September 1st, 2017

Hurricane Harvey – Update

Posted at 7:03 AM ET

hurricane-harvey-8-31-smFollowing initial landfall, Hurricane Harvey continued to meander over southeast Texas while weakening to tropical storm status due to land interaction. Harvey then briefly emerged over the Gulf of Mexico before turning to the northeast and making a third landfall near Cameron, Louisiana, early Wednesday morning as a tropical storm. Harvey has since continued to move to the north-northeast and weakened further due to land interaction and dry air. The National Hurricane Center (NHC) downgraded Harvey from tropical storm to tropical depression status at 8 p.m. EDT on August 30, and discontinued tropical storm warnings at that time.

Harvey has continued to produce record rainfall amounts during this time. Preliminary rainfall amounts from Harvey indicate a new record for storm-total tropical cyclone rainfall in the Continental United States. This rainfall has compounded the historic flood impacts in the Houston metro area, and produced an active flood emergency in Beaumont, Texas, and surrounding areas. Flood impacts include auto and property damage due to inundation or outright submersion, as well as probable water velocity damage. Wind impacts have been most severe near the point of landfall, and reports of wind damage in the Rockport, Texas area are especially severe. Media reports indicate at least 35 fatalities, and this number could well increase as damage assessment and recovery efforts progress. It will take time to fully assess the scope and severity of historic impacts of this historic storm.


Harvey track and estimated winds. Source: Guy Carpenter, National Hurricane Center.


7-Day Radar-Estimated Precipitation Amounts; Ending 8 a.m. EDT, August 31; Source: NOAA/NWS/AHPS


River Gauge Flood Status Map; Source: NOAA/NWS/AHPS


River Gauge Observed and Forecast - Neches River at Beaumont; Source: NOAA/NWS/AHPS


River Gauge Observed and Forecast - Buffalo Bayou at West Belt Drive; Source: NOAA/NWS/AHPS

Hazard data illustrated in the CAT-i map was taken from GC AdvantagePoint®, Guy Carpenter’s web-based risk management platform. GC AdvantagePoint users can view impacted areas on any map as well as see how their portfolios were affected. Please contact your broker or cat modeling analyst for further information.

Our first thoughts and concerns are with those directly affected by this historic event.

Meteorological Discussion

Since the weekend, Harvey continued to meander over southeast Texas before moving back into the Gulf of Mexico, while retaining tropical storm strength. Harvey then turned back to the northeast to make a third landfall just west of Cameron, Louisiana, around 5 a.m. EDT Wednesday, August 30, as a tropical storm, with maximum sustained winds of 45 mph. Harvey continued to produce significant rainfall amounts over southeast Texas and southern Louisiana during this time, to produce apparent devastating flood impacts in Beaumont, Texas, and surrounding areas.

Harvey then continued on a northeasterly track and weakened due to land interaction and dry air. Harvey was downgraded by the National Hurricane Center (NHC) at 8 p.m. EDT, August 30. Harvey then continued to pass about 35 miles east of Monroe, Louisiana. Harvey continues to move in a northeasterly direction and should move into northern Mississippi later today, into Tennessee by Friday and into the Ohio Valley states on Saturday as a post-tropical low. Harvey should then phase with another front and eventually clear the mainland over the weekend.

Harvey continues to bring heavy rainfall along with gusty winds and the risk of some tornadoes to affected areas. Rainfall amounts of three to five inches are expected from eastern Arkansas into the Appalachians, with local amounts of six to ten inches. These additional rainfall amounts will bring the risk of flooding and flash-flooding. The severe flood threat also continues for areas of Houston and recently affected areas of extreme eastern Texas and southern Louisiana, as well as the Beaumont area. Local National Weather Service (NWS) offices maintain watches and warnings to this effect, and these can be found at

Selected dates of note concerning Hurricane Harvey follow below, following advisories of the NHC.

