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 26, 2023 outlook: August is nigh

One-sentence summary

There are a couple of areas that we’re watching, but overall things are fairly quiet for July with no imminent threats to land; however we’re now just six days away from August and at some point the switch is going to flip.

Happening now: Not too much, thankfully

We’re watching a (very) poorly defined area of thunderstorms near the Bahamas that Matt mentioned yesterday. However the odds are still stacked against this becoming something to worry about. So I want to talk a little bit more about climatology today.

We’re still about three weeks away from when we typically would expect the Atlantic tropics to come alive. This often happens around mid-August, when sea surface temperatures near their summer peak, wind shear reaches a nadir across much of the Atlantic, Caribbean and Gulf of Mexico areas we’re concerned about, and tropical lows move off the Africa coast with some regularity. This period is easily visible when we look at historical activity in the Atlantic, typically running from August 10 to around October 20.

Historical activity in the Atlantic basin. (National Hurricane Center)

The past offers no guarantee for what will happen in the year 2023, of course. Already sea surface temperatures are absolutely sizzling in the Atlantic and Gulf of Mexico, and are plenty warm to support the development and strengthening of tropical systems. We are also (see next item below) starting to see tropical waves moving off the coast of Africa with a bit more frequency.

What’s been holding us back so far this year has been El Niño, and its tendency to keep wind shear levels in the Atlantic above normal. We’re going to really need that pattern to hold on this summer, or else the Atlantic basin is likely going to explode with activity in about two or three weeks.

The medium range (days 6 to 10): A new contender emerges

As expected, the National Hurricane Center has started to track a tropical wave that recently moved off of Africa into the Atlantic Ocean. The global models are somewhat bullish on this system as it moves westward across the Atlantic Ocean, and it may develop into a tropical storm in five to seven days, or so.

This probably will be a fish storm. We’ll see. (National Hurricane Center)

The most likely scenario for this system, however, is that it curves to the north before threatening the Caribbean Sea or continental United States, but we’ll continue watching it all the same.

Fantasyland (beyond day 10): Happily quiet

There’s not much else out there, even in the fevered minds of the global models 10 days or later from now. That will change, so for now we’re embracing the quietude.

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.