Freeman/Hasling Hurricane Damage Potential Scale
Authors: Hasling Jill F. 
Published: May 2011

The Freeman/Hasling Hurricane Damage Potential [HDP] Scale gives a more accurate and complete description of the impact expected to offshore structures from a hurricane moving through the Gulf of Mexico [GOM] oil leases than current industry methods. The Freeman/Hasling HDP Scale is not only based on the maximum sustained winds in the hurricane but also the central pressure, storm speed, storm heading, radius of 34 and 64 knot winds, the area of 34 feet or greater significant wave heights and the duration of the winds greater than 64 knots. This scale can be used to determine the number of offshore properties at risk of being damaged or destroyed as the hurricane moves through the GOM oil leases. This will then give the user an idea of the impact of the storm surge and hurricane generated waves to their properties.

Introduction

Hurricane Ike 2008 demonstrated that Size Matters, where the size of the hurricane is defined as the radius of hurricane force winds, [64 knots, R64]. Ike was a very large storm which generated a very high storm surge and waves over the GOM oil and gas leases. The author used Weather Research Center's [WRC] Hurricane Wind and Wave Model in real time to forecast Hurricane Ike as it moved through the leases. During the 2008 hurricane season, WRC meteorologists noticed the significant difference in the hurricane wind field size between Hurricane Gustav and Hurricane Ike [See Figure 1]. Using ARCGIS, WRC was able to graph the results for the hurricane wind and wave model. Figure 1 shows the comparison of the maximum sustained wind fields for Hurricane Gustav and Hurricane Ike. The yellow wind barbs indicate winds greater than 64 knots [Category 1 on the Saffir/Simpson Scale], the light orange wind barbs indicate winds greater than 83 knots [Category 2] and the dark orange wind barbs indicate winds greater than 96 knots [Category 3]. The radius of hurricane force winds for Hurricane Gustav extended out to the right of the hurricane track 60 nautical miles compared with Hurricane Ike which had hurricane force winds extending out 110 nautical miles.

WRC's Hurricane Wind and Wave Model also computes the significant waves, maximum waves and wave crests generated by the hurricane wind field so WRC's meteorologists were also able to plot the significant waves generated by Hurricane Ike using the ARCGIS software. A composite plot of the regions with significant waves greater than 30 feet, 34 feet, 40 feet, etc. can be made using the software. The GIS software also allows you to overlay other fields such as the Gulf of Mexico offshore platforms and pipelines.

Hurricane Ike was classified as a Category 2 hurricane on the Saffir/Simpson Scale, which usually means the significant waves generated cause little damage offshore. However, the size of Ike allowed a very long fetch for the hurricane force winds, which in turn generated very high significant waves, maximum waves, wave crests and storm surges for this hurricane intensity.

This led WRC meteorologists to review the past significant hurricanes that have influenced the GOM oil leases to determine if an improved damage potential scale could be generated. This research led to the development of the Freeman/Hasling Hurricane Damage Potential [HDP] Scale. The Freeman/Hasling HDP Scale is not only based on the maximum sustained winds in the storm but also the central pressure, storm speed, storm heading, radius of 34 and 64 knot winds, the area of significant wave heights and the duration of the winds greater than 64 knots. This scale can be used to determine the number of offshore properties at risk of being damaged or destroyed as the hurricane moves through the GOM oil leases which will give the user an idea of the impact of the hurricane generated waves to their properties.