Kimster
Weather Hobbyist
Reged: Sun
Posts: 77
Loc: Dunedin, FL
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Re: Hurricane v. Nor'easter
Wed Sep 17 2003 10:43 AM
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For those that believe a hurricane that passes the Mason/Dixon line becomes a Nor'easter,  , I offer the following information to help clarify this matter...(an elaboration of Jason's earlier def.)
Nor'easter: Similar to a hurricane a nor'easter is counter-clock wise turning cyclone (a storm system circulating around a center). Nor'easters are spawned by a very curvy Jet Stream that dips far south allowing cold arctic air to meet warm air. The warm air rises over the cold, creating instability up high and an area of low pressure below. Larger temperature differences create greater turbulence. Once the system is formed, the earths rotation causes the air to circle around the center (similar to when you drain the water out of your bath-tub). This creates the northeast wind, hence it's name nor'easter. They typically form near the Bahamas or north of Cuba, along the Appalachians or off Cape Hatteras. The Jet Stream plays a very important role also in the strengthening of the storm. As the incoming air rises around the center, the Jet Stream whisks it away further increasing the speed of the incoming air. The faster the air moves the faster the barometric pressure drops. Weather forecasters call a 24 millibar drop in 24 hours "The Bomb". Normal Jet Stream winter pattern is to follow the coast and consequently drags the storm northeast ward. Some time a High further north blocks its path and so it churns over the ocean for a long time sending beach-eating waves onshore. During the October to April nor'easter season February is the busiest month. Researchers say the biggest ones occur in October, January and March. What nor'easter don't achieve in wind-speed as compared with hurricanes, they achieve in duration (up to a week) and size (up to 1000 miles or more in diameter).
In addition, some distinct differences between the two:
A hurricane has a warm core. A nor'easter usually has cold air in it's core.
A hurricane's size can reach 200-300 miles across. A nor'easter can reach 1000 miles across.
A hurricane is symmetrical with often a clearly defined center. A nor'easter is irregularly shaped. It is sometimes hard to find the center.
Hurricanes pass a location usually in 6-8 hrs. A nor'easter can last a week.
Hurricane intensity is 74 knots and higher. Nor'easter's intensity is 35-50 knots onshore and higher over the ocean.
Hurricane season is June to November. Nor'easter season is October through April.
Hurricane tracking is easily spotted by satellites and path can be calculated with reasonable accuracy. Nor'easters can spring up out of various conditions. Once formed, they usually take a northeast course.
Hurricanes can virtually level an area, but limited in size. Nor'easter's spread damage around a greater area. Three times as many people died in the March 1993 nor'easter than in Hugo and Andrew combined.
Hurricanes are typically more to the south. Nor'easter's are typically more to the north.
With hurricanes, wind speed, duration, and fetch (distance of wind traveled over water) determine wave severity. With nor'easter's, generally larger systems give wind more time and distance to create large waves.
Only hurricanes are officially named, female and male gender since the early nineties. People generally tie the occurrence of a nor'easter to some date like "The Halloween Storm" or the National Weather Service uses superlatives like "The Superstorm of March 1993".
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