The threat of severe weather in South Texas can happen almost anytime during the year. It can range from severe thunderstorms with heavy rain, large hail, high winds, dangerous lightning, along with the possibility of tornadoes, to extreme heat and drought conditions. In addition during the winter months we can usually expect some icy conditions and the possibility of snow. While it doesn’t occur on a daily basis, we must always be prepared to deal with it whenever it does.
Here in the San Antonio area of South Texas we can and do receive a wide variety of severe weather based on several factors. The moisture from the Gulf of Mexico plays a major role. When cold fronts move into the area and mix with this moist atmosphere the results tend to produce showers and thunderstorms. Any of these storms moving in the area can become severe very quickly and this tends to occur in and around the Bexar County area. Unfortunately many frontal systems that move in from the West bring little rainfall to us here in Live Oak. Large cities tend to create heat islands and this can break up some storm fronts. In addition large cities tend to cap the atmosphere overhead and thus storms tend to miss us. As Live Oak is located on the Northeastern side of Bexar County we sometimes miss some severe weather as it tends to break up and weaken over the large city.
One important item to remember! On occasion storm systems can move into the area from the Northeast. While this is kind of rare, any large storm system moving into the area from the Northeast could bring severe weather to our City. This is especially true when it comes to tornadoes which we will discuss later on.
While severe weather occurs on a regular basis, it never really sneaks up on us thanks to the folks at the National Weather Service. The office serving the South Texas area is located at the New Braunfels Airport and it is known as the Austin/San Antonio office of the National Weather Service. The facility has state of the art NEXRAD radar and operates 24 hours a day, 365 days a year. They provide daily weather updates and issue an assortment of weather advisories, statements, and bulletins including weather watches and warnings, depending on conditions. Several other radar sites cover South Texas including one near Del Rio, Corpus Christi, and several other locations. In addition, the Storm Prediction Center in Norman, Oklahoma, monitors the weather across the nation and issues various statements regarding the possibility of severe weather.
All citizens should be familiar with the weather services statements and bulletins and fully understand what they mean. The most common are Watches and Warnings. They both pertain to a weather conditions but their meaning is very different.
Watches – A “Watch” of any kind simply means conditions are favorable for a certain type of weather to occur, over a certain area, and during a specific time frame. Generally speaking watches are issued based on atmospheric conditions when moisture is present and storms fronts are expected.
Warnings – A “Warning” on the other hand means that the condition is happening now. A Severe Thunderstorm Warning posted for Bexar County until a certain time means that a severe storm, based on high winds, hail, and rainfall is showing up on radar and is moving into the area. The most dangerous would be a tornado warning. These are issued when either an actual funnel cloud has been reported on the ground by a certified weather spotter or when radar indicates the possibility of a rotating storm cell which could indicate a tornado. Sometimes this indication is known as a “Hook Echo” on the radar. The hook so to speak is the actual funnel cloud however radar cannot tell if the funnel cloud is actually on the ground.
Severe weather can be dangerous and deadly too. One of the biggest problems around the area is flash flooding and there are many low water crossings that are located in San Antonio and Bexar County. Every year about 150 lives are lost due to flash flooding and the majority of these deaths occur at low water crossings. People continue to drive through low water crossings and are swept away by the rushing water.
Tornadoes also claim many lives each year as well. The San Antonio area is south of the famed “Tornado Alley” however every year we usually have at least one or two funnel clouds sighted in this area. As a reminder any thunderstorm can spawn a tornado with little or no warning. Generally speaking straight-line winds actually do more damage than tornadoes, and they also can occur during most thunderstorms.
Severe thunderstorms can occur anytime of the day or night however they occur most often in the late afternoon and into the early evening hours. Daytime heating combined with a lot of moist air from the Gulf and a frontal passage can trigger these storms on a regular basis, especially during the springtime from March – May. As such, the National Weather Service and the State of Texas promotes this as severe weather season and a proclamation is issued at the end of February by the Governor and our Mayor.
CoCoRaHS, the Community, Collaboration, Rain, Hail, and Snow network:
The National Weather Service (NWS) continues to look for additional folks to become members of their CoCoRaHS network.
This program was started back in the late 1990s by the National Weather Service in Colorado and it continues to grow. The network now has volunteers in all 50 states and hopes to have 20,000 members by the end of the year. Their goal is to have weather observers across the nation who report rain, hail, and snow amounts on a daily basis along with other data using the internet or by telephone.
At the present time there are 94 active stations in San Antonio/Bexar County, and we have 2 in the City of Live Oak.
