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16 September 2019, Blog No. 6

 

North Carolina averages 31 tornadoes annually1 - the sixteenth most of any U.S. state, and the second most on the East Coast behind Florida. Reliable data of confirmed tornadoes in the United States is quite a young dataset; beginning only in 1950. The data presented in this blog range from 1950-2017, and note that about a one and half year latency is common between when a tornado occurs and when it enters the official database. Damage surveys, data confirmation, and storm report verifications occur in this period. For instance, official 2018 tornado data will likely be released soon, and 2019 tornado data will likely not be available until late 2020 or early 2021.

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North Carolina's Tornado History

 

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NC's worst tornado outbreaks, most intense tornadoes, and other notable tornado records

Mapping North Carolina's tornado history

 

Using QGIS (basically ArcGIS for macOS), I plotted all recorded tornadoes mentioned above, plus as many as possible from 1 January 2018 - 31 May 2019 that were verifiable by local NWS offices and available via the experimental NWS Damage Survey Viewer. Using the buttons and the legend below, you can explore the spatial footprint of tornadoes in North Carolina. Data obtained from TornadoHistoryProject.com, SPC Archives, and the NCDC Storm Events Database.

Table 1. Table showing confirmed tornadoes that occurred in North Carolina between 1 January 2007 and 31 December 2017. Data is aggregated into tornado occurrences by Enhanced-Fujita intensity rating.

As you can see, beaucoups of detailed information and analysis can be done with tornado data. Countless possibilities remain in regard to how we can study past and prepare for future tornadoes in North Carolina. I plan to soon expand upon this blog and create an entire NC Tornadoes page to house all of this information. For now, this brief summary will have to suffice! #NCTornadoes

 

If you have any questions, comments, or concerns, feel free to send them along on Facebook, Twitter, or via email to [email protected] 

 

Sláinte,

Andrew

 

 

References:

1. https://www.ncdc.noaa.gov/climate-information/extreme-events/us-tornado-climatology

2. https://www.spc.noaa.gov/faq/tornado/f-scale.html

3. https://www.spc.noaa.gov/efscale/

4. https://climate.ncsu.edu/climateblog?id=282

5. https://www.nhc.noaa.gov/data/tcr/AL062018_Florence.pdf

6. https://projects.ncsu.edu/atmos_collaboration/nwsfo/storage/cases/20110416/

7. https://projects.ncsu.edu/atmos_collaboration/nwsfo/storage/cases/19921122/

 

 

Sources:

 

NWS Damage Assessment Toolkit:

https://apps.dat.noaa.gov/stormdamage/damageviewer/

 

SPC National Severe Weather Database Browswer/Online SeverePlot 3.0:

https://www.spc.noaa.gov/climo/online/sp3/plot-to-be-fixed.php

 

SPC U.S. Tornado Outbreak Interface:

https://www.spc.noaa.gov/exper/outbreaks/#

 

Tornado History Project:

http://www.tornadohistoryproject.com/

 

NCEI/NCDED Storm Events Database:

https://www.ncdc.noaa.gov/stormevents/

 

QGIS Software:

https://qgis.org/en/site/forusers/download.html

 

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Table 2. Table showing confirmed tornadoes that occurred in North Carolina between 1 January 1950 and 31 December 2006. Data is aggregated into tornado occurrences by original Fujita intensity rating.

Before we dig into the data, some bookkeeping - the original Fujita Damage Tornado Scale2 (F-scale) eveloped by Dr. Tetsuya Theodore "Ted" Fujita of the University of Chicago in 1971, was used in the United States until 31 December 2006, and was implemented to retroactively classify tornado intensities several decades back. Since 1 January 2007, the United States has used the Enhanced Fujita Scale3 (EF-scale) with adjusted wind speeds to classify tornadoes by the damage left in their wake.

 

The above tables tally the number of tornadoes in North Carolina in each of these time frames - 1,283 tornadoes in total from 1950-2017. The table below and to the right provides some tornado statistics for all of these 1,283 North Carolina tornadoes.

