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2025 Hazard Mitigation Plan Kittitas County, Washington hailstone. There is much uncertainty in the average speed hail falls; however, NOAA developed the estimates shown on Table 4-94.-184 Table 4-94. Hail Speed Estimates Tornado A tornado is a narrow, violently rotating column of air that extends from a thunderstorm to the ground. A tornado is hard to see unless it forms a condensation funnel made up of water droplets, dust, and debris. Tornadoes are among the most violent phenomena of all atmospheric storms and atmospheric scientists continue to conduct research to better understand how tornadoes form. Tornadoes come from mainly two (2) types of thunderstorms - supercell and non-supercell..l85 Table 4-95 outlines the types of tornadoes.,186 Table 4-95. Types of Tornadoes Strong Wind s/Damaging Winds Strong winds/damaging winds are classified as those exceeding 58 mph and are often called "straight- line" winds to differentiate the damage they cause from tornado damage. Damage from strong winds/damaging winds accounts for half of all severe weather reports in the lower 48 states and is more common than damage from a tornado. These types of winds can reach up to 100 mph and produce a 184 NOAA, National Severe Storms Laboratory. (n.d.). Severe Weather 101: Hail Basics. Retrieved from hflnc'//renrnar nccl nnaa n ucatio nlornuv4 A4 lhaill 185 NOAA, National Severe Storms Laboratory. (n.d.). Severe Weather 101: Tornado Basics. Retrieved from https://www.nss L noaa.qov/education/svrwxl 01 /tornadoes/. 1so NOAA, National Severe Storms Laboratory. (n.d.). Severe Weather 101: Types of Tornadoes. Retrieved from https ://www.nssl. noaa.qovieducation/svrwxl 01 /tornadoes/tvpes/. I -25Less than 1 1 - 1.75 20-40 2-4 44 -72 Over 1004 or greater Hail Size (inches)Fall Speed (mph) Supercell The most common and destructive tornadoes occur from supercells. A supercell is a rotating thunderstorm with a well-defined radar circulation called a mesocyclone. Supercells can also produce damaging hail, severe non-tornadic winds, frequent lightning, and flash floods. The rotating updraft from a supercell is the key development for a tornado. One way a column of air can begin to rotate is from wind shear when winds at two (2) different levels above the ground blow at different speeds or in different directions. Once the updraft is rotating and fed with warm moist air flowing in the ground level, a tornado can form. Nearly 20% of all tornadoes are associated with lines of strong thunderstorms called quasi-linear convective systems (OLCS). QLCS tornadoes frequently occur during the late night and early morning hours. These tornadoes, however, tend to be weaker and shorter-lived on average than those associated with supercell thunderstorms. NOAA's National Severe Storms Laboratory (NSSL) researchers are looking for ways to detect OLCS tornadoes more effectivelv. Non-Supercell Another type of non-supercell tornado is a landspout A landspout is a tornado with a narrow, ropeJike condensation funnel that forms while the thunderstorm cloud is still growing and there is no rotating updraft - the spinning motion originates near the ground. DescriptionType Chapter 4: Hazard ldentification and Risk Assessment 151