Presenter: Kevin Laws, SOO Birmginham, AL

Abstract: There are multiple layers to the process of improving warning performance, and these layers differ across the country. This session will present a process used at the Birmingham, AL, office. The layers that will be discussed include:

• "Warning fatigue" - The challenge of going beyond false alarm rates to the perception the users have of false alarms;
• Polygon structure - Starting with the concepts from WDTD's AWOC Severe training, then tailoring those concepts for local needs; and
• The human challenge - Modifying office culture, and how this has been addressed at WFO Birmingham.

Presenter: John Ferree, NWS Severe Storms Services

Abstract: The capability to deliver Impact-Based Tornado and Severe Thunderstorm warnings has been demonstrated at 46 of the 122 WFOs (38 in Central Region, 5 in Southern Region, 2 in Western Region, and 1 in Eastern Region) that includes both AWIPS 1 and 2 offices. The presentation will review two events (November 17, 2013 tornado outbreak in Central Region, and at the Jackson, MS office on April 28, 2014). Some recent research that addresses the ability of forecasters to discriminate storms with the greatest impact will be presented. The initial results of social science studies of emergency managers, and a preview of a longer term study of public response to impact-based warnings will be included. Finally, Michael Hudson, Central Region Chief Operations Officer, will join us for a question and answer period.

Presenter: Josh Weiss, WFO Wilmington, NC

Abstract: An ice storm of any scale or duration is rare in the Carolinas. From February 11 through February 13, 2014, a winter storm produced icing of 0.5” or more over the majority of the WFO Wilmington CWA, with some areas reporting up to 1.5”. The storm peaked late morning through the afternoon of February 12, with icing rates of 0.10-0.15 in/hr, prompting Josh to contact the SPC for a consultation, resulting in a Mesoscale Discussion highlighting the threat. Societal impacts were on the scale of a hurricane: extensive forestry damage, power losses, and economic losses due to businesses closed. This webinar will present “life in the nowcasting seat” for this event, the benefits of WFO and SPC collaboration, and the overall challenges of working an historic event.

Presenters: Hayden Frank and Joe DelliCarpini, WFO Boston, MA

Abstract: Early on Sunday morning, December 1, 2013, spotty light freezing rain and freezing drizzle produced icing on roadways throughout central Massachusetts. Traffic was heavier than usual for a Sunday since it was the end of the Thanksgiving weekend. Though icing was forecast over the previous two days, many accidents occurred throughout the region, most notably a 70-car pileup on elevated Interstate 290 which runs through Worcester, MA. This type of event has happened in many places across the U.S. It is especially challenging in terms of messaging and is tough for WFO staff given the time of day. This webinar will review the synoptic and mesoscale features that can produce light freezing rain/drizzle and present lessons learned to improve anticipation and messaging for future icing events.

Presenters: Chad Entremont and Daniel Lamb, WFO Jackson, MS

Abstract: One of the most notable benefits that has emerged from the recent upgrade to dual-polarization technology is the ability to detect tornadic debris. A study of over 180 tornadic debris signature (TDS) cases has found there is a significant correlation between maximum TDS height and tornado intensity. The primary goal of this research is to increase the confidence of the warning forecaster in the likelihood of a damaging/significant tornado occurring based on dual pol data. This knowledge will be particularly useful as the National Weather Service continues to move into the impact based warning era. To demonstrate this, we will take a look back at NWS Jackson's use of dual pol data during the April 28, 2014 tornado outbreak.

Presenter: Whitney R. Smith, WFO Columbia, SC

Abstract: Multiple supercell thunderstorms moved across the Midlands and Pee Dee regions of South Carolina during the afternoon and evening of 23 May 2014. The strongest storms produced up to 3 inch diameter hail in two of the warned areas, in addition to damaging winds of 50 to 65 mph. Based on the Probability of Detection and False Alarm Rate, the severe thunderstorm warnings issued by the NWS Office in Columbia, South Carolina (CAE) verified well for large hail and damaging winds. This study focuses on the radar data (including dual polarization) that went into the NWS forecasters’ decision making process in real time as well as lessons learned from post storm analysis. We will also examine how the nature of these storms affected the warning polygons, which complicated the messaging to those affected.

Presenter: Taylor Trogdon, WFO Memphis, TN

Abstract: In an operational environment, it is sometimes difficult to determine whether or not damaging wind gusts within a convective line are reaching the surface.  Dual-polarization radar allows users to make inferences about the internal structure of these storms both horizontally and vertically which can aid in decision-making behind the warning desk.  This presentation examines the 30 June 2014 bow-echo across eastern IA where a feature was observed, most notably in Differential Reflectivity, which may help to determine when damaging wind potential is increasing or decreasing during the life cycle of a bow-echo.  This feature has been termed a “ZDR Arch.”

Presenters: Marc Austin and Jonathan Kurtz, Forecasters, WFO Norman, OK

Abstract: The flash flooding that occurred in the Oklahoma City metro during the evening of May 31st and early morning of June 1st killed a total of 13 people, making this event the deadliest ever for the city. Yet, what is remembered most about that night is the enormous El Reno tornado and the excessive number of people choosing to flee in their vehicles. The challenges of communicating multiple hazards that night will be presented, as well as lessons learned for improving messaging for future multiple hazard events. The talk then moves to May 6, 2015, which brought another tornado and flash flooding event to the metro, and an opportunity to better address the messaging challenge.