You can join the network by simply going to their web site and signing up or to get additional information regarding the program. Signing up is free, however in order to establish a monitoring site in your backyard, you must purchase a special rain gauge, similar to the type actually used by the weather service. This is necessary to insure the accuracy of the program as not all store bought gauges are the same. The cost is nominal and it can ordered on line or by telephone.
For additional information you can visit the Austin/San Antonio office of the National Weather Service at www.srh.noaa.gov/ewx or you can go directly to the CoCoRaHS web site at www.cocorahs.org On the web site for the Austin/San Antonio office scroll down to the bottom of the opening page and you will see the icon at the bottom of the page on the right hand side.
You can also contact the Live Oak Office of Emergency Management at 653-9140, Extension 379 for additional information on this program.
Hurricane season begins on June 1st and runs through November 30th each year. At the present time, the State of Texas ranks 2nd in the nation for hurricanes that have some impact on the state. Florida ranks number 1 in case you are wondering who has top honors in that category. That time frame isn’t always the case as some storms have formed in May and sometimes hurricanes continue to form in December.
While a hurricane making landfall along the Texas coastline is not going to have a direct impact on the San Antonio area, things could actually get pretty intense here under the right circumstances. Being approximately 150 miles from the coast the storm surge is not going to affect us, however depending on the size of the storm (Category 1, 2, 3, 4, or 5) and the point where it makes landfall, along with the storms forward speed we could experience some severe weather conditions in Bexar County. The worst part of a hurricane making landfall is the so called Northeast Quadrant. This is where the most intense wind is located and where the best chance is for the formation of tornadoes. As a reminder, once a hurricane makes landfall it can spawn many tornadoes as it moves inland.
In 1988 Hurricane Gilbert made landfall along the Texas Coast and moved inland. It came in between Corpus Christi and Brownsville and we were on the Northeast side of the storm. We had very heavy rains in San Antonio and several tornadoes touched down in Bexar County and within San Antonio. One hit the former Kelly AFB causing heavy damage and another hit the medical center area and heavily damaged an apartment complex and the Texas Medical Center itself.
In the event a major hurricane (Category 3 or higher) makes landfall along the coast of Texas near Corpus Christi and it comes in with enough forward speed, the affects could reach all the way to Bexar County and the City of Live Oak. In addition to heavy rainfall, we could experience sustained winds reaching hurricane speed – 74 MPH, with gusts reaching 100 MPH. While this would be a very rare occurrence it could happen and this could cause a lot of damage to homes and businesses, specifically roof damage.
The State of Texas is first in the nation for tornadoes, primarily because of our size. The so called “Tornado Alley” includes a large part of the State however we are not included here in the San Antonio area. It ends about 100 miles North of Bexar County. Generally speaking weather conditions over South Texas are favorable for tornado development whenever storms are in the area. As a reminder any thunderstorm, especially if they are reaching severe limits has the potential of producing a tornado on short notice.
Residential Homes - If a tornado warning is issued go to the most center part of your home, on the first floor. A hallway closet or bathroom would be a good choice. The room should not have an outside wall if at all possible. If you have none, the hallway itself with all doors closed should be safe. Always stay away from windows and outside doors. A closet under a stairway may seem like a good place however it may not be because the staircase could collapse on top of you if your home is hit by the tornado. Once you are in a “safe” area sit or lie down on the floor and protect your head.
Manufactured Homes/Mobile Homes - This type of structure is not safe during tornadoes. For some reason tornadoes seem to find mobile home parks and turn them upside down. While some of the newest models are better built and feature better tie down capability they still may be destroyed by a tornado. If you live in a manufactured/mobile home you really need to plan ahead. If you live in a mobile home park some have actually built tornado shelters in conjunction with their office building or clubhouse. Generally speaking this building probably would be a better place then your home but it may not be large enough to hold many people and may be locked up at night. As a general rule, homeowners who live in a manufactured/mobile home should have a plan to move to another location if a tornado warning is issued. The bottom line is if you live in this type of home you need to plan ahead.
Apartments - There are so many different types of apartment buildings that you really need to plan ahead as well. If you live in a single story building or on the first floor of a building you can follow the same guidelines as a single family home. If you live on a second floor or higher that’s another matter. Generally speaking go to the most center part of your unit and go into a closet or bathroom. Get down on the floor and protect your head. Once again, residents should plan ahead. If you live on the top floor you could be in greater danger as a tornado could rip the roof off of the building and do considerable damage to that floor of the building. As a suggestion if you have time to get to a safe location you might consider going to the apartment of a friend on a lower level. The bottom line once again is plan ahead.Commercial Buildings, i.e. office building, big box stores, etc.
