SR SSD 2001-08
Improving Severe Weather Verification through a Team
Mark W. Rose
During significant severe weather outbreaks in north and central Alabama, the Birmingham Forecast Office typically receives several reports of tornado touchdowns. It is the responsibility of the NWS to survey these tornado events. This responsibility normally falls to the WCM, but there are times when the WCM is not available or the number of damage sites require more personnel.
On December 16, 2000, ten tornadoes swept through north and central Alabama. The worst storm killed 11 people in Tuscaloosa County. Because of the national media attention given to this deadly tornado, the WCM focused his attention on that storm. Other staff members handled the other storms. During the next several days, storm survey teams from the Birmingham office fanned out across the CWA to survey the other damage paths. Even though a majority of the tornadoes were rated F0 or F1, they would not have been documented if not for the extra efforts of the survey teams. These documentations are vital for accurate verification statistics, and what we learn from the damage assessment improves our ability to provide quality warnings.
To prepare for such response, forecasters Mark Rose and Mark Linhares developed a program to organize Storm Survey Teams (SST). The first priority was to acquire the types of equipment necessary to perform a storm survey. Two storm survey kits were assembled so team members would have all the necessary equipment in one bag. The kits include a road atlas, binoculars, laptop computer with Street Atlas software, GPS receiver, digital camera and compass. The kits also include an operator's manual on how to use the equipment, survey forms, narrative descriptions and photographs of the Fujita scale for tornado intensities, and phone numbers for area emergency management and law enforcement agencies. If the survey documentation is composed on the laptop, then the laptop can be easily connected to the office LAN and the product transmitted to AWIPS.
A training session was held on what the SST involves and a brief overview of the survey equipment was presented. WCM Brian Peters reinforced to the team members that their role is a fact-finding mission. A final determination of what caused the damage or the Fujita classification of tornado intensity can be made when the team arrives back at the office and reviews the findings with the office staff. He also stated the team members are not required to provide assessment information to the media until the final report is written, however, the SST will strive to provide a quick response to media inquiries and provide graphically enhanced Web based reports. One goal of the SST effort is to ensure reports will provide digital pictures of the storm damage along with a detailed map of the storm track.
While not all offices may have the staffing to organize a large contingent of survey team participants, it can be beneficial to have extra personnel trained, equipped and available to perform survey activities. It is advisable to have at least two people go out on a survey. Not only does it make it easier to perform the survey, but it is also much safer to have a navigator so that the driver can concentrate on driving.
Each office in the Southern Region has a local operating plan (LOP) which outlines goals for improving severe weather warnings. One of the most glaring deficiencies in verification statistics is the false alarm ratio for tornado warnings. The SST hopes to make improvements in this area by surveying those storms which look tornadic on radar but from which we receive no ground confirmation. Improvements can come from verifying that we did indeed have a tornado, or by providing information to improve our ability to distinguish what looks tornadic from what actually is a tornadic storm. Either way, accurate ground truth is essential. The SST idea was one of many proposals mentioned in the WFO Birmingham 2000 LOP, and hopefully the project will make a substantial improvement in the area of tornado warning and verification.
WFO Birmingham received accolades from the media and Southern Region Headquarters for the timely and detailed storm surveys which were posted on our Web site quickly following the December 16 tornado outbreak. For a look at the storm reports from this event, please visit the site at: http://www.srh.noaa.gov/bmx/december_16_2000/december_16_2000.html.