Analysis of the January 21-22, 2017 record breaking Tornado Outbreak across Georgia
Keith Stellman, National Weather Service Atlanta, Peachtree City, GA
Steven Nelson, National Weather Service Atlanta
Lara Pagano, National Weather Service Atlanta
Steven Listemaa, NWS Atlanta
David Nadler, NWS Atlanta

During the 2 day period starting Saturday January 21, 2017 and ending late Sunday January 22, 2017, 41 tornadoes were recorded across the state of Georgia which set a new record for a two-day period.   27 of the 41 tornadoes occurred in the NWS Atlanta/Peachtree City (FFC) area of responsibility.  24 of those 27 tornadoes within the FFC area occurred on Saturday the 21st as part of a large Quasi-Linear Convective System (QLCS) including two EF-2 tornadoes.  A separate round of severe weather occurred on Sunday the 22nd which featured supercell tornadoes including a nearly 71 mile long EF3 tornado that tracked across two NWS CWA’s (NWS TAE and FFC).

The event can be separated into 3 distinct rounds of severe weather which was a challenge not only for forecasters due to uncertainties in the forecast, but also in providing decision support services to partners given these uncertainties, as well as for internal planning for staffing.  Scheduled weather briefings and emails were provided throughout the event including an unprecedented personal phone call to 30 of our 96 county Emergency Managers on Sunday the 22nd.  Other DSS challenges included NWS FFC providing continuous weather support to the Atlanta/Fulton County EMA office who was supporting the NFL NFC Championship game in Atlanta on Sunday the 22nd.  

NWS FFC Management and staff recognized after the Saturday event that numerous tornado surveys were going to have to be performed and that additional, future tornadoes may negatively impair our ability to assess any damages from Saturday’s storms.  In an attempt to segregate damage areas, the AWIPS damage path tool was used late Saturday afternoon to draw smaller polygons (swaths) of known and “potential” damage areas to survey.  Data from the dual-pol (Correlation Coefficient and TDS), storm reports, and velocity couplet pairs were used to identify and draw 14 potential tornado/damage paths from the Saturday storms.  This process turned out to be not only very accurate in identifying damage areas, but also very helpful in the planning of storm survey teams deployments and potential damage tracks to NWS Southern Region HQ and FEMA IV as early damage assessment. 

Late Saturday evening and into the overnight hours of Sunday, three WSR-88D radar that cover a large portion of Central and South GA failed (KJGX, KVAX, and KTLH).  In addition, the SPC day 1 outlook issued overnight included a HIGH risk of severe storms for a large portion of the area covered by those radars.  It was the first HIGH risk in GA since the April 2011 outbreak.

This presentation will overview the event, the challenges to the staffing and surveying, and operational challenges with the forecast and providing DSS as well as how the partially disabled radars affected some decisions during the event.