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NASA Aids in Damage Assessment Following Alabama Tornadoes
Satellite image of Alabama tornado damage ASTER composite satellite views of North Alabama tornado damage from May 5, 2011. (NASA)
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A variety of lightning data associated with afternoon thunderstorms. A variety of lightning data associated with afternoon thunderstorms. (NASA/MSFC)
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Forecast model simulation of an early morning squall line. Forecast model simulation of radar reflectivity on April 27, 2011, representing predictions of an early morning squall line moving through the Southeast, comparable to early morning thunderstorms that affected North Alabama. (NASA/MSFC)
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More Information
Link: Terra Satellite
On Wednesday, April 27, a widespread and historic severe weather outbreak occurred across the southeastern United States, including numerous, significant, and long-track tornadoes across the state of Alabama, causing billions in state-wide damage. NASA's Short-term Prediction Research and Transition (SPoRT) Center at Marshall Space Flight Center in Huntsville, Ala. is helping in the aftermath of these severe storms by providing the National Weather Service (NWS) with unique NASA satellite data for observation and damage assessment.

On May 19, members of the NASA SPoRT team answered your questions about how NASA is involved in weather forecasting research and their support of National Weather Service activities. Research meteorologists Andrew Molthan and Brad Zavodsky will be joined by Applications Integration Meteorologist Brian Carcione of the National Weather Service Forecast office in Huntsville, Alabama and available to answer your questions, to learn more about SPoRT and NASA's activities in support of local severe weather prediction and response.

More About SPoRT

The SPoRT Center assists with damage assessments through application of high resolution imagery obtained from NASA polar-orbiting satellites, such as Terra and Aqua. SPoRT is using these capabilities and data sets to assist the NWS in the severe storms that occurred in the Tennessee Valley, such as the recent historic April 27 outbreak.

During severe weather, the SPoRT Center provides total lightning data to forecasters via the North Alabama Lightning Mapping Array, useful for monitoring storm severity and potentially increasing lead time for hail, wind, and tornadoes. The SPoRT Center provides training and support to the NWS in the use of total lightning data to aid in the prediction of short-term severe weather events.

The SPoRT Center continues to investigate new data sets and data assimilation techniques to improve weather predictive capabilities using high resolution weather forecast models. Improved forecast models increase the awareness of severe weather likelihood, providing additional lead time for public advisories and other preparedness activities.

More about the chat experts

Chat Transcript

(Moderator Jason): Welcome to today’s Web chat with members of NASA’s SPoRT team: research meteorologists Andrew Molthan and Brad Zavodsky and applications integration meteorologist Brian Carcione of the National Weather Service Forecast office in Huntsville, Alabama. Our topic today is how NASA is involved in weather forecasting research and the tools they develop using NASA satellite data to aid the National Weather Service with short-term weather predications. The SPoRT team will also discuss how NASA satellite images are aiding in the April 27 tornado damage assessment, helping to determine several tornadoes width and path length. Have questions for the experts? Now’s your chance! Please remember to stay on topic. This is a moderated chat. It may take a few moments for the queue to catch up to your question, so please don’t leave if you don’t see your question right away.

National_Weather_Svc_Brian: Hey everyone, welcome to the chat! Questions? :)

DIBYENDU_SUR: What are the basic parameters you have taken to predict the weather? like total lightning data

National_Weather_Svc_Brian: For severe thunderstorms, we focus on instability -- which is how much warm, moist air exists at the surface of the earth -- and wind shear, which is the changing winds with height. In this event on April 27, the atmosphere was very unstable and there was a lot of wind shear, so that resulted in over 300 tornadoes from Arkansas to New York.

(Moderator Jason): We're working on answering the first few questions. To ask your own, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions.

Jim_: What impact is the electrical disturbance have on the mission? I know it is significant, but can you elaborate?

Sport_Team_Andrew_and_Brad: Forecasters in Huntsville and nearby areas use total lightning data from the North Alabama Lightning Mapping Array (NALMA) to quantify electrical activity within storms and use fluctuations in lightning flash rate to infer storm intensity.

Batman: How many yards-miles can a tornado go and about what is the average time they stay on the ground?

National_Weather_Svc_Brian: Depending in the strength of the storm, it can be on the ground for a few yards or up to 100 miles. Most tornadoes are only on the ground for a few miles/minutes at best.

Jim_: Is the storm ceiling a factor?

National_Weather_Svc_Brian: Not quite sure of your question -- can you clarify, Jim?

DIBYENDU_SUR: Have you generated a model with those input weather parameter data?

Sport_Team_Andrew_and_Brad: Hey Dibyendu! High resolution forecast models begin with an analysis of the current weather conditions based upon satellite, surface, and upper air observations. These data sets are then integrated forward in time using a series of equations to predict future storms. In terms of "weather parameters," these models are capable of predicting the instability and wind shear that are precursors to severe weather outbreaks.

