1. Terrain and Precipitation Patterns on Southern Side of the Alps in Meso-Beta Scale Jože Rakovec †, Tomaž Vrhovec †, Saša Gaberšek † and Gregor Gregorič †‡ † University of Ljubljana, Ljubljana, Slovenia ‡ Present affiliation: Meteorological Office, EARS, Ljubljana, Slovenia

2. climatology of Alpine precipitation by Schwarb, Daly, Frei and Schär

3. flow deflection due to rotational effects explains the secondary Alpine precipitation maximum in Ticino

4. full lines: displacements   thin lines: displacements   Buzzi and Tibaldi 1977 Ro=0.7

5. Schär and Schneidereit 2000 Ro  0.75

6. Rotunno and Ferretti 2001 (the 1994 case) deflection & gradient of potential stability

8. what causes the small scale patches – e.g. the belt of small spots from Monti Lessini to Karnic Alps? which is the reason for the primary Alpine maximum in Karnic & Julian Alps? what causes the dry area in Trentino & Tyrol?

9. what can we learn from the simpliest kinematic simulation? this si not precipitation field! it is terrain induced vertical velocity in the mass-consistent model

10. terrain characteristics in 10-km resolution simple kinematics with “synthetic” reliefs and with a “real” relief some wet MAP cases simulations the methodology

12. the W-E averaged slope towards North

13. the S-N averaged height - concavity

14. synthetic reliefs (similar to the ones of Schär and Schneidereit and of Rotunno and Ferretti)

15. kinematic vertical velocities by uniform SW wind

16. kinematic vertical velocities by uniform S and SW wind

17. if Trentino Mts. are removed

18. if Trentino Mts are removed

19. if Julian Alps and Dinarides are removed

21. 24-h MM5 simulation dry uniform S flow

22. MM5, dry uniform S flow Trentino Mts. removed

23. MM5, dry uniform S flow Dinarides removed

24. MM5 wet simulation MAP IOP5 potentially unstable - only Trentino subregion will be presented here left: original relief; right: Trentino Mts. removed. top: vertical velocity; bottom: precipitation

25. IOP 5: vertical velocity at 700 hPa 4 Oct 99 06UTC original relief Trentino Mts. removed

26. IOP 5: 30hr precipitation accumulat. 4 Oct 99 06UTC original relief Trentino Mts. removed

27. IOP 9-10: vert. velocity at 700 hPa 24 Oct 99 00UTC original relief Trentino Mts. removed

28. IOP 9-10: 48hr precipitation accumulation 24 Oct 99 00UTC original relief Trentino Mts. removed

29. conclusions convexity/concavity seems to be important even the simpliest kinematics explains a lot of the climatological precipitation pattern

30. conclusions in potentialy unstable MAP IOP 5 case the main role of orograpical lifting was triggering; in Ticino and Trentino it was coupled with frontal processes and “very intense convective cells”* ) developed in stable MAP IOP 9-10 “a broad southwest current against the windward slopes was dominant feature of the dynamics” * ) * ) Robert Houze and Richard Rotunno: POC Science Director Notes especially in such cases the details of relief are essential