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Hurricanes: Science and Society
2017 - Hurricane Harvey

Introduction

Hurricane Harvey was a major Atlantic hurricane in 2017 that became a tropical storm on August 17 and after three landfalls became a tropical depression over land on September 1. Hurricane Harvey made landfall in Texas on August 26 as a Category 4 hurricane. Harvey falls directly behind Hurricane Katrina (2005) as the second costliest hurricane in United States history ($125 billion 2017 USD). It was the first major hurricane to make landfall in the U.S. since 2005. As of 2018, Harvey is the wettest hurricane in U.S. history. It caused devastating flood damage, as it stalled over Southeast Texas and Southwest Louisiana and resulted in more than 10,000 people being rescued from flooded homes.

Infrared satellite image of Hurricane Harvey showing the very well developed eye of the storm.
Infrared image of Harvey on 26 August 2017 at at 04:19 UTC, just after landfall as a category 4 hurricane in Texas. Image from NASA Terra Modis, courtesy of UW/CIMSS.

Meteorology and Forecasting

Description: On August 12th, 2017, an atmospheric wave was produced off the west coast of Africa. It propagated westward, forming a low pressure center on August 16th and a tropical depression the next day. Its strength fluctuated for several days until it rapidly intensified on August 23rd after having been exposed to light wind shear, very warm water, and high atmospheric moisture in the Gulf of Mexico. This caused the depression to intensify into a hurricane on August 24th, which grew to a category 4 hurricane by August 26th, the day it made landfall on the northern end of San Jose Island, near Rockport, Texas with winds on 115 knots (132 mph). A second landfall was reported 3 hours later southeast of Refugio on the northeast coast of Copano Bay with winds of 105 knots (121 mph). After moving inland Harvey slowed down and lost intensity, colliding with a stationary atmospheric front that stalled the storm and produced torrential rains over southeastern Texas. The storm drifted eastward and southeastward for the next couple days. On August 28th Harvey moved back over the ocean and strengthened. Harvey made a third and final landfall in Louisiana on Auguts 30 with 40 knot (46 mph) sustained winds. The storm weakened but maintained heavy rain as it moved on to Louisiana and Kentucky, where it dissipated by September 1.

Best track portions for Hurricane Harvey from August 26 to September 1, 2017. Map from the National Hurricane Center.

Intensity: Category 4 (Saffir-Simpson Scale)
Max. winds: 115 kt (132 mph) on August 25, 2017
Min. pressure: 937 mb
Rainfall:

  • Max. 60.58 inches over 4 days (near Nederland, TX)
  • Heaviest rainfall outside the core of hurricane, spreading over a large area of Texas
  • Storm collided with a weak stationary front over Texas from Aug 26-28, causing it to stay in position while producing large and intense rain bands (sometimes 6.8” rain per hour in southeastern Houston).
  • Intense rain was fueled by very warm waters in the northwest Gulf of Mexico, causing consistent influxes of warm and humid air to the coast.
  • Helped produce 57 tornadoes; at least 150 tornado warnings issued.
Map showing the total rainfall during Harvey over the Southeastern US.
Observed rainfall total from Hurricane Harvey and its remnants. Figure by David Roth, NOAA NWS Weather Prediction Center.

Damage

Map of Southeast US coast showing storm surge inundation levels from Hurricane Harvey with higher levels near landfall in Texas.
Analyzed storm surge inundation (feet above ground level) along the coast of Texas and Louisiana from Hurricane Harvey. Image from NOAA NHC Storm Surge Unit.

Storm tide: 6-10 ft. max. inundation above ground level (near San Antonio Bay)

  • Flooding along coasts of Texas and Louisiana, especially in Harris and Galveston counties
  • Tide gages may have measured high values of storm surge due to runoff from rain

Cost: $125 billion (90% confidence, range from $90 - $160 billion)

  • Large uncertainty in total damage estimate, partly due to the residential flood loss claims being outside of the 500-year flood plain
  • Much of the damage was not covered by the National Flood Insurance Program (NFIP), with tens of thousands of claims still outstanding.
  • Over 300,000 structures flooded; up to 500,000 cars flooded
  • Gas and oil refineries in Golden Triangle went offline for days - spike in gas prices across the U.S.

