Forecasting the possible emergence of tornadoes in Poland

Authors:

• Mateusz Taszarek

Abstract

This paper assesses current possibilities for tornado forecasting to take place in Poland. To that end, the author reviews current research relating to the mechanisms of tornadogenesis and tornado climatology in Poland. It is noted that tornado activity peaks in the May-August period, and between 4 pm and 8 pm. While the long-term average incidence of tornadoes stands at about 4 incidents per year, recent years have seen an increase in activity to 10-12 cases per year. Today we can distinguish two mechanisms responsible for tornadogenesis: the mesocyclonic and the non-mescyclonic. The fi rst mechanism applies to typical strong tornadoes associated with the presence of a mesocyclone (supercell), in which updrafts and downdrafts are separated. This tornado type can last for several hours and is much more readily detected and predicted, since the environment in which it is created is very characteristic. The second tornado type, often called the landspout, is less dangerous, but more diffi cult to predict. On the basis of current achievements in science in general, and meteorological methodology in particular, the author describes 3 methods applied in tornado prediction, i.e. numerical weather models, nowcasting, and atmospheric soundings. On the basis of this, he then sets four operational levels for tornado forecasting. The fi rst level is mostly based on global numerical weather models, and provides for the issuing of forecasts on the basis of analysed thermodynamic and kinematic parameters associated with tornadoes. The second level is similar, but also includes analysis of local mesoscale numerical weather models, as well as current atmospheric soundings. The third level is characterized mainly by the use of teledetection data with a view to identifying and monitoring convective cells. The last level in turn sees specialized radar products used in mesocyclone, hook-echo detection. In Poland, the most important institution dealing with convective issues is the Institute of Meteorology and Water Management (IMGW), which has access to the specialised infrastructure helping it to track and detect convective processes. This consists of the POLRAD remote sensing system (meteorological radar), as well as PERUN (lightning detection). The warnings for dangerous meteorological phenomena are on a 3-point scale, and are given by the BPM (regional meteorological forecasting offi ce). In addition, warnings and forecasts are provided to Crisis Management Centres and institutions responsible for from the reactions to emerging threats. ESTOFEX (the European Storm Forecast Experiment) issues forecasts daily, and forecasts expected convective phenom ena using a 3-point severity scale (for hail, lightning, tornadoes and strong winds). The products of ESTOFEX have a high level of verifi ability, though the lack of nowcasting means that they do not detect any direct threat, instead indicating hazardous areas. The Institution that deals with both nowcasting and mesoscale forecasting is Skywarn, the European association whose Polish branch is "PolscyŁowcyBurz". Skywarn Poland uses publicly-available data - global numerical weather models and remote sensing. Skywarn Poland engages in mesoscale forecasting using a 3-point scale for convection phenomena hazards (hail, lightning, tornadoes and strong winds), also providing nowcasting analysis and issuing up-to-date warnings for individual regions. Analysis shows that effective warning issuance for the occurrence of tornadoes enjoys greatest accuracy on the second and third levels, albeit with the accuracy and verifi ability of the forecasts remaining relatively low at this stage. Poland has the technical possibilities to monitor effectively the radar echoes associated with tornadic supercells on the fourth level. However, due to the limited incidence of tornado phenomena in Poland, specialized warning systems are lacking, ensuring that the achievable reaction time is too short for timely warnings to be issued to the public.