Presenter: Mike Evans, SOO WFO Binghamton, NY

Abstract: A potent storm system raked across the northeast U.S. on July 8, 2014, bringing numerous severe storms to the Binghamton (BGM) forecast area. Among the storms was the first deadly tornado to strike the BGM county warning area since the late 90s. This event was well-anticipated by forecasters through the use of new tools such as the SPC storm-scale ensemble of opportunity and a locally-developed severe weather analog tool.  However, the deadliest tornado was the most challenging to detect on radar, occurring within a Quasi-Linear Convective System structure. Additional challenges of discriminating between tornadic and non-tornadic supercells will be discussed, along with challenges associated with detecting the deadly tornado, and how Dual-Pol products aided in this event.

Presenters: Scott Overpeck and Lance Wood, WFO Houston, TX

Abstract: After record rainfall in May, a slow moving line of thunderstorms moved into Harris County during the evening of May 25th resulting in widespread, historic flooding. Excessive rainfall rates, including 4.8? in one hour and 10.1? in six hours, were measured. Despite hundreds of water rescues, the flooding resulted in 8 fatalities and thousands of flooded homes. Throughout the event NWS meteorologists were in constant communication with decision makers, broadcast meteorologists and storm spotters through NWSChat. The office?s first ever FFW emergency was issued and it expanded to include 3.2 million people!

Presenters: Jon Zeitler, Aaron Treadway, and Jason Runyen , WFO Austin-San Antonio, TX; Greg Waller, West Gulf River Forecast Center

Abstract: After nearly continuous rainfall throughout May 2015, a slow-moving longwave trough, strong upper level divergence, high precipitable water air from the Gulf of Mexico, and the topography of the Balcones Escarpment combined to produce heavy rainfall of 6-13 inches on the upper reaches of the Blanco River overnight on May 23-24. The resulting flooding at Wimberley, TX, shattered the previous record by almost 12 feet and resulted in 12 fatalities and nearly 3000 flooded homes/businesses. Interstate 35 was closed for three hours, and not fully-re-opened for six hours. Our focus will be on: challenging predictability of intense rain, resulting river flows and stages in headwater/flashy terrain, and promising research and operational tools coming in 2016. The need for action-based messaging and preparedness at the watch stage for these events will also be discussed.

Presenter: Joe Dellicarpini, WFO Boston, MA

Abstract: Although the winter of 2014-2015 in southern New England started slowly, with many believing it would be a lean winter, a record-setting snow blitz began in late January and lasted for six weeks. Boston and eastern Massachusetts were buried under feet of snow, after what seemed to be an endless series of coastal storms brought blizzard conditions, high winds, and coastal flooding. This active period of snow and prolonged cold led to nearly continuous IDSS activities at WFO Boston which included over 180 briefings to Emergency Managers, more than 600 media interviews, and an explosion of social media posts. Rather than discuss the meteorology, this presentation will focus on some of the human factors involved at WFO Boston during this historic stretch of winter weather. Many had to balance life at home and at work under stressful conditions, either being at work for days at a time or having to travel under varying road and weather conditions. IDSS activities focused on the “before, during, and after” each storm - as well as the “next one” which forced other office activities to be put on hold. Takeaways will be discussed in order to share best practices for other WFOs to utilize for similar significant weather events.

Presenters: Barry Goldsmith, WFO Brownsville and Robert Ricks, WFO Slidell

Abstract: It may be a blizzard, a hurricane, a tornado outbreak, flash flood, or other type of historic or high-impact weather event, but a career event may be right around the corner. How do you respond in these moments? What value can you add to the message and the framework that exists in the warning process? We will hear from one forecaster who answered these questions in a unique and impactful way before Hurricane Katrina reached the Gulf Coast back in 2005. And in the spirit of teamwork and understanding how no one can do it alone, we will also get a perspective from someone who helped put that framework into place well before the event, because response has a direct correlation to preparation in career-defining moments.

Presenters: Aaron Ward and Katie Pojorlie WFO Rapid City, SD

Abstract: On 3-5 October 2013, a potent low-pressure system produced a record-breaking blizzard that devastated northeastern Wyoming and western South Dakota. Prolonged damaging wind gusts of around 50 to 70 mph, combined with 2 to 5 feet of snow, created treacherous conditions across much of the region. Tens of thousands of livestock were killed, damage took months to clean up, and three indirect fatalities resulted from the blizzard. Four National Weather Service employees were stranded at the office for 42 to 54 hours. The meteorology of this system will be discussed briefly with a focus on the impacts of the storm and the challenges endured by these four employees (including the presence of a government shutdown).

Presenters: Rich Thompson and Joey Picca, Storm Prediction Center

Abstract: The Storm Prediction Center (SPC) is developing tornado damage rating conditional probabilities from datasets of tornadic and severe non-tornadic thunderstorms. Null storms have also been analyzed, and this study now includes their (unconditional) probabilities. Evidence from this research will show the skill of these probabilities in forecasting tornadic supercells and estimating real-time tornado intensities based on radar data and near-storm environments. These results will then be linked to the critical role of radar data quality for identification of low-level rotational velocity and assessing tornadic potential.

Presenter: Heather Stanley, Lincoln, Illinois WFO

Abstract: A powerful EF-4 tornado forever changed Washington, Illinois on November 17, 2013. In the days that followed, the NWS in Central Illinois conducted a detailed damage assessment, focusing on both the physical damage and the experiences of those impacted. Our speaker witnessed the devastation first hand, recounting both her experience and what was learned from those who suffered loss after this deadly storm. Their stories, their grief, and their triumphs provide a new perspective on the NWS mission and the service we provide.

