Earlier this evening, several supercells erupted in Central Oklahoma, producing several strong to violent tornadoes. These tornadoes impacted communities such as Edmond, Carney, Norman, Bethel Acres and Shawnee. Much of the attention now including prayers have been focused on those impacted in a mobile home park directly in the path of the tornado where at least one fatality has occurred.
The following link goes to an interactive map showing the approximate paths of the three most significant tornadoes that impacted Central Oklahoma. The map has a bookmark feature where you can view the Edmond, Carney and Norman to Shawnee tornadoes. Similar tornado path maps have been very helpful and highly accurate for other significant tornadoes events over the past several years.
Click on the graphic to launch an interactive map. The map contains bookmarks for the 3 tornadoes as well as an address lookup feature.
This information is unofficial information, but is based upon NWS Radar scans and uses the National Climate Data Center Weather/Climate Toolkit (NCDC WCT) and ESRI’s ArcGIS Online. For official storm survey results, please follow the National Weather Service in Norman, Oklahoma (@NWSNorman). In the coming days, the National Weather Service will be performing storm damage surveys. When more information is made available, I’ll be linking to those products.
On the evening of May 15th, strong to violent tornadoes went through portions of Hood County and Johnson County, TX. Six people were killed in the Granbury area from this storm, and multiple tornadoes were produced as the storm cell tracked through the region. The maps below were created from radar images, and depict the rotation paths of the tornadoes as they impacted areas near Granbury and Cleburne, TX. As you can see from the images, the storms progressed from WNW to ESE (you can look at the timestamps), however the tornadoes tracked from south to north while they were on the ground. I’m sure this scenario has occurred before, but the differences between the storm motion and the path of the tornadoes themselves could be lending to some of the initial confusion in reporting areas impacted.
Granbury Tornado (Hood County, TX) – As of the morning after the storm, authorities in Hood County were reporting -6- fatalities from the storm, with nearly 100 injuries. Based on radar observations, correlated to scanner reports of streets impacted, below is some preliminary information on primary impact area. The hardest hit area was located south and east of Granbury, TX on the north side of Lake Granbury. Some areas / roads in the area most impacted include the area near Rancho Brazos Estates / Tumbleweed Lane (http://goo.gl/maps/HRxfL - Google Maps Link). There were a number of tweets reporting structural damage, homes collapsed. Looking more closely at some of the buildings in this area show that many homes are mobile homes, likely contributing to the high casualty numbers.
NWS Dual-Pol Radar image showing Correlation Coefficient (CC) and the Tornado Debris Signature ~810pm CT. Low values of CC in areas with high rotation (likely tornado areas) are consistent w/ debris being produced by a tornado on the ground. This location correlates with law enforcement and social media reports describing the hardest hit areas. (click for larger image)
Rotation Path for the 5/15/13 Tornado – Hood County, TX (Aerial – Click for larger image)
Bing Maps imagery showing the area hardest hit by the Granbury tornado. Note the concentration of mobile homes in the center of the image. Many homes were “wiped off their foundation”. Because of their vulnerability to winds, my guess is that these homes were some of the hardest hit in the area. (Click for larger image)
Rotation Path for the 5/15/13 Tornado – Hood County, TX (Street Map – Click for larger image)
Later in the evening, another large tornado (reported by spotters to the NWS as a mile-wide tornado) impacted areas South and West of Cleburne, TX. One of my best friends from College lives there, so I’m quite familiar with that part of town. There is a lot of new residential development in that part of town – single story homes, most without basements, however the relative age of the homes hopefully means that they’re built to withstand stronger winds. The roofs in most of this area are hip roofs which hold up better to stronger winds. Here’s a link to Google Maps to Southwestern parts of Cleburne (http://goo.gl/maps/JfMvA) I’ll update more as I hear more from the Cleburne area, but the radar images did not look good. Thankfully though, the strongest radar images occurred outside of town. Below are the timestamps (UTC) showing the rotation path through the Cleburne area.
Picture of mile wide tornado (backlit from lightning) near Rio Vista, TX – via Fox4 Weather Facebook Page
Rotation Path for the 5/15/13 Tornado – Cleburne, TX (Aerial – click for larger image)
Rotation Path for the 5/15/13 Tornado – Cleburne, TX (Street Map – click for larger image)
4/13 – 928pm CT – Updated interactive map to include links to media video and photo of damage with locations. The locations verify quite well with the initial map points
It’s incredible to think of how today progressed…. First I shared a presentation on this topic to several of my peers around the country to share a methodology with the hopes of helping people tomorrow and in other tornado outbreaks, and the next thing I know, I’m talking to my brother in Oklahoma who is trying to get home to Norman after school, with a tornado warning for his home town. It’s amazing to see the impact of how technology and information can be brought together to help protect lives. I ended up helping guide him home to keep out of the storm while the tornado passed less than 1/2 mile from his house, telling him to stay put and keeping him out of harm, but still guiding him home. Thankfully everyone in the family is safe, but it’s incredible to know that it makes a difference so close to home.
