The Web Site and Blog of Ted Keller

Tropical Weather Update: 7/23/20

We are way ahead of schedule on tropical systems in the Atlantic in a year where tropical activity is forecast to be above normal.

With the formation of “Gonzalo” way out east of the Leeward Island chain, we now on named storm number seven.

All of the storms to date have fit the definition of a tropical weather system but have all been very weak storms.

Statistically, the period of late August through September is the peak of hurricane season. Does this mean we have only just begun to rack up named storms?

Most likely. The two basic ingredients for tropical storm and hurricane formation are warm water and weak wind shear. The water temperature is a given with warmer-than-normal water having the effect of spiking storm strength, all else remaining equal.

The weak wind shear is a generalization born of existence of a La Nina wind pattern over the Pacific, which tends to weaken the jet stream over the Atlantic basin allowing storms to mature.

This time of year, Gulf of Mexico development is favored. At this writing, tropical depression number eight is being monitored as it slowly moves west toward Texas.

As waves develop and travel west off of the coast of Africa, they become the seeds for tropical storm formation. This happens in the so-called Main Development Region (MDR). If young systems stay in weak wind shear and are not affected by too much dry air, they will flourish.

What about the U.S. and landfalls? This will very much depend on the overall jet stream trends. If troughs of low pressure continue to visit the eastern U.S. and adjacent Atlantic waters, there will be a tendency to steer tropical system back to sea especially for storms coming from the MDR.

Storms that develop in the Gulf may find a way to be drawn northward to U.S. landfall (Michael 2018, wow!)

It should be interesting to watch to be sure!

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