# Presentation: 559604

## Use of LDAR II Data at WFO Fort Worth During Spring 2005

- Greg Patrick
- NOAA/NWS Fort Worth TX

*Southern Thunder Workshop*
*July 25, 2005*

**Notes:**
This presentation for the 2005 Southern Thunder Workshop was derived from a presentation created for the 21st Weather and Forecasting Conference in Washington DC in August 2005. Nick Demetriades of Vaisala Corp was the co-author for that conference manuscript and presentation. Some of the slides are courtesy Vaisala Corp. 

## Overview

- WFO FWD Operations
- Background and Dataset
- Examples of LDAR II applications at WFO FWD
- Severe Weather
- Aviation
- Summary and Ideas for Future Work

**Notes:**
Overview of the 45 minute presentation. 

## 46 Counties of Responsibility for Warnings and Forecasts

- Tornado, Severe Thunderstorm, Flash Flood Warnings
- Hazardous Weather Events – warnings, watches, advisories, statements
- Short Term and 7 Day public forecasts

**Notes:**
Background info – WFO FWD has forecast and warning responsibility for 46 counties across north and central TX. 

## 46 Counties of Responsibility for Warnings and Forecasts

**Notes:**
Outline of FWD CWA shown in yellow. Bordering CWAs include Norman and Tulsa OK to the north, Shreveport to the east, Houston to the southeast, Austin/San Antonio to the southwest, and San Angelo to the west. 

## Aviation Forecasts

- Five TAF sites
- Airport Weather Warnings for KDAL and KDFW (35 kts or 1⁄2” Hail)
- Brief Airport Operations Personnel
- Coordinate with CWSU

**Notes:**
The AFW TAF starts on July 27, 2005. 

## WSR - 88D sites used by WFO FWD

_*Dedicated*_
-  KFWS, KGRK
_*Others*_
- KDYX, KFDR
-  KSHV, KEWX
-  KTLX

**Notes:**
We get a full suite of radar products from the dedicated radars. We get a limited suite of products from the other radars. 

## NCAR Auto-Nowcaster Project

- _Nic Wilson (OU – SOM) _
**Research Goals**
***Explore applications of total lightning data taken from LDAR II, specifically in the area of nowcasting***
***Research the effectiveness of Flash Extent Density as a representation of total lightning data and its applications toward identifying storm cells and their attributes***

*Initiation Likelihood Field from ANC*
- July 13, 2005

**Notes:**
Nic Wilson is pursuing a MSPM (M.S. in Professional Meteorology) from the University of Oklahoma. Part of his research project involves working with the RAL group in Boulder to investigate the utility of incorporating Vaisala LDAR II data into the thunderstorm auto nowcaster.   

## LDAR II Data 

**Notes:**
Transition slide

## LDAR II Network and Data

- 7 sensors in DFW area
- VHF pulses used to reconstruct individual cloud and CG flashes in 3D
- Range approx 150 km
- Data file (netCDF) arrives at  WFO Fort Worth every 2 min
- Nine data products available for display on AWIPS
*Flash Extent Density* (FED) is concise integration of data

**Notes:**
Map of sensors that make up the DFW LDAR II system. 

## Flash Extent Density 

- Individual sources shown as red dots...
- Flashes can be visualized better if you “connect the dots” in a realistic way, converting sources to branches....

**Notes:**
This slide and the following slides illustrate why we normally want to look at “Flash Density” images on AWIPS rather than “Source Density” images. “Sources” are the individual red dots on this image. Think of “Sources” as more or less the raw data as output from the sensors.

## Flash Extent Density 

- Individual sources shown as red dots...
- Flashes can be visualized better if you “connect the dots” in a realistic way, converting sources to branches....
- Define _***Flash Extent Density***_ as the number of branches/minute that pass through a grid box area...

**Notes:**
Vaisala computer algorithms map or combine the Sources into Branches. A single Flash is made up of many Branches. Flash Extent Density (available on AWIPS) will display the number of branches per minute that pass through a grid box area. 