Presenter:Vivek Mahale, Norman, Oklahoma WFO

Abstract: A tornado developed in southwest Oklahoma City as a supercell thunderstorm interacted with an effective frontal boundary. This tornado produced up to EF-2 damage in Moore, OK. An analysis of the event is conducted using the KTLX WSR-88D radar data and surface observations from the Oklahoma Mesonet. Precursors of tornadogenesis were found, including: 1) storm-scale cyclogenesis indicated by radar reflectivity observations of a developing ‘kink’ along the surface boundary coincident with localized surface pressure falls and backing winds; 2) a rapidly descending rear-flank downdraft (RFD) surge with maximum radial velocities of >75 knots); 3) a dual-RFD structure with two storm-scale wind maxima; and 4) highly divergent air aloft indicated by maximum storm-top divergence >190 knots

Presenter: Matt Elliott, Sterling, VA WFO

Abstract: CONUS-wide total lightning data has recently become available within AWIPS, allowing forecasters to utilize this rich dataset alongside traditional data sources (e.g., radar, satellite) during severe weather warning operations. This discussion will provide examples, best practices, strengths, and limitations for incorporating total lightning data into warning decisions. In addition, improved visualization techniques for total lightning data within AWIPS that enable forecasters to more easily establish trends in total flash rates will be presented.

Presenters: Justin Pullin, Chris Outler, & Stan Czyzyk: WFOs Tallahassee & Las Vegas

Abstract: October 2015 featured an abnormally wet and stormy pattern across the Las Vegas CWA, courtesy of one upper level low that impacted the region twice in a ten day stretch. This system yielded historic flash-flooding across Death Valley National Park as well as severe thunderstorms and several supercells across the region. A new way to conduct after action reviews at NWS Las Vegas was put to its first major test in between these systems, as the local after action team quickly took steps to gather feedback and present it to the staff, influencing much needed changes ahead of the second event. This talk will tell the story of these events, highlight how these after action items are conducted and show how they influence improvements for the second round of historic weather.

Presenters: Dave Noble and Chris Gibson, WFO Missoula, MT

Abstract: The staff at the NWS WFO in Missoula, MT anticipated a busy but routine day supporting wildfire suppression on August 10, 2015. By the end of that evening, the events that transpired will not soon leave the minds and memories of the people that lived this experience. An intense line of thunderstorms with damaging winds inflicted a cascade of issues and impacts across Missoula and the surrounding area. This wall of wind affected multiple outdoor events, aggravated wildfire fighting efforts, and even compromised the WFO’s building equipment and power for a time. With their building and their city surrounded by blowing dust, grass fires, and power outages, the staff fought through the challenges in one of the most memorable weather events in the area's history.

Presenter: Kevin Skow, WFO Des Moines, IA

Abstract: In the days following the passage of a strong QLCS across central Iowa on August 31, 2014, the entire 350-km path of the storm was imaged at 1-m resolution through the USDA National Agricultural Imagery Program. This imagery offers an extraordinary glimpse into the quantity, evolution, and scale of surface vortices generated throughout the entire lifespan of this QLCS. A total of 111 such tracks were cataloged and 35 classified as tornadoes. This presentation will showcase notable tracks, a proposed reclassification of tornadic debris signatures that is better suited for QLCS tornadoes, possible tornadogenesis mechanisms, and NWS WFO warning/Storm Data implications using aerial datasets.

Presenter: John Stoppkotte NWS North Platte, NE

Abstract: Understanding of supercell tornadogenesis through peer-reviewed research and development of fine-scale models has grown, yet applying these findings to the NWS WFO warning decision making process has been limited. Using a radar-based case study approach, this discussion will look at several tornadic and non-tornadic events that can be related to this recent research. The goal is to develop a more detailed conceptual model of supercell tornadogenesis for forecasters through storm-scale interrogation of WSR-88D dual pol parameters. A more detailed and operationally relevant conceptual model can enhance both our warning strategies and messaging.

Presenter: Andy Haner NWS Seattle, WA

Abstract: On August 11, 2014, three firefighters on the Beaver Fire in California became entrapped and were left with no other choice but to use their last-resort fire shelters in order to save their own lives. This occurred about 25 minutes following the arrival of a thunderstorm outflow boundary. As the Beaver Fire's Incident Meteorologist (IMET), Forecaster Andy Haner of NWS Seattle will recount both the meteorological and human events of this incident-within-an-incident, with a special focus on the topic of Critical Incident Stress Management.

Presenters: Randy Bower and Todd Lindley, WFO Norman;
Aaron Johnson, WFO Dodge City;
Stephen Bieda and Robert (BJ) Johnson, WFO Amarillo

Abstract: This is the story of how SPC and WFO forecasters worked together to overcome their internal “Normalcy Bias” for a “this has never happened” tornado outbreak in November, after dark, with multiple, significant, tornadoes. Normalcy Bias is a term used within the EM community, and overcoming that bias, for both the NWS forecasters and the EMs, was a key element in the success of the event. An equally vital takeaway from this story was within two weeks, a multi-office, dual-region Hot Wash was conducted. The Hot Wash captured the important lessons of forecasting an anomalous event, when NWS performance matters most.

