You may have noticed that we now officially have our first area of ​​interest, called Investment 90L, related to tropical development on the NHC map.


But before anyone goes and does potential development work, let’s take a look at this shuffle and why it won’t be such a big deal, relatively speaking.

If you review the satellite loop, you’ll notice a few things.

  • First: it has, in fact, a hub. It can be found southeast of the tip of Louisiana, just turned away.
  • Second: it is showing a pretty good amount of convection, especially in the last two hours or so.
  • Third: that convection is shifted away from the center. That’s really not where you want it to be for tropical growth.


The system, which is resisting some shear forces, is succeeding in pushing its convection away from the center. This is bad news for a tropical cyclone.

Unlike supercells, tropical cyclones do not need shear to organize them. In fact, they perform much better with little or no clipping. Tropical cyclones must be stacked vertically to operate at peak efficiency. The maximum amount of longitudinal shear that the TC can withstand without weakening is said to be around 20 kts (10 meters per second).

Besides the ability to cut the wind, another obstacle that the Invest 90L faces is dry air.


Not only do we have very dry air trying to get in from the southwest, but we also have Saharan Dust to look at.


This dusty air from the Sahara has been blowing over the Gulf Coast for about a day. Desert air is dry air, and dry air tends to suppress tropical activity.

One thing Invest 90L is all about is SST in the Bay Area.


Almost the entire Gulf is above the 26.5 degrees Celsius / 80 degrees Fahrenheit threshold needed for tropical growth. If that’s the only requirement, it might stand a chance.

That’s not the case, however, and with the Invest 90L’s proximity to the coast giving it limited time before interacting with land, cutting for combat and the surrounding dry air, development is at this point. really unlikely.


NHC gives it a 10% chance to grow over the next 48 hours and as evidenced by the picture above, EPS more or less agrees.

However, a word of warning. Just because this storm likely won’t have an official CTV name or status doesn’t mean there won’t be an impact. Certainly, there will be no stormy winds to deal with. However, heavy rain and inshore currents leading to some coastal flooding were a guarantee as well as gusty winds (probably due to TS forces) causing scattered power outages.


Of course, the heaviest rain will be felt along the coast where it makes landfall. As it exits to the northeast, more sizable rain is possible in the southeast.

Some of these areas have seen successive thunderstorms accompanied by heavy rain this weekend. The ground will probably remain saturated from now until the remnants of 90L move over. Flash floods can happen much faster than usual.

Don’t forget about onshore currents/surge and coastal flooding. The Florida handle can see some spikes early in the morning as the system moves ashore. This can affect locations that are particularly sensitive to rising water levels. If you are in such an area, exercise caution and keep that in mind.

The Southeast is unusually dry these days, so it needs rain. Though maybe not that much at once. Either way, stay safe!


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