1996 Lake Huron cyclone
Encyclopedia
The 1996 Lake Huron cyclone (commonly known as Hurricane Huron, or the Hurroncane) was a strong cyclonic storm system that developed over Lake Huron
in September 1996. It had some characteristics of a tropical cyclone
.
. Near the surface, a 1012 mbar low existed over Lake Michigan
. There was also a 500 mbar shortwave over Ontario
. The northwest tilt of the low indicated that the surface center was in a stage of baroclinic development. In addition to this, analysis concluded that the cyclone had a cold core in the mid-troposphere
. Analysis at the 700 and 850 millibar levels indicated that the cyclone also had a cold core in the lower troposphere, though a more dense observation would be needed.
The cyclone's height increased with surprising rapidity, as did its overall windspeed, from 11 mph (18 km/h) to 67 mph (108 km/h) up to strong tropical storm wind strength. At the same time, positive vorticity and thermal advection were causing moderate rain showers over Ontario, with a broken area of thunderstorms present in a warm portion of an advancing cold front. By September 12, the cyclone moved southward to a position over Lake Huron
, with upper portions centered over Michigan
. During this 24-hour period, the cyclone also dropped in pressure from 1012 millibars to 1006. After 1200 UTC September 12, the low moved southeastward and became vertically stacked atop the cyclone from the surface to 500 millibars.
For a brief time, the 300 and 200 mbar levels moved southeastward with the 300 moving over Lake Huron. All levels greater than 200 mbars then fell to mandatory levels, spawning the greatest intensification below the 500 mbar level. In addition to that, the cyclone's tilt was neutral, meaning that the storm was in the occlusions stage of baroclinic development. As the cyclone proceeded through this stage, the cold front, which was attendant to the surface low, became an occluded front that extended from Lake Huron to Pennsylvania
on September 13. A 155 mile (250 km) swath of showers and thunderstorms was positioned across the occlusion front, with an area of showers laid along a lacking trough. Also at this time, a third area of showers was centered near the occluded low.
Between 1200 UTC September 13 and 0000 UTC September 14, a shortwave rotated throughout the area of the occluded low. This caused the 500, 700 and 850 millibar levels to move eastward, centering themselves just east of Lake Huron. In these twelve hours alone, the same levels dropped 20 meters, whereas the 200 millibar level had raised 20 meters. During the same period, the surface low moved slowly over Lake Huron and fell five more millibars to 999 mbar. In response to this change, the maximum sustained winds increased as well. After 0000 UTC September 14, the lower and mid-tropospheric portions of the cyclone moved westward, becoming stacked atop one another again, but this time at the 200 mbar level. In contrast to the earlier developments, the baroclinicity of the system diminished rapidly. However, the lower tropospheric area continued to intensify, dropping to 993 millibars, with major height falls. The lowered baroclicity determined that the heat fluxes may have spawned the intensification.
Between 1200 UTC September 14 and 0000 UTC September 15, visible satellite imagery of the vortex revealed a resemblance to a tropical cyclone
, with an eye-like feature about 19 miles (30 km) wide. In addition to the eye, convective clouds had also formed, creating the eyewall of a tropical cyclone. Furthermore, feeder bands of convective showers continued extending westward to about 310 miles (500 km). Soon after the cyclone passed buoy 45008, winds turned to the east-northeast and rapidly increased. In contrast to earlier in the storm's life, which had more energy in the high levels, now it was near the surface. Surface analysis indicated that a weaker cyclonic circulation perisisted over the eastern shore of Lake Huron
with another center north of Lake Ontario
. During this 12-hour period, the cyclone diminished rapidly, mainly in the lower troposphere. Twelve-hour height rises also occurred ranging from 66 – 197 feet (20 – 60 m). The cyclone decayed and left Lake Huron September 15.
Lake Huron
Lake Huron is one of the five Great Lakes of North America. Hydrologically, it comprises the larger portion of Lake Michigan-Huron. It is bounded on the east by the Canadian province of Ontario and on the west by the state of Michigan in the United States...
in September 1996. It had some characteristics of a tropical cyclone
Tropical cyclone
A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...
.
Storm history
On September 11, 1996, a weak cyclone was situated close to Lake SuperiorLake Superior
Lake Superior is the largest of the five traditionally-demarcated Great Lakes of North America. It is bounded to the north by the Canadian province of Ontario and the U.S. state of Minnesota, and to the south by the U.S. states of Wisconsin and Michigan. It is the largest freshwater lake in the...
. Near the surface, a 1012 mbar low existed over Lake Michigan
Lake Michigan
Lake Michigan is one of the five Great Lakes of North America and the only one located entirely within the United States. It is the second largest of the Great Lakes by volume and the third largest by surface area, after Lake Superior and Lake Huron...
