National Weather Service United States Department of Commerce

Tornadoes Strike The Western Piedmont of

North Carolina on November 15, 2006

Patrick D. Moore
NOAA/National Weather Service
Greer, SC

A mobile home is destroyed by a tornado near Statesville, NC, Wednesday evening, 15 November 2006

A tornado destroyed this mobile home along Fraley Lane, off River Hill Road, east of Statesville, North Carolina, around 11:45 pm on Wednesday, 15 November 2006. Additional images showing at least one other mobile home destroyed are included below. Image taken by Donna Swicegood and copywright by the Statesville Record & Landmark. Used by permission

A large tree crushed a garage and landed on a car east of Denver, NC, Wednesday evening, 15 November 2006

A tornado toppled this tree, which landed on and flattened the garage along Red Robin Lane, near Lake Norman, east of Denver, North Carolina, around 11:15 pm on Wednesday, 15 November 2006. Additional images of the damage in eastern Lincoln County are included below. Image courtesy of Susan Spake, Lincoln County Emergency Management. Used by permission

Author's Note: The following report has not been subjected to the scientific peer review process.

1. Introduction

A line of thunderstorms intensified rapidly as it moved east across the Piedmont of the Carolinas on the evening of Wednesday, November 15, 2006. The line of severe storms spawned at least four separate tornadoes over the western Piedmont of North Carolina between approximately 1050 pm EST (0350 UTC 16 November) and 1145 pm EST (0445 UTC 16 November). [Note: all times from this point onward will be referenced to coordinated universal time (UTC). To convert to Eastern Standard Time, subtract five hours from the UTC time.] In addition, several reports of wind damage were received, stretching from Upstate South Carolina, across the Charlotte metropolitan area, to the Northwest Piedmont of North Carolina. The first tornado touched down near Cramerton, in Gaston County, damaging the West Cramerton Baptist Church. Two of the tornadoes struck Lincoln County. A brief touchdown occurred near the intersection of State Highways 16 and 73. The other, on the western shores of Lake Norman near Denver, was more significant. That tornado knocked down hundreds of trees, many across roads and some on homes, and was rated at F2 on the Fujita Scale. The final tornado touched down in Iredell County along an intermittent six mile path from southeast of Statesville along Amity Hill Road, to east of Statesville along Bell Farm Road and River Hill Road near the Vance community. Several trees were knocked down and several mobile homes were damaged. One mobile home was completely destroyed. This particular tornado was rated at F1 and resulted in one injury and one fatality.

(Click here for a preliminary summary of severe weather reports gathered during and immediately after the event. Note that some of the wind damage events were determined to be caused by tornadoes after a damage survey was conducted.)

Severe thunderstorm and tornado reports for the 24 hour period ending 7 am 16 November 2006

Fig. 1. Preliminary severe weather reports for the 24 hours ending at 7 am EST (1200 UTC) November 16, 2006. Note that the graphic does not reflect the results of the damage survey which determined that some of the wind damage across Gaston, Lincoln, and Iredell counties was caused by tornadoes. Click on image to enlarge.

The tornadoes across the western Piedmont were a part of a larger outbreak of severe weather across the Carolinas, which included the deadly Riegelwood Tornado in Columbus County and Pender County, North Carolina, early in the morning of Thursday, 16 November 2006. The events of 15 November were particularly challenging to the forecaster because of the rapid change in convective storm mode. In less than one hour, the primary threat potential changed from flooding caused by upslope heavy rain with embedded deep convection, to wind damage and tornadoes from a quasi-linear convective system (QLCS). Fractures across similar QLCSs have been associated with the occurrence of weak tornadoes in the Carolinas, such as the Bessemer City, North Carolina tornado (Lane and Moore, 2006) and the Liberty and Moore, South Carolina, tornadoes. The first tornado over Gaston County was associated with a break in the QLCS. However, unlike other tornado-producing QLCSs observed across the western Carolinas (see McAvoy et al. 2000), the system on 15 November continued to evolve as it moved into an environment with increasingly favorable surface-based instability. In the other local studies, after the QLCS fractured into a leading and trailing line segment, a gradual weakening trend of the trailing segment was observed as storm inflow was disrupted by the leading line segment. However, this was not the case with the QLCS on 15 November 2006.