Presenters: Kevin Cadima and Joe Dellicarpini, WFO Boston

Abstract: The East Coast Blizzard of January 23-24, 2016 was the first threat of significant snowfall for southern New England since the winter of 2014-2015, when record-breaking snowfall occurred. The 2016 Blizzard presented very different challenges, as southern New England was expected to be on its northern edge, with considerable uncertainty about snowfall amounts. There were also concerns with precipitation type, damaging winds and coastal flooding. Conveying this uncertainty in the days, and even 12 to 24 hours, before the snow began, was a constant challenge with Decision Support Services provided by NWS Boston to core partners. “Most likely” scenarios along with reasonable “best” and “worst” cases were used, along with experimental probabilistic snowfall forecasts. This presentation will focus on the “Living on the Edge” messaging strategies used by NWS Boston.

Presenters: Jamie Morrow and Steve Keighton, WFO Blacksburg, VA

Abstract: The President's Day holiday weekend in February of 2016 brought a mixed precipitation and flooding event to the Blacksburg, VA, CWA. This combination brought significant forecasting challenges, especially in regards to p-type transitions, which will be discussed. Messaging and communications proved crucial, and stakeholders had to make tough decisions. Social media aided in this role, as well as having a plan in place to ensure adequate staffing.

Presenters: Jonathan Guseman, WFO Jackson, KY

Abstract: A potent upper-level low pressure system dug into the Four Corners region on Sunday February 24, 2013, setting the stage for a blizzard over the southern Texas Panhandle. As the system continued to develop farther south into the Desert Southwest, it became necessary to extend the Blizzard Warning southward, including the city of Lubbock. Nonstop media coverage and numerous phone calls into the office immediately followed the extension of the warning. This is the story of an eye-opening experience for a young forecaster and relatively new resident of Lubbock; how it shaped his growth as a young forecaster, and informs his decision making today.

Presenters: Ray Wolf, WFO Quad Cities, IA

Abstract: High-shear low-CAPE severe weather events are the most challenging mode we face in the Quad Cities CWA based on analysis of our verification data. However, with an accurate and detailed forecast, staffing according to our recently revamped severe weather operations plan, and putting the right staff into the right positions to succeed, we experienced one of the best tornado warning efforts in several years. Success in severe weather operations is a result of a number of factors, and these will be discussed beginning with a quality forecast.

Presenters: Patrick Burke, WPC; Jennifer McNatt, SRH; and Trevor Boucher, WFO Austin/San Antonio, TX

Abstract: It’s May in Texas with a threat of severe weather and flooding. On May 31, 2016, Trevor arrived at work before a Flash Flood Watch was issued. Patrick arrived with a Slight Risk of Excessive Rainfall and no Flash Flood Watches. Jennifer at SRH was preparing to brief state partners, with the convection beginning within hours. By midday the Southern Plains was blanketed in a seamless Flash Flood Watch, a Moderate Risk of excessive rainfall, and an agreed upon strategy for QPF. Flash flooding can be particularly complex and difficult to forecast, especially with ongoing severe weather threats. Our chances for achieving success on a routine basis improve when national, regional, and local NWS Offices share their strengths, working together for a consistent and actionable forecast message. The events of May/June 2016 in Texas nicely illustrate how collaboration on precipitation and flash flooding can benefit all involved.

Presenters: Jim LaDue (WDTD) and Dan Bikos (CIRA)

Abstract: Dan and Jim will review a rare cool season severe weather event in Arizona that produced two tornadoes and multiple wind damage tracks throughout the Phoenix metropolitan area. The rapid development of multiple mesovortices along a QLCS prompted this analysis of how the mesovortices most likely formed, and what were the leading precursor signals. We further explore the evolution of important signatures leading up to this event and what information sources were most useful at specific times before the tornadoes.

Presenters: Ashley Ravenscraft (Meteorologist), Kris White (Applications Integration Meteorologist), and Brian Carcione (Science and Operations Officer)

Abstract: The Geostationary Lightning Mapper (GLM) is quickly becoming a critical tool for visualizing strengthening updrafts that may lead to tornadogenesis. This, in combination with the three-ingredients method, has helped maximize lead time with tornado warnings in an operational warning setting, where protection of life and property is the primary goal. The Winter of 2019 - 2020 was unusually active for the Huntsville, AL forecast area, where 13 tornadoes occurred from December through February. On at least two occasions, the rapid increase in lightning activity visually represented by GLM imagery enhanced the confidence of the warning forecaster that storm intensification was occurring. This presentation will demonstrate how GLM was used as a tool to increase forecaster confidence during the warning process on both December 16, 2019 and January 11, 2020, and possible avenues for additional research moving forward.

Presenters: Michael Dutter, Science and Operations Officer, WFO Wakefield, VA

Abstract: Tornadoes associated with the remnants of tropical cyclones such Hurricane Florence are not unusual. In fact, 31 tornadoes occurred with the remnants of Hurricane Florence in NC and SC from 13 Sep to 16 Sep 2018. This tornadic activity continued as the remnant circulation of Florence moved northward into WV and VA on 17 Sep. However, what made 17 Sep 2018 different was the limited spatial and temporal extent of the outbreak. Out of the 13 tornadoes on 17 Sep, 10 were in the Richmond VA metro region, while 5 were observed within the limits of the City of Richmond in about 90 minutes. These tornadoes all occurred when area schools were being released for the day and at the start of rush hour. This presentation will look at some of the mesoscale clues from surface analysis, radar and satellite imagery and high resolution model guidance, to gain a better understanding why this cluster of tornadoes happened when and where it did.

