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Severe Weather Awareness
Photo of severe weatherGovernor Rick Perry has proclaimed the week of March 3 through 9 as Severe Weather Awareness Week in Texas. In an official proclamation, he reminded Texans of the threat to life that thunderstorms pose, from lightning to floods to tornadoes and stressed the importance of staying aware of weather conditions, and being prepared.

Spring Time Weather
Spring marks the time of year when severe thunderstorms and tornadoes occur most often in Texas. They bring all the devastating elements - tornadoes, lightning, large hail, damaging winds and flash flooding. This is a time when Texans begin to take increasing advantage of the state’s great outdoor opportunities. So, it is particularly important that everyone be aware of the weather when outdoors. Each Texan must know what to do when severe weather threatens him or her at home, at work, at school, at play or even when traveling on the road. Severe Weather Awareness Week is an excellent time to review safety plans for the coming weather threats.

Check out this PDF of severe weather awareness that the National Weather Service has put together on how to plan ahead and be knowledgeable about severe weather, how to react, what the warnings mean, and ideas for how to create a plan for your family.

Here in southeast Texas our most common severe weather are severe thunderstorms and flash flooding. Here's some great info from NWS in regards to both of those severe weather events:

What classifies a severe thunderstorm?
A thunderstorm is classified as severe by the National Weather Service when it produces wind gusts in excess of 58 mph or hail of one inch in diameter or larger. 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 just about 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 just about any time of day in southeast Texas, but are most common in the afternoon and evening hours.

Severe weather threats
  • Downbursts
  • A downburst is a small area of rapidly descending air beneath a thunderstorm. Downburst winds are often referred to as "straight-line" winds. Severe downbursts produce wind gusts from 60 mph to more than 100 mph. The damage is often similar to damage from a weak tornado. Downburst damage is far more common in southeast Texas than tornado damage.
  • 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 travel upward and downward through the storm several times, growing in size. Once they become too heavy to be supported by the storm's updraft, they fall to the ground as hail. Hail of 3/4 inch in diameter or larger classifies "large" or damaging hail. Hail sizes are usually given as references to everyday objects to make it easier to estimate hail size. Baseball sized hail can break car windshields! Due to our proximity to the Gulf coast, hail greater than baseball size is rare in southeast Texas. Hail can damage crops and can also cause damage to automobiles and rooftops.
Examples of hail sizes:
 Pea sized  0.25 inch
 Penny sized  0.75 inch
 Nickel sized  0.88 inch
 Quarter sized                     
 1 inch
(classifies storm as severe)
 Golf ball sized  1.75 inches
 Baseball sized  2.75 inches

  • Tornadoes
  • 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 are Different Types of Floods?
  • Flash Floods
  • Flash floods are short-fuse weather events, typically lasting on the order of 6 hours or less. Usually, flash floods occur within a few minutes or hours following an excessive rainfall event. They can also be caused by a man-made event, such as a dam or levee failure. Flash floods cause most of the fatalities associated with flooding events. Usually, less warning lead time is provided for flash flooding which requires quick action on the part of the public.
  • Urban Floods
  • Flash flooding is most severe in urban areas like the Houston metropolitan area. Urbanization increases runoff by 2 to 6 times over what would occur in natural terrain. Flood waters can fill streets, freeway underpasses, and parking lots and can sweep away cars.
  • River Flood
  • Heavy rainfall falling over a widespread area (such as a large portion of a watershed) over a prolonged period (like several days) can cause river flooding. Typically, river flooding begins as a high crest on the upper part of a watershed that takes several days to move downstream. Due to the slow nature of river flooding, ample advanced warning is provided to evacuate people or property in the path of the flooding.

How does flooding impact southeast Texas?

Flash flooding is a relatively common event over Southeast Texas. Tropical systems during the summer and early fall, and strong winter storm systems can cause widespread flooding and flash flooding across the area. Flash flooding can also be produced by strong slow-moving thunderstorms especially during the spring and summer months. Flooding and flash flooding can occur anywhere in southeast Texas, but is usually most severe near major watersheds like the Colorado, Brazos, San Jacinto, or Trinity Rivers, and near urban areas like the Houston metropolitan area.

What the National Weather Service warnings and watches mean by definition
  • Hazardous Weather Outlook
  • Issued by the local National Weather Service office daily at 7 AM. Usually covers a large portion of southeast Texas. Outlines the reasons for the potential for severe weather, the area that could be affected and the time that severe weather is anticipated.
  • 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. A Severe Thunderstorm Watch means that conditions are favorable for severe thunderstorms that may produce large hail, damaging wind, dangerous lightning, or possibly tornadoes.
  • Severe Thunderstorm Warning
  • Issued by the local National Weather Service office. Usually covers a small area (one or 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
  • Follow-up information on a warning.
  • Flood Watch
  • Means that conditions in the watch area will be favorable for flooding during the specified period. Usually heavy rainfall is expected following a long period of wet weather.
  • Flash Flood Warning
  • Flash flooding is reported or is imminent in the counties specified in the warning. Take immediate precautions.
  • Urban and Small Stream Flood Advisory
  • Flooding of streets, low-lying areas like underpasses and storm drains, and small streams is expected. Caution should be taken while traveling.
  • Flash Flood Statement
  • Follow-up information on a Flood Watch or a Flash Flood warning.
  • River Flood Outlook
  • Indicates potential for flooding along rivers and streams.

What do you do in flash flood situations?
The worst place to be in a flash flood is traveling by car. Two feet of water will carry away most automobiles. Do not cross water flowing over a roadway if you do not know its depth.

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.

Things you can do ahead of time to prepare for major floods
  • Know the flood risk at your place of home or business and its elevation above flood stage.
  • Store drinking water in clean bathtubs or containers. This is very important as flood waters will contaminate the drinking water supply in your area.
  • Stock non-perishable food items requiring little cooking and no refrigeration.
  • Keep first aid supplies on hand.
  • Keep NOAA Weather Radio, battery-powered portable radio, emergency cooking equipment, and flashlights in working order.
  • Install check valves in sewer traps to prevent flood waters from backing into your home.