Severe Thunderstorms (Hail, Damaging Winds, Tornadoes)
Resource: National Weather Service Severe Weather Safety Page
How does NWS define whether a thunderstorm is "severe"?
A thunderstorm is classified as "severe" by the National Weather Service if it produces wind gusts in excess of 58 mph or hail one inch in diameter or larger. Significant thunderstorm wind damage can also indicate a thunderstorm was severe. An occurrence of a tornado will also classify a thunderstorm as severe. More information about tornadoes is given in the Tornado section.
How do severe thunderstorms impact southeast Texas?
While severe thunderstorms are most common in the spring and summer, they can occur any time of year in southeast Texas. On average, southeast Texas experiences 50 to 60 days a year with thunderstorms. Severe thunderstorms occur on about a third of those days. Severe storms can occur any time of day in southeast Texas, but are most common in the afternoon and evening hours.
Severe weather threats:
- Damaging thunderstorm winds/ Downbursts
A downburst is an area of rapidly descending air beneath a thunderstorm. Downburst winds are often referred to as "straight-line" winds as they tend to . Severe downbursts produce wind gusts from 60 mph to more than 100 mph. The resulting damage can be as severe as that from a tornado. Damage from a downburst is more common in southeast Texas than damage from a tornado. The image below describes a very concentrated downburst referred to as a microburst and the damaging outflow winds that result.
- Large Hail
Hail is formed as strong rising currents of air within a storm (updrafts) carry water droplets to a height where freezing occurs. The ice particles cycle upward and downward through the hail growth part of the storm several times, growing in size layer by layer. Once they become too heavy to be supported by the storm's updraft or are carried outside the updraft, they fall to the ground as hail. Hail of 1 inch in diameter or larger classifies as "large" or potentially damaging hail. Hail sizes are usually given as references to everyday objects to make it easier to estimate hail size.
Hail greater than baseball size is rare in southeast Texas but can occur. Large hail can break windows, damage roofs, automobiles, crops, etc. If you experience or expect hail, get inside a sturdy structure and stay away from windows. A hard topped vehicle also offers some protection. Shelter your vehicle in a garage or under an awning if possible ahead of the storm.
|Examples of hail sizes:
(classifies storm as severe)
Tornadoes are another threat from severe thunderstorms. See the tornado section for more information.
- Cloud-to-Ground Lightning
Severe thunderstorms can produce extremely dangerous lightning. See the Lightning section for more information.
- Flash Flooding
Heavy rains from severe thunderstorms can produce flash flooding. See the Floods/Flash Floods section for more information.
What were some severe weather events that impacted Southeast Texas?
- April 2, 2013
- A severe thunderstorm produced baseball to softball sized hail (up to 4.50 inches) in Hitchcock (Galveston County). The central and western parts of the town received extreme damage to vehicles and home roofs and windows. There was also significant damage to the Midway Church, a fire station, and in two trailer parks. Seven Hitchcock police cars were severely damaged by the large hail.
- October 22, 2008
- Showers and thunderstorms developed along and ahead of a strong cold front and produced golf ball size hail (up to 1.75 inches) in Houston (Harris County) near the intersection of Beltway 8 North and the Hardy Toll Road.
- May 4, 2006
- A severe thunderstorm developed in the afternoon and produced large hail (up to 3.00 inches - the size of tea cups) in the Champions Forest Subdivision near Houston Hooks Airport.
- May 8, 2005
- Severe thunderstorms with strong damaging winds and large hail moved across the southern half of southeast Texas with damage observed from the El Campo and Wharton area (trees and power lines down, roof damage and a hanger with an airplane inside destroyed) eastward to the coast. Further to the east (Brazoria County), strong winds downed trees and blew roofs off mobile homes in Rosharon, Danbury and Liverpool. In Alvin, a metal shed and billboards were also downed by the wind. Near the coast in Galveston County, large hail (up to golf ball size) fell in Texas City, and strong winds downed large trees and damaged property from League City to Dickinson to Galveston Island. On the Island, there was building damage along the Port of Galveston, vehicles were blown off the road and trees were downed. One home was shifted about ten feet into another home next door dislodging it from its piers (both homes were Galveston 1900 Storm survivors).
