# Presentation: 367782

## A Potentially Valuable WSR-88D Severe Storm Pre-cursor Signature in Highly Dynamic, Low CAPE, High Shear Environments

- Llyle Barker
- NOAA/NWS Lincoln Illinois
- 23rd Conference on Severe Local Storms
- November 6-10, 2006

## Reflectivity Tag WSR-88D Signature

- Associated with QLCS
- Evolve in a highly sheared, low/moderate CAPE, highly dynamic environment
- For the Midwest, these environments are most likely during the cool and transition seasons
- Best detected through the use of rapid looping

## F3 Tornado – Evansville Indiana Area0739 – 0822 GMT Nov 6, 2005

**F3 Tornado – Evansville Indiana Area****0739 – 0822 GMT Nov 6, 2005**

**F3 tornado with estimated maximum winds of 89 ms****-1**** (200 mph)**
**Path length of 66 km (41 miles) with maximum width of 460 m (500 yards)**
**Twenty-Five fatalities and 200 injuries **

- Webcam Image from Deaconess Women’s Hospital – Evansville Indiana

## F3 Tornado – Evansville Indiana Area0739 – 0822 GMT Nov 6, 2005

**F3 Tornado – Evansville Indiana Area****0739 – 0822 GMT Nov 6, 2005**

**Six tornadoes reported 0150 and 0500 GMT in southern Missouri and northern Arkansas**
**Long-lived supercell embedded in QLCS crossed southern Illinois into western Kentucky/extreme southwestern Indiana between 0600 and 0730 GMT**
**Evolving environment summarized by Wielgos and Spoden (2006), Davies (2006), and Spoden et al. (2006)**
**Approaching jet streak**
**Weak stable layer decoupling PBL**
**Enhanced low-level jet**
**Strong moisture advection ahead of QLCS  **

- Picture of damage in Evansville Indiana (NWS Paducah)

## KPAH 0.5 Degree Reflectivity Image0647 GMT Nov 6, 2005

## KPAH 0.5 Degree SRM Image0647 GMT Nov 6, 2005

## KPAH 0.5 Degree Reflectivity Image0733 GMT Nov 6, 2005

## KPAH 0.5 Degree SRM Image0733 GMT Nov 6, 2005

## KPAH 0.5 Degree Reflectivity Image0748 GMT Nov 6, 2005

## KPAH 0.5 Degree Reflectivity Image0748 GMT Nov 6, 2005

- 2

## KPAH 0.5 Degree SRM Image0748 GMT Nov 6, 2005

## KPAH 0.5 Degree SRM Image0748 GMT Nov 6, 2005

- 2

## GOES 6.7 um Image and 400 hPa Profilers0700 GMT Nov 6, 2005

## KVWX WSR-88D VAD Wind Profile0700-0804 GMT Nov 6, 2005

## LAPS Evansville Vicinity Sounding0700 GMT Nov 6, 2005

## Contributing Physical Processes

- The Reflectivity Tag signature at the very least represents an area of enhanced lift moving along the QLCS
- One possible process contributing to the change in storm character is the rapidly increasing jet-level winds
- Provides enhanced outflow in the upper portions of the storm
- Resultant increase in updraft vertical velocity
- Leads to storm intensification and a contracting circulation
- May lift and diminish the impact of the weak low-level stable layer enabling the PBL to interact with the free atmosphere
- The breakdown in the stable layer enables the change in storm mode from elevated to surface-based.

## Contributing Physical Processes

- Wave-like structure of signatures possibly due to meso-scale gravity waves
- Although, Jewett et al. (2003), Koch and Saleeby (2001), Stobie et al. (1983) and others have highlighted meso-scale gravity wave-convective storm interaction, the process has not been emphasized within the operational convective warning community
- Coleman and Knupp (2006) provide a discussion of current theories with regard to this interaction
- If this is the case, evidence of convergence/divergence or wind shift couplets in WSR-88D data may be evident

- Schematic illustration of the height variation in the phase relations between the horizontal wind component and wave-induced vertical motions (From Koch et al., 1993)

## KPAH 0.5 Degree Reflectivity Image0632 GMT Nov 6, 2005

## KPAH 0.5 Degree SRM Image0632 GMT Nov 6, 2005

## F1 Tornado – Jasper County Illinois2115-2123 GMT Nov 15, 2005

**F1 Tornado – Jasper County Illinois****2115-2123 GMT Nov 15, 2005**

**F1 Tornado with estimated maximum winds of 40 to 44.5 ms****-1**** (90 to 100 mph)**
**Path length of 16 km (10 miles) and width of 27 to 46 m (30 to 50 yards)**
**Three homes and eleven outbuildings damaged**

