1. 2.6 Synoptic Factors Associated with Severe Convection Subsections: 2.6a Topographic Influences 2.6b Solenoidal Circulations over Simple Terrain 2.6c Monsoons

2. Ingredients for Deep, Moist Convection MOISTURE INSTABILITY SOURCE OF LIFT

3. Overcoming Convective Inhibition

4. Vertical Motion SCALE VERTICAL MOTION Synoptic Scale1-10 centimeters per second Convective Scale 10 meters per second

5. Subsynoptic-Scale Lift Fronts Drylines Gravity Waves or some other form of subsynoptic-scale lift

6. 2.6a: Topographic Influences What is topography? Definition: General term for physical features of a region. Bodies of Water, VegetationSnow and Ice, Soil Type

7. Types of Topographical Influences 1. Orographic Effects 2. Other Topographical Effects 3. Air Mass Characteristics

8. 1. Orographic Effects Synoptic-Scale Cyclogenesis is NOT random

10. 2. Other Topographical Effects Non-orographic Topography Great Lakes: -Favor cyclones in the winter -Favor anti-cyclones in the summer Bottom Line: If body of water is big enough, can alter dynamics and evaporation of moisture as airstream travels above.

11. Around the World DMC ingredients mixed differently Example: Mediterranean Sea Long easterly run vs. short southerly crossing

12. Mountainous Terrain Supports Convection Even Without Favorable Synoptic-Scale Processes!

13. 3. Air Mass Characteristics Vertical Structure is formed by… Airstreams at different levels moving over a point… Patterns associated with DMC arise in part because of superposition of air masses.

14. “Loaded-Gun” Sounding Typical of Tornadic Situations Superposition of Air 1. Deep Moist Layer 2. Elevated Mixed Layer 3. Pacific Air * Low-level moisture is CRITICAL! BANG!

15. 2.6b: Solenoidal Circulations over Simple Terrain Many flows are subsynoptic and mesoscale Others: 1. Land-Sea Breeze 2. Convective Outflow Boundaries 3. Dryline

16. Land-Sea Breeze Important Contributor to Deep, Moist Convection Slowed moving against the flow  Enhanced when moving with it On the order of 10 km  Favored zones for DMC must be close to the coast

17. Convective Outflow Boundaries Can grow to mesoscale! Can be detected and followed

18. Dryline Solenoids may or may not be present Thermal gradient undergoes diurnal oscillation Much remains to be seen about how dryline initiates deep, moist convection Warm, Dry Air Warm, Moist Air

19. 2.6c: Monsoons Seasonal Shift in Surface Winds SUMMER

20. WINTER

21. Monsoons (Cont’d) Most well-known in Tropics and Subtropics of Asia But can occur in mid-latitudes

22. Monsoons (Cont’d) Do NOT inititate convection But DO provide subsynoptic-scale lift Zee End. Questions? Comments? Concerns?