Invest 94L may grow into a tropical depression by next week

Latest update on the tropics provided by Local 10 Hurricane Specialist and Storm Surge Expert Michael Lowry


It isn’t every year that we look to the Main Development Region of the eastern Atlantic – the deep tropical belt where most of our strongest hurricanes form – in June for tropical formation.

In fact, since the advent of satellite coverage in 1966, of the nearly 300 storms that have formed in the traditional Main Development Region, only two have done so in June – an unnamed storm in 1974 and Ana in 1979.

Even considering storms that formed technically just outside this belt, like Elsa last year that came together at only 9.4 degrees north latitude, storms forming here this early in the season are in the lowest percentile of storms originating this far east.


So it’s unusual, to say the least, to see the National Hurricane Center highlighting a disturbance – already designated Invest 94L – in the far eastern Atlantic for tropical development before even reaching July as they are Friday morning.

As we’ve discussed since the beginning of the week, there are a variety of factors coming together to make the typically hostile environment out here more conducive to tropical activity in the coming days.

Chief among these changes is a reduction in disruptive wind shear, which is usually the single most prohibitive factor to tropical development across the Main Development Region in late June and early July.

The lessening of this wind shear has only just begun and is forecast to follow the disturbance as it nestles safely to the south of stronger upper-level winds on its journey toward the Caribbean Sea.

(University of Wisconsin)

We also discussed last week the possibility of the tropical Atlantic heating up due to weaker than average trade winds from the east, which results in less ocean mixing and cooling.

Indeed, the warmth in the Atlantic continues to rise and as of this week, the Main Development Region is the seventh warmest on record going back 40 years – behind some very active hurricane seasons like 2005, 2010, 2020 and 2011.

The combination of the thermodynamic profile (the water temperatures) and conducive dynamics (lower wind shear) of the region are two big supportive factors in development ahead.

You can see this on our statistically-based intensity models which use these environmental factors as input and are fairly aggressive in forecasting strengthening next week.


About the Author:

Michael Lowry is Local 10's Hurricane Specialist and Storm Surge Expert.