Matt Lanza

July 27, 2023 Outlook: Odds of the next Atlantic wave developing increase, but it may be destined for the open ocean

One-sentence summary

The odds of an eastern Atlantic tropical wave developing have increased to 40 percent today, but while it’s worth watching (especially in Bermuda), for now it seems most likely to turn away from the Caribbean and America.

Happening now: We’re still a few days away from the next Atlantic wave’s development window

If I showed you a satellite image of the Atlantic this morning, and I asked you to identify the area you would be most interested in monitoring for tropical development, I would assume that you’d pick the one near Florida.

The current view of the tropics on Thursday morning: Storms near Florida and lots of disjointed activity in the open Atlantic. (College of DuPage)

While that is certainly beefy looking, it’s being entirely driven by an upper-level low, not a surface-based system. Tropical development is unlikely to nil in that case. Though, this will hopefully do something to temper the outrageously warm water temperatures surrounding Florida right now. That said, modeling is actually latching onto the tropical wave located this morning around 30°W longitude. If we look at that on satellite, we’re probably all giving it the Larry David treatment.

The tropical wave that models have become fairly bullish on is rather disorganized at this time. Odds of development are near zero in the immediate term but increase to 40 percent over the next 3 to 7 days. (Weathernerds.org)

But! As we go through the next few days, this area is expected to consolidate some and become a little better organized. It will track generally west or west-northwest. Modeling insists it could develop. There is actually very good agreement between the GFS and European operational models and their ensembles (which are 30 to 50 different runs of the model with various initial tweaks) that this will develop, albeit not in a huge way. That aside, this is arguably the best agreement we’ve seen since Don formed. In my estimation, models have tended to be rather aggressive with development in the main development region (MDR) and Caribbean this year. So, while odds of development are on the increase and there’s good model agreement on this, we’ll see. Model odds of development over the next week are probably closer to 80 or 90 percent, but given recent struggles, the NHC estimate of 40 percent seems much more realistic to me.

Anyway, development of this system will likely be slow as it comes westward over the next 3 to 5 days.

The medium range (days 6 to 10): That tropical wave (should) swim with the fishes

One other thing that the models are in good agreement on right now is that whatever happens with this tropical wave, it is likely to turn northwest and north and eventually out to sea, missing the Caribbean and the U.S. Never say never, but that’s comforting for now. I would argue that there’s good reason to watch this if you are in Bermuda though just in case.

As the disturbance comes west, it should be able to split the gap in a weakness between two high pressure systems over the Atlantic, which should allow it to turn north and avoid most land. (Tropical Tidbits)

Beyond this wave, there’s nothing terribly exciting to focus on in the tropics through day ten.

Fantasyland (beyond day 10): All good for now

Quite frankly, it’s almost disturbingly quiet on the models right now out in the extended range. It does seem like we’re entering a briefly hostile background period in the Atlantic beginning around the first day of August. This is due to background activity associated with the Madden-Julian Oscillation and convectively coupled Kelvin waves. I won’t get into the heavy details here, but you can read and learn about the MJO and hurricanes and convectively coupled Kelvin waves here. Eric Blake at the NHC is a great forecaster, and this presentation that the WMO has online is really useful. All that to say that I would suspect that things pick back up again after August 10th or so.

July 25, 2023 outlook: A new area to watch in the Atlantic

One-sentence summary

Invest 95L is running out of time to do much, but in addition to future waves off Africa, we are keeping an eye on another feature northeast of the Bahamas that got outlined for possible development late yesterday by the National Hurricane Center.

Happening now: Southwest Atlantic is the hot spot

Just to tie a ribbon on Invest 95L (for now at least), the NHC has dropped 7-day odds of development to 10 percent. Surely not zero, but getting closer. This morning, 95L is producing showers and thunderstorms in the Lesser Antilles. The Caribbean is loaded with wind shear right now, so it seems fair to say that 95L has a steep uphill battle ahead.

Meanwhile, northeast of the Bahamas, there’s a rather beefy area of thunderstorms.

