1. Characteristics of Isolated Convective Storms Morris L. Weisman Joseph B. Klemp Presented to you by: Elizabeth Polito

2. Talk Overview Introduction to paper Observed types of convective storms –Single-cell –Multicell –Supercell Physical Mechanisms Controlling Convective storm growth and evolution –Thermodynamic structure –Vertical wind shear Unidirectional shear, curved shear, significance of wind shear vector

3. Observed Types of Convective Storms Convective Cell –Strong updraft (10 ms-1 at least) –Horizontal cross section (10 - 100 km 2) –Vertically extend through troposphere –Each form identified on radar, with own repeatable pattern Single-cell Multicell Supercell

4. Observed Types of Convective Storms: The Single-Cell Storm Towering cumulus stage Mature stage Dissipating stage

5. Observed Types of Convective Storms: The Multicell Storm

6. Cell motion vs. storm motion Observed Types of Convective Storms: The Multicell Storm

7. Supercell evolution on radar Observed Types of Convective Storms: The Supercell Storm Initial storm1 hour90 minutes

8. Radar reflectivity time series Curved hodograph –Splitting storms Right mover more enhanced Left mover suppressed Observed Types of Convective Storms: The Supercell Storm

10. Physical Mechanisms Controlling Convective Storm Growth and Evolution Storm type and severity dependent on environment –Thermodynamic structure (strength) –Vertical wind shear (type) Aid from numerical models

11. Physical Mechanisms Controlling Convective Storm Growth and Evolution: Aid of Numerical Modeling More complex simulation 3 April 1964 –Splitting storm Models are simplified -- but provide foundation to analyze and understand real behavior of storms. ObservedModeled

12. Physical Mechanisms Controlling Convective Storm Growth and Evolution: Thermodynamic Structure Buoyant energy (B) measure more accurate to access instability B really just measure of CAPE W max = (2B) 1/2

13. Physical Mechanisms Controlling Convective Storm Growth and Evolution: Thermodynamic Structure Moisture Stratification: production of downbursts and microburst

14. Physical Mechanisms Controlling Convective Storm Growth and Evolution: Vertical Wind Shear

15. Unidirectional or straight hodograph Curved hodograph

16. Physical Mechanisms Controlling Convective Storm Growth and Evolution: Vertical Wind Shear Significance of Wind Shear Vector