- Picture of damage northwest of Newton Illinois (NWS Lincoln)

## F1 Tornado – Jasper County Illinois2115-2123 GMT Nov 15, 2005

**F1 Tornado – Jasper County Illinois****2115-2123 GMT Nov 15, 2005**

**Although 50+ tornadoes occurred across Arkansas into the Ohio and Tennessee Valleys on November 15****th**** 2005, the Newton Illinois tornado was the only tornado confirmed in the far northern segment of the QLCS**
**A Reflectivity Bulge appeared over south central Illinois and moved northeast along the QLCS eventually interacting with a previously rotating storm **

- Picture of damage northwest of Newton Illinois (NWS Lincoln)

## KILX 0.5 Degree Reflectivity Image2056 GMT Nov 15, 2005

## KILX 0.5 Degree Reflectivity Image2118 GMT Nov 15, 2005

## KILX 0.5 Degree SRM Image2056 GMT Nov 15, 2005

## KILX 0.5 Degree SRM Image2118 GMT Nov 15, 2005

## Microburst Wind DamageSaybrook Illinois0940 GMT March 13, 2006

**Microburst Wind Damage****Saybrook Illinois****0940 GMT March 13, 2006**

**Building in downtown Saybrook collapsed**
**Several other nearby buildings damaged**
**Debris path was five blocks wide and was comprised mostly of tree damage**
**Survey estimated wind speeds of 31 ms****-1 ****(70 mph)**

- Picture of damage in Saybrook Illinois (Courtesy of Roger Look)

## Microburst Wind DamageSaybrook Illinois0940 GMT March 13, 2006

**Microburst Wind Damage****Saybrook Illinois****0940 GMT March 13, 2006**

**Nine tornadoes touched down in central Illinois between 0030 and 0325 GMT**
**associated with an isolated supercell**
**Longest track was a tornado with F2 damage that hit Springfield Illinois**
**Tornado had continuous 106 km (66 mile) path **
**A QLCS developed overnight associated with a cold front and jet streak**
**Numerous non-tornadic wind reports of greater than 25 ms****-1**** were reported from Springfield Illinois to Decatur Illinois associated with a bow echo in the QLCS between 0835 and 0932 GMT**
**Northern segment of QLCS initially appeared benign**
**Microburst at Saybrook Illinois occurred as Reflectivity Tag interacted with developing bow echo.**

- Picture of damage in Saybrook Illinois (Courtesy of Roger Look)

## LAPS Saybrook Vicinity Sounding0900 GMT March 13, 2006

## KILX 0.5 Degree Reflectivity Image0811 GMT March 13, 2006

## KILX 0.5 Degree Reflectivity Image0938 GMT March 13, 2006

## Reflectivity Tag WSR-88D Signature

- Since WSR-88D upgrades in 2004, improvements in real-time data and temporal resolution have enabled NWS Central Illinois Warning Meteorologists to increasingly detect a radar signature, the “Reflectivity Tag”, when monitoring QLCS in highly sheared, low/moderate CAPE, highly dynamic environments
- Five of seven cool or transition season severe weather events investigated since 2004 in the central Midwest exhibit this signature concurrent with a subset of severe weather reports
- This is not a “stand-alone” signature due to a significant false alarm rate. It is additional input into the warning decision making process and can be used as a storm triage tool to identify areas in need of further investigation
- The signature is being utilized successfully in real-time operations (September 22, 2006)
- Further research will expand the dataset by looking at additional events beyond the central Midwest and prior to 2004

## Acknowledgements

- The author would like to express his appreciation to Dr. David Jorgensen and the staff at NOAA/NSSL/ Warning Research and Development Division for their initial thoughts on mechanisms that may lead to these signatures.
- The author would like to acknowledge the staff of the NOAA/NWS Lincoln Illinois office for their assistance in identifying these signatures.
- In addition, the author would like to thank Ron Przybylinski (NOAA/NWS Saint Louis Missouri) and Pat Spoden (NOAA/NWS Paducah Kentucky) for providing additional datasets for analysis.
- Finally, the suggestions and comments provided by Ernie Goetsch and Chris Miller of NOAA/NWS Lincoln IL were invaluable and greatly appreciated.

## References

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- Evansville

- Evansville

- Newton

- Newton

- Saybrook