Section 9: Hail. Contents. Why Hailstorms Are a Threat

Transcription

1 Section 9: Hail Contents Why Hailstorms Are a Threat Hazard Profile History of Hailstorms People and Property at Risk Potential Damages and Losses Why Hailstorms Are a Threat According to the National Oceanic and Atmospheric Administration, hailstones are balls of ice that fall during thunderstorms. 1 Inside a cloud, air moves up and down. It carries drops of water up high where it is very cold. The drops freeze into bits of ice. When they start to fall, a little water sticks to them and freezes. Sometimes the bits of ice keep going up and down on th4 streams of air. They get a bit bigger each time they freeze. Finally they fall as hail. Hail the size of golf balls is common. Forecasting hail is difficult, even with the use of Doppler radar, because of the complexities of hail formation and National Weather Service photo of hail stones. sub-cloud processes. Verification is also a cumbersome process, albeit important, because of the limited temporal and spatial distribution of hail events. Hail can be smaller than a pea or as large as a softball and can be very destructive to plants, cars, homes, buildings and crops. 1 NOAA Website: http: Hazard Mitigation in the Guadalupe River Basin -- Page 9-1

2 Hazard Profile Hailstorms are generally localized and their impact is considered limited since the injuries they cause are generally treatable with first aid. They can, however, shut down critical facilities and services for as long as 24 hours, and severely damage or destroy property. Hail events are highly likely in the GBRA jurisdictions. When they do occur, warning time at best is short. Figure 9-1. Hail Hazard Profile Summary Page 9-2 Hazard Mitigation in the Guadalupe River Basin.

3 History of Hailstorms Reports of hailstorms have increased in frequency in recent years. Figure 9-2 shows the frequency of reported historical hailstorms, by county, in the Guadalupe River Basin. Figure 9-2. Frequency of Hail events in the Guadalupe River Basin, NOAA Data, Year Source: National Oceanic and Atmospheric Administration Figure 9-3 maps the historical hail events (all sizes of hailstones) that have been reported in the Basin. Historical events in which hailstone size was greater than one inch in diameter are listed, by jurisdiction, in Table 9-1 below. Hazard Mitigation in the Guadalupe River Basin -- Page 9-3

4 Figure 9-3. Historical Reported Hail Events (NOAA Data ), all hailstone sizes Page 9-4 Hazard Mitigation in the Guadalupe River Basin.

5 Table 9-1. Hailstorms in the GBRA Area Having Hail 1 inch or Larger, Lower Basin CALHOUN COUNTY Calhoun Apr 1.00 Calhoun Apr 4.50 Calhoun May 1.00 Seadrift Jan 1.00 Calhoun Jan 1.75 Port Lavaca May 1.00 Calhoun Mar 1.75 Port O Connor May 1.00 Total Number of Storms: 8 REFUGIO COUNTY Woodsboro Dec 1.75 Refugio Apr 1.75 Refugio North of Dec 2.75 Bayside May 1.75 Refugio Refugio Apr 1.75 Refugio Feb 1.75 Total Number of Storms: 6 VICTORIA COUNTY Victoria Apr 1.00 Victoria Aug 1.00 Victoria Apr 1.75 Bloomington Apr 1.75 Victoria Apr 2.75 Placedo Apr 1.75 Victoria Apr 1.75 Victoria Apr 1.75 Victoria May 1.75 Victoria Jun 1.75 Victoria Mar 2.00 Nursery Jun 2.75 Victoria Mar 1.75 Nursery Jun 1.50 Victoria Mar 1.75 Victoria May 1.00 Victoria Feb 1.00 Victoria Jun 1.00 Victoria May 1.00 Nursery Jun 1.50 Victoria Oct 2.75 McFaddin May 1.75 Mission Valley Apr 1.75 Mission Valley Apr 1.75 Victoria Reg nl Airport May 1.00 Total Number of Storms: 25 Source: National Climatic Data Center, National Oceanic and Atmospheric Administration. Hazard Mitigation in the Guadalupe River Basin -- Page 9-5