There are so many different types of commercial buildings that it may be hard to determine a safe place. Generally speaking if a tornado warning is posted for the area all personnel should proceed to the lowest floor of the building. Stay away from windows, especially the large plate glass windows used in many retail buildings. As noted it is very hard to determine how large commercial buildings will hold up in a tornado. Roofs may collapse on large big box stores and people can be trapped under tons of debris if this should occur.
Generally speaking large shopping malls are somewhat safe. Stay away from windows and if you are on the ground level be aware what is above you. Large objects on the second level of a mall could fall to the lower level.
In large, multi-story office buildings the most important thing to remember is to stay away from large plate glass windows. Interior offices, restrooms, and hallways should be relatively safe.
One very important issue to remember is do not leave the building. You will be a lot safer in the structure then you will be outside or in your car.
Outdoors - If you are outdoors in open country look for shelter immediately. If there is no place to go then you need to look for a place to take cover. A highway culvert along the roadway or a simple ditch will do. Lie face down and cover your head with your hands. In the past it was suggested to look for a highway overpass or bridge however this is no longer recommended. While this may provide protection there really is nothing to hold onto. If the tornado passes nearby you could be sucked out from under the bridge. Generally speaking it is considered safer to get out of your vehicle and seek cover than staying inside your vehicle and trying to outrun the storm. Tornadoes can move very quickly and can change course rapidly. You may not be able to do that in your vehicle. If you're traveling and severe weather is forecast in the area you need to plan ahead. In some cases it may be wise to stop somewhere until the storm passes.
The City of Live Oak has a floodplain that affects several hundred homes. Many residents of the City are unaware that we have a floodplain, however back in October 1998 some folks figured that out. On the weekend of October 17th and 18th, 1998, the City received around 20 inches of rainfall over a 24 hour period. Minor flooding did occur, however damage was scarce.
The floodplain, defined by floodplain maps from the Federal Emergency Management Agency (FEMA), covers the area around the lake in the city park and throughout the drainage channels within the City. The lake itself is really a flood control area so to speak and the parkland around it is designed to flood, causing little damage to property.
The Martinez Dam and the lake is part of the flood control system. Back in 1998 flood waters covered most of the park and water actually went around the dam – not over it, as it should. As a matter of information the earthen dam is safe and was recently upgraded by Army Corp of Engineers. Several changes were made along with the area around it.
Following the flood of 1998 the City identified numerous problems and during the next few years several drainage improvements were completed. In 2002 when heavy rains once again fell around the area, no problems were noted.
If your home has a drainage channel behind your back fence or if you have a channel in your neighborhood your property could be located in or near a floodplain. Floodplain administration is not handled by the Office of Emergency Management but rather by the Planning and Zoning Department at City Hall. They have the maps and they can determine if any of your property or if your home is located in or near a floodplain.
As a matter of information for all citizens your homeowners; insurance policy does NOT cover flooding. Homeowners must have a separate flood insurance policy. Chances are if your home was financed through a mortgage company they have verified whether or not the property is located in a floodplain and will have required that you purchase a flood insurance policy. The City participates in the National Flood Insurance Program (NFIP) which allows residents to purchase flood insurance if required.
Any questions concerning the City’s floodplain should be directed to the Planning and Zoning Department and questions concerning insurance should be directed to your insurance agent.
Flash flooding is the number one (1) cause of storm related deaths around the nation and in the State of Texas. Each year approximately 150 people lose their lives as a result of flash flooding, with around 80% of those deaths occurring when people drive or try to walk into swift moving flood water. In most cases these deaths occur at low water crossings when people try to drive through it when flood waters are flowing across the roadway. The majority of the remaining deaths are children and young adults who are walking or playing near flood waters.
Whenever heavy rains occur around the area flash flooding is always a possibility, and the National Weather Service issues many flood watches and warning for the Bexar County/San Antonio area. There are numerous rivers, streams, and creeks within the county and there are almost 200 low water crossings in the area. Whenever heavy rains occur these low water crossings can fill rapidly and become deadly. Tests have shown that in most cases it takes less than two (2) feet of swift moving water to float most vehicles, depending on their size and type. Small compact cars and some pick-ups can float in just one (1) foot of water. In addition, only six (6) inches of swift moving water can knock the average person off their feet.
Flash flooding can occur at any hour of the day or night however it is even more deadly at nighttime when it is difficult to see. Flood waters may be deeper and moving much faster than they appear to be. In addition flood waters tend to hide many dangers such as large tree branches or other debris. Also all flood water must be considered to be contaminated water which can lead to other problems.
If you live near a low water crossing or pass by one on your daily commute, make sure you have an alternate route just in case. Pay attention when flash flood watches and warnings are issued. Remember that low water crossings can fill up quickly even though there is little rainfall where you are located. Water travels down the creeks and streams from other areas and can cause the water to rise over these crossings far from the heavy rainfall area.