1. September Atlantic Hurricane Season Update 06 September 2012 Fred Schmude StormWatch Manager ImpactWeather, Inc. fschmude@impactweather.com

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3. September Atlantic Hurricane Season Update 06 September 2012 Fred Schmude StormWatch Manager ImpactWeather, Inc. fschmude@impactweather.com

4. Review of the season through early September Why so many August storms (MJO, ENSO & CCKWs) Current Trends (Disturbance 45, Leslie and Michael) Forecast (ENSO, MJO and Kelvin) Seasonal update, including risk areas through October Topics For Today

5. Today Climatology suggests activity should increase significantly soon You are here

6. As of September 6 th – 13 named storms Ernesto Florence Gordon Helene Isaac Helene Joyce Kirk Leslie X X Isaac 6 Storms Formed after the 15 th !

7. Helene Isaac X X August, 2012 Verification

8. Why so Active in August? Favorable Geographic position for the MJO (Madden Julian Oscillation)

9. Madden-Julian Oscillation (MJO) a pulse of increased TC activity originates in Indian Ocean and tracks eastward (40-day cycle)

10. Wheeler Diagram helps us track the position and strength of the MJO Typically the MJO moves in a counterclockwise direction...from the Indian Ocean through the Pacific-Atlantic and Africa MJO Position from Aug 17-31 Increasingly More Favorable Increasingly Less Favorable UNFAVORABLE FAVORABLE Regions 7 & 8 are unfavorable areas for TC development over the Atlantic Basin, mainly due to elevated wind shear Regions 2 & 3 are favorable areas for TC development over the Atlantic Basin, mainly due to lower wind shear

11. Why so Active in August? Favorable Geographic position for the MJO (Madden Julian Oscillation) El Niño development remained slow during August

12. El Niño Territory Higher Wind Shear La Niña Territory Lower Wind Shear Neutral Slow increase into El Niño Territory

13. Why so Active in August? Favorable Geographic position for the MJO (Madden Julian Oscillation) El Niño development remained slow during August Suppressive CCKW phase kept most of the tropical cyclones as either weak tropical storms or only brief category 1 hurricanes

14. New Term: Convectively Coupled Kelvin Waves (CCKW) Somewhat Similar to MJO Period of 3-10 days Affect Tropics Mainly Between 0N-20N Development Occurs 1-2 Days After Passage of Wave Axis Suppressed Conditions Between Waves

15. GulfAfrica Time Longitude Orange-Yellow Unfavorable

16. Current Trends

17. Current Tropics Summary Disturbance 45Hurricane Leslie Hurricane Michael Next Disturbance

18. SAL Remains Inactive

19. Disturbance 45: Satellite

20. Disturbance 45: Forecast Track

21. Disturbance 45: 5-day forecast

22. Disturbance 45: Cold Front Effect

23. 5-Day Rainfall Projections (inches)

24. Leslie: Satellite

25. Leslie: 5-Day Forecast Track Category 2 Hurricane Category 1 Hurricane

26. Leslie: Scope of Winds

27. Leslie: Model Tracks

28. Michael: Satellite

29. Michael: 5-Day Forecast Track LESS LIKELY TRACK MORE LIKELY TRACK

30. Forecast

31. Developing weak El Niño (Niño 3.4 already up to+0.9C)...More Shear?

32. El Niño Territory Higher Wind Shear La Niña Territory Lower Wind Shear Neutral September / October Forecast ENSO Forecast through October

33. Water Temperature Animation

34. Developing weak El Niño (Niño 3.4 already up to+0.9C)...More Shear? MJO favors more neutral regions later in the month after the 20 th

35. Increasingly More Favorable Increasingly Less Favorable UNFAVORABLE FAVORABLE

36. MJO Forecasts GFS ECMWF UKMET Canadian

37. Developing weak El Niño (Niño 3.4 already up to+0.9C)...More Shear? MJO favors more neutral regions later in the month after Sept 20 Unfavorable Kelvin phase over the next week to 10 days (suppressive phase west of 45W and favorable east of 45W)

38. Kelvin Wave Forecast Africa Gulf Non Favorable 45W Favorable

39. Sept 10 Sept 15 Sept 20 Current UNFAVORABLE FAVORABLE

40. Developing weak El Niño (Niño 3.4 already up to+0.9C) = More Shear? MJO favors more neutral regions later in the month after Sept 20 th Unfavorable Kelvin phase over the next week to 10 days (suppressive phase west of 45W and favorable east of 45W) Overall signals are mixed with either favorable to neutral MJO conditions, an uncertain ENSO effect and mixed KW signals Projecting 5 more named storms from September 6 th through October (4 more in September and 1 more in October) Season Final Total Increased To: 18 - 10 - 3

41. Possible Development & Impact Regions Through October o 18 Named Storms o 10 Hurricanes o 3 Intense Hurricanes (Cat. 3-4-5) Mean Flow Pattern Monitor For Near Shore Activity Monitor For Near Shore Activity Slight Chance Sept 12-22 Longer Track Storms Still Possible Through Early October Longer Track Storms Still Possible Through Early October

42. Questions? Fred Schmude StormWatch Manager ImpactWeather, Inc. fschmude@impactweather.com