September Atlantic Hurricane Season Update 06 September 2012

1. September Atlantic HurricaneSeason Update 06 September 2012 Fred SchmudeStormWatch ManagerImpactWeather, Inc. fschmude@impactweather.com

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3. September Atlantic HurricaneSeason Update 06 September 2012 Fred SchmudeStormWatch ManagerImpactWeather, Inc. fschmude@impactweather.com

4. Topics For Today • 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

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

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

7. August, 2012 Verification X Isaac X Helene

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 Increasingly Less Favorable UNFAVORABLE UNFAVORABLE Regions 7 & 8 are unfavorable areas for TC development over the Atlantic Basin, mainly due to elevated wind shear MJO Position from Aug 17-31 Increasingly More Favorable Regions 2 & 3 are favorable areas for TC development over the Atlantic Basin, mainly due to lower wind shear FAVORABLE FAVORABLE

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

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

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 AfterPassage of Wave Axis • Suppressed Conditions Between Waves

15. Orange-Yellow Unfavorable Time Gulf Africa Longitude

16. Current Trends

17. Current Tropics Summary Hurricane Michael Disturbance 45 Hurricane Leslie 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 1 Hurricane Category 2 Hurricane

26. Leslie: Scope of Winds

27. Leslie: Model Tracks

28. Michael: Satellite

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

30. Forecast

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

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

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 20th

35. Increasingly Less Favorable UNFAVORABLE UNFAVORABLE Increasingly More Favorable FAVORABLE 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 45W Non Favorable Favorable Gulf Africa

39. UNFAVORABLE Current UNFAVORABLE FAVORABLE Sept 10 UNFAVORABLE Sept 15 FAVORABLE UNFAVORABLE Sept 20 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 20th • 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 6th through October (4 more in September and 1 more in October) • Season Final Total Increased To: 18 - 10 - 3

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

42. Questions? Fred SchmudeStormWatch ManagerImpactWeather, Inc. fschmude@impactweather.com