Factors Affecting Thunderstorm Formation

1. Instability (CAPE related to steepness of lapse rate)

2. Moisture (CAPE also relates to sfc dew point/mixing ratio)

3. Source of Lift (distinguish between parcel lift and lifting that affects whole sounding)

4. Vertical Shear

Types of Thunderstorms

1. Single Cell (Used to be called "Air Mass")

(BRN>100; 0-6 km shear < 1 X 10^-3 s^-1))

2. Multi-cell (BRN, 60-100; 0-6 km Shear 1 to ~3 X 10^-3 s^-1)

3. Supercell (BRN 5-60; 0-6 km Shear >~4 X 10^-3 s^-1; 0-1 km Positive Shear > 10 X 10^-3 s^-1; 0-3 km SREH > ~150 m² s^-2)

(Classic, Low Precip [LP], High Precip [HP]) Depends On anvil relative flow

Classification of Groups of Midlatitude Thunderstorms

1. Squall-line

2. Mesoscale Convective Systems

3. Mesoscale Convective Complexes

4. Comma-cloud (sometimes referred to as "PVA Comma")