The forecasting of tornado events: the synoptic background of two different tornado case studies
Treść / Zawartość
The synoptic analyses of two different tornado cases, observed in Latvia and Poland in the summer of 2012, are examined in this paper. The first of them, the tornado in Latvia seemed to be a “textbook example” of tornado occurrence. Its development took place in the contact zone of the warm, tropical air, characterized by a very high CAPE (Convective Available Potential Energy), with cold and moist polar marine air mass behind the convergence line that determined very good conditions for convective updraft. Additionally, the moderate environmental wind shear favoured the sufficient condition for concentrating the atmosphere’s vorticity into well-organized strong rotating upward motions that produced the supercell structures and tornado. Thus, from the forecaster’s point of view, the occurrence of this severe convective event was not a surprise. This phenomenon was predicted correctly more than a dozen hours before the tornado occurred. The second event occurred in the north of Poland and was associated with a thunderstorm where a supercell was formed in conditions of low CAPE but favourable wind profile, both vertical and horizontal. Helical environments (characterized by large shear vectors that veered with height in the lowest three kilometres, especially the nearest one kilometre) were arguably the most important factor that determined the Polish tornado’s occurrence. In this case the analysis of the synoptic situation was not so clear and the superficial analysis, even post factum, regarding radar, satellite or detection maps might have suggested “quite a normal” summer thunderstorm. However, the detailed examination showed the reasons why tornado genesis took place. The potential conditions for the occurrence of this severe phenomenon were indicated by forecasters, although the forecasts were less exact with regard to the place of occurrence and the heaviness of the strike.
- Agee E., Jones E., 2009, Proposed conceptual taxonomy for proper identification and classification of tornado events, Weather and Forecasting, 24 (2), 609-617, DOI: 10.1175/2008WAF2222163.1
- Boustead J.M., Mayes B.E., Gargan W., Leighton J.L., Phillips G., Shumacher P.N., 2013, Discriminating environmental conditions for significant warm sector and boundary tornadoes in parts of the Great Plains, Weather and Forecasting, 28 (6), 1498-1523.
- Brazdil R., Chroma K., Dobrovolny P., Černoch Z., 2012, The tornado history of the Czech Lands, AD 1119-2010, Atmospheric Research, 118, 193-204, DOI: 10.1016/j.atmosres. 2012.06.019
- Brooks H., Doswell C.A. III, 2001, Some aspects of the international climatology of tornadoes by damage classification, Atmospheric Research, 56 (1-4), 191-201, DOI: 10.1016/S0169-8095(00)00098-3
- Corfidi S.F., Weiss S.J, Kain J., Corfidi S., Rabin R., Levit J., 2010, Revisiting the 3-4 April 1974 super outbreak of tornadoes, Weather and Forecasting, 25 (2), 465-510, DOI: 10.1175/2009WAF2222297.1
- Davies-Jones R., 1984, Streamwise vorticity: The origin of updraft rotation in supercell storms, Journal of the Atmospheric Sciences, 41 (20), 2991-3006, DOI: 10.1175/1520-0469(1984)041<2991:SVTOOU>2.0.CO;2
- Davies-Jones R., 2006, Tornado genesis in supercell storms – what we know and what we don’t know? Preprints 86th AMS Annual Meeting, Atlanta, USA, available at https://ams.confex.com/ams/pdfpapers/104563.pdf (data access 26.05.2015)
- Doswell C.A. III., 1987, The distinction between large-scale and mesoscale contribution to severe convection. A case study example, Weather and Forecasting, 2 (1), 3-16, DOI: 10.1175/1520-0434(1987)002<0003:TDBLSA>2.0.CO;2
- Dotzek N., 2003, An updated estimate of tornado occurrence in Europe, Atmospheric Research, 67-68, 153-161, DOI: 10.1016/S0169-8095(03)00049-8
- Droegemeier K.K., Lazarus S.M., Davies-Jones R., 1993, The influence of helicity on numerically simulated convective storms, Monthly Weather Review, 121 (7), 2005-2029, DOI: 10.1175/1520-0493(1993)121<2005:TIOHON>2.0.CO;2
- Gold D.A., Nielsen-Gammon J.W., 2008, Potential vorticity diagnosis of the severe convective regime. Part III: The Hesston tornado outbreak, Monthly Weather Review, 136 (5), 1593-1611, DOI: 10.1175/2007MWR2092.1
- Houze R.A., 1993, Cloud dynamic, Junior Academic Press, USA, 573 pp.