Farouk: What efficiency does the system that you're working on has?

Sport_Team_Andrew_and_Brad: Farouk, could you please elaborate? Which system are you referring to?

Jim_: The altitude of the system, say 35,000 ft.

National_Weather_Svc_Brian: Thank you. The height of a storm can be an indicator of how strong it is, but it depends on the time of year. The tornado hitting Huntsville in January 2010 was a very shallow storm -- about 20,000 feet high -- whereas some storms in April and May can be up to 50,000 feet high.

(Moderator Jason): Do you have a question you've been waiting to ask? Go for it! To submit your own question, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions.

Sport_Team_Andrew_and_Brad: Thank you for attending and the questions thus far, please keep the questions coming!

DIBYENDU_SUR: Is the model done by Neural network in feedforward method?

Sport_Team_Andrew_and_Brad: No, in this case we are using the Weather Research and Forecasting (WRF) model, a model developed and maintained by the meteorological community. For more information, see .

hsd123: They are comparing this storm to the 1974 outbreak. Did any of the tornados stay on the ground in April 3, 1974 as long as some of them did in the April 27 storm?

National_Weather_Svc_Brian: Yes, some of the tornadoes were comparable in strength and duration to the 1974 tornadoes. In fact, one of them on April 27 took a very similar path to one in 1974.

National_Weather_Svc_Brian: Great questions, everyone! Keep them coming...

National_Weather_Svc_Brian: If you'd like more information about SPoRT and its products and services, visit the SPoRT Web site:

djd001: With the extent of the damage caused on April 27, will SPoRT be collaberating with the NWS on a regular basis for future storm damage and predictions? and will this set up be based just in America or are there plans to put a global system into place?

Sport_Team_Andrew_and_Brad: The NASA SPoRT Center collaborates with the NWS in several ways. We are currently assisting the NWS with storm survey and assessment through the use of ASTER and MODIS satellite imagery. We have done this previously and plan to continue supporting in future assessments. As far as global assessments, these satellite instruments are available for global disaster response as well, although SPoRT's focus is within the United States due to our NWS partnership. With respect to prediction, SPoRT is involved with developing new NASA data sets for use in high resolution forecast models, which aid predictions of high impact weather events. Here is an example of a recent article showing some capabilities of the ASTER instrument for damage assessment:

Jim_: NASA, this has been great, thank you

Sport_Team_Andrew_and_Brad: Jim -- thank you, we appreciate your feedback!

hsd123: Was the storm on April 27 as bad as you were expecting? Or less severe?

National_Weather_Svc_Brian: It was very close to what we expected -- a significant tornado outbreak, and that's what happened.

National_Weather_Svc_Brian: North Alabama/Southern Middle Tennessee tornado track information, with links to other affected NWS offices in the southeast:

(Moderator Jason): We're working to answer your great questions. Keep them coming! To submit your own question, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions.

ChristyC: It seems like the weather this year has been more severe than the past few years. Will models of this storm, and other currently being studied help us to draw parallels and identify new weather patterns, and/or plan for the future?

Sport_Team_Andrew_and_Brad: ChristyC -- severe weather occurs throughout the United States at different times of the year, although this was a particularly severe event. SPoRT's focus is on short-term weather events in the present to 48 hour time frame.

DIBYENDU_SUR: Which satellite data are you using?

National_Weather_Svc_Brian: Most weather forecasters use geostationary or GOES satellite imagery. However, because of our collaboration with NASA SPoRT, we're able to access the polar orbiting MODIS imagery which provides higher resolution data.

Batman: Were any of the April 27th tornados "Wedge Tornados" and does the altitude of the storm support these types of tornadoes?

National_Weather_Svc_Brian: Yes, several of the April 27 tornadoes were wedge tornadoes. A wedge tornado is so called because it's a very large tornado that it looks like a wedge moving across the ground. Most tornadoes are only a few hundred yards wide and look more like the classic tornado that everyone is familiar with.

ChristyC: Realizing that there are limitations to any type of weather prediction, and that tornado producing storms are extremely volitile, will these tools help to make predictions that are more "futuristic"? For example, many accounts describe only having minutes to prepare for the tornado's arrival. Could this be increased at all?

National_Weather_Svc_Brian: Many of the average lead times between tornado warning and tornado impact were nearly 20 minutes for this particular event, but there are many efforts underway to try to increase the time people have to prepare.

Will: What models performed best in terms of forecasting the event, both in terms of the regional & global models?

Sport_Team_Andrew_and_Brad: That's a great question, Will. Thanks in part to data assimilation activities in our community, global models typically do a great job at depicting the large ("synoptic") scale patterns that may contribute to severe weather. Finer scale "mesoscale" models are operated at higher resolution and tend to give us a better depiction of storm mode (squall lines versus supercells). Many forecast models were able to capture the overall characteristics of this event. SPoRT is currently investigating the impact of other NASA data sets in these high resolution mesoscale models to see if we can improve upon our current capabilities.

