Central North Carolina Tornadoes from the 16 April 2011 Outbreak Matthew Parker 1, Jonathan Blaes 2,...
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![Page 1: Central North Carolina Tornadoes from the 16 April 2011 Outbreak Matthew Parker 1, Jonathan Blaes 2, Gary Lackmann 1, and Sandra Yuter 1 1 North Carolina.](https://reader036.fdocuments.in/reader036/viewer/2022062621/551c5614550346b1458b4fac/html5/thumbnails/1.jpg)
Central North Carolina Tornadoes from the 16 April 2011 Outbreak
Matthew Parker1, Jonathan Blaes2, Gary Lackmann1, and Sandra Yuter1
1North Carolina State University2NOAA/National Weather Service
Raleigh, North Carolina, USA
Acknowledgments: NSF grant ATM-0758509, too many collaborators to list at NC State and the Raleigh WFO
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• Majority of tornadoes (by number) occurred east of the Raleigh CWA, however the longest track tornadoes (and a majority of the significant tornadoes) occurred in central NC
Record for summed path length in NC (196 miles in RAH CWA alone) Tornadoes A & B had paths > 55 miles: 2 of only 4 since 1980 in NC
• Two central NC tornadoes tracked through major urban areas (A & B) Tornado A passed within 1.7 miles of the RAH NWS office (NWS-
Blacksburg backed up RAH for 7 minutes as staff took shelter) Est. damage in RAH CWA >$328M (tor. A≈$172M, tor. B≈$116M)
AB
Raleigh (metro pop 1.1M)Fayetteville (metro pop 366K)
Raleigh CWA
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![Page 4: Central North Carolina Tornadoes from the 16 April 2011 Outbreak Matthew Parker 1, Jonathan Blaes 2, Gary Lackmann 1, and Sandra Yuter 1 1 North Carolina.](https://reader036.fdocuments.in/reader036/viewer/2022062621/551c5614550346b1458b4fac/html5/thumbnails/4.jpg)
Surface observations, manual surface analysis, and radar reflectivity1200-2000 UTC, 4/16/2011
![Page 5: Central North Carolina Tornadoes from the 16 April 2011 Outbreak Matthew Parker 1, Jonathan Blaes 2, Gary Lackmann 1, and Sandra Yuter 1 1 North Carolina.](https://reader036.fdocuments.in/reader036/viewer/2022062621/551c5614550346b1458b4fac/html5/thumbnails/5.jpg)
R
F
Convective ingredients1200-2000 UTC, 4/16/2011
R=RaleighF=Fayetteville
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Observed sounding:Greensboro, NC (GSO)1500 UTC 4/16/11
(modified with observed cell motion)
RUC Analysis sounding:Raleigh, NC (RDU)1800 UTC 4/16/11
(modified with observed sfc T, sfc Td, cell motion)
CAPE: 668 J/kgCIN: -10 J/kg0-6 km shear: 28 m/s0-3 km SRH: 807 m2/s2
LCL height: 264 m AGL
CAPE: 1043 J/kgCIN: 0 J/kg0-6 km shear: 30 m/s0-3 km SRH: 804 m2/s2
LCL height: 763 m AGL
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• The initial convective mode appeared to be linear, but the squall line evolved into discrete supercells over central and southern NC
• A number of cells appeared to have been initiated ahead of the primary squall line, but all of these pre-line cells dissipated
Base scan radar reflectivity and eventual primary tornado tracks1630-1900 UTC, 4/16/2011
“Raleigh”
“Fayetteville”
• The “Raleigh” and “Fayetteville” supercells can actually be tracked backward to origins in SC around 1600-1700 UTC
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Raleigh
Fayetteville
Surface observations, radar reflectivity, and eventual primary tornado tracks1800 UTC, 4/16/2011
1. Outflow temperature deficits were generally small (~5-6 C)- high ABL rel. humidity- no trailing strat. precip.
2. Low-level shear vectors were largely parallel to the squall line
3. Strongly curved clockwise hodographs favor dynamic lifting on the right flanks of supercells
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Idealized simulation with initial linear trigger
Homogeneous environment:1800 UTC RUC analysisSounding from RDU
• Simulated cold pool temperature deficit never exceeds 6 K
• Simulated squall line breaks up despite homogeneous environment
• Simulated supercells emerge after roughly 3 hours
Evolution appears to have been strongly controlled by
the environment
Simulated reflectivity
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• The three supercells highlighted above produced 10 total tornadoes (pink tracks), including two significant (EF2 or greater) tornadoes each
• The Raleigh supercell appeared to be quasi-steady during its lifetime, whereas the Fayetteville supercell appeared to be somewhat cyclic, with periods of multiple circulation centers
Base scan radar reflectivity and tornado tracks (RAH CWA only)1900-2030 UTC, 4/16/2011
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parent mesotornado
Sanford, NC1908 UTC (308 PM EDT), 4/16/2011 (early in lifetime)
Raleigh, NC1950 UTC (350 PM EDT) 04/16/2011
(late in lifetime)
parent meso
tornado
“Raleigh tornado”
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Smithfield, NC2049 UTC (449 PM EDT), 4/16/2011
(end of tornado 1, beginning of tornado 2)
“Fayetteville supercell”
tornado 1
tornado 2
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Preliminary conclusions
• The longest-track tornadoes on 4/16/2011 were centered in the Raleigh CWA. Wind profiles were impressive , with slight enhancement during the day. Non-zero CAPE wasn’t present until 2-3 hours prior to the tornadoes.
• The observed squall line-to-supercell evolution is somewhat unusual. Squall line moved off of the cold front, and the outflow behind the squall line
was not especially cold; the linear forcing is hypothesized to have been weak. Large vertical wind shear, strongly curved hodographs, and minimal low-level
line-normal shear appear to strongly favor discrete supercells.
• The 4/16/2011 outbreak was a record-setter for central NC. We have ongoing interest in trying to understand what was unique about the environment.
Anecdotally: long, strongly-curved low-level hodographs are somewhat unusual within the warm sector in central NC.
Anecdotally: low-level flow from off of the Atlantic tends to yield greater low-level stability. Such stability may permit larger low-level vertical wind shear to persist in the afternoon boundary layer, but the interplay between this process and the development of CAPE seems complex.
This slide to do:Add visual interest
questions/comments: [email protected]