Lake Erie is a fairly shallow body of water with a shape that happens to be aligned with the prevailing winds, which flow across it. It is approximately 250 miles long in a west southwest to east-northeast direction, and averages about 50 miles wide in a SSE to NNW direction. With the exception of Lake Superior, when the wind is in the prevailing direction, it crosses a longer expanse of water than in any other of the Great Lakes.

All of the lakes that make up the Great Lakes have a variety of weather monitoring sites around the shoreline, and a few coastal and island stations set up for that purpose (although they may also double up as lighthouses). These include Coast Guard, NOAA locations at major airports such as Cleveland and Buffalo, minor airports such as Dunkirk, NY and Erie, Pa as well as numerous radio and television stations, power plants and large industrial facilities. In addition, there are a few specially designed buoys and shore stations, which automatically record and transmit weather and lake data (water temperature, wave characteristics). A map of some of these sites is shown for Lake Erie in Figure 1.

Figure 1

Lake Erie Meteorological Stations

As air moves across the surface of the planet, it encounters a relatively immobile surface, and its velocity is decreased due to frictional forces. Wind speeds in this part of North America tend to increase with the height above the surface until a certain level is reached; this is known as the top of the boundary layer. The surface friction has effectively no impact on winds that are present above the boundary layer; these winds are usually the driving force behind the surface winds. The average boundary layer thickness tends to be a function of the roughness of the surface. Above a smooth surface there will be a thinner boundary layer, while a thicker boundary layer will exist above surfaces composed of objects that impede the air flow (such as buildings, forests, hills and mountains). When winds pass over long stretches of water, the boundary layer thickness tends to be at a minimum amount. This is especially true for winds coming across Lake Erie in a Toledo to Buffalo direction (over 250 miles across water or ice/snow in the winter.

Wind speeds near the surface of a lake or landmass in the range of 2 to 150 meters tend to follow a pattern that can be modeled as either a power law or a logarithmic pattern – both are very similar below 150 meters. On low friction surfaces such as lakes, this is known as the 1/7^th power law, where the wind shear exponent, a, has the value of 0.143, or 1/7. On rougher surfaces, the value of the wind shear exponent is a larger number. As a general rule, for a given upper layer wind driving force, wind speeds near the surface will be faster over smooth surfaces as compared to wind speeds at the same height over rougher surfaces. In addition, less of the energy in the wind is expended overcoming surface friction across smooth areas as contrasted to expanses of rougher surfaces.

This is why winds out on Lake Erie and along the shoreline of Lake Erie tend to be faster for a given height in the 2 to 150 meter range than are the winds further inland. Some exceptions to this general rule are correctly aligned valleys and the correct side and top of hills and mountains.

This general rule also applies to wind monitoring stations along the shoreline as compared to buoys. Unless there are no obstacles between the wind speed measuring device and the surrounding area (especially trees and buildings), the actual wind shear exponent will probably be greater than 1/7. Calculating its correct value is usually accomplished by taking readings at least two different heights, and it is very difficult when there is only one height employed. A good example of this can be found at the Buffalo Coast Guard Station, where a wind shear exponent value of 0.21 was estimated by NYSERDA in a 1981 report and where only one height (10 meters) is measured.

To date, some of the best wind data for the Lake Erie wind resource may be found via the buoys, which are operated by the National Oceanic and Atmospheric Administration (NOAA) in US waters and the Marine Environment Data Service (MEDS) division of Environment Canada (basically the weather and climate forecasting organizations in the US and Canada). For Lake Erie, this involves buoy # 45005, located NW of Cleveland, and # 45142, located south of Port Colborne, approximately 20 mile WSW of Buffalo, at 42.74 N and 82.40 W.

The average wind speed of 20 years of data at the Cleveland buoy is 10.23 knots, or 5.25m/s. When the wind speeds are corrected to a 12 month basis, the speed increases slightly to 5.47 m/s.

The average wind speed of 9 years of data from the Port Colborne buoy is 4.944 m/s. When this is corrected to a 12 month basis, using the Buffalo Coast Guard Station data, the average wind speed increases to 5.60 m/s.

The yearly wind speeds at the 5 meter level are remarkably similar. In Table 1, the wind speeds at heights above this level are given using power law values of 0.1 (1/10) and 0.143 (1/7) for some representative heights above the water.

In general, the winds that pass over the Port Colborne buoy tend to also impact the eastern shoreline of Lake Erie, particularly Lackawanna and Buffalo. These also have a very similar velocity to those blowing past Cleveland. And they seem to be much greater than those predicted by several models (such as the New York Wind Map). This may be due to the use of the Coast Guard station and Dunkirk NOAA C-MAN station wind data coupled with a low estimate of the wind shear exponent. For example, the given wind shear exponent at the Coast Guard station is near 1/7, for the 10 meter height average speed of 5.10 m/s extrapolates to 6.66 m/s at 65 meters and 7.08 m/s at 100 meters. Using the NYSERDA values of 0.21, the extrapolated wind speeds would be 7.55 m/s at 65 meters and 8.27 m/s at 100 meters height based upon the Buffalo Coast Guard data.