Laserfiche WebLink
<br />107 <br /> <br /> <br />Brooks, Stensrud, and Mitchell <br /> <br />000 <br /> <br />00 <br /> <br />10 <br /> <br />o. <br /> <br />0.01 <br /> <br />- <br />Q) <br />C'l <br />m <br />~ <br />Q) <br />> <br />~ <br /> <br />m <br />::J <br />c <br />C <br />oCt <br />-- <br />t/) <br />- <br />c <br />Q) <br />> <br />w <br /> <br />0.001 <br /> <br />6.5 <br /> <br />6 <br /> <br />5.5 <br /> <br />5 <br /> <br />4.5 <br /> <br />4 <br /> <br />3.5 <br /> <br />3 <br /> <br />2.5 <br /> <br />2 <br /> <br />.5 <br /> <br />(Inches) <br /> <br />Figure 2: Average number of heavy rainfall eVents in July in United <br />States reported in HPD. Events are aggregated in half-inch intervals, <br />with all events greater than six inches in the last category. Black <br />squares represent reports. Line is least squares fit to data from one to <br />four inches. <br /> <br />Observed HOUrlY Rainfa <br /> <br />tions fall to 13 % for each one-inch increase, while the value is 10% in the <br />winter. For three hours, the rate decreases to 16% in summer and 12% in <br />winter. This is possibly due to the impact of larger-scale weather systems that <br />produce more sustained periods of heavy precipitation, leading to observa- <br />tions of more than one inch in two and three hours. The extreme precipitation <br />values (e.g., 3 inches or more) still result predominantly from convective <br />environments, which are most pronounced in the summer. <br /> <br />Estimating Frequency of Extreme Events <br /> <br />Although the HPD provides the most complete set of high temporal and <br />spatial resolution observations of precipitation, it is clearly inadequate for <br />capturing extreme events. Since extreme events create the greatest risk of a <br />major disaster, it is important to have some basis for climatological estimates <br />of risk. The logarithmic decline of the number of events with increasing <br />precipitation allows us to make estimates of the number of more extreme <br />