- December 23, 2002
- The combination of abundant low level moisture, a strong upper level storm system and a warm front helped to produce nearly fifty severe weather events across Southeast Texas including tornadoes in Colorado, Burleson, Washington, Brazos, Grimes, Madison, Montgomery and San Jacinto counties. Large hail (up to 1.75 inches) was observed mainly north and west of the Houston area. Locations from Houston to the beaches felt the brunt of this event in the evening when a squall line moved rapidly eastward across Harris county and toward the coast and produced 60 to 80 mph winds.
- November 23-24, 2000
- Three tornadoes struck the Houston area on Thanksgiving night. An F1 tornado struck Katy injuring one person, flipping over two office trailers and damaging several homes. Pasadena was also struck by an F1 tornado which damaged a church and two schools, several homes in a neighborhood, and tore the walls off of a strip shopping center. Another F0 tornado struck Conroe, downing trees and tearing the steeple off a church.
- May 1-2, 2000
- A storm system produced widespread severe thunderstorms over the southern half of Southeast Texas during the overnight hours of the 1st and the early morning hours of the 2nd. Widespread wind damage impacted Harris, Fort Bend, Wharton, Brazoria and Galveston counties. The worst damage occured at Clover Field in Pearland where several planes were overturned and two small airplane hangers were destroyed. At Scholes Field in Galveston, several small planes were also overturned and the NOAA P-3 research aircraft was damaged. A massive hailstorm with baseball-sized hail struck Conroe producing over $10 million in damage.
National Weather Service Severe Thunderstorm Products:
- Hazardous Weather Outlook
Issued daily by the local National Weather Service. Looks out a week and identifies periods when hazardous weather is possible. Describes the potential hazard and the days when it might occur.
- Severe Thunderstorm Watch
Issued by the Storm Prediction Center in Norman, OK. Usually covers a large area (such as all or a portion of southeast Texas) and lasts for 6 to 8 hours. Indicates that conditions are favorable for severe thunderstorms that may produce large hail, damaging winds, or possibly tornadoes.
- Severe Thunderstorm Warning
Issued by the local National Weather Service office. Usually covers a small area (part of a county to a few counties) and has a short duration of 30 minutes to an hour. A SEVERE THUNDERSTORM WARNING means that a severe thunderstorm has been detected by radar, or reports of severe weather have been received by the National Weather Service in the area covered by the warning. The warnings are broadcast over NOAA Weather Radio and are usually scrolled on local television stations. The warnings are also relayed to local emergency management and public safety officials who can activate emergency procedures to help protect the public. If a warning is issued for your area, take action immediately!!
- Severe Weather Statement
Used to update a severe thunderstorm or tornado warning with new location, impacts, etc., and/or to cancel the warning.
What can you do to be prepared for severe weather?
- Know the county that you live in and the names of nearby major cities. SEVERE THUNDERSTORM WARNINGS are issued on a county by county basis with the names of major cities highlighted in the warnings.
- Have a NOAA Weather Radio in your home or place of business. Some receivers are specially built to alarm any time a severe weather Watch or Warning is issued by the National Weather Service.
- Make sure you are aware of the best spot in your home to take shelter from severe weather. The most appropriate place is usually an interior room on the lowest floor of your home and away from windows. If you know severe weather is approaching or a SEVERE THUNDERSTORM WARNING is issued, seek shelter immediately!! Being in a sturdy building on the lowest floor and away from windows is the only safe place in a severe thunderstorm!! Automobiles, boats, or out in the open are not safe places in severe thunderstorms.
Severe Thunderstorm Statistics for Southeast Texas (1992-2015 graphs)
- Severe Weather Reports by County
- Hail Events (by year)
- Hail Events (by month)
- Hail Events (by time)
- High Wind Events (by month)
- High Wind Event (by time)