2. Synoptic Features and Pre-Storm Environment

The atmosphere across the southeastern United States was strongly forced on 15 November 2006. A strong jet streak of greater than 125 knots at the 300 mb level lifting out of an upper trough moving from the southern Plains to the Mississippi Valley (Fig. 2) provided upper divergence spreading east across the Carolinas at 0000 UTC on 16 November. The upper low center over Oklahoma at 1200 UTC deepened as it moved to eastern Arkansas by 0000 UTC (Fig. 3), with strengthening winds aloft at the 500 mb level. At the 850 mb level, a strong southerly low level jet of 40 kts developed east across the Carolinas by 0000 UTC (Fig. 4) in response to the deepening upper low. A short loop of water vapor imagery clearly showed the upper low wrapping up across the lower Mississippi Valley on the evening of 15 November.

SPC 300 mb analysis at 1200 UTC 15 November 2006SPC 300 mb analysis at 0000 UTC 16 November 2006

Fig. 2. Storm Prediction Center (SPC) objective analysis of 300 mb isotachs, streamlines and divergence at 1200 UTC 15 November (left) and 0000 UTC 16 November (right). Click on images to enlarge.

SPC 500 mb analysis at 1200 UTC 15 November 2006SPC 500 mb analysis at 0000 UTC 16 November 2006

Fig. 3. SPC objective analysis of 500 mb geopotential height, wind, and temperature at 1200 UTC 15 November (left) and 0000 UTC 16 November (right). Click on images to enlarge.

SPC 850 mb analysis at 1200 UTC 15 November 2006SPC 850 mb analysis at 0000 UTC 16 November 2006

Fig. 4. SPC objective analysis of 850 mb geopotential height, wind, and temperature at 1200 UTC 15 November (left) and 0000 UTC 16 November (right). Click on images to enlarge.

At the surface, low pressure wrapping up across Arkansas early on the morning of 15 November moved slowly east and occluded during the day with a new primary low near Memphis by 1800 UTC. The potential for severe weather, including tornadoes, was well-anticipated across the western Carolinas. Weak cold air damming against the east side of the Appalachians was a limiting factor for severe thunderstorm development, which was correctly anticipated by the Storm Prediction Center (SPC) in the Day 1 Severe Weather Outlook issued at 1628 UTC. A coastal front developing in advance of the approaching warm front surged inland and was incorporated with the warm front across the Piedmont by late in the day (Fig. 5). Even though strong shear was already in place, it was not clear how far inland the coastal front would penetrate into the cold air damming wedge and to what extent surface-based instability would develop across the Piedmont (SPC Day 1 Outlook issued at 2134 UTC). In spite of the uncertainty, severe weather was still anticipated.

Surface analysis at 0000 UTC 16 November 2006

Fig. 5. Hydrometeorological Prediction Center surface fronts and pressure analysis at 0000 UTC 16 November. Click on image to enlarge.

3. Pre-Storm Environment

The upper air sounding taken at Greensboro, North Carolina (GSO), at 0000 UTC 16 November showed very strong low level shear (Fig. 6), above 40 knots in the surface to 3 km layer. Shear of this magnitude has been shown to be sufficient for the development of tornadoes in QLCSs (Weisman and Trapp, 2003). Although instability was marginal, the observation was taken in the cooler air to the north and west of the coastal front/wedge boundary. The upper air sounding taken at the same time to the south and east of this boundary at Charleston, South Carolina (CHS), revealed sufficient instability and the potential for strong updrafts with all measures of Convective Available Potential Energy (CAPE) above 500 J/kg (Fig. 7). The highly-sheared environment across the western Piedmont of North Carolina grew increasingly favorable for severe thunderstorms after 0000 UTC 16 November as the coastal front/wedge boundary shifted westward. An examination of surface observations showed that dewpoints across the Charlotte area jumped from the upper 40s at 2250 UTC 15 November to the lower 60s by 0150 UTC 16 November (Fig. 8), indicative of the westward passage of the boundary. Along and to the east of the boundary, an area of surface-based CAPE in excess of 250 J/kg lifted northward across South Carolina and over the southern Piedmont of North Carolina between 0100 UTC and 0300 UTC (Fig. 9).