Sport_Team_Andrew_and_Brad: Will, as a follow-up to our earlier response, check out this NASA "Wide World of SPoRT" blog article describing our involvement in the Weather Research and Forecasting (WRF) model:

Jim_: Does are Ozone Layer impose restriction on accurate observations, and alos magnetic strength?

Sport_Team_Andrew_and_Brad: Jim: It doesn't necessarily impose a restriction on the observations that we use, but there are some instruments that measure the amount of ozone present in the atmosphere.

DIBYENDU_SUR: Are there are scales to measure the level of the tornadoes?

National_Weather_Svc_Brian: Yes, we use a system called the enhanced Fujita (EF) scale to classify tornadoes. For example, the EF-0 has winds of 65-85 mph. An EF-5 has wind speeds of over 200 mph and produces much more damage.

Sport_Team_Andrew_and_Brad: Chat participants -- thank you for attending and your questions thus far. For more information about the SPoRT program and our involvement with NWS offices, check our our "Wide World of SPoRT" blog:

hsd123: There's a ton of video footage of the April 27 outbreak. Does this help you do comparisons from what you were seeing on the screens versus what was happening on the ground? Were there any surprises?

National_Weather_Svc_Brian: Live video during the heart of the event certainly helped us write more effective warnings for those impacted. As far as the videos posted to the Web now, it helps validate some of the damage that we observed on storm surveys and damage paths we viewed on high-resolution satellite imagery, such as that provided to us by SPoRT. Unfortunately, many of these tornadoes looked just as strong and damaging as they actually were.

vmts: Why don't you use Landsat in the damage assessment?

Sport_Team_Andrew_and_Brad: Thus far, we have used observations from the ASTER and MODIS instruments aboard NASA's Terra satellite, currently orbiting the Earth (for more than 10 years!). These instruments see the same area at the same time, and we benefit from this simultaneous view. Landsat data are also helpful and being explored, but we have not yet incorporated it into our analysis.

Farouk: Yes, I'm talking about the efficiency of the the system in term of time. the time between the detection for example of a tornado then the data analyses and finally alerting citizens. How much time could we gain and are you working to improooooooove it?

National_Weather_Svc_Brian: The average lead time between warning and impact was about 20 minutes. There are new advances in radar that could improve this, plus efforts to model these storms on a rapid basis that could potentially improve that lead time -- but both of these systems are a number of years away.

vmts: Is there a way to provide the results to local teams (e.g. CERT), including the smaller volunteer teams that are often the first to arrive?

Sport_Team_Andrew_and_Brad: SPoRT is developing capabilities to display our products in other tools such as Google Earth. We also provide our data in near real-time to the National Weather Service, and they can use our data to communicate storm tracks and other observations to their assessment teams.

Will: Excellent work!

Sport_Team_Andrew_and_Brad: Will -- thank you!

ChristyC: What happens with this data once it is collected? How is it used, and what are some of the longer range goals for the data?

National_Weather_Svc_Brian: Christy, the purpose of every data gathering is to help meteorologists understand the current state of the atmosphere and how it is expected to evolve. Long-range goals are always to help better understand how we can use the data more effectively to produce more accurate forecasts and warnings.

vmts: Since Terra is an aging satellite, do you have plans for an after-Terra period?

Sport_Team_Andrew_and_Brad: Terra's longevity is a great NASA success story and we look forward to using it in the future. NASA and NOAA are developing follow-on missions with similar capabilities so that we will continue to have access to these great observations. SPoRT is preparing for these future satellite capabilities and also helps the NWS to prepare by exposing them to high resolution observations that are currently available.

alesbolz: Hello from Italy, is possible to use this system also in other counties for similar events?

Sport_Team_Andrew_and_Brad: Alesbolz -- Ciao! Thank you for joining us. NASA's satellites provide a global coverage of observations and observations from MODIS and ASTER could be used in other countries for similar applications.

ChristyC: A lot of storms have the capacity to produce tornadoes and don't. At what point during the storm life cycle can you say with certainty that a torndao will be produced?

National_Weather_Svc_Brian: Doppler radar has given us a window into seeing the kinds of winds in a storm and thus the capacity for producing tornadoes. Stronger winds and stronger rotation on radar usually indicate to us that a tornado is on the ground, but in many cases we rely on a network of storm spotters, law enforcement, etc. to confirm the tornado is actually being produced -- so it can take some time to confirm whether a tornado is actually on the ground.

ChristyC: Do you have resources and outreach for teachers that want to use this infomation in their classrooms?

