Cool Season Tornadoes in the Southeast U.S.

Cool Season Cool Season Tornadoes in the Tornadoes in the Southeast U.S.Southeast U.S.

Steven NelsonSteven NelsonStephen KonarikStephen KonarikWFO Peachtree CityWFO Peachtree City

11 November 200211 November 200228 December 200528 December 2005

2 January 20062 January 2006

15 November 200615 November 2006

25 December 200625 December 2006





17 February 200817 February 2008 26 February 200826 February 2008

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OutlineOutline

• Brief Review of Severe ConvectionBrief Review of Severe Convection• Climatology of Cold Season TornadoesClimatology of Cold Season Tornadoes• Case StudiesCase Studies• Summary / Forecasting GuidelinesSummary / Forecasting Guidelines

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ReviewReview

• Ingredients for Deep Moist Convection: Ingredients for Deep Moist Convection: (note, most of the time, DMC = thunderstorms)(note, most of the time, DMC = thunderstorms)– Instability + Moisture + Lift (to the LFC)Instability + Moisture + Lift (to the LFC)

• Ingredients for Severe DMC:Ingredients for Severe DMC:– All the above plus…All the above plus…– Greater instability and/or vertical wind shearGreater instability and/or vertical wind shear

• Warm Season: High Cape / Low ShearWarm Season: High Cape / Low Shear• Cool Season: Low Cape / High ShearCool Season: Low Cape / High Shear

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Instability and ShearInstability and Shear

Low instability does notnot mean little or no chance of tornadoes !

Note the absence of F2+ tornadoes when minimum shear criteria is not met.

(1993)(1993)

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Cool Season Tornado ClimatologyCool Season Tornado Climatology

• Not studied much until recentlyNot studied much until recently• Used SvrPlot to study Georgia area Used SvrPlot to study Georgia area

significant cool season tornadoessignificant cool season tornadoes• More thorough studies by Wasula et al. More thorough studies by Wasula et al.

(2004) and Guyer et al. (2006)(2004) and Guyer et al. (2006)• Tornadoes produce majority of severe Tornadoes produce majority of severe

weather damage and loss of life in cool weather damage and loss of life in cool season.season.– Flooding and lightning much lower threat.Flooding and lightning much lower threat.

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Wasula et al. found approximately Wasula et al. found approximately 50%50% of all of all southeast U.S. F2+ tornadoes occur in the cool southeast U.S. F2+ tornadoes occur in the cool season (Nov 1 – Feb 28)season (Nov 1 – Feb 28)

1950-20011950-2001

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Guyer et al. found tornadoes much more likely Guyer et al. found tornadoes much more likely to persist overnight in the cool seasonto persist overnight in the cool season

Southeast U.S. Tornadoes by Hour Southeast U.S. Tornadoes by Hour (All year)(All year)

Southeast U.S. Tornadoes by Hour Southeast U.S. Tornadoes by Hour (Oct 15 – Feb 15, 1985-2004)(Oct 15 – Feb 15, 1985-2004)

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Cool Season Tornado ClimatologyCool Season Tornado ClimatologyInstability important but much lower Instability important but much lower

values needed for F2+ tornadoes in the values needed for F2+ tornadoes in the cool seasoncool season

MLCAPE for all F2+ tornadoesMLCAPE for all F2+ tornadoes MLCAPE for SE cool season F2+ tornadoesMLCAPE for SE cool season F2+ tornadoes

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0-3km SRH for 0-3km SRH for all F2+ tornadoesall F2+ tornadoes

SRH for SE cool season F2+ tornadoesSRH for SE cool season F2+ tornadoes

0-1km SRH for 0-1km SRH for all F2+ tornadoesall F2+ tornadoes

Somewhat more shear needed for F2+ Somewhat more shear needed for F2+ tornadoes in the cool seasontornadoes in the cool season

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DateDate Location (where casualties occurred)Location (where casualties occurred) IntInt FatFat InjInj19 Feb 1884 2pm19 Feb 1884 2pm Jasper, Pickens countiesJasper, Pickens counties ?? 2222 100100

10 Feb 1921 12pm10 Feb 1921 12pm Washington countyWashington county ?? 3131 100100

5 Dec 1954 4pm5 Dec 1954 4pm Fulton, Stewart countiesFulton, Stewart counties F3F3 22 9090

26 Dec 1964 2pm,12am26 Dec 1964 2pm,12am Jones countyJones county F3F3 22 1919

10 Jan 1972 10am10 Jan 1972 10am Fulton countyFulton county F3F3 11 99

18 Feb 1975 3pm18 Feb 1975 3pm Peach countyPeach county F3F3 22 5050

8 Nov 1989 4pm8 Nov 1989 4pm Wilcox countyWilcox county F2F2 11 88

15 Nov 1989 3-6pm15 Nov 1989 3-6pm Huntsville, Alabama and several Georgia countiesHuntsville, Alabama and several Georgia counties F4F4 2121 486 486 (463)(463)