6 Middle Basin Hailston e CALDWELL COUNTY Caldwell May 2.50 Caldwell Apr 1.75 Caldwell Apr 1.00 Caldwell Apr 1.75 Caldwell Apr 1.00 Lockhart May 1.75 Caldwell Apr 1.75 Luling May 1.00 Caldwell Mar 2.50 Martindale May 1.75 Caldwell Apr 1.75 Luling Apr 1.25 Caldwell May 3.50 Luling Apr 1.50 Caldwell Apr 1.00 Lockhart Feb 1.00 Caldwell 1980 Feb Luling Mar 1.50 Caldwell May 1.75 Martindale Jun 1.00 Caldwell May 1.75 Lockhart Jun 2.75 Caldwell May 1.00 Luling Jul 1.00 Caldwell May 1.00 Lockhart Jul 1.00 Caldwell Apr 2.00 Lytton Spgs May 1.00 Caldwell Sep 1.75 Luling Mar 1.75 Caldwell Jan 1.75 Luling Mar 1.75 Caldwell Aug 1.75 Martindale May 1.75 Caldwell Feb 1.75 Luling May 1.00 Caldwell Feb 1.75 Maxwell May 1.75 Total Number of Storms: 38 DEWITT COUNTY DeWitt May 2.00 DeWitt Feb 2.75 DeWitt Jun 1.00 DeWitt May 1.75 DeWitt Apr 2.00 DeWitt May 1.75 DeWitt Apr 1.75 Meyersville Oct 2.75 DeWitt Nov 1.75 Cuero Oct 1.75 DeWitt May 1.75 Meyersville Oct 2.75 DeWitt May 2.75 Hochheim Apr 1.75 DeWitt May 2.75 SW Hochheim Apr 1.75 DeWitt May 2.75 Meyersville Apr 1.75 DeWitt Apr 1.75 Meyersville Apr 1.75 DeWitt Apr 1.75 Yorktown May 1.00 DeWitt May 1.50 Cuero Dec 1.75 Page 9-6 Hazard Mitigation in the Guadalupe River Basin.

7 Hailston e DeWitt May 1.00 Cuero Dec 1.50 DeWitt Nov 1.75 Cuero Jun 1.00 DeWitt Nov 1.75 Cuero Dec 1.00 DeWitt Feb 4.50 Thomaston Jun 1.50 Total Number of Storms: 32 GONZALES COUNTY Gonzales Mar 1.75 Gonzales May 2.75 Gonzales Jan 1.00 Gonzales May 4.50 Gonzales May 1.25 Gonzales Apr 1.75 Nixon Feb 1.75 Gonzales Feb 1.00 Nixon May 1.50 Gonzales May 1.75 Cheapside Jun 1.50 Gonzales Apr 2.75 Gonzales Jul 1.50 Gonzales May 1.50 Leesville Jan 1.75 Gonzales May 2.00 Leesville Jan 1.50 Total Number of Storms: 17 Source: UPPER BASIN National Climatic Data Center, National Oceanic and Atmospheric Administration Hailston e GUADALUPE COUNTY Guadalupe Oct 2.00 Guadalupe Apr 1.75 Guadalupe May 2.00 Guadalupe May 4.00 Guadalupe Mar 1.00 Guadalupe May 2.50 Guadalupe May 2.00 Guadalupe May 1.75 Guadalupe May 1.75 Guadalupe Jun 2.75 Guadalupe Apr 1.75 Seguin Mar 1.75 Guadalupe Apr 1.00 New Braunfels May 1.25 Guadalupe Apr 1.75 Geronimo Mar 1.50 Guadalupe May 1.00 Seguin Feb 1.25 Guadalupe May 1.75 Schertz Mar 1.75 Guadalupe Oct 1.00 Seguin Mar 1.00 Hazard Mitigation in the Guadalupe River Basin -- Page 9-7

8 Hailston e Guadalupe Apr 1.75 New Braunfels Mar 2.50 Guadalupe May 1.75 Seguin Mar 2.00 Guadalupe May 1.75 Staples May 1.75 Guadalupe May 1.75 Marion Apr 1.75 Guadalupe Jan 1.00 New Braunfels Dec 1.00 Total Number of Storms: 32 HAYS COUNTY Hays May 3.00 Hays May 1.25 Hays May 1.00 Hays May 2.00 Hays Oct 1.00 Hays May 1.50 Hays Feb 2.25 Hays May 1.50 Hays Mar 3.00 Hays Feb 1.50 Hays May 1.75 Hays Apr 1.50 Hays Mar 1.75 Hays Apr 1.50 Hays Apr 1.75 Hays May 1.75 Hays Apr 1.75 Hays May 1.75 Hays Apr 1.75 Hays May 1.00 Hays Apr 1.75 Hays May 1.00 Hays Apr 1.75 San Marcos May 1.75 Hays May 1.75 Wimbereley Apr 1.75 Hays Apr 1.00 San Marcos Apr 2.00 Hays Apr 2.00 Buda Apr 1.75 Hays Apr 2.00 Henly Nov 1.75 Hays Apr 1.00 San Marcos Nov 1.75 Hays Jan 1.75 Niederwald May 1.75 Hays Jan 1.00 Wimberley Sep 1.50 Hays 1980 Feb Buda Sep 1.25 Hays Apr 1.00 Wimberley Mar 1.00 Hays May 1.00 Dripping Spgs May 1.75 Hays May 1.00 Buda May 1.00 Hays Apr 1.00 San Marcos Mar 4.50 Hays May 1.00 Dripping Spgs Apr 1.00 Hays Mar 1.00 Dripping Spgs May 1.75 Hays May 1.00 San Marcos Dec 1.50 Kendall Apr 1.75 Kendall May Kendall Oct 1.00 Kendall Mar 1.00 Page 9-8 Hazard Mitigation in the Guadalupe River Basin.

