Hazard: High Winds High Wind Profile

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HAZARD: HIGH WINDS HIGH WIND PROFILE: Wind is essentially the movement of air in response to pressure differences. A pressure gradient force tends to start the flow of air from higher to lower pressure. The stronger the pressure gradient, the stronger the wind. As shown on Figure 28, wind speeds are graded on the Beaufort Scale from 0 (calm) to 12 (hurricane-75 mph). Normally, damage to trees occurs above number 8 (gale force-39 mph on the Beaufort Scale), while structural damage to buildings starts at number 9 (47 mph) with considerable damage to buildings and trees being uprooted at number 10 (55mph). Winds above this speed are seldom experienced inland with the exception of the passage of tornadoes and hurricanes. COUNTY PERSPECTIVE AND PROFILE: Garrett County is situated in the lower part of the westerly wind belt which extends from latitude 35 to latitude 60. Over time, prevailing winds in Garrett County are from the southwest in summer and the northwest in winter. This northwest wind flow in winter has a strong influence over the “Lake Effect” precipitation that brings snow to Garrett County while areas to the east receive little or no precipitation. In winter these winds are very strong and approach gale force on the Beaufort Scale on numerous days from November through April. In addition to strong winds associated with winter “Lake Effect” storms, Garrett County is also subject to high winds associated with thunderstorms and the occasional hurricane or tornado that passes through or near the county. Because of the prevalence of high wind conditions, the local planning committee has ranked high winds as a high risk in Garrett County. MUNICIPAL PERSPECTIVE: As noted in other hazard profiles, municipalities are subject to the same winds as the remainder of the county. However, Grantsville and Accident are more exposed to wind due to their location on high, nearly level land, whereas Friendsville and Kitzmiller are more protected from high winds due to their valley setting. PREVIOUS MITIGATION MEASURES: Since high winds are usually associated with another event, such as winter storms, thunderstorms, tornadoes and hurricanes, most of the measures associated with those events apply to high winds as well. The county’s Building Code contains provisions for wind loading for new structures and tying down of mobile homes as shown on Figure 24. .

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