47.5 MB - The Whole Building Design Guide

flow is typically 6,000 to 12,000 feet across, and the vortex ringmay rise 2,000 feet above the ground. The lifecycle of a downburstis usually 15 to 20 minutes. Observations suggest that approximately5 percent of all thunderstorms produce a downburst,which can result in significant damage in a localized area.Northeaster (nor’easter): A northeaster is a cyclonic storm occurringoff the east coast of North America. These winter weatherevents are notorious for producing heavy snow, rain, and highwaves and wind. A nor’easter gets its name from the continuouslystrong northeasterly winds blowing in from the ocean ahead ofthe storm and over the coastal areas. These storms may last for severaldays.Figure 3-1: Hurricane-prone regions and special wind regionsSOURCE: adapted from asce 7-05MAKING CRITICAL FACILITIES SAFE FROM High Wind3-3