  • 11 a.m. EDT, August 17: The first tropical storm warning is issued by the NHC for the Windward Islands, for potential tropical cyclone nine (did not include U.S. mainland).
  • 5 p.m. EDT, August 17: Potential tropical cyclone nine becomes Tropical Storm Harvey.
  • August 18: Tropical Storm Harvey crosses the Windward Islands.
  • 2 p.m.  EDT, August 18: Tropical Storm Warnings dropped for the Windward Islands.
  • 5 p.m. EDT, August 19: Tropical Storm Harvey downgraded to Tropical Depression Status.
  • 11 p.m. EDT, August 19: Tropical Depression Harvey further downgraded by NHC to a tropical wave (elongated area of low pressure), while over the Caribbean Sea, with no apparent closed circulation.
  • Harvey then crosses the Yucatan Peninsula as a tropical wave (elongated area of low pressure).
  • 11 a.m. EDT, August 23: Harvey regains status as a tropical depression (closed circulation redevelops with clearly defined center). First U.S. hurricane watch issued by the NHC, with tropical storm watches for adjacent areas.
  • 12 a.m. EDT, August 24: Harvey upgraded to tropical storm status.
  • 5 a.m. EDT, August 24: First U.S. hurricane warning issued by the NHC.
  • 1 p.m. EDT, August 24: Harvey upgraded to hurricane status.
  • 11 p.m. EDT, August 24: Harvey begins period of rapid intensification, to continue prior to landfall.
  • 1 a.m. EDT, August 25: Harvey becomes a Category 2 hurricane.
  • 3 p.m. EDT, August 25: Harvey becomes a major Category 3 hurricane.
  • 7 p.m. EDT, August 25: Harvey becomes a Category 4 hurricane.
  • First landfall occurs between Port Aransas and Port O’Connor, Texas, around 11 p.m. EDT, August 25. Maximum sustained winds 130 mph, Category 4 on the Saffir-Simpson Scale. Minimum central pressure of 938 millibars (mb).
  • Second landfall occurs around 2 a.m. EDT, August 26, northeastern shore of Copany Bay. Maximum sustained winds 125 mph, Category 3 on the Saffir-Simpson Scale. Minimum central pressure of 941 mb.
  • 11 a.m. EDT, August 26: The hurricane warning was dropped by the NHC. Harvey has weakened to a minimal hurricane, with maximum sustained winds of 75 mph.
  • 8 a.m. EDT, August 28: Tropical Storm Harvey begins moving offshore into the Gulf of Mexico, just south of Matagorda, Texas.
  • 8 a.m. EDT, August 29: Tropical Storm Harvey begins turning back to the north over the Northern Gulf of Mexico.
  • Third landfall of Harvey occurs just prior to 5 a.m. EDT, August 30, just west of Cameron, Louisiana. Maximum sustained winds of 45 mph, a minimal tropical storm, and a minimum central pressure of 990 mb.
  • As of 5 p.m. EDT, August 30, Tropical Storm Harvey continues to produce tropical storm force winds near the coast. Tropical storm warnings remain active from Sabine Pass, Texas, to Grand Isle, Louisiana.
  • 8 p.m. EDT, August 30: Harvey downgraded by the NHC from tropical storm status to tropical depression status, with maximum sustained winds of 35 mph. All tropical storm warnings discontinued by the NHC. Flooding rains continue over extreme eastern Texas and western Louisiana. The depression gains forward speed.
  • 11 p.m. EDT, August 30. The NHC issues the final advisory package on Tropical Depression Harvey as it continues to produce heavy rainfall while moving inland. The U.S. Weather Prediction Center and local National Weather Service offices continue to issue watches and warnings for areas under ongoing threat at the local level.

Selected Storm-Total Rainfall amounts to date (as of 10 a.m. EDT, Thursday, August 31) include:

  • 51.88 inches at Cedar Bayou at FM 1942 (TX)
  • 49.40 inches at Clear Creek at I-45 (TX)
  • 49.20 inches at Marys Creek at Winding Road (TX)
  • 47.35 inches at Beaumont/Port Arthur (TX)
  • 43.38 inches at Houston Weather Forecast Office (TX)
  • 31.26 inches at Houston Intercontinental Airport (TX)
  • 22.84 inches at Galveston Scholes (TX)
  • 10.07 inches at Austin/Mueller Municipal Airport (TX)
  • 22.25 inches at Bayou Conway (LA)
  • 18.23 inches at Kenner Gully at Mark Lebleu (LA)
  • 16.37 inches at Belfield Ditch at Belfield Road (LA)
  • 14.10 inches at Indian Bayou at Coffey Road (LA)
  • 9.08 inches at Lake Charles Municipal Airport (LA)
  • 5.88 inches at New Orleans/Moisant (LA)
  • Selected rainfall totals can be found here.

Preliminary rainfall amounts indicate that this has set a new record for storm-total tropical cyclone rainfall events in the Continental United States.

Historic flooding has continued to affect certain regions of southeast Texas and southern Louisiana. Most gauges in southeast Texas and parts of southern Louisiana remain in major flood stage, with historical flood stage either reported or expected for certain stations. Some gauges in the Houston area also appear to have failed.


