July 10, 2021 – Hurricanes are one of the most dangerous types of storms because of wind, storm surge and flooding. Many injuries and deaths during hurricanes occur in the aftermath of the storm when people try to drive through flooded streets in their cars and trucks or venture out and are injured. One of the most severe hurricanes to strike the United States in recent years was Hurricane Harvey in August 2017. It struck the Middle Coast of Texas, the first time that part of Texas had been hit with a hurricane since 1970. Millions of people lived in the path of the storm. At least 68 deaths were directly attributed to Harvey and the hurricane caused aboout $125 billion in damage to buildings and property, according to the National Weather Service (NWS).
U.S. Coast Guard Video of Rescue Operations during Hurricane Harvey
Before studying the weather data from Hurricane Harvey, let’s review how meteorologists classify hurricanes according to maximum sustained winds. The scale was developed in the 1970s by Herb Saffir, a wind engineer, and Bob Simpson, a meteorologist. It’s called the Saffir-Simpson Hurricane Wind Scale.
To obtain accurate wind speed data and barometric pressure readings, NOAA (National Oceanic and Atmospheric Administration) flies an airplane, called a Hurricane Hunter, into the storm and its eye many times to record data.
Saffir-Simpson Hurricane Scale (National Weather Service – NWS, a division of NOAA)
The five categories of hurricanes are:
1. Category 1 (74-95 mph): A storm will not be classified as a hurricane unless maximum sustained winds are at least 74 mph. With winds at this level, the NWS states:
Very dangerous winds will produce some damage: Well-constructed frame homes could have damage to roof, shingles, vinyl siding and gutters. Large branches of trees will snap and shallowly rooted trees may be toppled. Extensive damage to power lines and poles likely will result in power outages that could last a few to several days.
2. Category 2 (96-110 mph): The NWS states:
Extremely dangerous winds will cause extensive damage: Well-constructed frame homes could sustain major roof and siding damage. Many shallowly rooted trees will be snapped or uprooted and block numerous roads. Near-total power loss is expected with outages that could last from several days to weeks.
3. Category 3 (111-129 mph): The NWS states:
Devastating damage will occur: Well-built framed homes may incur major damage or removal of roof decking and gable ends. Many trees will be snapped or uprooted, blocking numerous roads. Electricity and water will be unavailable for several days to weeks after the storm passes.
4. Category 4 (130-156 mph): The NWS states:
Catastrophic damage will occur: Well-built framed homes can sustain severe damage with loss of most of the roof structure and/or some exterior walls. Most trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last weeks to possibly months. Most of the area will be uninhabitable for weeks or months.
5. Category 5 (157 mph or greater): The NWS states:
Catastrophic damage will occur: A high percentage of framed homes will be destroyed, with total roof failure and wall collapse. Fallen trees and power poles will isolate residential areas. Power outages will last for weeks to possibly months. Most of the area will be uninhabitable for weeks or months.
Hurricane Harvey
The following are highlights from articles Redwood Learn published during the storm.
Aug. 25, 2017: Headline: Hurricane Harvey Ready to Hammer Texas
The first paragraph of the 2017 story said:
“Areas along the middle Texas coast are urged to rush preparations for Hurricane harvey this morning as conditions are expected to deteriorate throughout the day, according to the National Weather Service (NWS). Harvey is currently a Category 2 hurricane in the Gulf of Mexico but close to a Category 3 storm.”
The storm made landfall late on Aug. 25, 2017 near Rockport, Texas.
Aug. 26, 2017: Headline: Harvey Makes Landfall as Cat 4 Hurricane
“Officials are planning for four to five days of heavy rain because the storm will stall as it tries to move inland. Normally, hurricanes fall apart after hitting land and dissipate over a large area of land as the storm system moves to the north and east. But Harvey is facing a barrier in the form of a high pressure system to the northwest. That system will keep Harvey churning over southeastern Texas.”
Aug. 28, 2017: Headline: Harvey Causes Catastrophic Flooding in Houston
In one of their bulletins that day, the NWS stated the following using all capital letters to emphasize the message:
“UNPRECEDENTED FLOODING CONTINUES OVER SOUTHEASTERN TEXAS…DO NOT ATTEMPT TO TRAVEL IN THE AFFECTED AREA IF YOU ARE IN A SAFE PLACE. DO NOT DRIVE INTO FLOODED ROADWAYS.”
Aug. 29, 2017: Headline: Another 10 Inches of Rain Could Fall on Houston Today
“In 1929 and 1935, Houston experienced devastating floods so the U.S. Army Corps of Engineers built the Addicks and Barker Dams. The reservoirs for both dams are approaching flood stage today and will most likely overflow their banks because more rain is in the forecast. Mandatory Word of the Day evacuation orders have been issued for neighborhoods around the reservoirs.”
Aug. 30, 2017 – Harvey Makes Landfall – Again
“After dumping a record setting 51.88 inches of rain on Cedar Bayou, Texas, located about 30 miles east of Houston, and 43 inches in Houston, Tropical Storm Harvey made landfall again early today near the Texas-Louisiana border. The storm will dissipate this week but recovery efforts will last for years.”
NWS Weather Data* (Note: MB = millibars)
1. Aug. 24, 2017 (6 p.m. EDT): Wind: 85 mph Pressure: 974 MB (28.76 inches)
2. Aug. 25, 2017 (6 a.m. EDT): Wind: 110 mph Pressure: 950 MB (28.05 inches)
3. Aug. 25, 2017 (6 p.m. EDT): Wind: 130 mph Pressure: 941 MB (27.79 inches)
4. Aug. 26, 2017 (6 a.m. EDT): Wind: 80 mph Pressure: 975 MB (28.71 inches)
5. Aug. 27, 2017 (6 a.m. EDT): Wind: 45 mph Pressure: 998 MB (29.47 inches)
*Hurricane Harvey archive of weather data and bulletins
REVIEW QUESTIONS
1. Where and when did Hurricane Harvey make landfall?
2. Why was Hurricane Harvey an historic storm?
3. What was the peak rainfall during the storm?
4. What are the five categories of hurricanes based on maximum sustained winds?
5. What type of damage can be expected from a Category 4 hurricane?
INQUIRY QUESTIONS
1. How do the photos in the story support the text?
2. Graph the weather data above. How does the graph tell the story of the hurricane?
3. Why is flooding so dangerous during hurricanes?
4. Compare the two satellite images in the story. How do these images tell the story of the hurricane?
5. Data on Hurricane Harvey:
Friday (8/25) at 7 a.m. CDT: location: 26.3N, 95.8W; minimum central pressure: 28.05 inches
Friday (8/25) at 10 p.m. CDT: location: 28.0N, 97.0W; minimum central pressure: 27.76″
Saturday (8/26) at 10 a.m. CDT: location: 28.9N, 97.3W; minimum central pressure: 29.06″
Saturday (8/26) at 10 p.m. CDT: location: 29.3N, 97.3W; minimum central pressure: 29.36″
Sunday (8/27) at 10 a.m. CDT: location: 29.0N, 97.4W; minimum central pressure: 29.53″
Sunday (8/27) at 7 p.m. CDT): location: 28.9N, 96.8W; minimum central pressure: 29.53″
Monday (8/28) at 4 a.m. CDT: location: 28.6N, 96.3W; minimum central pressure: 29.47″
Graph the minimum central pressure data. Research what an increase and decrease in minimum central pressure means. Relate the data to the course of the storm. What data indicates Harvey made landfall? How does the above data provide evidence that Hurricane Harvey stalled over southeast Texas?
Plot the locations on a map. How does this data support the text in the story?