Presenters: Kyle Weisser (Lead Forecaster) and Philip Schumacher (Science and Operations Officer), NOAA/NWS Sioux Falls, South Dakota

Abstract: On 10 September 2019, three EF-2 tornadoes hit the south side of Sioux Falls, South Dakota between 11:24-11:28 PM CDT. These tornadoes were associated with 3 mesovortices that formed along a quasi-linear convective system (QLCS) during the evening. The storms were also produced 80-100 mph winds. One tornado was associated with a long-lived mesovortex that changed direction from east-northeast to north-northeast 2 to 4 minutes prior to tornadogenesis. The change in direction meant that, instead of going south of the city, the mesovortex moved into the city. A second tornado occurred within 5 miles of the KFSD radar. Radar data showed the rapid development of this tornado as the wind field went from strong convergence to strong rotation in 3 minutes.A new warning operations strategy was tried during this event. Two warning forecasters were assigned the QLCS with one having responsibility for all tornado warnings and the second for all severe thunderstorm warnings. The change in strategy appears to have improved both warning decisions as well as information flow with partners.

Presenters: Phil Ware, Todd Lindley, Randy Bowers (WFO Norman, OK), and Evan Bentley (Storm Prediction Center)

Abstract: Traditional radar base-data analysis techniques and incorporating environmental data and conceptual models continue to be the foundation for convective warning decision-making. This presentation will highlight the very large hail-producing right moving supercell that impacted portions of north Texas on May 7th. In addition to reviewing signatures for very large hail in base moments and dual-pol variables, this presentation will discuss important mesoscale analysis strategies for the near-storm environment to support the warning forecaster. WFO Norman's close collaboration with the Warn-on-Forecast team will be highlighted and we will show how, in collaboration with SPC, this enhanced forecast confidence and supported messaging of the downstream hail threat.

Presenters: Tony Anderson and Greg Heavener - WFO Pueblo

Abstract: The evening of July 22, 2019 was a near worst case scenario for the folks living in the shadows of the Spring Creek burn scar in Huerfano County, CO. Heavy rains developed over nearly all 108,000 acres of the 1-year old burn scar and though heavy rain had occurred before, the stability of the burn scar had never been tested quite like this. Sutron gauges installed in specific and highly scorched creek/stream basins indicated over 1.5 inches of rain fell within 45-60 minutes posing considerable, possibly catastrophic impacts to the small town of La Veta, CO. For this presentation, we’ll go through our locally devised burn scar flash flood warning methodology, multiple means of communication with core partners, and how well our radar, KPUX, and MRMS data handled the event.

Presenters: Clark Payne, Radar Meteorologist - Radar Operations Center

Abstract: Each WSR-88D VCP is designed to optimally perform under different meteorological situations. Choosing the right VCP for the right situation can seem a little daunting at first. Additionally, local needs may dictate slight modifications to a VCP such as scanning lower elevations more frequently. The Radar Operations Center (ROC) will address the strengths of each VCP and highlight the various modifications allowed for the different VCPs to assist with VCP selection. Secondly, AWIPS is an invaluable tool to view radar data during warning operations. It connects to an RPG/SPG to request data generated by these processors through Routine Product Set (RPS) Lists. The ROC along with the AWIPS NCF have developed a consolidated approach to managing RPS Lists to ensure you receive the products you need when you need them. We'll discuss these best practices for RPS Lists.

Presenters: Mike Evans and Christina Speciale - WFO Albany, NY

Abstract: Data from two convective events occurring in the Albany, NY County Warning Area in May, 2020 are presented. Both events were associated with quasi-linear convective systems (QLCS’s), and each included a small, EF-1 tornado. In one event, a tornado warning was successfully issued for the small tornado. In the other event, no tornado warning was issued for the location where the tornado occurred, and subsequent tornado warnings were issued for areas that experienced damaging winds, but no tornado. These two events highlight many of the challenges of issuing tornado warnings for QLCS’s in the Northeast. Radar and near storm environment data from these events highlight the utility of applying the recommendations from the Central Region Tornado Warning Improvement Project (TWIP) during severe weather operations. The TWIP recommends applying the three ingredients method as well as a set of radar and environmental signatures called confidence builders and nudgers to determine the potential for meso-vortex genesis, intensification and the resulting occurrence of a tornado. It was determined that a favorable environment for both genesis and intensification of meso-vortices was in place during both of the tornado and non-tornado cases shown here. Likewise, an examination of confidence builders and nudgers indicated several favorable radar-based signatures for tornadoes in both scenarios, despite only one resulting in a confirmed tornado. Results from a separate short study are also shown that compare the occurrence of confidence builders and nudgers with five recent QLCS tornado cases within the Albany County Warning Area, to five cases when tornado warnings were issued along a QLCS but did not result in a tornado. The results imply that application of the three ingredient method, confidence builders and nudgers can be very helpful for identifying QLCS tornadoes in our area, however, false alarms remain a challenge.

Presenters: Jim LaDue - Warning Decision Training Division (WDTD)

Abstract: In recent years, our ability to provide higher resolution and more accurate damage record has grown with the advent of the EF Scale and the Damage Assessment Toolkit. However, the needs of our partners and warning verification have also grown. This process is made especially challenging given that the data we must provide often requires a level of expertise that falls outside our collective comfort zone. Thus we all have a need to share our experiences and expertise in order to stay calibrated and provide more accuracy to our surveys. As part of that process, the NWS often deploys a Quick Response Team for big events. In addition, we often consult with others with more experience in evaluating structural and tree damage. With the greater ease of collaboration and remote meeting software, these consultations have become remote more often than in-person. This provides both an opportunity and a challenge. The opportunity is that we can access the opinions of more experts remotely than in-person and the challenge is that pictures often are incomplete in the details needed for accurate remote evaluation. In this presentation, I provide a few stories of some recent remote QRT events and share best practices to make them more effective.

