1. Convective indexes calculated from HIRLAM output St.Petersburg The Russian State Hydrometeorological University Faculty of Meteorology Meteorological Forecasting Department Kanukhina Anna

2. Aims: to estimate possible use of convective indexes calculated on HIRLAM outputs for forecasting of place, beginning time and type of mesoscale convective phenomena

3. Initial data are HIRLAM analysis and forecast files : - air temperature at surface and heights at various periods; - dew point temperature at surface and heights at various periods; - wind parameters at surface and heights at various periods; - surface pressure tendencies; - specific humidity at surface and heights at various periods;

4. 3 types of indexes: diagnostic - atmospheric preparedness for convection development (Г, С, MOCON); index having triggering function (  ); indexes estimating possible type of arising phenomena (CAPE,HEI);

5. atmosphere statical stability index Г Ге = Г =

6. moisture convergence MOCON= r – specific humidity, kg/kg ; V – wind speed at 10 m, m/s ;

7. generalized index indicating possibility of convective disturbance formation С Г =

8. convective instability indicator (Falkovich’s index) χ  =

9. EHI energy helicity index EHI =CAPE*H Н – relative wind helicity; CAPE convective available potential energy: CAP  =

10. Studied cases divided into 3 groups 1 group: days with thunderstorms and showers; indexes indicate high possibility of these weather phenomena; 2 group: days without any convective phenomena but indexes shows existing possibility of phenomena arising( atmospheric instability); 3 group: days associated with thunderstorms and showers; atmosphere is stable according to indexes consideration;

11. Used data HIRLAM forecast; HIRLAM analysis; sounding data; surface observations (synoptic charts OSCAR, registered thunderstorm charts from FMI site http://www.ava.fmi.fi/~tjt/salark.html).

12. Studied cases 29.06.2000 19.06.2001 21-23.11.2001 03-06.07.2002 16-20.07.2003

13. 23.11.2001 12UTC

14. Indexes profiles for Kardla, Estonia

15. MOCON, 1/s for Kardla (Estonia) on 23.11.2001 12 UTC analyse fc=12 fc=24

16. MOCON and χ scattering graph for 6 h forecast (on base of analisys on 23.11.2001 06:00 UTC and forecast 23.11.2001 00:00 UTC)

17. С and Γ scattering graph for 6 h forecast (on base of analisys on 23.11.2001 06:00 UTC and forecast 23.11.2001 00:00 UTC)

18. CAPE and HEI scattering graph for 6 h forecast (on base of analisys on 23.11.2001 06:00 UTC and forecast 23.11.2001 00:00 UTC)

19. 29.06.2000 12UTC

20. MOCON, CAPE analysis on 29.06.2000 12 UTC

21. Thunderstorms chat on 29.06.2000 (http://www.ava.fmi.fi/~tjt/salark.html)

24. СAPE and MOCON scattering graph for 24 h forecast (on base of analisys on 29.06.2000 12:00 UTC and forecast 28.06.2000 12:00 )

25. С and Γ scattering graph for 24 h forecast (on base of analisys on 29.06.2000 12:00 UTC and forecast 28.06.2000 12:00 )

26. Indexes’ correlation coefficients (forecast and analysis) Ряд 1 –С Ряд 2 – Γ Ряд 3 – χ Ряд 4 – СAPE Ряд 5 – MOCON Ряд 6 – HEI

27. Conclusions -χ values defined by forecasts have essential distinctions with calculations from analysis and χ can not be used for atmospheric state estimation when forecasting at period more than 6h. -The same could be said for HEI. -CAPE and MOCON may be used forecasting at period no more than 12h. -С and Γ forecasts are close to real situation even at 24h forecast period particularly for C values.