9 Hailston e Kendall Mar 1.75 Kendall Jun 1.75 Kendall Apr 2.75 Kendall Apr 1.75 Kendall Mar 1.75 Kendall May 1.75 Kendall Apr 1.75 Kendall Jun 1.75 Kendall Mar 1.75 Kendall Jun 1.75 Kendall May 1.75 Kendall Jun 1.75 Kendall May 1.75 Kendall Jun 1.75 Kendall Feb 1.00 Comfort Oct 1.75 Kendall Mar 1.75 Comfort Oct 2.75 Kendall May 1.75 Comfort Mar 1.75 Kendall May 1.75 Comfort Apr 1.75 Kendall Apr 1.75 Boerne Apr 1.00 Kendall May 1.00 Sisterdale Jun 2.00 Kendall Apr 1.75 Boerne May 4.00 Kendall Apr 3.00 Comfort May 1.75 Total Number of Storms: 34 Source: National Climatic Data Center, National Oceanic and Atmospheric Administration. Hazard Mitigation in the Guadalupe River Basin -- Page 9-9

10 People and Property at Risk Hail events have no defined geographic boundary. Because it cannot be predicted where hail may fall, all people, buildings, critical facilities, infrastructure, lifelines, and hazardous materials facilities are considered exposed to hailstorms. Table 9-2. Exposure to Hailstorms, by County, in the Guadalupe River Basin Jurisdiction Page 9-10 Population Residential Buildings Commercial Buildings Critical Facilities (2000) Number Value ($) Number Value ($) Number Caldwell 32,194 11,374 2,387,436, ,885, Calhoun 20,647 9,835 2,171,890, ,066, Comal 78,021 42,027 10,237,572, ,348, DeWitt 20,013 6,983 1,530,674, ,433, Gonzales 18,628 6,510 1,315,844, ,323, Guadalupe 89,023 39,668 8,760,265, ,030, Hays 97,589 45,837 12,655,070, ,433,860, Kendall 23,743 12,844 3,164,217, ,066, Refugio 7,828 2, ,396, ,484, Victoria 84,088 36,206 9,418,849, ,548,383, TOTAL 471, ,237 52,282,213,000 1,456 6,329,878, Jurisdiction Oil Pipe (km) Infrastructure and Lifelines Gas Pipe (km) Highway (km) Railroad (km) Hazardous Materials Facilities Number of Sites Number of Materials Caldwell Calhoun Comal DeWitt Gonzales Guadalupe Hays Kendall Refugio Victoria TOTALS 1,391 2,181 1, Hazard Mitigation in the Guadalupe River Basin.

11 Potential Damages and Losses PBS&J estimates that annualized expected property losses from hailstorms in the Guadalupe River Basin are $852,048 per year. Table 9-3 presents annualized expected property losses and annualized loss ratios, by County. The data indicate that Refugio County has the highest risk from hail relative to replacement value. Table 9-3. Potential Annualized Losses and Percent Loss Ratio from Hail Events, by County, in the Guadalupe River Basin Annualized Expected Property Losses ($) Annualized Loss Ratio Jurisdiction Total Exposure Caldwell 2,806,776,000 82, % Calhoun 2,681,601,000 39, % Comal 11,640,775,000 97, % DeWitt 2,021,890,000 69, % Gonzales 1,637,234,000 68, % Guadalupe 10,376,784, , % Hays 14,756,866, , % Kendall 3,728,076,000 85, % Refugio 740,701,000 82, % Victoria 11,424,428, , % Totals $61,815,131,000 $852,048 GBRA facilities (described on pages 4-18 and 4-19) are also at risk from this hazard. However, no estimate is currently available of potential damages and losses to those facilities. Hazard Mitigation in the Guadalupe River Basin -- Page 9-11