1999)
After passing through southern Quebec, the derecho crossed the international border for a second time entering northern New England in the pre-dawn hours on July 5th. Thousands of trees were blown down, several buildings damaged, and about 26,000 customers lost electrical power. A wind gust to 90 mph was measured in the Colebrook, New Hampshire (NH) area.
While crossing northern New England there were several casualties. In Vermont (VT), a camper was drowned in Lake Salem in Orleans County when a tent the person was sleeping in on a raft was blown into the lake and the camper became entangled in the submerged tent. In New Hampshire (NH) three people in campgrounds in Errol were injured by falling trees. In Maine (ME) 2 campers were injured in Coburn Gore when a large tree limb fell on the tent in which they were sleeping. Just south of Coburn Gore some other campers experienced the destructive derecho winds and one of them has an interesting story concerning her experience.
Sarah Jamison, a National Weather Service meteorologist who was an intern at the Portland/Gray Maine office at the time, was enjoying the 4th of July 1999 holiday weekend camping and celebrating with family members and friends in the Rangeley Lakes region of western Maine (red "X" on Fig. 1). It was a very hot and humid day on July 4th with a high temperature near 90. Although conditions seemed "oppressive", Sarah, along with her family and friends, enjoyed the day swimming, boating, and relaxing in the shade. As the Independence Day celebration came to an end, sleeping arrangements were made for the night at their campsite near the shore of Cupsutic Lake. Sarah's mother and father would be sleeping on their boat near the docks, her brother would be sleeping in their sports utility vehicle (SUV), and Sarah and her friends would share a tent.
As the night progressed, Sarah mentioned that "the air was very stagnant with no wind which made it very uncomfortable in the hot tent". Sarah and her friends were having trouble sleeping, so at about 3 AM she and a friend got outside of the tent to get some fresh air. They noticed some lightning in the distance and went back into the tent and started to zip up the flaps to keep the anticipated rain from getting things wet.
In the meantime, Sarah's mother woke up also. She became concerned by the amount of lightning she was seeing to the northwest as the storm was approaching her boat and the campsite. As she left the boat to warn Sarah and her friends about the approaching storm, the gust front hit the campsite and the winds began to really pick up. She ran about 20 to 30 yards from the boat to Sarah's tent. Once she reached it, she started yelling for Sarah and her friends to get out of the tent, but the roar of the winds was so loud that they were unable to hear her at first. Finally, she was able to get their attention and they jumped out of the tent. Then they all ran to the SUV where Sarah's brother was sleeping, but unfortunately he slept with the doors locked so it took some time to get his attention. By the time he was able to unlock the door the first tree was blown down in the campsite. Given that scary experience, everyone quickly jumped into the SUV, plowing Sarah's brother over. Before the doors were closed, a much larger tree was uprooted and landed on the tent! Once everyone was inside the vehicle, they could see trees falling all around them during every lightning flash. The roar of the storm's winds was so loud that none of them could recall actually hearing the trees snapping or falling on the ground. After about 5 minutes the winds began to weaken and within a half hour the storm had moved on. Fortunately, no one in the group was hurt. However, if Sarah's mother had not recognized the danger or had been a minute or two later arriving at the tent, things could have been much worse!
As is often the case in derecho events, the damage that hit Sarah's campground was associated with a narrow band of intense very damaging downbursts embedded within the larger scale strong, but less severe, winds associated with the derecho producing system. The worst damage in the area extended from an island in the lake, where every tree was snapped off or uprooted, across Sarah's and adjacent campsites. In Sarah's and two adjacent campsites about two dozen trees were blown down with several being larger than two feet in diameter. One of these large trees and two smaller trees had fallen on Sarah and her friends' tent, completely crushing it. In Sarah's opinion it would have been impossible for them to have survived if they had stayed in the tent during the most intense portion of the storm.
After leaving the Cupsutic Lake campground, the derecho continued to cause damage across central and southern Maine. Finally, after traveling over 1300 miles, the bow echo system weakened and the derecho ended just before reaching the Atlantic coast.
...SUMMARY..
The very long-lived Boundary Waters-Canadian Derecho was one of farthest north "progressive" derechos to have been recorded. It traveled through a large part of the boreal forests of North America, uprooting and breaking off hundreds of square miles of trees. Two people were killed and 70 were injured and almost all of these casualties (67) were the result of trees or tree limbs falling on the victims. Additionally, almost all of the victims were outdoors (e.g., camping, hiking, or canoeing). This includes one of the casualties that was not the result of a falling tree (or limb). However, this person's death was due to being blown off a boat and drowning which is another one of the types of casualties most frequently associated with warm season derechos.
Most of the damage to homes and businesses occurred in areas of higher population density such as near the beginning of the event in the Fargo, North Dakota metropolitan area and near the end of the event over portions of south central and southeastern Quebec (Fig. 1). It was these areas that contributed the most to the recorded property damage which exceeded 100 million in 1999 U.S. dollars and to the total of over 700,000 households and businesses that lost electrical power from this long-lived derecho event.
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Scientific data and other information concerning July 4-5, 1999 derecho in Ontario and Quebec were provided by Environment Canada meteorologists Phil Chadwick, Rene Heroux, Michael Leduc, Serge Mainville, and Pierre Vaillancourt.
(References....Mainville, 1999;Miller and Johns 2000; Price and Murphy, 2002; Storm Data for July 1999, "Wake of the Green Storm" by Marlin Bree)
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