Upper air sounding at GSO at 0000 UTC 16 November 2006

Fig. 6. Skew-T log P diagram (upper left) and hodograph (upper right) for upper air sounding at GSO at 0000 UTC 16 November. The tables at the bottom summarize several objective parameters used by the SPC to determine severe weather potential. Click on image to enlarge.

Upper air sounding at CHS at 0000 UTC 16 November 2006

Fig. 7. As in Figure 6, except at CHS. Click on image to enlarge.

Surface plot at 2343 UTC 15 November 2006Surface plot at 0243 UTC 16 November 2006

Fig. 8. Regional surface observations plots at 2300 UTC 15 November (left) and 0200 UTC 16 November (right). The traditional station model is used. Note how the dewpoint jumped and south wind increased at CLT as the surface boundary shifted west. Click on images to enlarge.

SPC analysis of surface based CAPE and CIN at 0100 UTC 16 November 2006SPC analysis of surface based CAPE and CIN at 0300 UTC 16 November 2006

Fig. 9. SPC objective analysis of surface based CAPE (contours) and Convective Inhibition (color fill) at 0100 UTC (left) and 0300 UTC (right) 16 November. Click on images to enlarge.

4. Radar Observations

A large area of moderate rain with embedded heavier showers moved slowly east across Upstate South Carolina at 0005 UTC 16 November, as observed by the Weather Surveillance Radar - 1988 Doppler (WSR-88D) located at the Greenville-Spartanburg Airport (KGSP). Within this larger area of precipitation, a QLCS developed rapidly between about 0145 UTC and 0215 UTC (Figs. 10 and 11), as indicated by the north to south band of high reflectivity (greater than 40 dBZ) across the east side of Spartanburg County and the east side of Laurens County. The formation of a Line Echo Wave Pattern suggested the development of a mesoscale area of low pressure over eastern Spartanburg County. Wind damage was reported near Laurens as the line passed. Persistent rotation along a portion of the line coincident with evidence of a new strong updraft over extreme eastern Laurens County prompted the issuance of a Tornado Warning for Union County, South Carolina, at 0227 UTC. The rotational signatures along the rapidly developing QLCS prompted the SPC to issue Tornado Watch #861 at 0230 UTC.

Click here to view a 26 frame java loop of composite reflectivity from the KGSP radar from 0045 UTC to 0246 UTC.

KGSP Composite Reflectivity at 0143 UTC 16 November

Fig. 10. Composite radar reflectivity from the KGSP WSR-88D radar at 0143 UTC 16 November. The radar is located at the point labelled 'KGSP'. Click on image to enlarge.

KGSP Composite Reflectivity at 0225 UTC 16 November

Fig. 11. As in Figure 10, except for 0225 UTC. Click on image to enlarge.

Wind damage occurred at 0259 UTC near Lockhart, in extreme eastern Union County, South Carolina, as the QLCS passed. The couplet of inbound and outbound velocities traversed Union County and moved into southwestern York County, where an inflection point developed along the line by 0316 UTC. This appeared as an "S-shape" pattern in the higher reflectivity seen on the 0.5 degree scan from the KGSP radar (Fig. 12). The storm relative motion on the 0.5 degree scan showed a rotational couplet coincident with the inflection point in the reflectivity (Fig. 13). This signature, identified as a mesocyclone by the WSR-88D mesocyclone algorithm, could be traced back along the line for over one hour. In that sense, the signature was indicative of a mini-supercell embedded within the QLCS. In this instance, however, the QLCS did not fracture. Wind damage was reported in Sharon at 0320 UTC, but apparently this was not caused by a tornado.

