Test 1 1 real bubble in 3 D

Test 1. 1 …real bubble in 3 D simulation Buoyancy is Scale-Dependent!!!

Test 1. 2 Multicell:

Test 1. 2 RKW Theory C/∆u > 1 Rotunno et al. (JAS, 1988) “Optimal” condition for cold pool lifting C/∆u = 1 C/∆u < 1

Test 1. 3

Test 1. 3

Test 1. 3 Davies-Jones, 1984 …from linear theory of circular, convective cells in a sheared environment, covariance of vertical velocity and vertical vorticity is proportional to the storm-relative environmental helicity *assumes steadystate, propagating storm

Test 1. 5 Supercell Tornadoes? …only about 15% of supercells produce tornadoes

Test 1. 5

Test 1. 5 Brandes 1978

Test 1. 5

Test 1. 5 Markowski et al. MWR 2002

Test 1. 5 Swirl Ratio: S = Vo / Wo

12 UTC 500 mb May 7, 1995

12 UTC SFC May 7, 1995

18 UTC SFC May 7, 1995

Radar Composite 7 May 1995 VORTEX

Convective Systems: Squall lines and Bow Echoes

Knupp et al. BAMS 2014

Knupp et al. BAMS 2014

Bow Echoes, Derechos

IOP 8 d. Bz 900 h. Pa Mean Wind Profile 1730 UTC 11 June 70 60 50 40 X 30 20 10 Widespread Instability m/s

Example of a “Serial” MCV/MCS Case 0915 UTC 27 May 1998 0015 UTC 28 May 1998 0715 UTC 28 May 1998 2315 UTC 28 May 1998 0515 UTC 29 May 1998 1215 UTC 29 May 1998

Houze et al. (BAMS, 1989)

Symmetric, 2 -D Squall Line

Johnson and Hamilton (1988)

Houze et al. (BAMS, 1989)

Biggerstaff and Houze (1991)

Johnson and Hamilton (1988)

Newton 1966

Squall Line Environments:

Houze and Hobbs (1982)

Tropical Squall Lines: (Zipser, 1977) Severe Mid-Latitude Squall Lines: (Newton, 1963) Frontal Squall Lines: (Carbone, 1982)

Leary and Houze (1979)

Symmetric, 2 -D Squall Line

Basic Equations: 2 D Squall Line ⁄ -- *Also, no vortex tilting or stretching Or, more simply, consider the 2 D horizontal vorticity equation: where

RKW Theory Rotunno et al. (JAS, 1988) “Optimal” condition for cold pool lifting C/∆u > 1 C/∆u = 1 C/∆u < 1

Early System Evolution “Optimal” C/∆u << 1 C/∆u ~ 1

Mature System: C/∆u > 1

RKW (1988)

RKW (1988)