Kenneth R. Cook James Caruso Mickey McGuire National Weather Service, Wichita, KS

NSTs/Landspouts – Weak and Brief? NST = Non-Supercell Tornado  11 April 2002  9 July 2003  27 August 2004  19 May 2012

Question  What conditions are present when NSTs grow upscale and persist?

Brief Literature Review  Part I:  Condition of the Misocyclone environment  Updrafts provide a significant contribution to convection initiation  Part II:  Confirmed Part I  Family of tornadoes  TORs from stretching of vertical vorticity  Part III: Parameter tests - As CAPE increased:  NST vortex strength increased  Vertical vorticity stretched in shorter time periods  knots of change in the line parallel wind field (from Lee and Wilhelmson Pt I, 1997; Pt II, 1997; Pt III, 2000)

Brief Literature Review (from Jon Davies) A Conceptual Model:

27 August 2004 Case Examples

27 August Steep 0-2 km lapse rates - Strong MLCAPE along front (3860 J/kg) - High LCL Height of 1622 m - Deep Layer Bulk Shear 13 knots

27 August Convection developed in an “unzipping” fashion along intersection - Tornadoes occurred in boundary interaction with front

NST rated F2 south of Wellington, Kansas on 27 August 2004 (photo courtesy John Brand). NST rated F2 south of Wellington, Kansas on 27 August 2004 (photo courtesy John Brand).

9 July 2003 Case Examples

09 Jul Steep 0-2 km lapse rates - Strong MLCAPE along front (2809 J/kg) - High LCL Height of 2101 m - Deep Layer Bulk Shear 38 knots

09 July Convection developed in an “unzipping” fashion along intersection - Tornadoes occurred in boundary interaction with front

11 April 2002 Case Examples

11 April Steep 0-2 km lapse rates - Moderate MLCAPE along front (1020 J/kg) - High LCL Height of 1525 m - Deep Layer Bulk Shear 26 knots

Caruso and Davies (2005) 11 April Convection developed in an “unzipping” fashion along intersection - Tornadoes occurred in boundary interaction with front

11 April 2002 Tornado southeast of Pretty Prairie, Kansas on April 11, 2002 (video images courtesy Jim Reed and Katherine Bay Photography

19 May 2012 Case Examples

19 May 2012 Strong Instability High LCL Height Deep layer sheer less than 40 knots

19 May 2012 Unzipping takes place at boundary interaction Source:

19 May 2012 Tornadoes grew upscale Developed supercell- like characteristics Bulk Deep Layer shear marginal Brief TDS seen on radar (not shown)

19 May mph wind gust turbine height (212 feet)

Duration – Brief?

(16 Years) 720 Tornados WFO Wichita Tornadoes

(16 Years) 720 Tornados WFO Wichita Tornadoes These 4 Cases

84 % WFO Wichita Tornadoes These 4 Cases

84 %

These Cases Refute!  17 Year Average 0:04 minutes  11 April 2002: 0:16; 0:00 (2)  9 July 2003: 0:06; 0:02; 0:01 (2); 0:00 (2)  27 August: 0:19; 0:00 (3)  19 May 2012: 0:29; 0:16; 0:15; 0:14 (3); 0:05

Conclusions  Significant NST formation occurred where rapid updraft growth was present over the front/outflow boundary intersection (area of enhanced vertical vorticity w/ “unzipping” effect)  Exhibited strong CAPE (2500+ J/kg, confirms LW00)  Occurred in high LCL high CAPE environments  Grew upscale to develop some supercell characteristics  50% of NSTs in these cases exceeded average life cycle duration, 40% long duration  Some produced up to EF3 damage  Were very difficult to forecast  HRRR/CAMS may offer insight in the 0-6hr timeframe if storms anchored on front and “unzip”

References Bluestein, H. B., 1985: The formation of a “landspout” in a “broken-line” squall line in Oklahoma. Preprints, 14 th Conf. on Severe Local Storms, Indianapolis, IN, Amer. Meteor. Soc., Brady, R.H. and E.J. Szoke, 1989: A case study of nonmesocyclone tornado development in northeast Colorado: similarities to waterspout formation. Mon.Wea. Rev., 117, Caruso J. M. and J. M. Davies, 2005: Tornadoes in Nonmesocyclone Environments with Pre-existing Vertical Vorticity along Convergence Boundaries. NWS Electronic Journal of Operational Meteorology 1 June 2005 at: Cook, K. R., D. A. Baumgardt and T. Shea, 2005: Increasing situational awareness for nonsupercell tornadogenesis: 16 June th Annual Northern Plains Convective Workshop, St. Paul, MN, March Available on the workshop CD. Davies, J. M. 2006: Total CAPE, low-level CAPE, and LFC in significant tornado events with relatively high LCL heights. Preprints, 23rd Conf. Severe Local Storms, St. Louis, MO, Amer. Meteor. Soc., paper P1.3 ______, 2003: Ingredients supporting nonmesocyclone tornado events. Available on the web at: , 2004: Estimations of CIN and LFC associated with tornadic and nontornadic supercells. Wea. Forecasting, 19, Total CAPE, low-level CAPE, and LFC in significant tornado events with relatively high LCL heights ______, 2002: On low-level thermodynamic parameters associated with tornadic and non-tornadic supercells. Preprints, 21st Conf. Severe Local Storms, San Antonio, TX, Amer. Meteor. Soc., On low-level thermodynamic parameters associated with tornadic and non-tornadic supercells ______, 2012: Jon Davies Severe Weather Notes ( Lee, B. D. and R. B. Wilhelmson, 1997: The numerical simulation of non-supercell tornadogenesis. Part I: initiation and evolution of pre-tornadic mesocyclone circulations along a dry outflow boundary. J. Atmos. Sci, Vol. 54, pp ______, 1997: The numerical simulation of non-supercell tornadogenesis. Part II: evolution of a family of tornadoes along a weak outflow boundary. J. Atmos. Sci, Vol. 54, pp ______, 2000: The numerical simulation of non-supercell tornadogenesis. Part III: parameter tests investigating the role of CAPE, vortex sheet strength, and boundary layer vertical shear. J. Atmos. Sci, Vol. 57, pp Lemon, L. R., and E. M. Quoetone, 1995: WSR-88D and visual observations of a non-supercellular storm and tornado. Preprints, 27 th Conf. on Radar Meteorology, Vail, CO, Amer. Meteor. Soc., NOAA/NCDC Storm Events Database: Wakimoto, R. M., and J. W. Wilson, 1989: Non-supercell tornadoes. Mon. Wea. Rev., 117, Warning Decision Training Branch, 2002: Tornado Warning Guidance Document Version. Available on the web at: Weather Story, WFO Wichita, KS.