Since the weekend, media reports indicate that Harvey has caused at least 35 fatalities, and this could well increase as floodwaters recede, according to local authorities. It is too early to determine the full scope and severity of impacts for this historic event, and full damage assessments could take several days to weeks to complete.

There is evidence from NWS statements that the flood situation is showing slow general improvement in the Houston metro area. As floodwaters recede for certain areas, local homeowners are faced with clearing affected contents and materials and recovering personal effects. The threat of mold and mildew along with water contamination are increasing concerns. Certain streets and underpasses still have water in urban areas and will be slow to drain, along with life-threatening conditions. A mandatory evacuation remains active for Northwood Pines residents in the Houston area, according to a civil emergency message carried by the NWS. Areas adjacent to the Addicks Reservoir and Barker Reservoir also remain under inundation threat, according to NWS flood warnings.

Meanwhile, record flooding has been observed in the Beaumont area and impacts appear to have been especially severe. Reports indicate that police are recruiting boat-owners to support ongoing search and rescue efforts. Baptist Beaumont Hospital evacuated nearly 200 patients by air due to lack of drinking water. Drinking water systems have been disrupted after pumps servicing the area were covered in floodwaters. For the greater area around Port Arthur and Beaumont, media reports indicate that 5,500 homes were destroyed and 16,000 sustained major damage.

Nearly 313,000 homes and businesses were without power as of 10 a.m. EDT on August 30 in Texas, according to local officials. The power outages also caused two explosions at a chemical plant in Crosby, Texas. A 1.5 mile radius around the plant was evacuated as a result, out of concern for potential further explosions.

Airlines cancelled approximately 10,000 flights across the United States since Harvey first began affecting flight schedules last week, according to media reports. Passenger flights resumed severely limited operations on August 30 from Houston Bush Intercontinental and Houston Hobby airports. Nationwide, more than 1,400 flights were grounded due to Harvey for August 31.

Power outages are expected to lead to a reduced supply of U.S. crude, gasoline, and other refined products and an increase in gasoline prices is expected, according to media reports. The U.S. Energy Department authorized the first emergency release of crude oil from the Strategic Petroleum Reserve since 2012. Approximately 500,000 barrels of oil will be delivered to a Phillips 66 refinery in Louisiana unaffected by the storm, according to an Energy Department official. Major U.S. railroads are also impacted by flooding and power outages. Railroad closures will affect automakers, agricultural transport and cross-border trade with Mexico. Several roadways were washed out due to flooding, and damage to infrastructure including transportation, drinking water, communications and sanitary systems are all of concern for certain of the most severely affected areas.

Initial estimates from Moody’s Analytics indicate that economic losses for southeast Texas will range between USD 51 billion and USD 75 billion, according to media reports. Media reports also indicate that insurance penetration rates of the National Flood Insurance Program in the Houston area are comparatively low, but that losses to the program will be significant. Other reports indicate estimates by Reuters of economic losses for property damage at around USD 23 billion, due to flooding in Harris and Galveston counties.  Reports indicate property damage as a result of wind and interior water damage from leaking roofs, sewer back-ups and inundation. Vehicle damage from inundation has also been reported.  Media statements indicate that RMS estimates economic losses as high as USD 70 billion to USD 90 billion, due in large part to losses from inland flooding in the Houston metro area. RMS also estimates insured losses due to wind alone of USD 6 billion or less. Meanwhile, AIR Worldwide estimates insured losses due to wind and surge alone of between USD 1.2 billion and USD 2.3 billion, according to media reports. Reports also indicate that CoreLogic has produced an estimate of insured losses of USD 1.5 billion to USD 3 billion due to wind and surge alone.

Sources: Reuters, Agence France-Presse, Associated Press, National Hurricane Center, National Weather Service, The Weather Channel, San Antonio Express-News, AIR-Worldwide, RMS

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Guy Carpenter publishes CAT-i reports for major natural catastrophes worldwide. These reports cover catastrophes including worldwide tropical cyclones, earthquakes, major UK and European floods and any other natural event that is likely to incur a significant loss to the (re)insurance industry. Please email if you wish to be added to the free email distribution list.

Guy Carpenter compiles RISK-i reports for major technological or man-made events worldwide. These reports cover risks to property, transport and life including explosions, fires, crashes, engineering disasters and terrorist attacks that are likely to incur a significant loss to the (re)insurance industry. Please email if you wish to be added to the free email distribution list.

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