1. THE BLACK FOREST STORM OF 15 JULY 2007: NUMERICAL SIMULATION AND SENSITIVITY STUDIES Evelyne Richard 1, Jean-Pierre Chaboureau 1 Cyrille Flamant 2 and Cédric Champollion 3 1. Laboratoire d’Aérologie, CNRS/UPS Toulouse, France 2. LATMOS/IPSL, CRNS/UPMC, Paris, France 3. Géosciences, Montpellier, France

2. COPS IOP8b – 15 July 2007 (Courtesy of DLR) > 60 dBz 12 km

3. Radar reflectivity : Time evolution of the 10 dBZ contour Montancy radar Simulation (ECMWF) 12:15 –13:00 13:15 – 14:00 14:15 – 15:00 15:15 – 16:00

4. Radar reflectivity : Time evolution of the 10 dBZ contour Montancy radar Simulation (ARPEGE) 12:15 –13:00 13:15 – 14:00 14:15 – 15:00 15:15 – 16:00

5. Motivations and outlines The real time Meso-NH forecast of this event was surprisingly good … but ■ Is this good forecast obtained for the good reasons? ■ What makes the ARPEGE based forecast different?  CAPE / CIN  Surface conditions  Sensitivity tests

6. CAPE MESO-NH / ECMWFMESO-NH ARPEGE 11:00 UTC 14:00 UTC

7. CIN MESO-NH / ECMWFMESO-NH / ARPEGE 11:00 UTC 14:00 UTC

8. Karlruhe Meiztreizheim Achern Hornisgrinde Heselbach Burnhaupt TIME 6 KM 0 KM Water vapor mixing ratio (g/kg) OBS. ECMWF ARPEGE

9. Karlruhe Meiztreizheim Achern Hornisgrinde Heselbach Burnhaupt TIME 6 KM 0 KM OBS. ECMWF ARPEGE Potential temperature (K)

10. Surface moisture analysis : 00UTC ECMWF ARPEGE

11. Sensitivity tests ■ ECMWF surface moisture reduced by 20% ■ ECMWF surface moisture reduced by 50%  Thermodynamical conditions  Convection

12. Karlruhe Meiztreizheim Achern Hornisgrinde Heselbach Burnhaupt TIME 6 KM 0 KM OBS. ECMWF ARPEGE Potential temperature (K)

13. Water vapor mixing ratio @ 13 UTC Control Observation 20% reduction

14. Water vapor mixing ratio @ 13 UTC Observation 20% reduction 50% reduction

15. Cloud top height (color) + Instant precipitation (contour) @ 15 UTC Control 20% reduction 50% reduction Convection is strongly controlled by initial moisture conditions

16. Summary / Conclusion ■ Convection is well captured by the ECMWF- based Meso-NH forecast although the PBL is too cold and too moist. ■ The PBL structure is more correct in the ARPEGE-based MESO-NH forecast but convection is over predicted. ■ There is a large discrepancy between ECMWF and ARPEGE surface moisture analysis ■ The sensitivity tests shows that the convection triggering is strongly controlled by the surface moisture conditions ■ Do we have enough data to validate the surface moisture conditions?

18. MESO-NH Forecasts  3 domains (32, 8, and 2 km) with 2-way interaction.  30h forecast starting at 00 UTC from ECMWF analysis  Mixed phase microphysics (including hail particles)  No convection parameterization in the 2km-mesh model 16/07 06UTC MNH-ECM 12UTC 12UTC15/07 00UTCMNH-ARP MNH-ECM MNH-ECM Run starting from the ECMWF analysis and forced with ECMWF forecasts MNH-ARP MNH-ARP: Run starting from the ARPEGE analysis and forced with ARPEGE forecasts 16UTC Convection over the Black-Forest

19. Karlruhe Meiztreizheim Achern Hornisgrinde Heselbach Burnhaupt TIME 6 KM 0 KM COR

20. Morning Afternoon 1000 m 2000 m Rv mod – 2g/kg Squares : Rv obs ( 2 lidars + Do28)

21. Water vapor mixing ratio : 13:00 – 13:30 UTC Lidar observations Lidar observations

22. Water vapor mixing ratio : 13:00 – 13:30 UTC Meso-NH Forecast Lidar observations

23. Upward motion

24. Convergence > 0.5 10 -3 s -1 + streamlines @1000m

25. 11 UTC 12 UTC 13 UTC14 UTC

26. Convergence > 0.5 10 -3 s-1 + streamlines @ the surface

27. Moisture supply  Soundings (3 hourly)  Airborne lidar (Leandre II + DLR Dial)  In situ aircraft data (Dornier 28)  Soundings (3 hourly)  Airborne lidar (Leandre II + DLR Dial)  In situ aircraft data (Dornier 28)

28. Convergence line in the lee of the Feldberg : Feldberg Radar 13:08 UTC Doppler velocity Wind @ 900hPa Moisture @750hPa > 7g/kg Meso-NH Forecast 13:00 UTC

29. Water vapor mixing ratio : 13:00 – 13:30 UTC Meso-NH Forecast Lidar observations

30. Observation / Simulation METEOSAT TB = 280 K METEOSAT TB = 280 K

31. Observation / Simulation MONTANCY R = 1dBZ MONTANCY R = 1dBZ METEOSAT TB = 280 K METEOSAT TB = 280 K