KGSP 0.5 degree Reflectivity at 0316 UTC 16 November

Fig. 12. Radar reflectivity on the 0.5 degree scan from the KGSP radar at 0316 UTC 16 November. Note the "S-shape" in the higher reflectivity to the southwest of Sharon. Click on image to enlarge.

KGSP 0.5 degree Storm Relative Motion at 0316 UTC 16 November

Fig. 13. As in Figure 12, except for storm relative motion. The warmer (cooler) colors represent targets moving away from (toward) the radar. Click on image to enlarge.

a. The Cramerton Tornado

After 0320 UTC, the QLCS passed the midway point between the KGSP radar and the Terminal Doppler Weather Radar (TCLT) located north of the Charlotte - Douglas International Airport (Fig. 14). After that time, the TCLT radar had an increasingly favorable view of the low levels of the storm as it moved closer to the Charlotte metro area, compared to the more distant KGSP radar. Nevertheless, the KGSP radar still yielded important clues to the evolution of the system. The convective line remained intact as it moved across York County through 0328 UTC while a new weak mesocyclone developed at low levels near the point on the line that failed to break earlier. It should be noted that the KGSP radar mesocyclone algorithm did not detect a mesocyclone in the storm after 0328 UTC because of the broad and weak nature of the circulation above the lowest elevation cut, which over central York County was approximately 4500 feet above ground level and 60 miles distant.

Click here to view a 15 frame java loop of radar reflectivity on the 0.5 degree scan from the KGSP radar from 0303 UTC to 0402 UTC.

Click here to view a 15 frame java loop of storm relative motion on the 0.5 degree scan from the KGSP radar from 0303 UTC to 0402 UTC.

KGSP 0.5 degree Reflectivity at 0320 UTC 16 November

Fig. 14. Radar reflectivity on the 0.5 degree scan from the KGSP radar at 0320 UTC. The location of the KGSP radar is shown at the far left while the TCLT radar location is shown in the upper right edge of the figure. Click on image to enlarge.

An inflection point developed in the QLCS over northern York County at 0341 UTC with some evidence of a weak echo channel behind the segment of the line that bowed east into the northeast York County (Fig. 15), although rotation was relatively weak (Fig. 16). The weak echo channel was more significant on the 1.3 degree scan. The convective line began to fracture at 0349 UTC as it moved across southern Gaston County, North Carolina (Fig. 17), but the break did not appear complete until 0358 UTC. The rotational signature, which had weakened as the QLCS moved across the state line, strengthened considerably at 0349 UTC as it moved toward Cramerton (Fig. 18).

KGSP 0.5 degree Reflectivity at 0341 UTC 16 November

Fig. 15. As in Fig. 14, except at 0341 UTC. The weak echo channel is indicated by the magenta arrow. Click on image to enlarge.

KGSP 0.5 degree storm relative motion at 0341 UTC 16 November

Fig. 16. Storm relative motion on the 0.5 degree scan from the KGSP radar. Click on image to enlarge.

KGSP 0.5 degree Reflectivity at 0349 UTC 16 November

Fig. 17. As in Fig. 14, except at 0349 UTC. Note the break in the high reflectivity (red shades) between Gastonia and Cramerton, compared to the high reflectivity line in Figure 15. Click on image to enlarge.

KGSP 0.5 degree storm relative motion at 0349 UTC 16 November

Fig. 18. As in Fig. 16, except for 0349 UTC. Note the couplet of inbound and outbound velocity shown to the southwest of Cramerton. Click on image to enlarge.

