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Madden Julian Oscillation (MJO)
The MJO is an eastward progressive wave of enhanced and suppressed tropical rainfall that moves around the globe in 30-60 day cycles.

Current Global MJO Activity
About this Product: The green contours indicate enhanced moisture and rainfall activity that can help in the formation of a tropical cyclone.  The red contours indicate a suppressed phase of the MJO with little to no moisture and rainfall that can suppress the environment for tropical cyclones to form.  Note that the MJO is not always needed for development however, but can be a huge help to distinguish favorable and unfavorable environments.



GFS Ensemble Forecast
About this Product: Below illustrates the GFS ensemble model forecasts for the MJO.  When these model members reach quadrants 1 and 8 the Atlantic Basin is in a favorable MJO pattern for tropical cyclone formation. The yellow lines are the twenty ensemble members and the green line is the ensemble mean (thick-week 1, thin-week 2). The dark gray shading depicts 90% of the members fall in this area and the light gray shading indicates 50% of the members.



200 hecto Pascals Velocity Potential Anomalies

GFS MJO index forecast phase diagram



North Atlantic Oscillation (NAO)

The NAO is a meteorological phenomenon of differences of mean sea level pressure in the North Atlantic.

North Atlantic Oscillation
About this Product: The image below shows the observed NAO activity dating back to the beginning of the current year (solid black line) and the model ensemble forecasts.  Studies have shown that Atlantic hurricanes are more prone to make landfall during a positive NAO cycle due to a stronger Bermuda/Azores high pressure system.

200hPA Height Anomalies
About this Product: The image below shows the 200hPA global height anomalies over the last 30 days based off the 1981-2010 base periods.  The darker colors indicate above normal heights while the lighter colors indicate below normal heights.

200 hecto Pascals height anomalies animation