ENWO - European Numerical Weather Outlooks
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In each time step we filter a particular parameter to areas where the model produces convective precipitation (with a rate of at least 0.25 mm/hour). Then, we aggregate all time steps in 24-hour intervals (from 0600 to 0600 UTC) by choosing a maximum or minimum values of the selected parameters (previously filtered with convective precipitaion). We perform such filtering to focus on the areas where the convective initiation is expected by the model. Below, we present an example, how the SB CAPE parameter is filtered by convective precipitation and aggregated into 5h composite map.

In our operational maps we do the same but for 24-hour periods. We use 0600 to 0600 UTC time interval due to this timeframe being most often used as a convective forecast period by the European institutions (including ESTOFEX). Our maps base on highlighting the most important ingredients conducive for severe thunderstorms. However, we compute also a few composite parameters aimed to highlight threat for particular severe weather phenomena. Among them we can list:
WMAXSHEAR - a product of vertical wind shear and instability. Parameter aimed to estimate severe weather potential of thunderstorms (large hail, tornadoes, severe wind gusts). In our modelmaps it takes into account: MU CAPE and 0-6km or 0-3km shear. For more information on the importance of this index check Brooks et al. (2003), Craven and Brooks (2004), Pucik et al. (2015), and Taszarek at al. (2017).

Energy Helicity Index (EHI) - parameter aimed to highlight environments conducive to the occurrence of rotating updrafts (supercells, tornadoes). In our modelmaps it takes into account: SB CAPE and 0-1km or 0-3km SRH. For more information on the importance of this index check Rasmussen (2003) and NOAA SPC webpage

Significant Tornado Parameter (STP) - parameter aimed to highlight environments conducive to the occurrence of significant tornadoes. In our modelmaps it takes into account: SB CAPE, SB LCL, 0-1km SRH, and 0-6km shear. For more information on the importance of this index check Thompson et al. (2003) and NOAA SPC webpage

Supercell Composite Parameter (SCP) - parameter aimed to highlight environments conducive to the occurrence of supercell thunderstorms. In our modelmaps it takes into account: SB CAPE, 0-3km SRH, and 0-6km shear. For more information on the importance of this index check Thompson et al. (2003) and NOAA SPC webpage

Universal Tornadic Index (UTI) - parameter aimed to highlight environments conducive to the occurrence of tornadoes. It takes into account: SB CAPE, SB LCL, 0-1km SRH, 0-6km shear and 0-1km shear. For more information on the importance of this index check Taszarek and Kolendowicz (2013).

Large Hail Parameter (LHP) - parameter aimed to highlight environments conducive to the occurrence of large hail. Its values are calibrated to show the expected hail size in centimeters. It takes into account: buoyancy at -10C height, half storm top height shear, MU LCL temperature, and mixing ratio. Original formula was derived from ESTOFEX modelmaps, courtesy of Pieter Groenemeijer.

Hail Size Index (HSI) - an experimental parameter aimed to highlight environments conducive to the occurrence of large hail. Its values are calibrated to show the expected hail size in centimeters. It takes into account: SB CAPE, 0-6km shear, 800-500 hPa temperature lapse rate, isotherm 0C, SB LCL and SB EL height. Formula developed on the basis of sounding-derived parameters associated with large hail events in Europe. For more information on the importance of these ingredients check Taszarek et al. (2017) or send email.

Lightning Potential Index (LPI) - an experimental parameter aimed to highlight the lightning potential of convective cells. It takes into account: MU CAPE, 800-500 hPa temperature lapse rate, mixing ratio, MU equilibrium level temperature and height. When the temperature of equilibrum level is over -10C, the values of parameter significantly drops. Formula developed on the basis of sounding-derived parameters associated with thunderstorms in Europe. For more information on the importance of these ingredients check Taszarek et al. (2017) or send email.
An example of 24-hour forecast from 6 February 06 UTC to 7 February 06UTC with Lightning Potential Index (left figure) and lightning detected by the blizortung network in the same period (right figure).
Waterspout Index (WI) - an experimental parameter aimed to highlight environments conducive to the occurrence of non-mesocyclonic tornadoes over water surface (waterspouts). It takes into account: 0-3km SB CAPE, 0-3km temperature lapse rate, 0-3km shear, and SB LCL height. The lower is shear and LCL, and higher instability and lapse rate the higher is the index. Formula developed on the basis of sounding-derived parameters associated with waterspouts events in Europe. For more information on the importance of these ingredients check Taszarek et al. (2017) or send email.


References:

Brooks, H., Lee, J., Craven, J. 2003: The spatial distribution of severe thunderstorm and tornado environments from global reanalysis data. Atmospheris Research, 67, 73-94.

Pucik, T., Groenemeijer, P., Ryva, D., Kolar, M. 2015: Proximity soundings of severe and nonsevere thunderstorms in central Europe. Monthly Weather Review, 143, 4805-4821.

Rasmussen, E.N. 2003: Refined supercell and tornado forecast parameters. Weather and Forecasting, 18, 530-535.

Taszarek, M., Kolendowicz, L. 2013: Sounding-derived parameters associated with tornado occurrence in Poland and Universal Tornadic Index. Atmospheric research, 134, 186-197.

Taszarek, M., Brooks, H.E., Czernecki, B. 2017: Sounding-derived parameters associated with convective hazards in Europe. Monthly Weather Review, in press.

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

This project was partly supported by the grants of Polish National Science Centre (UMO-2014/13/N/ST10/01708, UMO-2015/16/T/ST10/00373)