. There was also a 500 mbar shortwave over Ontario
Ontario
Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....
. The northwest tilt of the low indicated that the surface center was in a stage of baroclinic development. In addition to this, analysis concluded that the cyclone had a cold core in the mid-troposphere
Troposphere
The troposphere is the lowest portion of Earth's atmosphere. It contains approximately 80% of the atmosphere's mass and 99% of its water vapor and aerosols....
. Analysis at the 700 and 850 millibar levels indicated that the cyclone also had a cold core in the lower troposphere, though a more dense observation would be needed.
The cyclone's height increased with surprising rapidity, as did its overall windspeed, from 11 mph (18 km/h) to 67 mph (108 km/h) up to strong tropical storm wind strength. At the same time, positive vorticity and thermal advection were causing moderate rain showers over Ontario, with a broken area of thunderstorms present in a warm portion of an advancing cold front. By September 12, the cyclone moved southward to a position over Lake Huron
Lake Huron
Lake Huron is one of the five Great Lakes of North America. Hydrologically, it comprises the larger portion of Lake Michigan-Huron. It is bounded on the east by the Canadian province of Ontario and on the west by the state of Michigan in the United States...
, with upper portions centered over Michigan
Michigan
Michigan is a U.S. state located in the Great Lakes Region of the United States of America. The name Michigan is the French form of the Ojibwa word mishigamaa, meaning "large water" or "large lake"....
. During this 24-hour period, the cyclone also dropped in pressure from 1012 millibars to 1006. After 1200 UTC September 12, the low moved southeastward and became vertically stacked atop the cyclone from the surface to 500 millibars.
For a brief time, the 300 and 200 mbar levels moved southeastward with the 300 moving over Lake Huron. All levels greater than 200 mbars then fell to mandatory levels, spawning the greatest intensification below the 500 mbar level. In addition to that, the cyclone's tilt was neutral, meaning that the storm was in the occlusions stage of baroclinic development. As the cyclone proceeded through this stage, the cold front, which was attendant to the surface low, became an occluded front that extended from Lake Huron to Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
on September 13. A 155 mile (250 km) swath of showers and thunderstorms was positioned across the occlusion front, with an area of showers laid along a lacking trough. Also at this time, a third area of showers was centered near the occluded low.
Between 1200 UTC September 13 and 0000 UTC September 14, a shortwave rotated throughout the area of the occluded low. This caused the 500, 700 and 850 millibar levels to move eastward, centering themselves just east of Lake Huron. In these twelve hours alone, the same levels dropped 20 meters, whereas the 200 millibar level had raised 20 meters. During the same period, the surface low moved slowly over Lake Huron and fell five more millibars to 999 mbar. In response to this change, the maximum sustained winds increased as well. After 0000 UTC September 14, the lower and mid-tropospheric portions of the cyclone moved westward, becoming stacked atop one another again, but this time at the 200 mbar level. In contrast to the earlier developments, the baroclinicity of the system diminished rapidly. However, the lower tropospheric area continued to intensify, dropping to 993 millibars, with major height falls. The lowered baroclicity determined that the heat fluxes may have spawned the intensification.
Between 1200 UTC September 14 and 0000 UTC September 15, visible satellite imagery of the vortex revealed a resemblance to a tropical cyclone
Tropical cyclone
A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...
, with an eye-like feature about 19 miles (30 km) wide. In addition to the eye, convective clouds had also formed, creating the eyewall of a tropical cyclone. Furthermore, feeder bands of convective showers continued extending westward to about 310 miles (500 km). Soon after the cyclone passed buoy 45008, winds turned to the east-northeast and rapidly increased. In contrast to earlier in the storm's life, which had more energy in the high levels, now it was near the surface. Surface analysis indicated that a weaker cyclonic circulation perisisted over the eastern shore of Lake Huron
Lake Huron
Lake Huron is one of the five Great Lakes of North America. Hydrologically, it comprises the larger portion of Lake Michigan-Huron. It is bounded on the east by the Canadian province of Ontario and on the west by the state of Michigan in the United States...
with another center north of Lake Ontario
Lake Ontario
Lake Ontario is one of the five Great Lakes of North America. It is bounded on the north and southwest by the Canadian province of Ontario, and on the south by the American state of New York. Ontario, Canada's most populous province, was named for the lake. In the Wyandot language, ontarío means...
. During this 12-hour period, the cyclone diminished rapidly, mainly in the lower troposphere. Twelve-hour height rises also occurred ranging from 66 – 197 feet (20 – 60 m). The cyclone decayed and left Lake Huron September 15.