The closer proximity of the TCLT radar allowed for better interrogation of low level storm features once the QLCS moved into York County. The TCLT radar beam at 2.4 degrees passed through almost the exact same part of the QLCS as the KGSP radar at 0.5 degrees at 0341 UTC. This allowed for an interesting comparison of radar features sampled coincidentally by two radars. The reflectivity image from TCLT shows the same weak echo channel (Fig. 19) as observed by the KGSP radar (see Fig. 15), which developed as early as 0329 UTC on the TLCT imagery. The storm relative motion image from TCLT shows considerably more detail, with a rotational velocity of 44 kts and a diameter of 0.7 miles at a distance of 21 miles (Fig. 20). This equated to a strong mesocyclone. In contrast, the rotational velocity observed by KGSP was only 23 knots (see Figure 16), which at the distance from KGSP, fell on the line between a minimal and moderate mesocyclone. The TLCT radar, with its smaller beamwidth and closer location, was able to sample the storm at a higher resolution, and thus detected the stronger circulation. A weak echo channel could be seen developing as early as 0329 UTC on the 0.2 degree and 1.0 degree scans. This feature was prominent in all scans leading up to the time of the tornado.

TCLT base reflectivity on the 2.4 degree scan at 0341 UTC 16 November

Fig. 19. Radar reflectivity on the 2.4 degree scan from the TCLT radar at 0341 UTC. The reflectivity scale is shown in the upper left. The radar location is labelled TCLT. Note the channel of lower reflectivity wrapping to the southeast of Clover. Click on image to enlarge.

TCLT storm relative motion on the 2.4 degree scan at 0341 UTC 16 November

Fig. 20. Storm relative motion on the 2.4 degree scan from the TCLT radar at 0341 UTC. Green shades represent motion toward the radar and red shades show motion away from the radar. Note the couplet of inbound and outbound velocity northeast of Clover. Click on image to enlarge.

The weak echo channel was observed on the 1.0 degree scan at 0347 UTC, the last volume scan before the tornado touched down, but there was little evidence of an incipient break in the QLCS (Fig. 21). This could be an artifact of the higher resolution of the TCLT radar data. The mesocyclone strengthened gradually through 0347 UTC (Fig. 22), and after this time the strongest rotational velocity was observed on the 1.0 degree scan. Rotation reached a maximum on the 0.2 degree scan at 0402 UTC, well after the tornado touched down.

TCLT base reflectivity on the 1.0 degree scan at 0347 UTC 16 November

Fig. 21. Radar reflectivity on the 1.0 degree scan from the TCLT radar at 0347 UTC. Note the channel of lower reflectivity wrapping to the northeast of Clover. Click on image to enlarge.

TCLT storm relative motion on the 1.0 degree scan at 0347 UTC 16 November

Fig. 22. Storm relative motion on the 1.0 degree scan from the TCLT radar at 0347 UTC. Note the couplet of inbound and outbound velocity east of Crowders. Click on image to enlarge.

A graph of rotational velocity observed on the lowest four elevation scans with time revealed an unexpected result (Fig. 23). The QLCS moved toward the radar, so the radar beam sampled a lower height in the storm with each successive scan at the same elevation. The peak rotational velocity on the 2.4 degree scan was observed at 0341 UTC, followed by a peak on the 1.0 degree scan at 0353 UTC, and a peak on the 0.2 degree scan at 0402 UTC. The approximate height above ground at each point was 5100 feet, 2400 feet, and 350 feet, respectively. This suggested the mesocyclone developed downward with time, which is a trait observed more often in supercell thunderstorms. In contrast, other local studies of tornadic QLCSs determined that the mesocyclone developed upward.

Rotational velocity observed by TCLT radar

Fig. 23. Rotational velocity observed by the TCLT radar on the 0.2 degree, 1.0 degree, 2.4 degree, and 5.0 degree scans. The purple line shows the distance from the mesocyclone to the TCLT radar in nautical miles, using the vertical scale on the right-hand side. Click on image to enlarge.

