Proposed Thunderstorm Operational Research Project
(THOR Project)

Stephan B. Smith
Techniques Development Laboratory
National Weather Service

May 2000


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:

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.


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.

Figure 1: Schematic showing operational concept for THOR. Stick figure represents NWS forecasters.

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).


a) Implementation plan
b) Baseline accuracy of both human and automated thunderstorm forecasts/detections.
c) Prototype digital/graphical products for high impact users
d) Societal impacts evaluation
e) A paradigm for further Federal government technology transfer efforts for other high impact weather phenomena.


FY Milestone
2001 Develop prototype SCAN and RTVS software on AWIPS at THOR site(s)
" Develop Forecaster Training
2002 Year 1 Nowcasting evaluation
2003 Year 2 Nowcasting evaluation
" Year 1 Short-term evaluation
" Year 1 Synoptic evaluation
" Year 1 Prototype digital forecasts/warnings
2004 Year 3 Nowcasting evaluation
" Year 2 Short-term evaluation
" Year 2 Synoptic evaluation
" Year 2 Prototype digital forecasts/warnings

THOR Test Sites

A. Central Florida WFO's Melbourne (MLB) and Tampa Bay (TPA)
CWSU/ARTCC Jacksonville
Orlando TRACON
B. Dallas/Fort Worth WFO Dallas Ft. Worth (DFW)
C. Northern Alabama WFO Birmingham (BMX)


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

Mahoney, J. L., B. G. Brown, and J. Hart, 2000: Statistical verification of results for the Collaborative Convective Forecast Product, NOAA Technical Report, OAR 457-FSL 6, 29 pp

NWS, 1999: Vision 2005 - National Weather Service Strategic Plan for Weather, Water, and Climate Services 2000-2005, Dept of Commerce, NOAA, 24 pp.

OFCM a, 1999: National Aviation Weather Initiatives. Joint Action Group for Aviation Weather, FCM-P34-1999.

OFCM b, 1999: Proceedings for the Weather Information for Surface Transportation: Delivering Improved Safety and Efficiency for Tomorrow Symposium.

OFCM c, 1999: The Federal Plan for Meteorological Services and Supporting Research FY2000, FCM P1-1999. 152 pp.

Smith, S. B., S. Goel, M. T. Filiaggi, M. E. Churma, and L. Xin, 1999: Overview and status of the AWIPS System for Convection Analysis and Nowcasting (SCAN). Preprints, 15th International Conf. on IIPS, Amer. Meteor. Soc, Dallas, 326-329.