Over the past several years, NCAR has been developing an automated, expert system for providing time and place specific 0-2 hr forecasts of thunderstorms. While the backbone of this system is the use of the WSR-88D radar data, an important aspect is the integration of other data sets into the nowcast system which includes GOES satellite, surface mesonet, soundings and numerical model output. One of the most challenging tasks for a forecaster is to be able to predict the initiation of convection 30 min - 2 hr in advance for specific forecast zones, counties, aviation and military site-specific regions. On a day of active and potentially severe weather, this can be a labor-intensive effort for the forecaster to monitor the above datasets for the presence of features important to thunderstorm initiation and growth, such as surface convergence boundaries, changing stability and active cumulus convection. In addition, while the forecaster has tools available to track the movement of storms once they form, these tools do not provide the forecaster with information on storm growth or decay. The NCAR Automated Thunderstorm Nowcasting System (Auto-Nowcaster) is unique in its ability to ingest all available operational data sets and through the use of functional templates, interest fields and weighting schemes, provide forecasters with predictions of storm initiation, growth and decay.
This paper highlights how the Auto-Nowcaster is currently being used by forecasters at two different operational sites: 1) at the NWS WFO at Sterling, Virginia as part of the System for Convection Analysis and Nowcasting (SCAN; Smith et al. 1998) and 2) at the Forecast Offices at the DOD White Sands Missile Range and Aberdeen Proving Ground (Mueller et al., 1997). Forecasters at Sterling, by using the Auto-Nowcaster as guidance, have already been able to increase their lead time on providing advanced warning of thunderstorms expected to impact particular counties. One of the goals of SCAN is to demonstrate how data-integrated, detection and forecasting tools can be incorporated into the AWIPS environment in the future. To this end, some discussion on the specific algorithms being run this summer will also be presented. For the first time, an adjoint numerical model is being run operationally at the NWS office providing buoyancy, boundary layer convergence and wind information to the Auto-Nowcaster. Lightning data is being incorporated into the Auto-Nowcaster at the DOD forecast offices. Satellite-based, cloud classification and cloud growth algorithms are being run at both sites.
References:
Mueller, C., R. Roberts, and S. Henry, 1997: Thunderstorm Automated Nowcast System - Real-Time Demonstrations. Preprints, 28th Conf. on Radar Meteor., Austin, Amer. Meteor. Soc., 406-407.
Smith, S.B., J.T. Johnson, R.D. Roberts, S.M. Zubrick, and S.J. Weiss, 1998: The System for Convection Analysis and Nowcasting (SCAN) 1997-1998 field test. Preprints, 19th Conf. on Severe Local Storms, Minneapolis, Amer. Meteor. Soc.