September Atlantic Hurricane Season Update 06 September 2012 Fred Schmude StormWatch Manager ImpactWeather, Inc.

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September Atlantic Hurricane Season Update 06 September 2012 Fred Schmude StormWatch Manager ImpactWeather, Inc.

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

Today Climatology suggests activity should increase significantly soon You are here

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 !

Helene Isaac X X August, 2012 Verification

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

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

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 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

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

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

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

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

GulfAfrica Time Longitude Orange-Yellow Unfavorable

Current Trends

Current Tropics Summary Disturbance 45Hurricane Leslie Hurricane Michael Next Disturbance

SAL Remains Inactive

Disturbance 45: Satellite

Disturbance 45: Forecast Track

Disturbance 45: 5-day forecast

Disturbance 45: Cold Front Effect

5-Day Rainfall Projections (inches)

Leslie: Satellite

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

Leslie: Scope of Winds

Leslie: Model Tracks

Michael: Satellite

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

Forecast

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

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

Water Temperature Animation

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

Increasingly More Favorable Increasingly Less Favorable UNFAVORABLE FAVORABLE

MJO Forecasts GFS ECMWF UKMET Canadian

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)

Kelvin Wave Forecast Africa Gulf Non Favorable 45W Favorable

Sept 10 Sept 15 Sept 20 Current UNFAVORABLE FAVORABLE

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:

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

Questions? Fred Schmude StormWatch Manager ImpactWeather, Inc.