- Kerr B.W., Darkow G.L., 1996, Storm-relative winds and helicity in the tornadic thunderstorm environment, Weather Forecast, 11, 489-505
- Lilly D.K., 1986a, The structure, energetics, and propagation of rotating convective storms. Part I: Energy exchange with the mean flow, Journal of the Atmospheric Sciences, 43 (2), 113-125, DOI: 10.1175/1520-0469(1986)043<0113:TSEAPO>2.0.CO;2
- Lilly D.K., 1986b, The structure, energetics, and propagation of rotating convective storms. Part II: Helicity and storm stabilization, Journal of the Atmospheric Sciences, 43 (2),126-140, DOI: 10.1175/1520-0469(1986)043<0126:TSEAPO>2.0.CO;2
- Maddox R.A., Doswell C.A. III, 1981, An examination of jet stream configuration, 500 mb vorticity advection and low level thermal advection patterns during extended periods of intense convection, Monthly Weather Review, 110 (3), 184-197, DOI: 10.1175/1520-0493(1982)110<0184:AEOJSC>2.0.CO;2
- Maddox R.A., Hoxit L.R., Chappell C.F., 1980, A study of tornadic thunderstorm interactions with thermal boundaries, Monthly Weather Review, 108 (3), 322-336, DOI: 10.1175/1520-0493(1980)108<0322:ASOTTI>2.0.CO;2
- Marcinoniene I., 2003, Tornadoes in Lithuania in the period of 1950-2002 including analysis of the strongest tornado of 29 May 1981, Atmospheric Research, 67-68, 475-484, DOI: 10.1016/S0169-8095(03)00060-7
- Mercer A.E., Shafer C.M., Doswell C.A. III, Leslie L.M, Richman M.B., 2012, Synoptic composites of tornadic and nontornadic outbreaks, Monthly Weather Review, 140 (8), 2590-2608, DOI: 10.1175/MWR-D-12-00029.1
- Rauhala I., Brooks H., Szchultz D.M., 2012, Tornado Climatology of Finland, Monthly Weather Review, 140, 1446-1456, DOI: 10.1175/MWR-D-11-00196.1
- Rotunno R., 1981, On the evolution of thunderstorm rotation, Monthly Weather Review, 109 (3), 577-586, DOI: 10.1175/1520-0493(1981)109<0577:OTEOTR>2.0.CO;2
- Rotunno R., Klemp J.B., 1982, The influence of the shearinduced pressure gradient on thunderstorm motion, Monthly Weather Review, 110 (2), 136-151, DOI: 10.1175/1520-0493(1982)110%3C0136:TIOTSI%3E2.0.CO;2.
- Schaefer J.T., Doswell C.A. III, 1984, Empirical orthogonal function expansion applied to progressive tornado outbreaks, Journal of the Meteorological Society of Japan, 62 (6), 929-936
- Schumann M.S., Roebber P.J., 2010, The influence of uppertropospheric potential vorticity on convective morphology, Monthly Weather Review, 138 (2), 463-474, DOI: 10.1175/2009MWR3091.1
- Setvák M., Šálek M., Munzar J., 2003, Tornadoes within the Czech Republic: from early medieval chronicles to the ‘‘internet society’’, Atmospheric Research, 67-68, 589-605, DOI: 10.1016/S0169-8095(03)00075-9
- Uccelini L.W., Johnson D.R., 1979, The coupling of upper and lower tropospheric jet streaks and implication for the development of severe convective storms, Monthly Weather Review, 107 (6), 682-703, DOI: 10.1175/1520-0493(1979)107<0682:TCOUAL>2.0.CO;2
- Weisman M.L., Klemp J.B., 1982, The dependence of numerically simulated convective storms on vertical wind shear and buoyancy, Monthly Weather Review, 110 (6), 504-520, DOI: 10.1175/1520-0493(1982)110<0504:TDONSC>2.0.CO;2
- Wurman J., Kosiba K., 2013, Finescale radar observations of tornado and mesocyclone structures, Weather and Forecasting, 28 (5), 1157-1174, DOI: 10.1175/WAF-D-12-00127.1
- Wurman J., Kosiba K., Markowski P., Richardson Y., Dowell D., Robinson P., 2010, Finescale single- and dual-doppler analysis of tornado intensification, maintenance, and dissipation in the Orleans, Nebraska, Supercell., Monthly Weather Review, 138 (12), 4439-4455, DOI: 10.1175/2010MWR3330.1