Non-mesocyclone tornadoes in Hungary

Polyánszky Zoltánpolyanszky.z@met.hu

Hungarian Meteorological ServiceAviation and Severe Weather Forecasting Division

XXX OSTIV Congress2010 Szeged, Hungary

Conceptual modell

- In the final stage, vortex C collocates with the updraft of towering cumulus and develops into a tornado under the influence of vortex stretching.

- In the beginning stage, there is a convergence boundary and horizontal shear across it. Along the convergence there are vertical vorticity circulation. At the same time, cumulus clouds form over the boundary owing to the forced uplift.

Wakimoto and Wilson, 1989

Supercell thunderstorm

- Supercell tornadoes are preceded by a midlevel mesocyclone and subsequent tornado development occurs when the mesocyclone intensifies at lower levels.

Hivatkozás© 1990 *Aster Press -- From: Cotton, Storms

Distribution of Vortices

2005(2)

2006(4)

2008(7)

2009(18)

Tornadoes and funnel clouds

- F1: One of the two F1 tornadoes developed in Ipolytarnóc on 24 August 2008 and devastated with a maximum path width of 80-120 m and a path length of 200-300 m. It caused damages to roof timbers and firewalls of twenty-two houses. The other one was formed in Nagybánhegyes on 11 May 2006 and caused 1-2 million HUF damage in a cemetery and in several houses.

-F0:The one of the five F0 tornadoes occured in Onga and it lifted up a plastic projecting roof and a piece of a slate roof to 200-250 m high and it threw them 300 m away from their original place.

(Photo: Robert Kerékgyártó)

-F2: The strongest tornado rated F2 occured in Tyukod on 17 July 2005. It threw away a container (weighs 9 tons) about 5-6 meters. It has a path length of 200 m and a path width of 30 m.

Synoptic Setting: Short-Wave

From31

cases

in 3

events

Synoptic Setting: Long-Wave

From31

cases

in 8 events

Synoptic Setting: Upper Low

From31

cases in 18 events

GFS modell

WRF ARW 3.0modell field

Convective analysis field: Surface information assimilated to WRF fields

The most important analysed parameters

150 - 1800 J/kg(>150)SBCAPE

Parameters Values

0-3 km-es SbCAPE (J/kg) 50 - 300 J/kg(>125)

0-2 lapse rate 6.5 - 10 oC

LCL 500-1750 m

0-6 km deep shear (m/s) <10 m/s

CIN 25-58 J/kg

General characterisation

- The radar reflectivity values fell in the range between 25 dBZ and 58 dBZ

- The convective cells appeared as individual ones or embedded in the stratiform rain

- Often at the same time, many funnel clouds were observed to develop usually for a short time, but some of them existed for half an hour and did not change place.

-The characterisation of parent clouds of these vortices, -These parent clouds are mostly in the developing stage with inferred strong updrafts often owing to the flat, dark cloud base.

- The beginning of intensive precipitation, occurance of vortices

-The radar echoes fairly indicated the place of the event hence the region of the ascending currents.

Case study: Ipolytarnóc

Meander Cape

Meander nedv. Konv.Meander Moisture Convergence

Saját_térképekSbCape

Térképek0-3 km SbCape

TérképekConvergence at 10 m

Térképek0-1 km convergence

0-6 km mean vorticity

Moisture convergence at 10 m

Vorticity at 10 m

Conclusion- On the basis of these parameters and the synoptic situation, we can evaluate the potential of the phenomena in question.

- The axis of through at upper level and cyclone curvature of isobars or flat pressure area in the ground support especially development of these vortices.

- The calculated parameters were not good discriminators on the strength of the studied funnel clouds or F0 tornadoes, but many of them (e.g., 0-3 km SBCAPE, and convergence between 0-1 km) had high values in the environment of two F1 tornadoes.

- The conditions of the environment seemed not so significant, these parameters can indicate that the dynamic processes are more dominant than thermal processes for this type of tornado development.

- The smaller scale processes, which were not examined in detail, may play an important role in the events, as well. It may be assumed that the smaller scale thunderstorm outflow boundaries can enhance the pre-existing vertical circulations along wind shift boundaries.