Showers and thunderstorms associated with a trough of low pressure have beefed up some overnight northeast of the Bahamas. (Weathernerds.org)

While the NHC only gives it about a 20 percent chance of development over the next 5 to 7 days, it certainly is worth keeping an eye on as it comes west. Right now, it has no real surface reflection, so despite looking a bit menacing on satellite, this is nowhere near ready to go. Wind shear may be a serious mitigating factor that keeps this thing from getting going, but dry air should not be a serious factor.

Slide back and forth to toggle between the GFS and European model forecast of this disturbance on Friday morning. Neither does much to organize it before it reaches Florida. (Tropical Tidbits)

It’s moving across a region of warm water temperatures, right around 85 to 86 degrees, which will get warmer closer to the U.S. coast. So, it has an opportunity here. Not to say that this has a great chance to develop significantly (and you can see from the model images above that neither the GFS or the Euro really tighten this one up at all), but it’s an item that stands out more today than previously. Regardless, it appears showers and thunderstorms will be on the increase Friday or this weekend in Florida. There is some chance this could make it into the Gulf, but that also remains to be seen. So we’ll keep an eye on it into the end of the week.

The medium range (days 6 to 10): Still watching off Africa

Our main medium range area to watch continues to be off Africa, as we watch waves emerge off the continent. I still think the next emergent wave has the best chance to emerge from the morass as the system to watch.

The next wave in particular that emerges off Africa may have a shot at developing as it comes west across the Atlantic. (weathernerds.org)

But exactly what comes of this stuff remains to be seen. The overall background state of the Atlantic should begin to become a good bit more hospitable to systems this weekend and next week. In other words, there should be a general reduction in shear and dry air. This guarantees nothing, but it does seem to suggest that something out of these emerging waves is possible. Modeling continues to bounce around and tells us nothing of much value right now, except that chances of development from this area are not zero.

Fantasyland (beyond day 10): Just keep watching

We’ve covered most of the bases today in the first couple sections. Anything beyond day 10 would likely come from those items, so we’ll keep watch and keep you posted.

July 24, 2023 outlook: Don’t invest in 95L, but there will be other investment opportunities to come

One-sentence summary

Invest 95L had a moment where it looked like it might become an interesting feature, but that has since faded so our attention will focus to the next wave to emerge off Africa.

Happening now: Invest 95L struggles & Don finally exits

At one point by Friday evening, the 7-day odds of Invest 95L developing had bumped up to as high as I think 70 percent? The odds were considered “high.” That is down to 20 percent this morning. Why? Invest 95L was unable to hold thunderstorms together enough to stay shielded from the dry air and shear that surround it. Back in Friday’s post, we mentioned that 95L would basically have to insulate itself from dry air to have a chance. The 30 knots of shear around it aren’t helping either.

Invest 95L’s development chances have lowered a good bit due to dry air and wind shear and the fact that it never held itself together over the weekend. (University of Wisconsin CIMSS)

Modeling has pulled back a ton on development chances with 95L since last week, and given the hurdles noted above, it will be tough for 95L to get its act together. That said, it will still deliver areas of heavy rain and thunderstorms to the Lesser Antilles, especially south of about Dominica and Martinique. But as far as organized tropical activity is concerned, it does not appear that 95L will be the one to make it so.

Meanwhile, to the north, Tropical Storm Don briefly became the season’s first hurricane over the weekend. It has since fizzled, and it will become an “extratropical” storm later today. Basically, it’s driven by cooler weather processes and looks more like a nor’easter than a tropical storm.

Don (center top) swirls its way into oblivion out to sea. (Weathernerds.org)

Don is the type of storm we hope we see much of this season: Out at sea, mostly harmless to any land, and working to cool ocean waters a bit. Fare thee well, Don.

The medium range (days 6 to 10): More action off Africa to come

So what’s next? For that, let us again look at Africa.