## Flash Extent Density 

_***Flash Extent Density***_ is the number of lightning branches that pass through a specific grid box area during a specific time interval
- Computed after all lightning sources are grouped together into flashes
- FED units are _Flashes km__-2__ min__-1_

**Notes:**
In AWIPS, the units for Flash Extent Density (FED) are # Flashes per square kilometer per minute. The data files arrive in our AWIPS system every 2 minutes; the FED numbers represent the average number of flashes in the two minute period ending at the time stamped on the display. 

## Gridded LDAR II Data in AWIPS

_*Available via Volume Browser*_
- Flash Extent Density
- 0-20 km Source Density
- Flash Initiation Point Density
- 0-3 km Source Density
- 3-6 km Source Density
- 6-9 km Source Density
- 9-12 km Source Density
- 12-15 km Source Density
- 15-18 km Source Density

_*Available via main D2D Menu*_
- Flash Extent Density
- 0-20 km Source Density

**Notes:**
Two primary ways to display LDAR II data in AWIPS. Of course, forecasters can also create customized procedures to facilitate quick display on any LDAR II data. 

## AWIPS Display of LDAR II Data

- Option 1: Use Volume Browser

**Notes:**
Screen shot of Volume Browser – users choose ‘Vaisala’ as the source and ‘LMA’ for the field to display LDAR II data. If we want to look at source density at a certain level, we use the ‘Planes’ to choose that level. 

## AWIPS Display of LDAR II Data

- Option 2: Use D2D Main Menu - Obs

**Notes:**
Thanks to Matt Sardi, our Information Technology Officer at WFO FWD, we can quickly display Flash Extent Density and the Total Source Density imagery using the main D2D pulldown menu. 

## Current FWD Color Scale for LDAR II Gridded Imagery 

- Compressed the scale used for radar imagery
- Customized based on values of FED observed during spring 2005

*Units - Flash Products:* Flashes km-2 min-1
*Units - Source Products:* Discharges km-2 min-1

**Highest Value of FED observed ~ 30**

**0-20 km Source Density values can be in this range****  **

**Notes:**
With the help of Nick, we developed a customized default scale that is used to display the LDAR II imagery. Since FED is the most often used total lightning product, the curve was developed based on values of FED we observed with storms – ranging from non-severe to supercells. Some of the FED imagery used in this presentation has a slightly different color scale than that shown in this slide. 

## AWIPS Examples
Increase in Total Lightning Activity and Patterns in FED imagery highlight severe weather potential

April 10, 2005

*Increase in Total Lightning Activity and Patterns in FED imagery highlight severe weather potential*
- April 10, 2005

**Notes:**
Transition Slide

## FED 4 Panel 2324 UTC to 2330 UTC

**FED 4 Panel 2324 UTC to 2330 UTC**

**2324Z**

**FED 5**
**VIL 53**

**2326Z**

**2328Z**

**2330Z**

**FED 8**
**VIL 53**

**FED 13**
**VIL 51**

**FED 15**
**VIL 51**

**Notes:**
These four images of FED show examples of valuable trend information in the total lightning displays on AWIPS. We will focus on the storm in eastern Wise County moving into Denton County. The FED image at 2324Z shows some dark blue and light green colors with the Wise County storm with corresponding values of up to 5 flashes per square kilometer per minute.  The radar VIL value (not shown) on this storm at 2326Z was 53. The image of FED at 2328Z (lower left) shows a noticeable increase in the flash rate with the storm that is just moving into Denton County. Maximum values of FED are around 13 flashes at 2328Z. The increase in FED was a sign that the updraft was strengthening and that the storm was becoming better organized. The radar VIL value of this storm at 2331Z was 51 – little change from the previous volume scan. The flash rates, as indicated by FED, increased more by 2330Z, as shown by the lower right image. 

## 2338Z

**2338Z**

**FED 11**
**VIL 44**

**Notes:**
The storm continues moving northeast with continued high values of FED. This is a zoomed-in image of the Denton County storm.  The max values of FED are around 11 flashes at this time (2338Z). The relative minima in FED between the two maxima and the overall shape of the image may indicate the development of a SW to NE  downburst. Forecasters are strongly urged to view all ‘suspicious’ shapes such as this with skepticism and use radar reflectivity imagery to help confirm or deny the existence of storm scale features. Also, looking for sustained trends/shapes in FED activity will help make sense of what we are seeing with this new dataset. The next slide, which is FED at 2340Z, continues to show the bowing shape. The radar reflectivity image at 2345Z (two slides ahead) and the spotter reports (not shown) of wind damage near and west of Sanger seem to confirm the presence of a significant downburst with this storm.   