During the evening of March 19, 2012, numerous supercell thunderstorms were observed across portions of the Southern Plains. One of these storms impacted areas just southwest of San Antonio, TX near the towns of Devine, Natalia and Lytle, TX. While further from the radar site (~60 miles from the radar in Austin, TX), the rotation signatures are definitely present on radar. Additionally these signatures and their paths are typical of a supercell thunderstorm that “cycles” – essentially where one area of rotation weakens, and a new area of rotation emerges. Note the time stamps (UTC times) and follow the intersection of the red/green colors along the path as the radar animation progresses. Also, note how the paths curve to the left before weakening, and then a new area of rotation emerges to the right of the old one. This is quite typical of a supercells that cycle.
We’ll learn more in the morning and as tomorrow progresses, but if I was to make an educated guess on the areas potentially impacted, they would be as follows: Continue reading →
The beta version of the National Climate Data Center (NCDC) Weather and Climate Toolkit (WCT) has been released and is now available for download from http://lwf.ncdc.noaa.gov/oa/wct/install.php. This beta release adds support for several new functions including Level 2 and Level 3 Dual-Polarization products like the graphic below. The tool is available for use in Windows, Mac OS/X and Unix/Linux environments. I personally use the standalone download because it’s easier to save versions locally to test out the features of the newer release. Continue reading →
2011 has been a prolific year for major tornado outbreaks. We know of the storms that have impacted our cities and towns across the country. We also are generally familiar with the devastating outbreaks affecting cities like Joplin, Tuscaloosa, St. Louis & Raleigh. There is one outbreak though that many people overlooked because of the timing of the event. This outbreak occurred in Central Oklahoma, produced 2 EF-4 tornadoes and one 60+ mile long EF-5 tornado. However, due to the timing of the event, most of the nation’s focus was elsewhere on another community that was severely impacted.
On May 24th (2 days after Joplin), a number of tornadoes impacted central Oklahoma (NWS – Norman Event Summary). The most powerful of these was rated as an EF-5 tornado impacting the El Reno area. That storm was not only sampled by mobile and fixed weather radar, but the outer edges of the tornado actually were directly measured by the Oklahoma Mesonet station at El Reno (see images below).
The mesonet station measured a wind gust to 151mph (click on the photo to the left to visit the AMS blog). There are nearly 120 stations throughout Oklahoma as a part of the Oklahoma Mesonet. This information proves invaluable to having field verified weather observations that are directly measured. Even though this tornado was on the ground for nearly 60 miles and had a width of 1 mile, direct measurements of this nature are not usually seen. There were 9 fatalities and nearly 200 injuries with this storm.
At nearly the same time as the El Reno/Piedmont storm was hitting those areas, two other storms were rolling through Central Oklahoma, further to the Southeast. These two storms ended up tracking to less than ten miles from Norman Oklahoma where the National Weather Center is located – housing some of the nation’s brightest and best minds in severe weather research. Continue reading →
Many people are aware of the Enhanced Fujita (EF) Scale for tornadoes. Most also know about the Saffir-Simpson Hurricane Wind Scale. However there is also a rating scale for Winter Storms that fewer people know about. In 2004, Paul Kocin and Louis Uccellini from the National Weather Service (Kocin and Uccellini, 2004) developed the Northeast Snowfall Impact Scale (NESIS). Below is a description from the National Climate Data Center (NCDC) website for NESIS:
“The index differs from other meteorological indices in that it uses population information in addition to meteorological measurements. Thus NESIS gives an indication of a storm’s societal impacts. This scale was developed because of the impact Northeast snowstorms can have on the rest of the country in terms of transportation and economic impact.
NESIS scores are a function of the area affected by the snowstorm, the amount of snow, and the number of people living in the path of the storm. The diagram below illustrates how NESIS values are calculated within a geographical information system (GIS). The aerial distribution of snowfall and population information are combined in an equation that calculates a NESIS score which varies from around one for smaller storms to over ten for extreme storms. The raw score is then converted into one of the five NESIS categories. The largest NESIS values result from storms producing heavy snowfall over large areas that include major metropolitan centers. Continue reading →
Many people are looking for weather data (especially higher resolution radar data) that supports response and recovery activities as well as research into previous significant weather-related natural disasters. The National Climate Data Center (NCDC) Weather and Climate Toolkit (WCT) allows users to interact with an incredible amount of data (historical or current) and display that within the Java based application. The website provides solid how-to guides for accessing current data, ordering historical datasets and using the various functions of the tool. Continue reading →
