Orange County NC Website
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States for Number of Tornadoes,Fatalities, and Damages, 1950 to 2007;NOAA). <br /> Tornados in North Carolina are typically less severe than in other parts of the country, and <br /> the North Carolina Division of Emergency Management has rated Orange County as a <br /> "moderate"risk for tornados. <br /> According to available records,six tornados impacted Orange County between 1956 and <br /> 2008. The most violent was an F3 tornado that occurred on November 23, 1992, which , <br /> caused two (2)deaths,ten(10)injuries, and$500,000 in property damage. ' <br /> Droughts and Heat Waves <br /> Droughts are not rare or random events but normal,recurrent features of climate. Droughts <br /> occur in virtually all climatic zones,but drought characteristics vary significantly from one <br /> region to another. <br /> Drought is a temporary aberration and differs from aridity, which is restricted to low <br /> rainfall regions, and is a permanent feature of climate. Drought originates from a deficiency <br /> of precipitation over an extended period of time,usually a season or more. This deficiency <br /> results in a water shortage for some activity, group,or environmental sector. <br /> Drought should be considered relative to some long-term average condition of balance <br /> between precipitation and evapotranspiration(i.e.- evaporation+transpiration)in a <br /> particular area, a condition often perceived as "normal". It is also related to the timing (i.e.- <br /> principal season of occurrence,delays in the start of the rainy season, occurrence of rains in <br /> relation to principal crop growth stages)and the effectiveness (i.e.-rainfall intensity, <br /> number of rainfall events)of rain events. Other climatic factors such as high temperature, <br /> high wind, and low relative humidity aze often associated with drought and can <br /> significandy aggravate drought severity. <br /> The more recent understanding that a deficit of precipitation has different impacts on <br /> groundwater, reservoir storage, soil moisture, snowpack, and streamflow led to the <br /> development of the Standardized Precipitation Index (SPn in 1993.The SPI was designed <br /> to quantify the precipitation deficit for multiple time scales.These time scales reflect the <br /> impact of drought on the availability of the different water resources. Soil moisture <br /> conditions respond to precipitation irregularities on a relatively short scale. Groundwater, <br /> streamflow, and reservoir storage reflect longer-term precipitation inconsistencies. <br /> Sequence of Drought Impacts <br /> When drought begins, the agricultural sector is usually the first to be affected because of <br /> heavy dependence on stored soil water. Soil water can be rapidly depleted during extended <br /> dry periods. If precipitation deficiencies continue, then people dependent on other sources <br /> of water will begin to feel the effects of the shortage. Those who rely on surface water <br /> (reservoirs and lakes) and subsurface water(ground water),for example, are usually the last <br /> to be affected. A short-term drought that persists for 3 to 6 months may have little impact <br /> on these sectors, depending on the characteristics of the hydrologic system and water use <br /> requirements. <br /> 11 <br />