## FED 2340 UTC on 10 April 2005

**2340Z**

**FED 13**
**VIL 48**

**Notes:**
FED image at 2340Z showing two maxima, with a max value of around 13 flashes. The elongated bow shape persisted for at least 2 time intervals (2338Z in previous slide and 2340Z this slide) and appeared to be confirmed with the 2345Z radar reflectivity imagery (next slide).

## 0.5Z 2345 UTC on 10 April 2005

**0.5Z 2345 UTC on 10 April 2005**

**85 mph Tstm Gust at 2348 UTC**

**2345  UTC**

**Notes:**
KFWS 88D 0.5 degree reflectivity image at 2345z showing only values of 35+ dBZ. . Note the weak echo channel that shows up just south of the main reflectivity core. The orientation of the possible downburst is similar to that indicated on the FED imagery. Wind gusts up to 85 mph were reported 4 miles west of Sanger at 2348Z. 

## AWIPS Examples

New updraft development on the southern flank of a supercell

April 25, 2005

*New updraft development on the southern flank of a supercell*
- April 25, 2005

**Notes:**
April 25, 2005 was a day with several supercells across north TX. Strong shear and moderate instability created an environment favorable for supercells and tornadoes. 

## FED 2114 UTC 25 April 2005

**2114  UTC**

**Notes:**
This Flash Extent Density image at 2114Z shows high values associated with the supercell storm in southeast Tarrant County. The white lines are the output from the 88D Storm Tracking Algorithm. The storm of interest is near the center of the image. The small area of blue FED near Mansfield may be the beginning flashes of a young updraft south of the main storm core.   

## FED 2116 UTC 25 April 2005

**2116  UTC**

**Notes:**
This FED image at 2116Z shows an increase in values (bright reds are ~ 20 flashes) in the main storm core that is being tracked well by the storm tracking algorithm output (white line). The main feature of interest in this image is the development of an appendage of higher flash rates on the southern flank of the primary storm core. The appendage is likely related to the development of a strengthening updraft on the southern flank of the supercell. 

## FED 2118 UTC 25 April 2005

**2118  UTC**

**Notes:**
FED image at 2118Z on 4/25/05. The ‘appendage’ of FED noted on the previous slide (2116Z) has apparently merged in with the main area of lightning activity to the north; the primary region of high FED is now south of the white storm track line. The Total Lightning imagery seemed to capture the development of a new updraft region that appeared to reflect the rightward turn of this storm as it moved into Dallas County. The radar imagery (see next slides) seemed to verify this trend.  

## 4 Panel Reflectivity 2112Z

- 0.5 deg
- 600’ AGL

- 10.0 deg
- 10,000’

- 19.5 deg
- 19,000’

- 14.0 deg
- 14,000’

## 4 Panel Reflectivity 2117Z

- 0.5 deg
- 600’ AGL

- 10.0 deg
- 10,000’

- 19.5 deg
- 19,000’

- 14.0 deg
- 14,000’

**Notes:**
BWER depicted on this 4 panel 88D imagery from KFWS at 2117Z. Note the location of the BWER (very strong updraft) well south of the output from the storm tracking algorithm (solid white line). Radar and FED imagery both depicted the re-development of a new updraft to the right (south) of the ‘original’ storm. 

## AWIPS Examples
“Pulse” Severe Thunderstorm over Dallas County in a high CAPE and weak shear environment

July 11, 2005

*“**Pulse” Severe Thunderstorm over Dallas County in a high CAPE and weak shear environment*
- July 11, 2005

**Notes:**
Summertime example from just a few weeks ago. 

## FED 2206 UTC 11 July 2005

**FED 5**
**VIL 50**

**Notes:**
Focus on the storm between Garland and University Park in this image. This is late afternoon on a hot, humid, unstable day. Wind shear was very weak and several non-severe storms had already developed and dissipated across north TX. This FED image at 2206Z shows a strong thunderstorm just northeast of Dallas. The VIL (grid based) was 50 and the FED was an unimpressive 5 Flashes at this time. 