22 Nov 1992 4pm22 Nov 1992 4pm Cobb, Putnam, Greene counties (large 3-day outbreak killed 26 Cobb, Putnam, Greene counties (large 3-day outbreak killed 26 and injured 641, mostly across the southeast)and injured 641, mostly across the southeast) F4F4 77 179179

21 Feb 1993 8pm-12am21 Feb 1993 8pm-12am Polk, Pike countiesPolk, Pike counties F3F3 22 4444

30 Oct 1993 4am30 Oct 1993 4am Lee county (Albany)Lee county (Albany) F2F2 33 2727

16 Feb 1995 5am16 Feb 1995 5am Cullman, Marshall counties (Joppa/Arab, Alabama)Cullman, Marshall counties (Joppa/Arab, Alabama) F3F3 66 133133

8 Nov 1996 4pm8 Nov 1996 4pm Lumpkin, Dodge countiesLumpkin, Dodge counties F2F2 11 1818

13 Feb 2000 11pm-1am13 Feb 2000 11pm-1am Mitchell, Tift, Colquitt, Grady counties (Camilla hit twice that night Mitchell, Tift, Colquitt, Grady counties (Camilla hit twice that night and yet again in March 2003 causing 4 fatalities and 200 injuries)and yet again in March 2003 causing 4 fatalities and 200 injuries) F3F3 1919 202 202

(175)(175)

11 Nov 2002 1am11 Nov 2002 1am Veterans Day Outbreak (Southeast had much higher casualties Veterans Day Outbreak (Southeast had much higher casualties than Van Wert, OH F4)than Van Wert, OH F4) F3F3 2525 188188

Historical Cool Season TornadoesHistorical Cool Season Tornadoesin the Southeastin the Southeast

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Case StudiesCase Studies13 February 2000 – Camilla, GA F313 February 2000 – Camilla, GA F3

• Early morning (12am)Early morning (12am)• 19 deaths, 202 inj19 deaths, 202 inj• CAPE ~ 800 J/kgCAPE ~ 800 J/kg• 0-3km SRH ~ 400 m0-3km SRH ~ 400 m22/s/s22

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Case StudiesCase Studies11 November 2002 – Veterans Day Outbreak (F2)11 November 2002 – Veterans Day Outbreak (F2)

• Early morning (2am)Early morning (2am)• SPC High RiskSPC High Risk• 25 deaths, 188 inj25 deaths, 188 inj• Van Wert, OH F4Van Wert, OH F4• CAPE ~ 2500 J/kgCAPE ~ 2500 J/kg• 0-3km SRH ~ 350 m0-3km SRH ~ 350 m22/s/s22

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DateDate LocationLocation IntInt CAPECAPE 0-1km 0-1km SRHSRH

28 December 2005 4pm28 December 2005 4pm Laurens county (also had softball size hail in Laurens county (also had softball size hail in Sumter)Sumter) F1F1 10001000 250250

2 January 2006 5pm2 January 2006 5pm Fulton, Fayette, Pike (baseballs in Pike and Jones)Fulton, Fayette, Pike (baseballs in Pike and Jones) F3F3 12501250 400400

15 November 2006 3pm15 November 2006 3pm Chattahoochee (Ft Benning)Chattahoochee (Ft Benning) F1F1 300300 500500

25 December 2006 3am25 December 2006 3am Ben Hill, TelfairBen Hill, Telfair F1F1 100100 500500

31 December 2006 4pm31 December 2006 4pm Dooly county (Unadilla)Dooly county (Unadilla) F2F2 300300 300300

5 January 2007 11am5 January 2007 11am CowetaCoweta F0F0 300300 200200

7 January 2007 7pm7 January 2007 7pm CowetaCoweta F2F2 200200 250250

15 December 2007 10pm15 December 2007 10pm Wilcox, Dodge, TreutlenWilcox, Dodge, Treutlen EF2EF2 300300 300300

17 February 2008 4 pm17 February 2008 4 pm Carroll, Crawford, Bibb, JonesCarroll, Crawford, Bibb, Jones EF1EF1 300300 400400

26 February 2008 6 am26 February 2008 6 am CarrollCarroll EF3EF3 100100 350350

7 March 2008 8 pm7 March 2008 8 pm DouglasDouglas EF1EF1 500500 200200

14 March 2008 9 pm14 March 2008 9 pm AtlantaAtlanta EF2EF2 800800 250250

Recent Cool Season Tornadoes Recent Cool Season Tornadoes in Georgiain Georgia

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Recent ExamplesRecent Examples25 December 2006 – The “Santa Claus” Tornado25 December 2006 – The “Santa Claus” Tornado

• CAPE ~300 J/kgCAPE ~300 J/kg• 0-3km SRH ~ 600 m0-3km SRH ~ 600 m22/s/s22

• No watch or outlookNo watch or outlook• No CG lightning with storm!No CG lightning with storm!• Ben Hill F1 at 630 am EST, F0 Ben Hill F1 at 630 am EST, F0 tornado near Kibbee ~ 700 am.tornado near Kibbee ~ 700 am.