Two waves in the Atlantic are up next. The lead wave does not seem to have much model support and looks rather disjointed this morning anyway. The trailing wave over Africa has more potential. (Weathernerds.org)

Right now, the next wave up does not appear to have much to it, and model support is also lacking as it comes west. But the wave over Africa this morning will emerge into the Atlantic by midweek. Both the GFS and European models suggest this one has a chance to develop, with the GFS being extremely bullish and the Euro being extremely modest, a trend the Euro has won more often than not this season thus far. Ensemble support is moderate for this as well, with the European ensemble actually a little more excited about development odds than the GFS ensemble, a trend that the GFS ensemble seems to have won more often than not so far this season. Remember, ensembles differ from operational models because they are run 30 to 50 different times with small tweaks in their initial snapshots to help produce more “spread” to give us a better view on possible outcomes.

Regardless of what the models specifically say, it appears this will be the next area to watch heading into the weekend and next week. It seems that steering currents would suggest that anything developing would stay out at sea, but it’s far too early to say so with any conviction. For now, we will watch and wait.

Fantasyland (beyond day 10): Babysitter’s club

We currently don’t see any real specific concerns in the long range, with the exception of this wave emerging off Africa, as discussed above. The main theme heading into early August will likely just be to keep babysitting this stuff. We aren’t overly impressed with anything right now, but given the time of year and water temperatures out there, it makes a lot of sense to keep tabs on everything.

July 21, 2023 outlook: A new “Invest” in the Atlantic worth watching over the next week

One sentence summary

Don continues to menace the open waters of the North Atlantic, while odds for development of a wave east of the Caribbean inch upward.

Happening now: Don & development chances

Let’s get the easy one out of the way first. Tropical Storm Don is swirling out over the open North Atlantic. We’re beginning to see Don turn northwest, and it will turn north and eventually northeast before exiting and being absorbed by the jet stream this weekend.

Tropical Storm Don will exit the picture later this weekend, ultimately being absorbed into the jet stream. (NHC)

Meanwhile, farther to the south of Don, the area of tropical “noise” in the main development region (MDR) between Africa and the Caribbean has been deemed Invest 95L. For those new to this stuff, “invests” are just classification systems for more intriguing tropical waves than usual. Basically, it’s the first step in the process (not always, but much of the time). Some invests never become storms. The classification goes from 90 to 99 and then recycles. The “L” indicates that it’s in the Atlantic basin. Other ocean basins have other letters to define them. All it does is give meteorologists a center point to focus on and run additional tropical-focused modeling on.

Invest 95L in the Atlantic has about a 40 percent chance of organization into a depression or storm over the next 5 to 7 days, though it will be facing some obstacles. (Weathernerds.org)

Over the next 3 or 4 days, 95L will not move a whole lot. Basically, at this point it’s just trying to get itself together. As we have been noting through the week. this disturbance is going to have to fight off some dry air as a potent dust event pushes across the Atlantic. Since earlier this week, it does look like the dust may ease up or push away somewhat which won’t hurt development chances.

By Monday, Invest 95L will be east of the Caribbean islands, still not organized, but modestly insulated from the drier air surrounding the system.

On Monday afternoon, Invest 95L will be several hundred miles east of the Lesser Antilles. It will be somewhat insulated from the drier air surrounding it, though not completely. This strikes me as a system that is going to make a real effort to organize but one that will probably struggle a bit. Wind shear will also be at play here, though it looks a bit less menacing than the dry air to me at this point.

The bottom line: Watch for slow organization from Invest 95L through Monday.

The medium range (days 6 to 10): Watching the MDR

For next week, the main story will continue to be Invest 95L and whatever it decides to do. In general, a track from the Atlantic into the Caribbean seems likely, and it will likely continue to march across the Caribbean next week. I don’t want to speculate too much on what comes of this right now because, as noted above, the dry air and to a lesser extent wind shear will probably act to keep this a bit slow to really get going. Still, it certainly bears watching. Outside of 95L, nothing else is particularly notable.

Fantasyland (beyond day 10): More Atlantic noise?

It is tough to really pin down anything specific behind Invest 95L, but it seems like there will be some noise to consider out in fantasyland. The Atlantic, in general, should slowly become more hospitable to tropical development so we will continue to keep eyes on things.