By the numbers: Inside the National Hurricane Center's Hurricane Harvey report
HOUSTON – Hurricane Harvey was quite the storm, but a new report shows -- by the numbers -- how it stacks up against other storms, as well as why it was such a devastating storm for our area and the a large swath of the South.
Below are some of the highlights straight from the National Hurricane Center Tropical Cyclone Report (PDF), published in conjunction with the National Weather Service and the National Oceanic and Atmospheric Administration.
What is the most remarkable number for you? Let us know in the comments below.
Harvey’s maximum winds of 132 mph occurred during a several-hour period concluding with its first Texas landfall.
The highest observed sustained winds on land were 111 mph near Aransas Pass, with the highest observed gust being around 145 mph near Rockport, Texas.
6 feet to 10 feet
The combined effect of the surge and tide produced maximum inundation levels of 6 to 10 feet above ground level to the north and east of Harvey’s center landfalls in Texas in the back bays between Port Aransas and Matagorda, including Copano Bay, Aransas Bay, San Antonio
Bay and Matagorda Bay.
Harvey was the most significant tropical cyclone rainfall event in United States history, both in scope and peak rainfall amounts, since reliable rainfall records began around the 1880s. The highest storm total rainfall report from Harvey was 60.58 inches near Nederland, Texas, with another report of 60.54 inches from near Groves, Texas. Both of these values (and from five
other stations) exceed the previously accepted United States tropical cyclone storm total rainfall
record of 52.00 inches at Kanalohuluhulu Ranger Station, Hawaii, in August of 1950 from
Hurricane Hiki. For the continental United States, the previous tropical cyclone rainfall record was 48 inches in Medina, Texas, from Tropical Storm Amelia in 1978.
18 recorded values over 48 inches of rain
It is remarkable that during Harvey, 18 values over 48 inches were recorded across southeastern Texas, with 36 to 48 inches recorded in the Houston metro area. These rains caused catastrophic flooding in Harris and Galveston counties.
9 of 19 river gauges set records in southeast Texas
Nine out of the 19 official river gauges in Harris County (which includes the city of Houston) recorded all-time high flood stages.
Large sections of southeastern Texas received 3 feet or more of rainfall
in Harvey, whereas only very small portions of the Houston metro area had those totals in Tropical Storm Allison.
6.8 inches of water in an hour
The rain rates observed in these bands on Aug. 26-27, 2017, were exceptional, with 6.8 inches of rain in just one hour documented in southeastern Houston from extremely heavy rain bands training over the same location. The front hardly moved from August 27-28, leading to the extreme rainfall totals in the Houston metro area since the main inflow band originated over the very warm waters of the northwestern Gulf of Mexico, which provided multiple influxes of warm and humid air.
Harvey was a prolific tornado producer. There were 57 tornadoes preliminarily reported during Harvey, about half of which occurred near and south of the Houston metro area.
68 people died
Harvey is responsible for at least 68 direct deaths in the United States, all in Texas. Over half of the deaths (36) were in Harris County in the Houston metro area. All but three of the deaths were from freshwater flooding, and none of the deaths can be linked to the storm surge, which is quite remarkable for a category 4 hurricane landfall. Still, Harvey is the deadliest U.S. hurricane in terms of direct deaths since Sandy (2012) and is the deadliest hurricane to hit Texas since 1919. About 35 additional deaths are ascribed to indirect causes, such as electrocution, motor-vehicle crashes and isolation from necessary medical services. Four people were reported injured by a tornado north of Reform, Alabama.
NOTE: Deaths occurring as a direct result of the forces of the tropical cyclone are referred to as “direct” deaths. These would include those persons who drowned in storm surge, rough seas, rip currents, and freshwater floods. Direct deaths also include casualties resulting from lightning and wind-related events (e.g., collapsing structures). Deaths occurring from such factors as heart attacks, house fires, electrocutions from downed power lines, vehicle accidents on wet roads, etc., are considered indirect” deaths.
The latest NOAA damage estimate from Harvey is $125 billion, with the 90% confidence interval ranging from $90 to $160 billion. The mid-point of the estimate would tie Katrina (2005) as the costliest United States tropical cyclone, which was also $125 billion (see
https://www.ncdc.noaa.gov/billions/). However, the unadjusted costliest tropical cyclone list is not
the most relevant record to examine because of inflation and other cost increases since 2005. A
more reasonable comparison uses the Consumer Price Index (CPI)-adjusted technique, which
modifies 2005 dollars to 2017. The adjustments make Katrina’s total $161.3 billion in 2017 dollars,
leading to Harvey being the second costliest U.S. tropical cyclone. There is, however, still a large
uncertainty in the total damage estimate (hence the large confidence interval). This is due to
many factors, including that a majority of the residential flood loss claims are from outside the
500-year flood plain, where there is low National Flood Insurance Program (NFIP) participation,
with tens of thousands of claims still outstanding.
The damage caused by Harvey’s flooding was catastrophic over a large area of southeastern Texas. Over 300,000 structures in that region were flooded.
At least 160,000 structures were flooded in Harris and Galveston counties.
Beyond the Houston metro area, the most serious flood damage was noted farther east in Texas over Jefferson, Orange, Hardin and Tyler counties, with about 110,000 structures (about
one-third of the total structures damaged by Harvey) in those counties flooded.
Up to 500,000 cars reported flooded during Harvey.
About 336,000 customers lost power during the hurricane.
15,000 homes destroyed at Harvey landfall site
Near the initial landfall location in Texas, wind damage was extreme in Aransas County, Nueces County, Refugio County and the eastern part of San Patricio County. Approximately 15,000 homes were destroyed in these areas, with another 25,000 damaged, and extensive tree damage was noted.
Nearly 200,000 people were evacuated in Fort Bend County due to levee concerns and
restrictions after the Brazos and San Bernard Rivers experienced record floods.
Major-to-record flooding also occurred on the San Bernard River at both East
Bernard and Boling, with the hardest hit area being Tierra Grande. At least 8,500 homes in this
county were damaged by Harvey.
In Brazoria County, over 9,000 homes experienced flood damage from the storm.
In Wharton County, an estimated 2,000 homes were damaged or destroyed in the county.
In Matagorda County, roughly 2,900 homes were damaged.
In San Jacinto County, about 3,300 homes were damaged in the county.
In Liberty County, at least 1,000 homes were damaged in the county.
In Chambers County, an estimated 3,000 homes were damaged, and numerous businesses had significant damage.
In Jasper, 4,000 homes flooded.
In Newton, 2,000 homes flooded.
400 homes and businesses
In Fayette County, 400 homes and businesses flooded in La Grange and across the county.
In Louisiana, 2,000 homes flooded in Calcasieu, Beauregard, and Cameron Parishes, with many flooded roads and rivers noted.
For more information and to read the full report, go to the pdf document here.
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