1. Extreme Convection Near the Himalayas and Andes PMM Science Team Meeting, Salt Lake City, October 28, 2009 Robert A. Houze, Jr. Ulrike Romatschke, Socorro Medina, Kristen Rasmussen Dev Niyogi, Anil Kumar

2. Convective systems Convective component Stratiform component Extreme characteristic Contiguous convective echo 3D volume  40 dBZ Top height  10 km “Deep convective core” Horizontal area  1 000 km 2 Horizontal area  1 000 km 2 “Wide convective core” Extreme characteristic Contiguous stratiform echo Horizontal area  50 000 km 2 “Broad stratiform region”

3. Data & Models  TRMM PR  3D reflectivity  Sample, 1998-2008  South Asia: June-September, 1999-2006  South America: December-February, 1998-2008  NCEP reanalysis  Large-scale environment  WRF model  Simulation of representative cases

4. Himalayan Region

5. Terrain gradients Land-ocean contrast Land cover differences Snow/Ice Tundra Wetland Forest Irrigated crop Crop Savanna Shrub/Grass Dryland/crop Grass Shrub Barren Thar Desert Ganges Delta

6. Monsoon Season Wind & Moisture Climatology SFC 500 hPa 200 hPa

7. Monsoon Season Climatology of Extreme Convective Features Deep Convective Cores

8. Wide Convective Cores Broad Stratiform Regions July TRMM Rainfall Monsoon Season Climatology of Extreme Convective Features Deep Convective Cores

9. Wide Convective Cores Broad Stratiform Regions Monsoon Season Climatology of Extreme Convective Features

10. Example of a wide convective core system in the western region

11. Backward trajectories (HYSPLIT/NCEP) 2.5 km 1.0 km

12. TRMM PR ObservationsWRF Simulation

13. Mixing ratioCAPE

14. WRF Simulation Hydrometeor mixing ratio just after convection formed Isochrones of integrated hydrometeor content

15. Diurnal Variability in the Himalayan Region

16. Deep convective cores (mostly land) Wide convective cores: Land

17. Wide convective cores Nocturnal formation in Himalayan foothills

18. 1730 0530 Composite winds Wide convective core cases Nocturnal downslope flow in Himalayan foothills 0530 1730

19. Andes Region

20. Regions of analysis La Plata Basin La Plata Basin Foothills South Foothills South

21. Wide convective cores Wide convective cores Precip. climatology Precip. climatology Deep convective Cores Broad stratiform regions Summer Season (DJF)

22. Example of a Wide Convective Core

23. 12 November 2003 Multiple tornado reports Tennis ball sized hail reports Gusts of 135+ mph winds reported In Buenos Aires, ~70 mm rain recorded in 9 hours Approximately 30% of affected cities lost power 14 fatalities

24. Wide Convective Case 12 November 2003 Time of TRMM Swat 4:13 UTC (00:13 LT)

25. Wide Convective Case 12 November 2003 925 mb NCEP/NCAR Reanalysis Temperature & Winds 2 h after TRMM overpass 6 UTC (2 LT) 0 UTC (20 LT on the previous day)

26. Wide Convective Case of 12 November 2003 Surface pressure anomaly 500 mb height anomaly

27. Surface pressure anomaly [mb] Composite for Wide Convective Wide Core Cases in South Region 500 mb height anomaly Surface wind (~02 LT)

28. 06 UTC ~02 LT 06 UTC ~02 LT 18 UTC ~14 LT 18 UTC ~14 LT 10 m s -1 Divergence Divergence 06 UTC ~02 LT 06 UTC ~02 LT 18 UTC ~14 LT 18 UTC ~14 LT 10 m s -1 Divergence Composite for Wide Convective Core Cases in South Region Surface wind & divergence

29. Deep convective cores over land only associated with daytime heating often in arid regions Wide convective cores over both land and ocean affected by nocturnal downslope flow line structures common in S. America, not in S. Asia low-level moist jet overrun by dry flow from high terrain triggered over foothills Broad stratiform regions most common over ocean and wetlands absent in arid regions correspond to climatological rain areas Conclusions

30. End

31. Sponsored by: NASA Award# NNX07AD59G