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Recent ExamplesRecent Examples15 December 2007 – Wilcox, Dodge, Treutlen EF215 December 2007 – Wilcox, Dodge, Treutlen EF2

• CAPE ~ 300 J/kgCAPE ~ 300 J/kg• 0-1 km SRH ~ 300 m0-1 km SRH ~ 300 m22/s/s22

• Surface Td > 70 FSurface Td > 70 F• Supercell moved NE along Supercell moved NE along strong warm frontstrong warm front

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Recent ExamplesRecent Examples26 February 2008 – Carroll EF326 February 2008 – Carroll EF3

• Very low CAPE ~ 150 J/kg?Very low CAPE ~ 150 J/kg?• 0-1km SRH ~ 350 m0-1km SRH ~ 350 m22/s/s22

• Early morning event (6am)Early morning event (6am)• 2 injuries, no fatalities2 injuries, no fatalities• QLCS tornadoQLCS tornado

11Z MLCAPE11Z MLCAPE

11Z MUCAPE11Z MUCAPE

11Z 0-1km SRH11Z 0-1km SRH

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• ““Ingredients” for cool season tornadoes the same as with Ingredients” for cool season tornadoes the same as with all tornadoes: lift, moisture, instability and vertical wind all tornadoes: lift, moisture, instability and vertical wind shear.shear.

• 50% of F2+ tornadoes in the southeast occur between 50% of F2+ tornadoes in the southeast occur between November and February.November and February.

• Cool season tornadoes more likely to occur overnight. Cool season tornadoes more likely to occur overnight. • Tornado-producing storms in low CAPE environments will Tornado-producing storms in low CAPE environments will

produce very little or produce very little or nono lightning. lightning.– 25 Dec 2006 “Santa Claus” Tornado25 Dec 2006 “Santa Claus” Tornado

• Strong large-scale “dynamics” observed in several cases, Strong large-scale “dynamics” observed in several cases, but not necessary for significant cool season tornadoes.but not necessary for significant cool season tornadoes.

SummarySummary

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• For F2+ tornadoes in the cool season, For F2+ tornadoes in the cool season, – Some instability is necessary (Some instability is necessary (usuallyusually CAPE > 500 J/kg), CAPE > 500 J/kg),

but large values not needed if sufficient shear is presentbut large values not needed if sufficient shear is present– Likewise, shear is necessary (0-1km SRH > 125 mLikewise, shear is necessary (0-1km SRH > 125 m22/s/s22), but ), but

large values not needed if relatively strong instability is large values not needed if relatively strong instability is presentpresent

• Example guidelines for cool-season F2+ Example guidelines for cool-season F2+ tornadoes based on research and case studies:tornadoes based on research and case studies:– CAPE > CAPE > 15001500 J/kg and 0-1km SRH > J/kg and 0-1km SRH > 125125 m m22/s/s22 – CAPE > CAPE > 500500 J/kg and 0-1km SRH > J/kg and 0-1km SRH > 200200 m m22/s/s22 – CAPE > CAPE > 150150 J/kg and 0-1km SRH > J/kg and 0-1km SRH > 300300 m m22/s/s2 2 ????

GuidelinesGuidelines

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BONUS!!BONUS!!What kind of warning would you issue?What kind of warning would you issue?

• Slight risk to your westSlight risk to your west• No watchNo watch• 00Z sounding not yet in00Z sounding not yet in• ASOS observation just to the ASOS observation just to the east of storm: east of storm:

KXXX 150048Z 04004KT 1 3/4SM KXXX 150048Z 04004KT 1 3/4SM BR FEW090 14/13 (57/55 F) BR FEW090 14/13 (57/55 F) A2971A2971

• 10 minutes after this time, 10 minutes after this time, tornado touches down ½ tornado touches down ½ mile west of downtown!mile west of downtown!

• Anemometer on roof of CNN Anemometer on roof of CNN center records 126 mph gust center records 126 mph gust before it was destroyed.before it was destroyed.

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Questions?Questions?

[email protected]@[email protected]@noaa.gov

Cool Season Tornadoes in the Southeast U.S.

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