The tornado touched down on the west side of Cramerton at 0351 UTC, damaging the West Cramerton Baptist Church, knocking down tree limbs, and causing minor damage to houses. Additional wind damage was reported in the Lowell and McAdenville communities, although a tornado could not be confirmed in those locations.

b. The Lincoln-Iredell Mini-Supercell Storm

After the split occurred in the QLCS over eastern Gaston County, the trailing segment of the line maintained its integrity as it moved north toward eastern Lincoln County. At 0400 UTC, a surface warm front stretched from southwest to northeast across the northwest Piedmont of North Carolina (Fig. 24). The boundary represented the western edge of a weakly unstable air mass with a mixed layer CAPE of greater than 250 J/kg (Fig 25). Storm relative helicity in the vicinity of the boundary ranged from 400 to 500 m2/s2 in the surface to 1 km layer (Fig. 26). Southeasterly wind on the east side of the boundary allowed for inflow unhindered by the leading segment of the QLCS moving eastward across Mecklenburg County at that time. Although instability was limited, the low level shear was well within the range for supercells.

KGSP Composite Reflectivity at 0358 UTC 16 November

Fig. 24. Composite Reflectivity for the 0358 UTC volume scan from the KGSP radar, with surface observation plot at 0400 UTC. The warm front is indicated in red. Click on image to enlarge.

SPC mixed layer CAPE analysis at 0400 UTC 16 November

Fig. 25. SPC objective mesoscale analysis of 100 mb mixed layer CAPE (contoured, J/kg) and convective inhibition (shaded, J/kg) at 0400 UTC. Click on image to enlarge.

SPC 0-1 km storm relative helicity analysis at 0400 UTC 16 November

Fig. 26. SPC objective mesoscale analysis of storm relative helicity in the 0-1 km layer (contours, m2/s2) and storm motion (barbs, kt) at 0400 UTC. Click on image to enlarge.

The storm at the southern end of the trailing line segment acquired characteristics of a mini-supercell (as described in Markowski and Straka 2000) as it intercepted the surface boundary over northeastern Gaston County and southeastern Lincoln County between 0359 UTC and 0411 UTC. There was evidence of a hook-like reflectivity appendage at 0359 UTC (Fig. 27), but the radar beam appeared to be attenuated to some degree by the leading edge of very heavy precipitation associated with the leading QLCS line segment which had moved between the TCLT radar and the developing supercell near Lowell. Radar echo tops remained under 35,000 feet owing to the weak instability. The shape of the low level reflectivity resembled that of a kidney bean by 0411 UTC (Fig. 28), with a persistent mesocyclone observed on the easternmost appendage of the storm (Fig. 29). It should be noted that data from the TCLT radar at the lowest elevation cut (0.2 degrees) were not available after 0405 UTC. The second tornado touched down briefly at 0415 UTC near the intersection of State Highways 16 and 73 north of the Lowesville community. The third tornado touched down along Lake Norman near Denver, in extreme northeast Lincoln County, at 0422 UTC. Unfortunately, the beam from the TCLT radar was blocked in the direction of the storm at the 1.0 degree elevation, so the structure of the storm could not be seen at that time.

Click here to view a 15 frame java loop of radar reflectivity on the 1.0 degree scan from the TCLT radar from 0347 UTC to 0505 UTC.

TCLT base reflectivity on the 0.2 degree scan at 0359 UTC 16 November

Fig. 27. Radar reflectivity on the 0.2 degree scan from the TCLT radar at 0359 UTC. The radar site is located over northern Mecklenburg County. Note the hook-like reflectivity appendage between Gastonia and Mount Holly. Click on image to enlarge.

TCLT base reflectivity on the 1.0 degree scan at 0411 UTC 16 November

Fig. 28. Radar reflectivity on the 1.0 degree scan from the TCLT radar at 0411 UTC. The kidney-bean shape of the higher reflectivity (greater than 35 dBZ) over eastern Lincoln County is circled in magenta. Click on image to enlarge.

