Hurricane Season Sees Calmer Skies Sailing into Mid-September

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Leslie and Michael race in the Atlantic this week. Image Credit: NASA

Hurricane season has its ups and downs.

After the torrent of public and political concern around Isaac’s torrential rains, the Atlantic coast had a reprieve last week.

The skies were also quiet in the Pacific, with the remnants of old hurricanes subsiding into tropical depressions.

As we move into a new week, it’s the Canadian East Coast that is being battered by wind and rain.

Tropical Storm Leslie Moves North

In the Atlantic, Tropical Storm Leslie is shaping up to blast Newfoundland this week. The storm is currently taking out power in St John’s, Newfoundland, and power outages, winds and rain have grounded flights across the area. There is a hurricane watch in effect for Newfoundland from Stones Cove to Charlottetown.

Hurricane Michael Is Weakening

By September 7th, Michael was a Category Two hurricane and its hurricane-force winds extended outward 25 miles from its center. Hurricane Michael had a weak steering flow, which meant that it was moving quite slowly. The hurricane appears to be weakening, tempering concerns that Michael and Leslie would merge into one large hurricane on Canada’s East Coast.

NASA noted that Michael has a particularly clear eye, and satellites were able to see the ocean through the storm.

Hurricane Speed and Damage

Isaac proved that even a Category One hurricane can cause major damage due to flooding, especially if it sticks around an area for a long time. While a storm’s intensity gives it its rating, a storm’s duration also plays a large role in the amount of damage produced by the hurricane.

Hurricanes gain power from warm ocean waters, but it is air that helps them move along and determines their speed. Everyday wind, cold fronts, and high pressure systems are all caused by the planetary movement of cool and warm air. Isaac got stuck in the quieter upper atmosphere, and was beyond the ability of larger-scale wind patterns to move it quickly. Once a storm gets north and into the jet stream, it starts to speed up.

As a hurricane moves onto land, it loses some of its power, since a hurricane’s power comes from the water. A hurricane also tends to slow down once it moves onto land. A less intense storm will moderate damage from the wind, but a longer-lasting storm means that there is more damage from rain.

Hurricane Damage Next Week?

It remains to be seen whether faster-moving Leslie will swallow up slow-moving Michael this week to add to the rain and wind expected on the Newfoundland coast.

Resources

Taber, J. Tropical storm Leslie barrels through Newfoundland with 130 km/hr winds. (2012). Globe and Mail. Accessed September 11, 2012.

NASA. Hurricanes and Tropical Cyclones. (2012). Accessed September 11, 2012.

NBC Miami. Hurricane Michael Weakens as Tropical Storm Leslie Heads Toward Newfoundland. (2012). Accessed September 11, 2012.

Mustain, A. Why Hurricane Isaac is Moving Slowly. (2012). Our Amazing Planet. Accessed September 11, 2012.

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