Proposed Thunderstorm Operational Research Project
(THOR Project)

Stephan B. Smith
Techniques Development Laboratory
National Weather Service

May 2000

Introduction

Thunderstorms are high impact weather phenomena. The lightning, winds, hail, tornadoes and heavy precipitation they produce pose significant threats to life and property and have large negative impacts on transportation and commerce in the United States. Not surprisingly, accurate forecasts of thunderstorms are a high priority for government agencies whose missions and operations are affected by them. These include the Federal Aviation Administration (FAA), the Federal Highway Administration (FHWA), the Federal Emergency Management Agency (FEMA), the National Aeronautical and Space Administration (NASA), the Department of Defense (DoD), the Department of Energy (DoE) and of course, the National Oceanic and Atmospheric Administration (NOAA). NOAA, FAA, and DoD in particular have independently funded thunderstorm research and development activities to help meet their operational needs. Given the level of interest and size of the problem, it makes sense to coordinate and leverage these various efforts and the information technology (IT) infrastructure of various government agencies (FAA 1999; OFCM a,b, and c 1999) in a comprehensive effort to improve operational services for the American public and provide the biggest bang for the U.S. tax dollar.

NOAA's National Weather Service (NWS) has invested a great deal into its modernization in an effort to improve its traditional thunderstorm products, severe thunderstorm and tornado watches and warnings for the general public (NWS 1999). The NWS also possesses a wealth of thunderstorm forecasting expertise embodied in the staff of its Weather Forecast Offices (WFOs), Storm Prediction Center (SPC), Aviation Weather Center (AWC) and Central Weather Service Units (CWSU's). This invaluable human resource could be better leveraged to support the missions of other high impact government users. The advent of the NWS Advanced Weather Interactive Processing System (AWIPS) and high speed, broadband communications, ushers in a new era of digital/graphical products which will convey more information, exploit common GIS formats, and could be the cornerstone of other governmental IT weather-decision support systems. In order to make this vision a reality for thunderstorm forecasts, several questions must be answered:

• How do automated thunderstorm forecast guidance compare with one another? In particular how does a state-of-the-art numerical weather prediction model perform in forecasting thunderstorms compared with simpler, less sophisticated techniques?
• How can the human forecaster be best utilized in improving upon automated thunderstorm guidance?
• What types of thunderstorm forecasts and warnings best meet the needs of users?
• What skill do we have in detecting tornadoes?
• To arrive at answers to these critical questions, I am proposing a multi-year, multi-agency effort named the Thunderstorm Operational Research (THOR) Project.

The Goals of THOR would be to:

1. Establish operational baseline accuracy for thunderstorm forecasts at multiple projections starting from 30 min and extending to 48 hours.
2. Establish operational baseline accuracy for tornado detection
3. Prototype a seamless operational suite of digital/graphical thunderstorm forecasts and warnings for the general public, emergency managers, and high impact government agencies.
4. Prototype an operational automated thunderstorm forecast verification system.
5. Provide a societal impacts evaluation of current operational and prototypical severe thunderstorm and tornado warnings.

Methodology

New thunderstorm forecast applications would be implemented on AWIPS in the System for Convection Analysis and Nowcasting (SCAN; Smith et. al 1999). The AWIPS Local Data Acquisition and Dissemination (LDAD) function would be used to import the output of experimental products running outside of the AWIPS firewall into AWIPS. In this manner, NWS forecasters would be able to use current and experimental guidance via the principle AWIPS graphical user interface, the Display 2 Dimensional (D2D), in order to prepare and issue digital thunderstorm forecasts. These value-added human forecasts would be verified along with those of the guidance products to establish baseline thunderstorm forecast accuracies at multi-hour projections. Storm-based tornado detection decisions would be made on relevant days and verified with ground chase teams. These would be used to establish baseline accuracies for tornado detection and compared with automated guidance. A version of the NOAA Forecast Systems Laboratory's (FSL's) Real-time Verification System (RTVS, Mahoney et. al 2000) would be used to provide verification of both human and automated forecasts (Figure 1). Evaluation of current operational and experimental products would be provided by the societal impacts team.

Implementation Teams

Implementation teams would be formed to cover the following areas:

Coordination, Nowcasting(0-1 hr), Tornado detection, Short-range forecasting(1-6 hr), Synoptic-range forecasting (6- 48 hr), Verification, Societal Impacts, Forecasting/Training, and IT Systems (AWIPS, others Federal government weather information systems).

Deliverables

Milestones

THOR Test Sites

References

FAA, 1999: Decision-based weather needs for the Air Route Traffic Control Center Traffic Management Unit.