total lightning activity as diagnostic for severe weather

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


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+)


ERW - 3

Intracloud and Cloud-to-Ground Lightning:A Key Distinction

Cloud-to-GroundLightning

IntracloudLightning


ERW - 4

Behavior of Intracloud and Cloud-to-Ground Lightning

IC/C

G R

atio

105 Flashes/km2/15 min(Ground Flash Rate)

1.0

0.1

100

10

10 100 1000 10000


ERW - 5

Illustration of Microburst Hazardto Aircraft


ERW - 6

Microburst Accidents

Jun 24, 1975 EAL 66 JFK New York

Jun 23, 1976 AL 121 Philadelphia

Jun 03, 1977 CO 63 Tucson

Aug 22, 1979 EAL 693Atlanta (incident)

Jul 09, 1982 PAA 759 New Orleans

May 31, 1984 UA 663Denver (incident)

Aug 02, 1985 DL 191 DFW Dallas

Jul 02, 1994 US 1016 Charlotte


ERW - 7

National Response to Microburst Accidents

1. Regional field experiments to study the problem

Doppler radar measurementsSurface Mesonet arraysCorona point sensorsLightning interferometer system

2. Development and deployment of Terminal Doppler Weather Radars (TDWR)


ERW - 8

Microburst Field ExperimentsMIT Lincoln Laboratory

Huntsville, Alabama 1986 – 1987 C-band Doppler

and ASR-9 radars

Corona Part Array

Denver, Colorado 1987 – 1989 S-band DopplerMesonet

Corona Part Array

Kansas City, Missouri

1990 S-band Doppler

Mesonet

Orlando, Florida 1991 - 1993 Triple Doppler Network

Corona Part NetworkLightning Interferometer

Albuquerque, New Mexico

1994 – 1995 C-band Doppler and ASR-9 radarsLightning Interferometer


ERW - 9

Total Lightning Rate Precedes Microburst Outflow & Cloud-to-Ground Rate Does Not


ERW - 10

Distribution of Orlando Microburst Strength

(Orlando 1990 - 1992)

0

100

200

300

400

500

600

700

800

900

10-14 15-19 20-24 25-29 30-34 35-39 40-44 > = 45

DELTA V (m/s)

NU

MB

ER

OF

MIC

RO

BU

RS

TS

1990 (547, Radar was downfor an extended period)

1991 (1575)

1992 (1660)


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)


ERW - 12

Integrated Terminal Weather System (ITWS)

Microburst PredictionGust Front Prediction

Storm Location & MotionStorm Cell Information

Pilots

Controllers

AircraftLightning

ASR-9

LLWAS

ITWSReal-timeProcessor

AWOS/ASOS

TDWR NEXRAD

SupervisorsTraffic Managers – TRACON – ARTCC TMU

CWSUAirlines

– Dispatch– Ramp Tower

TornadoTerminal Winds


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


ERW - 14

Fallspeed of Hail vs. Size

100

Par

ticl

e F

all S

pee

d (

m/s

ec)

50

20

10

5

2

1

Non-Severe Severe

Particle Diameter (mm)

1 2 5 10 20 50 100


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


ERW - 16

Schematic Evolution of Total Lightning and Severe Weather


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


ERW - 18

22 May 1997Isolated Severe Storm1-inch HailOrlando, Florida

1-inch DiameterHail on Ground

0

50

100

150

200

250

300

350

Lig

htn

ing

(L

DA

R)

Fla

sh

Ra

te (

min

-1)

0

10

20

30

40

50

60

70

Dif

fere

nti

al

Ve

loc

ity

(k

no

ts)

Time (UT)

1810 19301830 19101850

Total Lightning Precursor to 1” Hailand Strong Outflow


ERW - 19

Histogram of Total LDAR flash rate


ERW - 20

Severe Storm Cases in LISDAD


ERW - 21

From Mesocyclone to Tornado


ERW - 22

Total Lightning Precursor to a Tornado

Goodman (2004)

LMA Flash trends Nov. 10-11, 2002 Cell e

0

5

10

15

20

25

23:49:30

23:54:29

23:59:29

0:04:28

0:09:27

0:15:31

0:20:30

0:25:32

0:30:31

0:35:30

0:40:29

0:45:29

0:50:28

UTC

Flash Rate/(5 minutes)

1 KM 2 KM 4 KM 8 KM F2 Tornado


ERW - 23

Global Lightning Based on the NASA LIS


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


ERW - 25

Updraft Widths in Cumulonimbi


ERW - 26

Flash Rate / Thermodynamic Comparison


ERW - 27

Storm Flash Rate vs. Cloud Base Height

500 1000 1500 2000 2500 3000

0.81

2

4

6

810

20

40

Cloud Base Height, m

Total FR vs. CBH (Tropics,Jan-Jun 2000)Fl

ash

Rat

e, 1

/min


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.


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)


ERW - 30

Laboratory Simulations Temperature / Cloud Water Diagrams

Takahashi (1978)

Saunders et al (1991)

Pereyra et al (2000)


ERW - 31

Microphysical Effect of Cloud Base Height onLiquid Water Content Aloft

Cloud water loss by coalescence

Superadiabatic loading in warm rain region

High Cloud BaseLow Cloud Base

0° C

W

W


ERW - 32

Extreme Weather in the Conus


ERW - 33

4” and Larger Hail Events(1955 – 1994)

(Polston, 1996)


ERW - 34

Climatology of Wet Bulb Potential Temperature (Noontime – July)


ERW - 35

Climatology of Cloud Base Height(Noontime – July)


ERW - 36

Inverted Polarity CloudsIs it Aerosol, or is it Hot, Dry Conditions?

(Lyons et al, 1998) (Smith et al, 2003)

May, 1998


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


ERW - 38

Slide left intentionally blank.


ERW - 39

Pre-Squall Line Soundings in Great Plains: CAPE vs. θw


ERW - 40

Storm Flash Rate vs. Dry Bulb Temperature

26 28 30 32 34 36 38 40

0.6

0.8

1

2

4

6

8

10

20

Maximum Dry Bulb Temperature, C

Total FR vs. DBT (Tropics,Jan-Jun 2000)Fl

ash

Rat

e, 1

/min


ERW - 41

Thermal Width/Updraft Width Scaling with Boundary Layer Depth?

OceanRH = 80%

Rondonia Wet SeasonRH = 70%

Rondonia PremonsoonRH = 60%

500 m

1000 m

1500 m


ERW - 42

The Role of Strong Instability in Promoting High Liquid Water Content

Large CapeStrong UpdraftBounded Weak Echo RegionVHF Radiation “Holes”

0° C

CapeW


ERW - 43

Cross-section of Dryline

Ziegler and Rasmussen, (1998)


ERW - 44

Delay of First NLDN Ground Flashfrom First LDAR Lightning in Storm

Nu

mb

er o

f O

bse

rvat

ion

s

Delay (min)

20

10

15

10

5

00 20 30 40 50 60

Mean Delay = 11 minutes


ERW - 45

Microburst Accidents Prompting Attention

• New Orleans, Louisiana – July 9, 1982

• Dallas / Ft. Worth, Texas – August 2, 1985


ERW - 46

Classic Microburst Image


ERW - 47

14 16 18 20 22 24 26 28 30

26

28

30

32

34

36

38

40

42

Dew Point Temperature, C

Dry

Bul

b T

empe

ratu

re, C

FR vs. Temperatures and CBH (Jan-Jun 2000)

Lightning Flash Rate vs Thermodynamics(Tropical Afternoon Storms Over Land)


ERW - 48

FAA Wind Shear Detection Systems

total lightning activity as diagnostic for severe weather

Documents