Cumulonimbus and aviation at this altitude, updraughts with speeds that can exceed . Such an updraught speed corresponds to the wind speed of a small hurricane. The speed can even exceed . The maximum number in the Beaufort scale is 12 ("hurricane force" wind) and is assigned to wind speeds of 64 knots or greater. If the Beaufort scale were extended, these updraughts would have a Beaufort number of 14 "in the vertical direction". The turbulence is then "extreme" at this altitude. Moreover, the diameters of the updraught columns vary between 2 km (air mass thunderstorm) and 10 km (supercell thunderstorm). The height
1887 Halloween tropical storm the storm was in Virginia. Cape Henry was hit with a combination of wind, rain, and blown sand on October 31 and communications between Cape Henry and Norfolk were lost. In Norfolk, the storm was the longest-lasting and most damaging since the Great Beaufort Hurricane of 1879. The storm conditions made beaches in the area so hazardous that they were watched day and night. Effects from the storm reached as far north as Provincetown, Massachusetts, where winds of were recorded. Despite causing damage along the East Coast, the storm is best known for causing a record number of maritime incidents.