Monday, 12 January 2009: 11:15 AM
Developments in the nowcasting total lightning flash rates using GOES satellite infrared convective cloud information
Room 131A (Phoenix Convention Center)
Accurately forecasting the initiation and immediate impacts of thunderstorms and lightning remains a significant problem in various aspects of meteorology. This presentation will highlight satellite-based methods that suggest ability to nowcast lightning initiation (LI)in the 0-90 min timeframe, and perhaps assess the early trends in lightning intensity (in terms of flash numbers and intensity). This LI research rests on our current convective initiation (CI) nowcasting method that relies on the use of infrared (IR) and visible (VIS) satellite data from GOES, and cloud-motion winds for tracking cumulus clouds. The CI technique develops relationships between VIS and IR data and cumulus cloud phase (e.g., first time glaciation of cumulus cloud tops), cloud growth and deepening, and is built with new and existing methods. Current results shows that 30-60 minute CI nowcasts (the first occurrence of a >35 dBZ radar echo) can be provided over large geographical regions in realtime, with PODs on the 1 km scale up to 99%, with FARs near 65%.
Recent research at the University of Alabama in Huntsville (UAH) demonstrates an extension to the CI method by showing an improved means of correlating VIS and IR fields from GOES of convective clouds to LI, as verified by the North Alabama Lightning Mapping Array (LMA). LMA data are plotted over GOES infrared information [using the CI interest fields of Mecikalski and Bedka (2006)] for evolving new convective storms; lightning flash rates (for in-cloud, cloud-to-ground, and cloud-to-air lightning "sources") are used to assess LI. The goals of this work include: (a) developing adjustments to the CI infrared interest fields that are optimal for nowcasting LI, and (b) developing ways of implementing the 3.9 um channel from GOES, which helps document the glaciation process near cloud-top, yet which presents challenges during daytime. This presentation will provide several examples and demonstrations of LI across mesoscale geographical regions, and suggest improvements when using data from other and forthcoming geostationary satellites.