In brief: Invest 96L is not a concern for land. The wave behind does bear watching for much of the Atlantic basin, and today’s post walks through the process over the next 5 to 7 days. Back on land, more serious flooding risks are in the cards today for Iowa and Wisconsin in particular.
Happy Saturday! Let’s get you caught up on all things tropics and flooding.
Invest 96L
It’s been an interesting ride for Invest 96L. Once the darling of some weather models in the open Atlantic, support for development of this one has floundered for now.
Over the next few days, 96L is going to turn northwest or northward into the open Atlantic. More than likely, it will head out to sea, though a couple models do kind of keep some fingerprint of the system hanging around in the central Atlantic for a bit. Either way, this one is not a concern for land, and it is unlikely to really develop much, if at all.
Next tropical wave
The National Hurricane Center added an area of interest yesterday for the tropical wave that is emerging off Africa this weekend. No development is expected initially, but by next week, development is becoming increasingly likely.

Many of you have been monitoring the progress of this one since earlier this week, as modeling has been periodically going ballistic with development once in the western Atlantic. Let’s focus on what we can actually realistically discuss first, then we can talk about what comes next.
First, the wave emerging off Africa has what you’d want to see from a tropical wave that may develop. It’s got thunderstorm activity. There’s a whiff of “spin” evident. Modeling shows a good deal of mid-level vorticity as it is emerging. Basically, it’s the initial seeds you’d want to see for a development candidate.
Over the next 2 to 3 days, the wave will continue to march west, eventually passing the Cabo Verde Islands (which may see some hefty rainfall) and settling just west of there. Interestingly, this wave is emerging around 9 to 10 degrees North latitude, but it probably won’t establish itself before curling a little to the north, up around 15 degrees or so North. This is somewhat important information for the rest of the system’s life, as where it establishes latitudinally could play a role in ultimately where it goes. For example, in the western Gulf, it would be exceptionally rare for a Cabo Verde storm establishing north of about 13°N to make it there. Ike was the one exception to that rule in 2008, so it serves as a reminder that rules are made to be broken, but the odds would not favor that part of the world if this is indeed where this wave establishes.
By Monday evening, we should expect to see at least a tropical wave setup north of 15°N, with only slight chances it has formed into a depression yet.

Heading out to day 5, we still don’t see a ton of development with this one, but we see a pretty strong signal over the central Atlantic, east northeast of the Lesser Antilles.

There are still a number of differences in placement, speed, etc. that we can’t quite resolve yet, but the general trend is pretty much in okay agreement through day 5. From this point, let’s look at the upper pattern.

Initially, the disturbance will be steered around the base of high pressure east of Bermuda. This should allow it to turn more west-northwest or northwest even by mid to late next week. However, high pressure over Florida may flex later next week, which could jam up the disturbance just northeast of the Leeward Islands and Virgin Islands. Particularly if this remains fairly weak through late week, this would be the case.
From this point, it becomes a little more difficult to project where the disturbance goes. High pressure may retreat into the western Gulf by next weekend, which may open the exit door back up, allowing the system to head out to sea. Or if it holds a little firmer and longer, we could see the system get closer to the Bahamas or Florida. Or perhaps it turns north and threatens Bermuda. Or it could drift closer to the East Coast. There are many, many possibilities beyond day 5-7 right now. European ensemble member solutions range from something near Hispaniola or the Bahamas to something already halfway to Europe out to sea. There are just a ton of options out there.
So, what can we say right now? We expect a disturbance to pass the Cabo Verde Islands by Monday. From there, it will come west across the Atlantic, settling about 1,000 miles east of the Leeward Islands by Wednesday. Limited development is expected through Wednesday. From that point, the upper pattern suggests a slower movement that may adjust the disturbance some. Beyond day 7, the forecast turns sharply chaotic with numerous possibilities, intensities, locations, and tracks. Folks from the Caribbean up the East Coast and out to Bermuda should continue to monitor the progress of this tropical wave over the coming days.
Iowa and Wisconsin flooding risks
Hey, remember when I said we finally broke the streak of days without a “slight” risk of excessive rain and flooding earlier this week? Yeah, that was incorrect. A slight risk (2/4) was issued later that day. So the streak continues. And today, it’s a moderate risk (3/4).

Heavy rainfall is moving eastward this morning across Wisconsin, as well as northern Iowa. Additional heavy rain is falling in southern Iowa.
As the day progresses, heavy rain will march east, new heavy rain will follow, and rain amounts of 3 to 5 inches and locally higher amounts are possible across eastern Iowa and southwest Wisconsin.
Some parts of Iowa have seen 3 to 6 inches or more over the last 2 weeks, so the ground is already primed for flooding here, especially in southeast Iowa. Folks in that region should use caution today and tonight.