- It may be assumed that these types of tornadoes can give the majority of relatively weak tornadoes in our area

References• 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, pp. 843-856.

• Caruso, J. M., and J. M. Davies, 2005: Tornadoes in non-mesocyclone environments with pre-exisitng vertical vorticity along convergence boundaries. NWA Electronic Journal of Operational Meteorology, June 2005.

• Bluestein, H. B.,1985: The formation of a „landspout” in a „broken line”squall line in Oklahoma. Preprints, 14th Conference on Severe Local Storms, Indianapolis, Amer. Meteor. Soc., pp. 312-315.

• 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, pp. 843-856.

• Davies-Jones, R., D. Burgess and M. Foster, 1990: Test of helicity as a tornado forecast parameter. Proc. 16th Conf. Severe Loc. Storms, Kananaskis Park, Albert, Canada, Amer. Meteor. Soc., pp. 588-592.

• Doswell, C.A. III, and D.W. Burgess, 1993: Tornadoes and tornadic storms: A review of conceptual models. The Tornado: Its structure, Dynamics, Prediction, and Hazards, Geophys. Monogr., No. 79. Amer. Geophys. Union, pp. 161-172. Fábián, T., 1973: A Nagyatádi tornádórol. Légkör., 18, pp. 38-43.

• Bartha, I., 1972: Tornádószerű víztölcsér a Balatonon. Légkör., 17, pp. 70-74.

References• Fujita, T.T., 1981: Tornadoes and downbursts in the context of generalized

planetary scales. J. Atmos. Sci., 38, pp. 1511-1534.• Kecskés, L., 1988: Tornádók és előfordulásuk Magyarországon. Légkör.,

33, pp. 27–30.• Keul, A. P., M. V. Sioutas, and W. Szilagyi, 2009: Prognosis of Central-

Eastern Mediterranean waterspouts. Atm. Res., 93, pp. 426-436. • Kósa-Kiss, A., Horváth, Á., 2002: Tornádótölcsér Nagyszalonta határában.

Légkör., 47, pp. 13.• Lee, B. D., and R. Wilhelmson, 2000: The numerical simulation of

nonsupercell tornadogenesis. Part III: Tests investigating the role of CAPE, vortex sheet strength, and boundary layer vertical shear. J.Atmos.Sci., 57, pp. 2246–2261.

• Lemon, L.R., 1977: Newsevere thunderstorm radar identification techniques and warning criteria: A preliminary report. NOAA Tech. Memo. NWSNSSFC-1 (NTIS Accession No. PB-273049), pp. 60.

• Horváth, Á., 1997: Tornádó! Légkör., 42, pp. 2-8.• Marquis, J. N., and Y. P. Richardson, 2006: Kinematic Observations of

Misocyclones along Boundaries during. Mon. Wea. Rev., 117, 1749-1768.• Polyánszky, Z., and Á. Molnár, 2007: Nem mezociklonális tornádók

Magyarországon. Légkör., 52, pp. 35-40.

References• Rassmussen, and D. O. Blanchard, 1998: A baseline climatology of

sounding-derived supercell and tornado forecast parameters. Wea. Forecasting., 13, pp. 1148-1164.

• Rennó, N. O., M. L. Burkett, and M. P. Larkin, 1998: A simple thermodynamical theory for dust devils. J. Atmos. Sci., 55, pp 3244–3252.

• Sárközi, Sz., 2007: A systematic approach to synoptic tornado climatology of Hungary for the recent years (1996-2001) based on official damage reports. Atmos. Res., 83, pp. 263-271.

• Sinclair, P. C., 1969: General characteristics of dust devils. J. Appl. Meteor., 8, pp. 32-45.

• Thompson, R. L., R. Edwards, J. A. Hart, K. L. Elmore, and P. Markowski, 2003: Close proximity soundings within supercell environments obtained from the Rapid Update Cycle. Wea. Forecasting., 18, pp. 1243-1261.

• Wakimoto, R. M., and J. W. Wilson, 1989: Non-supercell tornadoes. Mon. Wea. Rev., 117, pp. 1113-1140.

Thank you for your attention!