Presenters: Aaron Treadway, WFO Austin/San Antonio (EWX)

Abstract: MRMS FLASH has been an invaluable tool during warning operations at WFO EWX since we were among the first WFOs to ingest the FLASH products beginning in 2015. This presentation concentrates on two cases from Flash Flood Alley and the Texas Hill Country that highlight the use of FLASH in more rural areas and helps emphasize the improvements that MRMS v.12 has on the FLASH products. While the full implementation of MRMS v.12 does not occur until later this year, thanks to forecasters at our office noticing issues with the QPE hail cap in MRMS v.11, FLASH v.12 has been flowing through Regional LDMs since June of 2019 and the better data has led to warnings that are more timely, represent the threat area more accurately, and are now employing the current Impact-Based Warning Tags. While local studies on FLASH have led to improved River and Flash Flood Warnings, including looking for certain values as trigger points, it is still important to utilize local knowledge and considerations when applying IBW tags. Combining local knowledge, MRMS FLASH v.12, and utilizing multiple resources available online and in AWIPS, forecasters can be more confident in issuing accurate IBW Flash Flood Warnings.

Presenters: Gene Brusky (Science and Operations Officer), WFO Green Bay

Abstract: Within an 18 hour period, two damaging Quasi-Linear Convective Systems (QLCS) raced across the northern half of Wisconsin at speeds of 27-31 m/s (60-70 mph). The first QLCS evolved during the evening of July 19 over northern Wisconsin. It was characterized by an intense line surge and bookend vortex that produced primarily straight-line wind damage along an approximate 80 km long and 2-4 km wide swath, destroying nearly 300,000 acres of forest. Estimated maximum surface wind gusts were likely in excess of 53 m/s (120 mph). The second QLCS evolved the following morning over east central Wisconsin and was also characterized by an intense line surge and bookend vortex. However, this second QLCS was primarily accompanied by several damaging (EF1) mesovortex tornadoes. This presentation will briefly address some of the similarities and differences between these two events, with respect to the NSE and radar evolution. Preliminary radar analysis suggests that storm-scale interactions appeared to play an important role in initiating the intense line surges observed in both events. A brief description of the blowdown damage characteristics will also be provided using high-resolution satellite imagery and aerial survey information.

Presenters: Bryan Smith and Chris Karstens, NWS/NCEP Storm Prediction Center

Abstract: This presentation will feature Research to Operations (R2O) work done at the SPC with goals of helping a meteorologist more accurately and credibly communicate tornado damage intensity both in real-time during a tornado and in a preliminary assessment immediately after the tornado. These new capabilities leverage the development of a 10-year database of tornado events used to create a quantitative IDSS of tornado damage intensity evaluated on a peak damage indicator level of detail, vortex signature intensity from the nearest WSR-88D from the best time-matched lowest scan, and near-storm environment data based on the SPC mesoanalysis archive. The derivative products being developed range from those that serve as guidance for real-time impact-based tornado warnings to preliminary tornado damage paths contoured by EF-scale wind speeds. The presenters invite discussion on potential paths forward for the use of a wind speed range to estimate tornado damage intensity, the value of an integrated EF-scale damage path for IDSS, and general discussion on the benefits and challenges of providing high-resolution damage indicator data archived by the Damage Assessment Toolkit (DAT).

Presenters: Stephen Strader, Villanova University

Abstract: This presentation will highlight the ongoing work centered around the employment of the National Weather Service’s (NWS) Damage Assessment Toolkit (DAT) EF1+ tornado footprints within tornado impact modeling efforts. Specifically, differences between applying the Storm Prediction Center’s (SPC) SVRGIS and the DAT tornado footprints to estimate impacts on the underlying societal landscape will be illustrated. To further highlight the usefulness of the DAT tornado footprints, the continual development of the Tornado Intensity Distribution (TID) dataset will be discussed. The TID allows for improved tornado wind speed and damage intensity estimates within tornado damage paths. Over 1,300 DAT EF1+ tornado footprints from 2011 to 2020 have been curated and matched with their corresponding SVRGIS tornado damage footprint (I.e., maximum tornado width multiplied by length) to determine the overestimate in damage area using traditional damage survey methods (i.e., Storm Data attributes). A systematic and differential correction method allows for improved estimates of tornado damage area using the Tornado Impact Monte Carlo (TorMC) model. Lastly, recommendations and suggested improvements to the DAT from an impact modeling perspective will also be presented.

Presenters: Christine Standohar-Alfano, PhD, PE, CCM (Haag Engineering)

Abstract: Forensic evaluations are frequently performed by engineers after tornadoes to determine the cause of failure, extent of damage, and/or feasibility of repairs. The detailed tornado survey performed by the National Weather Service (NWS) can assist engineers in determining the likely wind speed and direction at a building to supplement their evaluations. This presentation will provide an overview of the forensic engineering and meteorology fields and highlight cases in which the DAT was used to support the inspection and litigation processes.

