North Atlantic Tropics Saharan Dust Continues But Mid-Atmosphere RH Increasing

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Steady pulses of African dust continue to emit westward in the North Atlantic tropics suppressing tropics cyclone activity. However, the relative humidity/available moisture at mid-level atmosphere is increasing. The mid-level atmosphere increased humidity is very supportive of the tropics starting to percolate.

Saharan Dust Continues an Inhibiting Factor on Tropics

But! Mid-level RH is increasing!

Fig. 1: Latest CAMS model identifying Saharan Dust intensity across the tropical North Atlantic.

Discussion: Saharan dust remains intense in its source region with waves of fallout emitted westward in pulses lowering to moderate intensity across the tropical North Atlantic basin (Fig. 1). The dust clouds remain an inhibiting factor on tropical development. Normally, seasonality eases this issue. We signs of that already. One of the leading predictors of tropical cyclone activity is the amount of moisture at mid-levels of the troposphere. At 600 MB the available moisture is buoyant for many sectors of the North Atlantic tropics/subtropics and likely to increase (Fig. 2). The last third of August should bring a significant uptick in TC activity.

Fig. 2: The available moisture at 600 MB (mid-level troposphere) is an excellent predictor of tropical cyclone potential.