TCLT storm relative motion on the 1.0 degree scan at 0411 UTC 16 November

Fig. 29. Storm relative motion on the 1.0 degree scan from the TCLT radar at 0411 UTC. Note the velocity couplet west of Lowesville corresponding to the reflectivity appendage in Figure 28. Click on image to enlarge.

The storm weakened as it crossed Lake Norman around 0430 UTC, but knocked down a few trees in the Mt. Mourne area of Iredell County. The supercell reintensified as it moved north-northeast into Iredell County after 0430 UTC. It should be noted that although the TCLT had a better view of the low level structure of the storms over the Piedmont, the KGSP radar still revealed useful information for tracking the storms, even if rotational signatures were rather weak. The Vertically Integrated Liquid and Echo Tops from the KGSP radar increased from the 0433 UTC scan onward, indicating the main updraft in the storm had strengthened. On the TCLT radar, the rotational velocity in the mesocyclone increased on the 1.0 degree and 2.4 degree scans from 0429 UTC through 0441 UTC. A hook-like appendage reappeared in the reflectivity data on the 1.0 degree scan at 0441 UTC to the southeast of Statesville (Fig. 30), corresponding to the mesocyclone seen in the storm relative motion data (Fig. 31). The fourth tornado touched down at 0445 UTC along an intermittent six mile path from five miles east-southeast of Statesville to six miles northeast of Statesville. The supercell continued to track across the northern part of Iredell County, producing more wind damage northeast of Harmony around midnight. It should be noted that another supercell-looking storm moved northward across western Rowan County and western Davie County without producing damage.

Click here to view a 20 frame java loop of radar reflectivity on the 0.5 degree scan from the KGSP radar from 0341 UTC to 0502 UTC.

Click here to view a 20 frame java loop of storm relative motion on the 0.5 degree scan from the KGSP radar from 0341 UTC to 0502 UTC.

TCLT base reflectivity on the 1.0 degree scan at 0441 UTC 16 November

Fig. 30. As in Fig. 28, but for 0441 UTC. Note the reflectivity appendage to the southeast of Statesville shown by the white arrow. Click on image to enlarge.

TCLT storm relative motion on the 1.0 degree scan at 0441 UTC 16 November

Fig. 31. As in Fig. 29, but for 0441 UTC. Click on image to enlarge.

5. Summary

A QLCS developed rapidly within a larger area of moderate rain across Upstate South Carolina on the evening of 15 November 2006. The QLCS showed at least one "S-shape" bend in the high reflectivity that failed to break the convective line, and several persistent small mesocyclones early in its lifetime. The QLCS moved east into an environment that possessed an increased amount of surface-based instability across the western Piedmont of North Carolina. An inflection point eventually developed on the QLCS that resulted in a break in the convective line around the time that a tornado touched down to the west of Cramerton, North Carolina. An investigation of the data from the TCLT radar revealed a persistent mesocyclone with a lifetime of at least 20 minutes before the tornado. More interesting, the mesocyclone appeared to have developed downward, which is a trait associated with supercell thunderstorms and not with similar-looking QLCS tornadoes observed across the western Carolinas. The QLCS appeared to fracture over eastern Gaston County between 0349 UTC and 0358 UTC, but unlike other QLCS splits, the trailing line segment did not weaken. In this case, the trailing segment acquired supercell thunderstorm characteristics as it interacted with a pre- existing warm front and uninterrupted inflow across the Northwest Piedmont of North Carolina. The mini-supercell moved north-northeast along the warm front and spawned three additional tornadoes across eastern Lincoln County and Iredell County before moving out of the County Warning Area at 0500 UTC. The TCLT radar was favorably located to observe the low level structure of the tornado producing storms. The narrower beamwidth and closer range allowed the TCLT radar to detect much stronger rotation within the storm prior to the first tornado as compared to the KGSP radar. However, the TCLT data were not without limitations. Elevation angles were available only up to 5.0 degrees which prevented interrogation of the mid and upper levels of the storms. The 0.2 degree scans were not available from 0405 UTC to 0454 UTC. The 5.0 degree scans were severely attenuated after 0435 UTC north of the radar in the direction of the supercell. Radar algorithms were not available for TCLT, which might have helped issue more effective warnings in this case. This capability will be added in a future software build.