Sport_Team_Andrew_and_Brad: Christy -- NASA Marshall Space Flight Center has several education resources, and you can request a spokesperson through our speaker's bureau. If you are outside our area, please contact your nearest NASA field center, ( for more information.

(Moderator Jason): Do you have a question you've been waiting to ask? Go for it! To submit your own question, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions.

Farouk: What's the most influent factor that leads to have tornados and does the global warming have an influence on that.

Sport_Team_Andrew_and_Brad: Farouk -- tornadoes form as a result of severe thunderstorms which develop in an environment where both atmospheric instability and wind shear are present. With regard to global warming, that is a question beyond our expertise but something that other climatologists are investigating.

DIBYENDU_SUR: But ionosphere may certainly impose some sort of impact in measurements, is it?

Sport_Team_Andrew_and_Brad: There are instruments that are sensitive to the ionosphere, but our focus is on instruments that are focused on measuring the troposphere (where the most of our weather occurs), stratosphere (ozone), and the land surface (where we live).

curiosity: We see often movies that talk about storms and investigations and I would want know if decreasing the power of a storm is a line of investigation or just science fiction.

National_Weather_Svc_Brian: There are some efforts underway to try to affect the weather, but it's far too early to say if they could have any effect on a storm capable of producing a tornado.

National_Weather_Svc_Brian: A useful link, a blog article with MODIS true color/Alabama tornado tracks:

(Moderator Jason): We're working to answer your great questions. Keep them coming! To submit your own question, please type it in the box at the bottom of the window and click the 'Ask' button on the right side of the box. Thanks for your patience as we answer your questions.

ChristyC: Do these technologies have applications beyond tornadoes? With hurricane season about to "officially" begin, could these same processes be used to predict, record, and assess those storms as well?

National_Weather_Svc_Brian: Yes, NASA SPoRt produces a high-resolution sea surface temperature product that helps coastal NWS offices better predict the impact of a hurricane on their area of responsibility.

vmts: Great work! It's great when we can talk directly to the researchers in the front-lines of technological innovation!

National_Weather_Svc_Brian: Thank you -- we appreciate that!

vmts: Is the processing conducted by SPoRT or you acquire the imagery from other center/project? I imagine the infrastructure to be huge to process all that data. Could you tell us something about that?

Sport_Team_Andrew_and_Brad: We acquire data in real time from NASA's "Direct Broadcast" capabilities onboard NASA satellites, with collaboration from our academic partners. We also have a ground station here in Huntsville to acquire data from the NOAA geostationary satellites. The weather community does a great job of sharing data between facilities, and this helps tremendously. We then reprocess data for our NWS forecast office partners to make it easier to use in their weather analysis and display systems. As new satellites provide greater capabilities and our numbers of partners grow, we will grow to accomodate these needs. We have a relatively small team (10-15 people) but provide data to an ever-growing number of partners.

ChristyC: This has been awesome, thank you!

National_Weather_Svc_Brian: You're welcome -- appreciate your great questions, Christy!

DIBYENDU: How long are you capturing the data?

Sport_Team_Andrew_and_Brad: We continuously capture the data in near real-time through NASA's "Direct Broadcast" capabilities and then distribute it to our partners as soon as possible. NASA has a variety of data centers responsible for creating longer term archives of data from current and past instruments.

Farouk: Eell done guys !! Many thanks to you indeed for this opportunity and for answering my questions.

Sport_Team_Andrew_and_Brad: Farouk -- thank you for the great feedback, and we're glad you've enjoyed this chat opportunity!

Sport_Team_Andrew_and_Brad: Your questions this afternoon have been great. Keep them coming! We have about five more minutes.

National_Weather_Svc_Brian: We have time for a few more questions. Agree, these are great questions!

curiosity: Thanks and I wish you more success.

Sport_Team_Andrew_and_Brad: Curiosity -- thank you for participating!

(Moderator Jason): We've got time for just a few more questions.

vmts: Best regards from Portugal to everyone at NASA!

National_Weather_Svc_Brian: Thank you! Glad to have Portugal here on our chat!

Sport_Team_Andrew_and_Brad: For more information about the SPoRT program, check out a couple of our web links: Also, search for the NASA SPoRT Center on Facebook.

DIBYENDU: Can we get some videos of this great work?

Sport_Team_Andrew_and_Brad: Dibyendu -- We do not have videos of our work, but you can find some web graphics of our data and other information at our website:

National_Weather_Svc_Brian: A great link for more information and also your local forecast:

DIBYENDU: Will it be possible one day to predict earthquake by using weather parameters? or it is too random to modelize that?

Sport_Team_Andrew_and_Brad: Dibyendu -- Great question, but that is unfortunately outside our expertise. We still stick to just forecasting the weather!

[End Transcript]

Kim Newton, 256-544-0034
Marshall Space Flight Center, Huntsville, Ala.