Table 3. Table of statistics from North Carolina's recorded tornadoes from 1950-2017. Note that economic losses are an estimate based off of tornado damage classification schemes used prior to 1996. Data collected from TornadoHistoryProject.com, Storm Prediction Center Archives, and NCDC Storm Events Database.

In Tables 1 and 2, we can see the majority of tornadoes are of the less intense variety. This is consistent with research that has been conducted over the past several decades, and makes sense - more intense tornadoes are going to be rarer, because favorable conditions must align perfectly to create an environment conducive to strong tornadoes. Note here that an F5/EF5 tornado has never been recorded in North Carolina.

 

In regard to the economic and humanitarian damage caused by tornadoes in NC, Table 3 to the right depicts statistics for the 1,283 recorded tornadoes in the state. Nearly $1 billion in total economic losses, over 4,300 miles of tornado track, and thousands of injuries. With these data, each tornado averages about 2 injuries, over $700,000 in damages, a track length of over 3 miles, and is on average 89 yards wide.

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Clearly, the eastern half of North Carolina, namely the Coastal Plain (highlighted in Blog No. 5) is the hotspot for tornadoes in the state. The geography and climatology is more favorable there: flat, wide open fields, and no mountains or major changes in elevation to disrupt flow within the lower troposphere, warmer temperatures on average relative to the rest of North Carolina and elevated humidity within close proximity to the Atlantic Ocean. This region extending from the South Carolina Midlands up through the Coastal Plain of NC is often deemed "Carolina Alley," for these reasons. In regard to which areas/counties suffer the most tornado strikes, let's refer to Table 4 below.

Table 4. This table shows the number of tornado touchdowns aggregated by county using the above-mentioned 1950-2017 dataset. North Carolina has 100 counties, so this should result in five equal columns of twenty counties, but alas, prior to 2018, Ashe County in northwestern NC had never recorded a tornado, hence the blank space at the bottom of the fifth column. 

Data obtained from TornadoHistoryProject.com, SPC Archives, and the NCDC Storm Events Database.

gallery/nc_tors_county (1)

North Carolina's most active tornado days and worst tornado outbreaks

 

Tornadoes usually occur on the order of minutes, perhaps hours for some of the most intense tornadoes. However, when you string together numerous individual tornadoes, it can make for a long day of forecasting, and widespread damage can occur. While no official definition quantifies an "outbreak," of tornadoes, I have taken any calendar day or string of days where six or more tornadoes occurred to be an "event," for ranking purposes below. These data below are subject to change and are preliminary - with more recent events, you will see "PENDING," indicating that data is still under review and not finalized, data is inconclusive, or I was unable to publicly obtain the data at this time. Let's check out some of North Carolina's most notorious tornado events:

 

All data were compiled from the aforemntioned data sources and are subject to change. Data with an asterisk* are still under review and will be updated when official data becomes available.

 

Click the column headings in the table below to sort the table by that column.

Click the date listed in the "DATE(S)" column to view a map of the event courtesy of SPC National Severe Weather Database Browswer Online SeverePlot 3.0.

Map plots unavailable for events after 31 December 2017.