## FED 2210 UTC 11 July 2005

**FED 15**
**VIL 54**

**Notes:**
Big change in FED, small change in VIL with the storm southwest of Garland. 

## FED 2222 UTC 11 July 2005

**FED 12**
**VIL 56**

**Notes:**
Maximum flash rate, as shown by FED, decreased slightly since the 2210 UTC image, but was still high. The VIL was nearly steady in the mid 50s. The Severe Thunderstorm warning was issued at 2223 UTC based on an increase in radar reflectivities aloft. 

## FED 2230 UTC 11 July 2005

**FED 15**
**VIL 55**

**G60 and 3⁄4 in hail at 2230 UTC**

**Notes:**
FED back up to 15, with an increase in the red shading areas. VIL nearly steady in the mid 50s. First reports of severe weather were received at this time – public reports of 3⁄4 inch hail and wind gust to 60 mph northwest of Mesquite. 

## FED 2240 UTC 11 July 2005

**FED 20**
**VIL 46**

**Notes:**
Note that a new cell has developed rapidly to the northeast of the old cell and FED values are up to 20. 

## FED 2252 UTC 11 July 2005

**FED 6**
**VIL 41**

**Wind Damage near Mesquite  2250 UTC**

**Notes:**
Storm starting to dissipate at this time. Wind damage was reported in Mesquite at 2250 UTC. Conclusion: FED trends showed intensifying trend better than some radar-derived intensity trend indicators. 

## AWIPS Examples
Interesting Branching and Anvil Lightning

April and May, 2005

*Interesting Branching and Anvil Lightning*
- April and May, 2005

## Anvil Lightning – 25 April 2005

**Anvil Lightning – 25 April 2005**

**Notes:**
Supercell over southwest Dallas County with FED values up to 25 flashes per km2 per min. Low values of FED extend as far as 60 km to the northeast into Rockwall county. Image taken at  2134 UTC 25 April 2005. Upper level winds (250 mb - not shown) were from the southwest at 80 kts. No cloud to ground strikes were noted as far away as Rockwall County during this time frame, but NLDN (not shown) showed some occasional CG strikes in the anvil region across east central Dallas County. 

## Branching – 14 May 2005 

**Notes:**
Elevated convective case on 14 May 2005. Main convection was south (bottom part of this image), but significant branching noted to the north in area of weaker radar returns. This image at 0626 UTC shows significant branching in FED data across Denton County as well as a few cloud to ground strikes -- well to the north of the main area of FED. Next image shows what radar looked like at around this time....

## -

**Branching – 14 May 2005**** **

**Notes:**
Zoomed in radar image for Denton County at 0620 UTC on 14 May 2005. Radar image is from 0.5 scan from KFWS showing only 25 dBZ and higher reflectivity values. Higher reflectivity noted around Lewisville, but the only CG strike at this time was occurring well to the north of the higher reflectivity. The next slide may help explain the isolated CG strike in northern Denton County....

## -

**Branching – 14 May 2005**** **

**Notes:**
This is the 0622 UTC image of FED from 14 May 2005, very close to the same time as the previous radar image. Note the isolated CG strike appears to be related to branching that originates from the higher FED area in southeast Denton County. Without the total lightning data, forecasters would have a hard time understanding the processes occurring here.

## Summary and Ideas for Future Work

- FED imagery, with a 2 minute update frequency, has been used as a complement to WSR-88D imagery to help forecasters detect important storm-scale clues on convective organization
- Total lightning has proven valuable in aviation forecasting, specifically with regard to the inclusion or exclusion of thunderstorms in TAFs.  FED imagery helps forecasters visualize and understand the thunderstorm and CG lightning threat.
- A time-integrated source density product could be developed and used to disseminate a graphical lightning hazard message. This product would be especially useful for delineating the CG threat in thunderstorm anvils and stratiform regions of MCSs.
- Explore the application of Source Density and Flash Initiation Point Density products

**Notes:**
2 summary points and 2 ideas for future work/investigations.

## Acknowledgements

**Matt Sardi** (ITO FWD) and **Jason Burks** (ITO HUN) accomplished the special configuration needed to allow LDAR II data to be displayed in AWIPS D2D
**Nick Demetriades** (Vaisala Corp) is the co-author on the conference presentation and supplied some of the images used in this presentation.