Tornado damage west of Cramerton, NC, on 15 November 2006, damaging the West Cramerton Baptist ChurchTops of trees sheared off by tornado near McAdenville, NC, on 15 November 2006

Damage caused by the tornado that touched down west of Cramerton, North Carolina, shortly before 11 pm on Wednesday, 15 November, 2006. The West Cramerton Baptist Church, shown in the distance on the left image, sustained damage to the front doors and signs, and the steeple was knocked down. The shingles in the foreground are from a nearby house. The image on the right shows the tops of trees sheared off by the tornado. Images taken by Vince DiCarlo, NWS. Click on images to enlarge.

Tornado damage on Red Robin Lane, east of Denver, NC, on 15 November 2006Tornado damage on Red Robin Lane, east of Denver, NC, on 15 November 2006 Tornado damage along the shore of Lake Norman, east of Denver, NC, on 15 November 2006Tornado damage along the shore of Lake Norman, east of Denver, NC, on 15 November 2006

Additional images of the damage along the shore of Lake Norman along Red Robin Lane and Lakeshore Drive, east of Denver, North Carolina. Images courtesy of Susan Spake, Lincoln County Emergency Management. Click on images to enlarge.

Tornado damage on Fraley Lane, east of Statesville, NC, on 15 November 2006Tornado damage on Fraley Lane, east of Statesville, NC, on 15 November 2006 Tornado damage on Fraley Lane, west of Statesville, NC, on 15 November 2006Tornado damage on Fraley Lane, east of Statesville, NC, on 15 November 2006 Tornado damage on Fraley Lane, west of Statesville, NC, on 15 November 2006Tornado damage on Fraley Lane, east of Statesville, NC, on 15 November 2006

Additional images of the damage to mobile homes along Fraley Lane, off River Hill Road, east of Statesville, North Carolina. Images taken by Donna Swicegood of the Statesville Record & Landmark. Click on images to enlarge.

References

Lane, J. D., and P. D. Moore, 2006: Observations of a non-supercell tornadic
	thunderstorm from a Terminal Doppler Weather Radar. Preprints, 23rd Conf. 
	on Severe Local Storms, St. Louis, MO, Amer. Meteor. Soc.

Markowski, P. M., and J. M. Straka, 2000:  Some observations of rotating updrafts
	in a low-buoyancy, highly sheared environment. Mon. Wea. Rev., 128, 449-461.

McAvoy, B. P., W. A. Jones, and P. D. Moore, 2000: Investigation of an unusual 
	storm structure associated with weak to occasionally strong tornadoes over 
	the Eastern United States. Preprints, 20th Conf. on Severe Local Storms, 
	Orlando, FL, Amer. Meteor. Soc., 182-185.

Weisman, M. L., and R. J. Trapp, 2003: Low-level mesovortices within squall lines 
	and bow echoes. Part I: Overview and dependence on environmental shear. Mon.
	Wea. Rev., 131, 2779-2803. 

Acknowledgements

The author wishes to express his gratitude to Ms. Donna Swicegood of the Statesville Record & Landmark for her willingness to share the images of the damage in Iredell County. Jonathan Blaes at NWS Raleigh provided copies of the SPC mesoanalysis sector images. The severe weather plot, upper air maps, and upper air sounding graphics were obtained from the Storm Prediction Center. The surface analyses were obtained from the Hydrometeorological Prediction Center. Satellite imagery and the surface observation plots were obtained from the University Corporation for Atmospheric Research. The imagery from the KGSP radar was made using the Java NEXRAD viewer obtained from the National Climatic Data Center.