Lightning Mapping Technology & NWS Warning Decision Making Don MacGorman, NOAA/NSSL Available or Feasible Technologies VLF-to-MF National Networks (mostly CG mapping) Vaisalas National Lightning Detection Network WDTs United States Precision Lightning Network VHF Mapping Systems (best accuracy & detection eff.) Vaisalas Safir Interferometer and LDAR TOA New Mexico Techs Lightning Mapping Array Long-range VLF Networks PACNET and British Meteorological Office Optical Satellite Mapper (future, NASA/MSFC) Large detection efficiency VHF Satellite Mapper (future, DOD & Los Alamos) Much smaller detection efficiency Mapping Oceanic Lightning Lightning mapping: only technically feasible means for global detection of thunderstorms Longitude Latitude Global Flash Rate Density: LIS and OTD Courtesy of Hugh Christian, NASA/MSFC km -2 yr -1 Noninductive Charging Mechanism Need Riming graupel Liquid water Ice crystals Thunderstorm Charge & Lightning Adapted from Stolzenburg et al., 1998: J. Geophys. Res., 103, Lightning Initiation Electric force on air becomes too great & causes Bidirectional development Thunderstorm Charge & Lightning Bilevel Lightning Flash Cloud-to-ground lightning flash: requires something more, a lower charge Some Relationships in Model & Observations From Ziegler et al. (2003) Graupel mass Lightning Lightning rates proportional to graupel mass, to graupel volume, to cloud ice, and to updraft mass flux through 10 E C level Oklahoma Lightning Mapping Array Comparison of CG versus All Lightning 21 June min accumulations ending at 0015 UTC & 0300 UTC 10 km X 10 km grid Ground Strike Points OnlyAll Lightning Convective Region Flash TELEX Mesoscale Convective System 19 June 2004 CG TIME LAG FOR DFW STORMS 10% had no CG flashes 14% had CG within 1 min 50% had CG within 8 min 74% had CG within 23 min CG TIME LAG FOR HIGH PLAINS STORMS 20% had no CG flashes within 60 min 0% had CG within 1 min 50% had CG within 31 min 75% had CG within 44 min Cloud Flash to Ground Flash Ratio from Boccippio et al. (2001) % Initial Applications of CG Mapping Warning of the lightning hazard itself Thunderstorm detection, particularly with poor or absent radar coverage Storm system configuration, growth, and reformation Severe Weather and Lightning Williams et al. (1999) Lightning and Graupel Mass Tornadic Storm Oklahoma City 13 June 1998 Data from the NLDN, NMIMT lightning mapping array, and NSSL polarimetric radar Plan Projection of Lightning Density June 2000 Kansas Supercell Storm 8 May 2003 Tornadic Supercell Lightning density in 5-minute moving interval NORTH (km) EAST (km) ALTITUDE (km) 20 ALTITUDE (km) WDDSII: Lightning Mapping & Radar Depictions of Storms Lightning MappingKTLX WSR-88D Vertical Projection 21 April 2004 WDSSII Effect of Spatial Averaging WDSSII Effect of Time Averaging 1-min average5-min average15-min average Height Lightning Data Assimilation into Weather Forecast Models Assimilation PeriodForecast Period -12 Hours0+12 Hours Assimilation by Estimating latent heat release Influencing the convective trigger function Simply turn convection on or off Influence character of convection Assimilation Effects on 3-Hour Rainfall Accumulation at Initiation No Assimilation All Lightning Assimilated No Convection Suppressed All Lightning Assimilated Convection w/o Lightning Suppressed Only CG Strikes Assimilated Convection w/o Lightning Suppressed Assimilation Effects on Rainfall Accumulated for 3-Hours after Initiation Only CG Strikes Assimilated Convection w/o Lightning Suppressed Forecast After No Assimilation Forecast After All Lightning Assimilated Convection w/o Lightning Suppressed Radar Reflectivity Composite 21 July 2000 Lightning Forecasts? Extrapolation Forecast Photo copyright by Michael James, 2003