RANK DAY MONTH YEAR DATE(S) TORNADOES MAX RATING FATALITIES INJURIES TOTAL TORNADO MILES NOTES
1 16 4 2011 16 April 2011 31 EF3 24 446 315.6 -
2 13 9 2018 13-17 September 2018 27 EF1 0 0 30.1 Hurricane Florence
3 27 5 1973 27-29 May 1973 24 F2 0 6 45.8 -
4 5 9 2019 5 September 2019 20* EF2 0 2 53.7* Hurricane Dorian
5 7 5 1998 7 May 1998 19 F4 0 9 73.1 -
6 15 4 1996 15 April 1996 18 F2 0 34 20 -
7 15 9 1999 15 September 1999 17 F2 0 0 29.7 Hurricane Floyd
8 26 10 2010 26-27 October 2010 14 EF2 0 11 11.03 -
9 27 4 2011 27-28 April 2011 13 EF1 0 1 21.07 -
10 7 9 2004 7-8 September 2004 12 F2 0 0 21.4 Tropical Depression Frances
10 19 4 2019 19 April 2019 12 EF2 0 1 71.7 -
11 28 3 1984 28 March 1984 11 F4 51 1024 205.3 -
11 4 11 1992 4 November 1992 11 F1 0 0 5.8 -
11 2 7 2003 2 July 2003 11 F1 0 0 13.4 -
12 5 5 1989 5 May 1989 10 F4 7 142 89.6 -
12 29 3 1991 29 March 1991 10 F2 0 37 79.5 -
12 20 3 1998 20 March 1998 10 F3 2 34 20 -
12 7 7 2005 7 July 2005 10 F2 0 0 41.8 -
12 11 5 2008 11 May 2008 10 EF2 0 8 23.71 -
12 25 4 2014 25 April 2014 10 EF3 1 19 105.03 -
13 9 5 2003 9 May 2003 9 F1 0 0 16.8 -
13 14 5 2006 14 May 2006 9 F1 0 0 6.9 -
13 27 3 2009 27 March 2009 9 EF2 0 1 14.5 -
13 13 8 2004 13-14 August 2004 9 F1 0 0 0.7 Tropical Storm Charley
14 1 4 1998 1 April 1998 8 F1 0 3 7 -
14 26 8 1998 26 August 1998 8 F1 0 0 4 Hurricane Bonnie
14 15 4 1999 15 April 1999 8 F2 1 37 53.5 -
14 5 5 2009 5 May 2009 8 EF2 0 1 11.2 -
14 2 4 1974 2-4 April 1974 8 F4 6 37 56.1 -
15 18 2 1976 18 February 1976 7 F1 0 2 21.5 -
15 4 3 1977 4 March 1977 7 F3 0 6 19.8 -
15 8 10 1996 8 October 1996 7 F2 0 1 3.3 Tropical Storm Josephine
15 11 10 2002 11 October 2002 7 F2 0 0 20 Tropical Storm Kyle
15 4 6 2004 4 June 2004 7 F1 0 1 2.9 -
15 27 9 2004 27 September 2004 7 F1 0 0 16.2 Tropical Storm Jeanne
15 14 9 2007 14 September 2007 7 EF0 0 0 3.22 -
15 15 11 2008 15 November 2008 7 EF3 2 6 23.54 -
15 18 8 1991 18 August 1991 7 F1 0 0 1.1 Hurricane Bob
16 23 10 2017 23 October 2017 6 EF2 0 1 67.51 -
16 18 3 1956 18 March 1956 6 F2 0 2 4.6 -
16 15 5 1975 15 May 1975 6 F1 0 7 1.6 -
16 27 8 2008 27-28 August 2008 6 EF0 0 0 9.25 Tropical Storm Fay
16 24 2 2016 24 February 2016 6 EF2 0 0 7.7 -
16 8 10 2017 8 October 2017 6 EF1 0 0 32.49 -
16 16 8 1994 16-17 August 1994 6 EF2 0 1 8.5 -

Table 5. Table showing the most significant tornado events in North Carolina's modern history. Click column headings to sort table. 

Data obtained from TornadoHistoryProject.com, SPC Archives, and the NCDC Storm Events Database.4,5,6,7

North Carolina's tornado extremes

 

Out of these more than 1,200 tornadoes to impact North Carolina since 1950, some stand out as the most notable and destructive. While North Carolina has never observed an F5/EF5 tornado since 1950, it doesn't take these monster tornadoes to cause damage and wreak havoc on communities. Any tornado is a life-threatening situation and requires adherence to safety precautions to ensure your safety. Some of these tornado extremes are listed in the table below:

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Table 6. Table outlining tornado extremes in the dataset of North Carolina tornadoes from 1950-2017. 

Data obtained from TornadoHistoryProject.com, SPC Archives, and the NCDC Storm Events Database.

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