# Presentation: 490074

## The Integration of Total Lightning into NCAR’s Auto-nowcaster: A Status Report

- Nic Wilson
- University of Oklahoma, Vaisala and NCAR-RAL
- Southern Thunder Workshop
- Ft. Worth, TX
- 26 July 2005

## Today’s Topics

- Introduction to the Research Project
- Observations from Dallas-Ft. Worth Spring/Summer 2005
- The Application of Total Lightning Toward the Auto-Nowcaster
- Comments and Future Work

## Southern Thunder

- The Book

- The Band

## Southern Thunder

- The Tattoo Parlor

- The T-shirt

## Research Introduction

- A partnership between the University of Oklahoma, Vaisala and NCAR-RAL
- Master’s of Science in Professional Meteorology Degree Path
- Topic: Exploring the application of total lightning data toward convective storm nowcasting

## Research Introduction Con’t

- NCAR’s Auto-nowcaster (ANC) was chosen as the most advanced nowcasting software package in existence today
- Natural relationship existed with Vaisala’s LDAR II and NCAR’s ANC both running operationally within NWS Ft. Worth
- RAL has research funding from ATEC for eventual implementation into the WSMR ANC

## Total Lightning Storm Observations from Dallas-Ft. Worth: Spring/Summer 2005

## LDAR II Products: 25 April 2005

- 2-min. Flash Extent Density

- 2-min VHF Source Points

## LDAR II Products: 25 April 2005

- 2-min. Flash Initiation Points

- 4-min. Flash Extent Density

## Why Use Flash Extent Density?

- Very limited research has been done to evaluate its effectiveness at lightning cell identification and attribute trend analysis
- FED data is gridded and offers more consistency than traditional VHF source points, making it advantageous for cell identification and nowcasting purposes

## What Does FED Represent?

- Maximum FED activity is located downshear from the main convective updraft within areas of reflectivity gradient greater than 20 dBZ
- The downshear reflectivity contains the largest vertical velocity gradients, which enhance charge separation
- FED supports non-inductive charging mechanisms

## FED and NIC Mechanisms at Work

- On this day -10 C was at 5.5 km and -20 C was at 7 km

## FED and NIC Mechanisms at Work

- Significant amounts of ice, graupel and supercooled water droplets are now suspended aloft at 5.5 km and above, creating cloud flashes extending thru the anvil

## Supercell Flash Interaction

## Supercell Flash Interaction

## Splitting Cell FED – 20:24 UTC

## Splitting Cell – 20:38 UTC

## Splitting Cell FED – 20:36 UTC

## Splitting Cell – 20:43 UTC

## Splitting Cell – Cross Section

## Maximum Flash Extent Density Trends Related to Severe Weather Events

## Maximum Flash Extent Density Trends Related to Severe Weather Events

## The Application of Total Lightning to Nowcasting

## The Auto-nowcaster

## Auto-nowcaster Background

- An interactive software package that integrates multiple meteorological data sets in real-time and uses fuzzy logic to combine them and create a 60-minute convective forecast every 5 minutes
- Currently run over four domains:
- 1.) Illinois/Indiana [T-Storm Operational Research Project (THOR)]
- 2.) White Sands Missile Range, NM
- 3.) Beijing, China
- 4.) Dallas-Ft. Worth, TX

## ANC’s Products for Ft. Worth

- 60-minute Initiation Likelihood Field
- 60-minute Nowcast Field
- Interactive display systems at NWS Ft. Worth and NCAR’s Aviation Weather Development Laboratory

## KFWS WSR-88D 13 July 2005 – 20:38 UTC

## 60-minute Initiation Likelihood Field

## 60-minute Nowcast Field

## TITAN Cell Identification

- The thunderstorm, identification, tracking, analysis and nowcasting (TITAN) software package is used in the ANC to grow,  maintain and decay ongoing convection
- LDAR II data can supplement the radar data used by TITAN to identify storms using certain size and intensity thresholds

## TITAN Identification of Cells

- 35 dBZ Cell

- 0.25 FED Cell

## Application of LDAR II Data

- Case study analysis shows that TITAN identifies 35 dBZ reflectivity cells before 0.25 FED cells in DFW
- Total lightning is not effective at assisting with initiation forecasts in this region
- However, LDAR II data can complement and improve upon the reflectivity-derived attributes currently used to forecast storm size and intensity

## Total Lightning Latency

- 25 April 2005 Supercell Event:
- 23 mins. before the 1st VHF source
- 42 mins. before the 1st 0.25 FED cell
- Total lightning cell identification ineffective during warm precipitation processes
- All Other Cases:
- 18 mins. before the 1st 0.25 FED cell

## Auto-nowcaster: Growth/Decay

- The ANC currently combines four membership functions to grow, maintain or dissipate ongoing convection.  These three are derived from 2.5 km.-to-troposphere composite reflectivity
- 1.) 35 dBZ TITAN Normalized Area Growth Rate: A history-weighted normalized trend of the storm’s area greater than 35 dBZ
- 2.) 45 dBZ TITAN Normalized Area Growth Rate: Same as above but encompasses only the most intense convection of a storm
- 3.) Maximum dBZ: Ensures that intense convection isn’t dissipated

## Reflectivity Membership Functions

- Wt: 0.30

- Wt: 0.15

- Wt: 0.20

- Wt: 0.21

## Ongoing Research at NCAR

- Main Research Thrust: Develop LDAR II-based membership functions that compliment the current reflectivity-derived fields and improve the ANC’s overall performance
- Secondary Thrusts:
- 1.) Evaluate the effectiveness of flash extent density
- 2.) Identify underlying physical relationships between reflectivity and       total lightning
- 3.) Identify the temporal and spatial limits for the use of LDAR II data as a nowcasting tool

## TITAN-Derived Cell Attributes to Predict Growth/Decay

## 60-min Area Correlation

## FED Membership Functions

- 0.25 FED Normalized growth rate emulates the 35 dBZ field

- FED max emulates the dBZ max membership function

## ANC Membership Function Performance

## Growth Forecast Performance

## Growth Forecast Performance

## Decay Forecast Performance

## Decay Forecast Performance

## Decay Forecast Performance

## Forecasting Storm Intensity Using Total Lightning

## 60-min Max dBZ Correlation

## Intensity Membership Functions

- Reflectivity derived membership function

- FED derived membership function

## Hypothetical ANC Membership Function Performance

## ANC Growth/Decay Problems

- LDAR II Range Issues

## ANC Growth/Decay Problems

- Assigning Attributes to Storm Cells

## Future Research

- Statistical forecast verification using the newly created total lightning membership functions within the Ft. Worth ANC
- Look at how the FED TITAN storm motion vectors compare to dBZ cross-correlation
- Possible adjustments to how growth/decay is handled within the ANC?
- Implementation of the total lightning fields operationally in Ft. Worth and WSMR

## Future Presentations

- AMS Radar Conference: Albuquerque, NM Wed. Oct. 26th , 2005 – Session 6R 11:45am
*The Complementary Use of TITAN-derived reflectivity and total lightning thunderstorm cells*
- AMS Meteorological Applications of Lightning Conference: Atlanta, GA  Jan. 2006
- Nic Wilson’s Contact Information
- Email: _[nwilson@ou.edu](mailto:nwilson@ou.edu)_
- Project Website: http://weather.ou.edu/~nwilson/project.html