1. MIT Lincoln Laboratory INPE Rio July 05 ERW - 1 Total Lightning Activity as Diagnostic for Severe Weather Earle R. Williams INPE Rio de Janerio, Brazil July 25-28, 2005

2. MIT Lincoln Laboratory INPE Rio July 05 ERW - 2 Outline Experience with Thunderstorm Microbursts (Alabama, Florida; 1980s) Experience with Severe Weather (Florida; 1990s) Lightning and Severe Weather over the Continental U.S. (2000+)

3. MIT Lincoln Laboratory INPE Rio July 05 ERW - 3 Intracloud and Cloud-to-Ground Lightning: A Key Distinction Cloud-to-Ground Lightning Intracloud Lightning

4. MIT Lincoln Laboratory INPE Rio July 05 ERW - 4 Behavior of Intracloud and Cloud-to-Ground Lightning IC/CG Ratio 10 5 Flashes/km 2 /15 min (Ground Flash Rate) 1.0 0.1 100 10 100 100010000

5. MIT Lincoln Laboratory INPE Rio July 05 ERW - 5 Illustration of Microburst Hazard to Aircraft

6. MIT Lincoln Laboratory INPE Rio July 05 ERW - 6 Microburst Accidents Jun 24, 1975EAL 66JFK New York Jun 23, 1976AL 121Philadelphia Jun 03, 1977CO 63Tucson Aug 22, 1979EAL 693 Atlanta (incident) Jul 09, 1982PAA 759New Orleans May 31, 1984UA 663 Denver (incident) Aug 02, 1985DL 191DFW Dallas Jul 02, 1994US 1016Charlotte

7. MIT Lincoln Laboratory INPE Rio July 05 ERW - 7 National Response to Microburst Accidents 1.Regional field experiments to study the problem Doppler radar measurements Surface Mesonet arrays Corona point sensors Lightning interferometer system 2.Development and deployment of Terminal Doppler Weather Radars (TDWR)

8. MIT Lincoln Laboratory INPE Rio July 05 ERW - 8 Microburst Field Experiments MIT Lincoln Laboratory Huntsville, Alabama1986 – 1987C-band Doppler and ASR-9 radars Corona Part Array Denver, Colorado1987 – 1989S-band Doppler Mesonet Corona Part Array Kansas City, Missouri 1990S-band Doppler Mesonet Orlando, Florida1991 - 1993Triple Doppler Network Corona Part Network Lightning Interferometer Albuquerque, New Mexico 1994 – 1995C-band Doppler and ASR-9 radars Lightning Interferometer

9. MIT Lincoln Laboratory INPE Rio July 05 ERW - 9 Total Lightning Rate Precedes Microburst Outflow & Cloud-to-Ground Rate Does Not

10. MIT Lincoln Laboratory INPE Rio July 05 ERW - 10 Distribution of Orlando Microburst Strength

11. MIT Lincoln Laboratory INPE Rio July 05 ERW - 11 The LISDAD Project (1996 – 1999) Integration of multiple observations into one real-time system:  Lincoln Laboratory ITWS  Melbourne NEXRAD radar  Orlando TDWR radar  National Lightning Detection Network  Lightning Detection and Ranging System (NASA KSC)

12. MIT Lincoln Laboratory INPE Rio July 05 ERW - 12 Integrated Terminal Weather System (ITWS) Microburst Prediction Gust Front Prediction Storm Location & Motion Storm Cell Information Pilots Controllers Aircraft Lightning ASR-9 LLWAS ITWS Real-time Processor AWOS/ASOS TDWR NEXRAD Supervisors Traffic Managers – TRACON – ARTCC TMU CWSU Airlines – Dispatch – Ramp Tower Tornado Terminal Winds

13. MIT Lincoln Laboratory INPE Rio July 05 ERW - 13 What is ‘Severe’ Weather? Formal thresholds in the U.S.  Hail diameter > ¾ inch  or, Wind speed > 50 knots  or, Tornado on the ground

14. MIT Lincoln Laboratory INPE Rio July 05 ERW - 14 Fallspeed of Hail vs. Size 100 Particle Fall Speed (m/sec) 50 20 10 5 2 1 Non-Severe Severe Particle Diameter (mm) 125102050100

15. MIT Lincoln Laboratory INPE Rio July 05 ERW - 15 Updraft Strength is the Key Quality Supplier of super-cooled water Driver of cloud electrification and lightning Origin of hail growth and the thunderstorm ice factory Source of vortex stretching and tornado genesis

16. MIT Lincoln Laboratory INPE Rio July 05 ERW - 16 Schematic Evolution of Total Lightning and Severe Weather

17. MIT Lincoln Laboratory INPE Rio July 05 ERW - 17 Processes Aloft Naturally Precede Events at the Surface Accretion of supercooled water in updraft precedes arrival of large hail at the surface Active intracloud lightning aloft precedes cloud-to-ground lightning at the surface Mesocyclonic rotation aloft precedes the tornado at the surface

18. MIT Lincoln Laboratory INPE Rio July 05 ERW - 18 22 May 1997 Isolated Severe Storm 1-inch Hail Orlando, Florida 1-inch Diameter Hail on Ground 0 50 100 150 200 250 300 350 Lightning (LDAR) Flash Rate (min -1 ) 0 10 20 30 40 50 60 70 Differential Velocity (knots) Time (UT) 1810 1930 183019101850 Total Lightning Precursor to 1” Hail and Strong Outflow

