Conditions for Convection

1. Conditions for Convection The Ingredients Method

2. Conditions for Convection • Instability • Moisture • Upmotion

3. Conditions for Deep Moist Convection • Analyse and forecast Upmotion Moisture NWP omega fields Lifting mechanisms: fronts, troughs, conv. lines, sea breezes, orography Instability Surface and lower tropospheric dew points, dry lines Lifted Index, CAPE, lapse rate, potential instability Based on observations, radar, satellite, NWP

4. Conditions for Deep Moist Convection • Analyse and forecast Upmotion NWP omega fields Lifting mechanisms: fronts, troughs, conv. lines, sea breezes, orography Moisture Instability Surface and lower tropospheric dew points, dry lines Lifted Index, CAPE, lapse rate, potential instability Based on observations, radar, satellite, NWP

5. Conditions for Deep Moist Convection Charles Doswell III Moisture Instability Upmotion

6. Conditions for Deep Moist Convection Instability Upmotion CIN CIN Moisture Moisture Click on a topic for more detail

7. Conditions for Deep Moist Convection Instability Upmotion CIN CIN Moisture Moisture Click on a topic for more detail Animate

8. Conditions for Deep Moist Convection Instability Upmotion CIN CIN Moisture Moisture Click on a topic for more detail

9. Instability Sounding Basics COMET module Surface influences Analysis Modification Albedo Animated Vegetation Potential instability Soil moisture CAPE and other indices Convective Inhibition (CIN) Development Tasman Sea Baiu front CAPE Role Other Development and erosion Early vs late storms

10. Moisture Roles Energy for updrafts Instability Other Roles Detection Entrainment Parameters (Td, Tw, RH, precipitable water, moisture conv.) Sources Downdrafts Ocean/sea/lake Mid-level evaporation Surface obs. Surface evaporation Soundings Precipitation Satellite imagery Advection Hail formation Radar Evaporating precipitation

11. Upmotion Convergence Zones Strongly forced Gravity waves Differential heating Mechanical Other Fronts Outflow boundaries Barrier: mountain range Convective rolls Troughs Low level jet Other Dry lines Funnelling: canyon Urban effects Land-sea breeze Mountain breeze Cloud cover Land surface Sea breeze Land breeze Lake breeze Anabatic Katabatic Cloud edge Anvil Change of vegetation Previous rain or outflow Romanian examples

12. Convergence Models - Romania Convergence zone Sea breeze Northern convergence flow Mountain breeze Southern convergence flow Back building squall line

13. Convergence Zone

14. Sea Breeze

15. Sea Breeze example

16. Back Building Squall Line

17. Back Building Squall Line (cont)

18. Back Building Squall Line example

19. Mountain Breeze

20. Mountain Breeze example

21. Northern Convergence Flows

22. Northern Convergence Flow example

23. Southern Convergence Flows

24. Southern Convergence Flows ex. 1 When a low pressure system is situated North of Romania, the inland sea breeze circulation is deflected toward North, and a convergent flow forms in the SE of Romania. If other ingredients are in place, severe convection develops along the convergent flow. This was the case of the strongest tornado recorded in Romania, Facaeni 12 August 2002. The wind field analyzed by ALADIN model for this case and the radar image of the hook echo are shown.

25. Southern Convergence Flows ex. 2

27. Southern Convergence Flows ex. 2

28. Southern Convergence Flows ex. 2