Deaths: At least 68 direct deaths, over half in Harris County (Houston, TX) due to freshwater flooding (rain). At least 35 indirect deaths due to electrocution, auto accidents, and medical needs. Highest death total in Texas since 1919.
Displaced: Estimated 40,000 victims displaced to other parts of TX and LA.

Adaptation (What was learned)

The destruction from Hurricane Harvey resulted from unprecedented rainfall that caused record flooding in the Houston area. Studies have predicted that precipitation from tropical cyclones will increase substantially over the next century due to global warming; this will occur by allowing the warmer atmosphere to hold more water vapor that can become rain. Thus, extreme rainfall from tropical cyclones will continue to become more common as the planet warms.

Severe flooding from these rainfall events is exacerbated by urban expansion that gives little consideration to the risks associated with climate change. The consequences of unconstrained development were demonstrated by the disastrous flooding the Houston area experienced during and after Hurricane Harvey.

Houston has expanded its population from 400,000 to 6 million residents over the past several decades, becoming a hub for the energy, space, and medical industries. This has led to unrestricted urban and residential development in coastal areas, floodplains, and reservoirs that had once relied on now non-existent prairies to absorb floodwater. To make matters worse, many residents in these areas were not notified of the associated flood risks before they bought or rented their homes because Texas law does not require it (Satija et al. 2017).

In Harris County, where Houston residents were hit hardest by flooding from Hurricane Harvey, only one in six homeowners was insured with the National Flood Insurance Program (NFIP) - a federal program developed to financially protect property owners in locations vulnerable to flood risks.

Adaptation to more severe extreme weather brought about by climate change is necessary to avoid disasters like the one caused by Hurricane Harvey. Some of the most important adaptive measures include development of the following:

  • Building codes and zoning restrictions for areas vulnerable to flooding
  • Infrastructure for water management and drainage
  • Effective emergency response plans (evacuation routes, shelters, power supplies)
  • Realistic insurance programs that match the growing risks associated with climate change
  • Public education and conversations on extreme weather and adaptive strategies

References

Blake, E.S. & Zelinsky, D.A. (2018). National Hurricane Center Tropical Cyclone Report: Hurricane Maria (AL092017). National Hurricane Center. https://www-nhc-noaa-gov.uri.idm.oclc.org/data/tcr/AL092017_Harvey.pdf.

Hanscom, G. (2014). Flood pressure: Climate disasters drown FEMA’s insurance plans. Grist. Jan 13, 2014. https://grist.org/cities/flood-pressure-how-climate-disasters-put-femas-flood-insurance-program-underwater.

IPCC (2013). Climate change 2013: The physical science basis. In T.F. Stocker, et al. (Eds.), Intergovernmental Panel on Climate Change (1535 pp.). Cambridge, United Kingdom: Cambridge University Press.

Kimmelman, M. (2017). Lessons From Hurricane Harvey: Houston’s Struggle Is America’s Tale. New York Times. Nov 11, 2017. https://www.nytimes.com/interactive/2017/11/11/climate/houston-flooding-climate.html.

Morss, R.E., Wilhelmi, O.V., Meehl, G.A., & Dilling, L. (2011). Improving societal outcomes of extreme weather in a changing climate: An integrated perspective. Annual Review of Environment and Resources, 35, 1-25.

Satija, N., Collier, K., & Shaw, A. (2017). Houston officials let developers build homes inside reservoirs. But no one warned buyers. The Texas Tribune. Oct 12, 2017. https://apps.texastribune.org/harvey-reservoirs/?utm_campaign=trib-social&utm_medium=social&utm_source=twitter&utm_content=1507778503.

Trenberth, K.E., Cheng, L., Jacobs, P., Zhang, Y., & Fasullo, J. (2018). Hurricane Harvey Links to Ocean Heat Content and Climate Change Adaptation. Earth’s Future, 6. doi: 10.1029/2018EF000825.