19. MIT Lincoln Laboratory INPE Rio July 05 ERW - 19 Histogram of Total LDAR flash rate

20. MIT Lincoln Laboratory INPE Rio July 05 ERW - 20 Severe Storm Cases in LISDAD

21. MIT Lincoln Laboratory INPE Rio July 05 ERW - 21 From Mesocyclone to Tornado

22. MIT Lincoln Laboratory INPE Rio July 05 ERW - 22 Total Lightning Precursor to a Tornado Goodman (2004)

23. MIT Lincoln Laboratory INPE Rio July 05 ERW - 23 Global Lightning Based on the NASA LIS

24. MIT Lincoln Laboratory INPE Rio July 05 ERW - 24 Dynamic Effect of Cloud Base Height on Updraft Intensity and Lightning Activity Effect of cloud-base height on updraft width Less dilution by mixing High Cloud BaseLow Cloud Base W W

25. MIT Lincoln Laboratory INPE Rio July 05 ERW - 25 Updraft Widths in Cumulonimbi

26. MIT Lincoln Laboratory INPE Rio July 05 ERW - 26 Flash Rate / Thermodynamic Comparison

27. MIT Lincoln Laboratory INPE Rio July 05 ERW - 27 Storm Flash Rate vs. Cloud Base Height

28. MIT Lincoln Laboratory INPE Rio July 05 ERW - 28 Clustered Positive Ground Flashes in Severe Weather Curran and Rust(1992) Branick and Doswell (1992) Seimon(1993) Stolzenburg(1994) MacGorman and Burgess(1994) Knapp(1994) Later work in STEPS (2000) provided strong evidence that such storms were inverted in polarity relative to ordinary thunderclouds.

29. MIT Lincoln Laboratory INPE Rio July 05 ERW - 29 Important Advances in Steps in 2000 Development and implementation of VHF lightning mapping techniques for identifying the polarity of the lightning ‘tree’ (New Mexico Tech) Inverted polarity storms characterized by large dew point depressions / low relative humidity  Rust and MacGorman (2002)  Wiens et. al. (2003)  Lang et. al. (2004)

30. MIT Lincoln Laboratory INPE Rio July 05 ERW - 30 Laboratory Simulations Temperature / Cloud Water Diagrams Takahashi (1978) Saunders et al (1991) Pereyra et al (2000)

31. MIT Lincoln Laboratory INPE Rio July 05 ERW - 31 Microphysical Effect of Cloud Base Height on Liquid Water Content Aloft Cloud water loss by coalescence Superadiabatic loading in warm rain region High Cloud BaseLow Cloud Base 0° C W W

32. MIT Lincoln Laboratory INPE Rio July 05 ERW - 32 Extreme Weather in the Conus

33. MIT Lincoln Laboratory INPE Rio July 05 ERW - 33 4” and Larger Hail Events ( 1955 – 1994 ) (Polston, 1996)

34. MIT Lincoln Laboratory INPE Rio July 05 ERW - 34 Climatology of Wet Bulb Potential Temperature ( Noontime – July )

35. MIT Lincoln Laboratory INPE Rio July 05 ERW - 35 Climatology of Cloud Base Height ( Noontime – July )

36. MIT Lincoln Laboratory INPE Rio July 05 ERW - 36 Inverted Polarity Clouds Is it Aerosol, or is it Hot, Dry Conditions? (Lyons et al, 1998) (Smith et al, 2003) May, 1998

37. MIT Lincoln Laboratory INPE Rio July 05 ERW - 37 Conclusions Total lightning activity (dominated by intracloud lightning) is a natural precursor to microbursts and severe weather at the surface Cloud to ground lightning has relatively little benefit to this endeavor Recipe for inverted polarity and extraordinary total lightning activity: High cloud base height AND appreciable instability

38. MIT Lincoln Laboratory INPE Rio July 05 ERW - 38 Slide left intentionally blank.

39. MIT Lincoln Laboratory INPE Rio July 05 ERW - 39 Pre-Squall Line Soundings in Great Plains: CAPE vs. θ w

40. MIT Lincoln Laboratory INPE Rio July 05 ERW - 40 Storm Flash Rate vs. Dry Bulb Temperature

41. MIT Lincoln Laboratory INPE Rio July 05 ERW - 41 Thermal Width/Updraft Width Scaling with Boundary Layer Depth? Ocean RH = 80% Rondonia Wet Season RH = 70% Rondonia Premonsoon RH = 60% 500 m 1000 m 1500 m

42. MIT Lincoln Laboratory INPE Rio July 05 ERW - 42 The Role of Strong Instability in Promoting High Liquid Water Content Large Cape Strong Updraft Bounded Weak Echo Region VHF Radiation “Holes” 0° C Cape W

43. MIT Lincoln Laboratory INPE Rio July 05 ERW - 43 Cross-section of Dryline Ziegler and Rasmussen, (1998)

44. MIT Lincoln Laboratory INPE Rio July 05 ERW - 44 Delay of First NLDN Ground Flash from First LDAR Lightning in Storm Number of Observations Delay (min) 20 10 15 10 5 0 02030405060 Mean Delay = 11 minutes

45. MIT Lincoln Laboratory INPE Rio July 05 ERW - 45 Microburst Accidents Prompting Attention New Orleans, Louisiana – July 9, 1982 Dallas / Ft. Worth, Texas – August 2, 1985

46. MIT Lincoln Laboratory INPE Rio July 05 ERW - 46 Classic Microburst Image

47. MIT Lincoln Laboratory INPE Rio July 05 ERW - 47 Lightning Flash Rate vs Thermodynamics (Tropical Afternoon Storms Over Land)

48. MIT Lincoln Laboratory INPE Rio July 05 ERW - 48 FAA Wind Shear Detection Systems