Presenters: Frank Lombardo (University of Illinois) and Zach Wienhoff (Haag Engineering)

Abstract: The damage level sustained by a structure for a given wind speed is highly variable and incorporates many factors related to both the wind and the structure(s) in question. Currently, the EF scale is the primary method for assessing wind-related damage and assigning a wind speed associated with it. The associated variability in the wind speed-to-damage relationship is currently presented in terms of the lower bound (LB), expected (EXP) and upper bound (UB) values for degrees of damage (DOD) associated with a particular damage indicator (DI). This presentation will focus on the relationship between DODs and assigned wind speeds for DI2 (one- or two-family residences) using damage data from recent tornadoes maintained within the DAT. From these data, empirical probability distributions are created. Early assessment suggests differences between the probability distributions as a function of DOD (Figure 1). Broader questions are currently being addressed with the results. Using wind speed to DOD relationships independent of the EF scale, a simulation framework is being built to compare the results of the two processes and assess the potential for misclassification of tornado characteristics (e.g., frequency, intensity, dimensions). Findings based on the simulations show weaker tornadoes, on average, are overestimated whereas violent tornadoes are more likely to be underestimated when damage occurs. Potential challenges and limitations of these findings will also be discussed.

Presenters: Marc Levitan (Lead Research Engineer, NIST) and Nico de Toledo (Wind Research Associate, NIST)

Abstract: Despite the significant hazard that tornadoes pose, much remains to be learned about the impacts of tornadoes on critical facilities (e.g., schools, fire stations, etc.) in the United States. While a number of post-storm reports have documented the damage from individual tornadoes or tornado outbreaks, there is a major gap in the availability of data describing the cumulative national impacts of tornadoes on these essential facilities. In this talk, we will describe how we used NWS data from the Storm Events Database (SED) and Damage Assessment Toolkit (DAT) to create a database of schools hit by tornadoes as the first stage in the development of a database of tornado impacts on critical facilities (Figures 1 and 2). We will cover challenges that we faced with the data and suggestions for improvements to the SED and DAT to increase their positive impacts. The school impacts data have been used to support the upholding of storm shelter requirements in several states and to support the introduction of the first tornado load requirements in the International Building Code (2024 edition). Future improvements to the DAT and SED could enable more accurate and efficient tornado impact analyses, further enabling local decision-makers to make well-informed risk assessments and consider employing tornado-resistant design and/or shelters.

Presenters: Ben Herzog (Meteorologist, WFO St. Louis, MO)

Abstract: In the early afternoon hours of April 4, 2023, a supercell moved into central Missouri, producing hailstones up to 4 inches in diameter. This thunderstorm developed in a near-storm environment (NSE) strongly supportive of very large hail, characterized by steep lapse rates in the low- and mid-levels, ample instability in the hail growth zone, and strong deep layer bulk wind shear. The threat for tornadoes was much lower, given weak wind shear in the lowest levels and high lifted condensation levels. Despite these environmental cues, the warning decisions on this storm proved challenging due to a number of unique radar features. These features included sidelobe contamination, something that initially appeared to be a very broad and deep tornadic debris signature, and classic large hail signatures including low differential reflectivity and the presence of a bounded weak echo region.

This presentation will briefly cover the NSE in which this storm developed, utilizing the SPC mesoanalysis and an in-situ sounding flown by the University of Missouri Atmospheric Sciences program. Next, we will explore the above radar signatures from the perspective of both the WSR-88D in St. Louis, MO and the University of Missouri X-band dual-polarization radar located just southeast of Columbia, Missouri.

Presenters: Ernie Ostuno (Meteorologist, WFO Grand Rapids, MI)

Abstract: Debris lofted into the air by tornadoes can be observed by National Weather Service radar. Several examples of radar observations of debris plumes are presented, showing their evolution in time and space. An attempt is made to show a correlation between the vertical height and persistence of the debris and tornado intensity as determined by post-storm damage surveys. Cases of debris plumes associated with misocyclones are also presented. No damage was noted from ground surveys and the debris plumes may have been composed of leaves or grass. A classification problem is presented by these examples since it is not clear whether they are weak tornadoes or sub-tornadic vortices.

Presenters: Pierce Larkin and Matt Gropp (Meteorologists, WFO Columbia, SC)

Abstract: The January 4th 2023 QLCS developed within a complex environment across eastern Georgia and South Carolina, with very poor model guidance and unusual diurnal-seasonal timing providing for a challenging forecast and warning scenario. A series of cell mergers upstream enhanced the RIJ as it progressed into our warning area in conjunction with surprisingly favorable QLCS shear and thermodynamic profiles. Despite the quickly evolving environment and poor model guidance, the three ingredient method served as a benchmark for tornado warning decisions and allowed for skillful tornado and severe thunderstorm warnings in the Columbia forecast area.

Presenters: Sarah Corfidi, Barb Mayes Boustead, Steve Corfidi, Hannah Wells (WDTD, Norman, OK)

Abstract: It's probably not a spoiler to say that damaging thunderstorm winds can prove especially challenging to diagnose and warn. In response to field office requests for more training on convective winds, WDTD has added training modules and a WES case to focus on the environment, radar and data interpretation, and warning strategies for organized wind events, such as MCSs and derechos. The wind warning team will offer deeper insights and a peek at a 2022 event that posed some pretty interesting operational challenges!

Presenters: Dr. Barb Mayes Boustead (WDTD, Norman, OK)

Abstract: The I-SPIDA Warning Workflow provides a framework for convective warning meteorologists to work through their process to assess storms and issue warnings. Based on research of workflows from other high-pressure decision-making situations, the I-SPIDA workflow provides a visual cycle to follow from environmental assessment to storm interrogation to warning decision and action. Its six steps include:
- Identify potential hazards based on mesoscale and near-storm environment.
- Scan for storms in and near your sector that need attention.
- Prioritize storms and pick the one that needs to be addressed first.
- Interrogate the highest priority storm.
- Decide whether to issue a warning/statement or intentionally not issue, and if so, what product to issue.
Act on the warning decision you have made, following the 10 Steps process.

