1. Severe Convective Storms An Overview  Doswell C.A. III, 2001: Severe Convective Storms – An Overview  Severe Convective Storms, Meteor. Monogr., 28, no. 50, Amer. Meteor. Soc., 13-26

2. General Outline I.Severe Convection - classification, problems, issues - distinction between non- and severe convection II.Observations of Severe Convection - large-scale - mesoscale III.Prediction of Severe Convection - current accuracy - goals for severe convective storm forecasting, to mitigate threats

3. Severe Convection Classification and problems  >=3/4 in. hail  >=50 knot sustained wind gusts  Tornado  Should the average hail size and wind gust be reported as “severe” instead of the single largest size reported?  Precipitation not officially defined beyond severe  Flash floods and heavy rain consideration must include areas’ hydrological circumstances  Hales 2-tiered system for severe thresholds

4. Observations of Severe Convection Large-Scale –Rawinsonde observations are primary –PROBLEMS: - significant gaps worldwide - limiting analysis to the few “oubreak” events –Fig 10: Chart idealizing significant synoptic features in an outbreak of severe convective storms

6. Observations of Severe Convection  Ingredients-based approach –conditional instability –moisture –a source of lift  V.S. Characteristic pattern alone

7. Observations of Severe Convection Mesoscale  Satellite images (qualitative)  Radar, limited  Important aspect: Convective Outflow  Processes –free “internal” instabilities –forced “external” processes –fronts –gravity waves

8. Prediction of Severe Convection ~Current accuracy levels  Progress  Advances in forecasting severe storms and tornadoes, SEE FIG. 12  Increased prediction accuracy  Better public awareness and communication  Frustrations  Not as much attention to non tornadic events  Flash floods/heavy convection not offically “severe”  Hail formation and short-range forecasts

10. Prediction of Severe Convection ~Lessening the threats posed  Needed outside North America –systemic reporting –A way to including events in climatological database –sufficient planning for possible severe events in area’s where threat is rare –public awareness, appropriate reactions

11. Prospects and Unsolved Problems  Forecasting –Improvements in observing systems (ie radar) and related forecasting systems –Difficulties/ less progress  Tornadic vs nontornadic supercell differentiation  Forecasting nonsupercell tornado situations  System to forecast and mitigate flash flood damage

12. Prospects and Unsolved Problems  Weather Modification possibilities –Public appeal –Lack of many severe convective weather processes  New Observations –Doppler RADARs are likely only a beginning –Dual polarization observations possible –Satellite remote sensor improvements  Economic difficulties

13. Severe Convection Final thoughts  Mesoscale and smaller events  “Chaotic” systems  Important unobservables –Resources needed

14. Severe Convective Storms This is the paradox of all science: we are both excited and frustrated by what we do not know, even as we create new understanding”. - Charles A Doswell III, May 2000