Presenters: Andy Wood and Katy Christian (CIWRO/WDTD, Norman, OK)

Abstract: Velocity data artifacts due to sidelobe contamination have been shown to be a significant problem NWS forecasters must account for during warning operations. This presentation will review the common traits related to these data artifacts, show the three-step process to help identify imposter circulations related to these artifacts, and then walk through a specific example where significant elevation sidelobe contamination occurred. The three-step identification process from Boettcher and Bentley (2022) includes:
- Identify the circulation's location.
- Analyze the velocity texture.
- Examine the vertical structure for a sidelobe source.
Once a forecaster identifies an imposter circulation, they can ignore it and then focus on the other relevant data to make the most scientifically defensible decision possible.

Presenters: Andy Wood (CIWRO/WDTD, Norman, OK)

Abstract: The WSR-88D scanning strategies differ significantly from those originally fielded back in the 1990s and continue to evolve as new RDA/RPG build updates are fielded. This presentation will review the six current volume coverage patterns (VCPs), what meteorological situations they were designed for, and what considerations are important when choosing between multiple VCPs that could apply during certain events. We will also discuss the three dynamic scanning strategies available at each WSR-88D:
- AVSET: Automated Volume Scan Evaluation and Termination.
- SAILS: Supplemental Adaptive Intra-Volume Low-Level Scan(s).
- MRLE: Mid-Volume Rescan of Low-Level Elevations.
We will discuss how these three scanning strategies can be of benefit and what tradeoffs do you need to balance out when picking between the different options.

Presenter: Kristian Mattarochia (SOO, WFO Hanford, CA)

Abstract: A popular tool used by National Weather Service (NWS) warning forecasters to determine the presence of a mesocyclone is the rotational velocity nomogram. This nomogram categorizes mesocyclone strength and/or presence, based on the sum of the absolute value of the inbound and outbound base velocity divided by two. However, this method of detection fails for California because it requires mesocyclones 5 nm or greater in diameter. Research on California tornadoes has identified that several emanate from mini-supercells whose most dominant feature is 0-1 km low-level shear with mesocyclone diameters of 2 nm or less. To help improve detection and lead time of California tornadoes, a rotational shear nomogram was calibrated, which limits mesocyclone diameter to 2 nm or less. To achieve this, I looked back at confirmed tornadoes from January 2001 through December 2021 and found that several EF1/F1 tornadoes would have been classified only as a "minimal mesocyclone" using rotational velocity but as "tornado probable" or "tornado likely" using rotational shear. A rotational shear nomogram with classifications for minimal mesocyclone, tornado possible, tornado probable and tornado likely, for California, will be explained.

Presenter: Amanda Wagner (Villanova University)

Abstract: The relationships between storm mode, tornado warning outcomes, and social vulnerability are examined within eight United States (U.S.) regions and 79 National Weather Service (NWS) county warning areas (CWAs). Specifically, gridded radar data, tornado warnings, and tornado reports were gathered from 2007 to 2017 to assess spatiotemporal patterns in storm mode types, false alarm warnings, lead time warnings, and missed events. Tornadic storms were classified into five storm mode categories (i.e., discrete, linear, multicell, tropical, or disorganized) using machine learning techniques. Social vulnerability was assessed at the regional and CWA level using the CDC's Social Vulnerability Index (SVI) data. While social vulnerability, storm modes, and warning outcome results vary regionally, the Southeast U.S. has the highest tornado-society impact potential given its elevated social vulnerability, more frequent linear storm modes, greater odds of winter (December, January, February) storms, and greater nocturnal tornado risk. Identifying the relationships between storm mode, social vulnerability, tornado reports, and warning outcomes provides a more comprehensive understanding of tornado disaster risk, especially at the local scale. This information will help NWS weather forecast offices (WFOs), emergency managers, and policymakers better prepare for tornado threats and develop community mitigation and resilience-building strategies.

Presenter: Justin Gibbs (WFO Paducah, KY)

Abstract: A fast-moving QLCS produced widespread wind damage and 19 tornadoes in just four pre-dawn hours on April 2, 2024 across parts of the Paducah CWA. This event would have been challenging from a meteorology and messaging standpoint under any circumstance, but a national communications outage, lasting most of the event, made for a very complex night of stress and creativity for the forecasters at the office. We will touch on the events, unusual meteorology, including multiple crossing tornado paths, and the challenges and lessons learned from having such enormous communications problems during a high impact event.

Presenter: Robbie Munroe and Rose Schoenfeld, NWS Los Angeles, CA

Abstract: WFO Los Angeles will discuss local forecast team building and collaboration approaches including the gamification of the challenge communicated through multiple channels. Forecast techniques, tools, and lessons learned will also be touched on such as the increased use of DESI.

Presenter: Patrick Ayd, NWS Duluth

Abstract: Dual radar data can provide tremendous insight into processes impacting precipitation types and rates in winter weather. However, the application of dual pol data can be a bit daunting in how all the moments and signatures fit together. This presentation will demonstrate the key winter dual pol signatures from refreeze to dendritic aggregation, and how all the radar moments fit together to unlock these processes.

Presenter: Raven Vasquez, CIWRO/WDTD

Abstract: The TornadoArchive is a platform for visualizing historic global tornado data, enhanced with environmental overlays and customizable filters. This presentation will explore how a group of weather enthusiasts were brought together to create and sustain the project. We will discuss the data sources used, the process of digitizing and collecting tornado records, and present ideas of how the NWS can engage in improving the past documentation of tornado events.