Matt Lanza

Caribbean development chances a near-certainty, as forecasts keep things somewhat interesting in the Gulf

Headlines

  • The Caribbean disturbance now dubbed Invest 97L is likely to become a depression or tropical storm in the next 24 to 36 hours.
  • It will reach Jamaica later tomorrow, then Cuba, then the Gulf on Wednesday.
  • From there, uncertainty is very high, with models spread out all across the Gulf of Mexico both in terms of track and intensity.
  • While wind shear is still expected to generally protect the northern Gulf Coast, this system should probably still be watched over the next 5 days to see how forecasts evolve.

Rafael on the horizon in the Caribbean

Last week we expected Patty to develop in the Caribbean by today or early this coming week. Patty front ran us all by forming way out in the northeast Atlantic. While that storm is not a land threat right now, what develops in the Caribbean likely will be.

Invest 97L is beginning to organize in the southern Caribbean today. (Weathernerds.org)

The disturbance has been dubbed Invest 97L for now, and it will likely become a tropical depression or tropical storm tonight or tomorrow. Its first stop on tour will be in Jamaica probably tomorrow afternoon. Tropical storm conditions and torrential rain are a good bet there.

From there, 97L or Rafael will likely continue northwest across Cuba and into the Gulf of Mexico by Wednesday. Once in the Gulf, Rafael’s motion will be dictated by the upper pattern which features weakening high pressure near Florida. This will steer Rafael to the northwest into the open Gulf but as the high falls apart, it’s likely that the motion becomes slower and more erratic. This is why the forecast out 5 to 6 days with respect to likely Rafael’s track is very uncertain.

A wide range of possibilities exists from a track continuing west to a track north to something back toward Florida with the next system later this week. (Weathernerds.org)

The good news is that wind shear in the northern and western Gulf is expected to be decent, which should allow for weakening before it does whatever it will do. However, there is a fair bit of uncertainty with all this admittedly. It is November, and you expect November things to happen here normally. But this is not a normal year. The Caribbean remains at near record warm levels, which is to say warmer than normal for any time of year, let alone November.

The Caribbean is near-record warm levels for November, which may aid in development in the coming days. (University of Arizona/Kim Wood)

The Gulf is at near record warm levels for the date as well. So from an ocean support standpoint, this system will have a good bit going for it given the time of year. Could Rafael become a hurricane? Absolutely. Could it ultimately threaten the U.S. Gulf Coast? Certainly, though I would not call that “likely” at the moment, and the most aggressive modeling seems to be the GFS, which has historically had a bit of a tough track record in the autumn in the Gulf. But the bottom line is that this will be a system that merits attention, first in Jamaica, then Cuba, and then for the Gulf Coast. We’ll see where things point tomorrow.

Additional development is possible in the western Atlantic over the next 10 days, but nothing has the robust agreement we see with Invest 97L right now.

Caribbean system set to try and form this weekend or next week and another wave causes flash flooding in Puerto Rico

Headlines

  • We are getting a clearer picture of the Caribbean development potential this weekend and next week, with a disturbance possibly developing as it approaches Jamaica from the south Sunday or Monday.
  • From there, it should turn west or west-northwest, threatening Cuba, the Cayman Islands, and perhaps the Yucatan as a tropical system.
  • As it likely tracks into the Gulf next week, it will encounter hostile wind shear that should weaken it considerably.
  • A tropical wave is also producing heavy rain and flash flooding in Puerto Rico.

Caribbean system starting to come into better focus

Our potential system in the Caribbean continues to see support grow for its organization. The NHC is up to 70 percent odds this morning, and it’s possible those increase further today.

Disorganized thunderstorms continue to percolate in the Caribbean, with development odds increasing this weekend or early next week. (Weathernerds.org)

Thunderstorms remain broad and disorganized today in this region, so I think we’ve got at least a couple days before anything happens here. Modeling seems to agree that a piece of the Central American Gyre (CAG) will break off north of Panama tomorrow and track generally northward toward Jamaica. I doubt we’ll see rapid development here, but it is possible that by Monday, we have a depression or something close to that near Jamaica.

The Euro ensemble is in agreement on a possible system near Jamaica on Monday evening. (Weathernerds.org)

This is good model support, though the details and specifics are always tricky. But support from the ensembles and most operational guidance now exists on this as the most likely outcome through Monday evening. From this point, the system will likely begin to be steered by high pressure anchored over Florida. This should turn it northwest and then possibly due west toward the Yucatan. This will be the timeframe that is most critical in terms of potential impacts for Cuba, the Cayman Islands and Mexico. Most modeling keeps the system in check, only strengthening it a bit, but there are a handful of models that are aggressively intensifying this as it comes northwest.

The Euro ensemble is in good agreement on a track that places it broadly between Cuba and the Yucatan next Wednesday. (Tropical Tidbits)

By next Wednesday, we should have a tropical system somewhere between Belize and Cuba. From here, the future track of this system becomes uncertain. High pressure should allow the system to keep going west or west-northwest into the Gulf of Mexico. But by late next week, assuming it starts to turn more northerly, it’s going to get hammered by wind shear. So even if it does come northward toward the central or eastern Gulf of Mexico, it is likely going to deal with November headwinds which should keep its intensity in check. So, for now, we continue to suspect that this won’t be a big concern for the U.S. Gulf Coast. But you should check back in later this weekend or early next week just to make sure. For areas between Belize and Jamaica, including Cuba, this will be a system to watch closely through the weekend. We’ll keep you posted.

Elsewhere: Flooding in Puerto Rico

The NHC is highlighting two other areas, one north of the islands and one near the Azores. Neither has much more than a 10 to 20 percent chance of development and none are a serious concern, although heavy rain in Puerto Rico has been causing flash flooding concerns, and additional rain will continue to cause flash flooding in the eastern and northern portions of the island.

Puerto Rico is under threat from heavy rain and flash flooding through tonight as a robust tropical wave passes. (NWS San Juan)

Most of this should hopefully ease up over the weekend.

Caribbean development odds slowly increasing as we exit October

Headlines

  • Development odds are increasing in the Caribbean.
  • Slow development is possible in about 3 to 5 days with a slow west or northwest movement.
  • Interests in Central America, Mexico, Cuba, Jamaica, and the Caymans should continue to monitor development closely.
  • U.S. impact risks remain quite low due to cooler water in the Gulf and wind shear.

Caribbean development odds inching up

The system that could develop in the Caribbean over the next several days is up to 60 percent today, as the forecast continues to look a touch more bullish on development.

The NHC is slowly boosting odds of development in the Caribbean today. (NOAA NHC)

Back on Tuesday, we noted that it would probably move north or west from where it gets going, and today the NHC basically says the same thing. The upper pattern is favoring something a little anomalous for November, as most often, systems will move north or northeast from the Caribbean this time of year.

Anyway, we have at least loose model agreement almost across the board today that something should get going in the western or west-central Caribbean in about 3 to 5 days. In fact, looking at the Euro ensemble, we can see a clear development signal in the Caribbean by Sunday.

European ensemble on board with tropical development in about 3 to 4 days, much like most other modeling. (Tropical Tidbits)

There will be a number of factors in play that will impact the strength and track of this system. First off, notice that there is also a low pressure signal on the north side of Cuba or Hispaniola. That low-probability system could have an impact on how shear impacts the Caribbean disturbance. Initially, high pressure over Florida and the eastern Gulf will likely help steer this system slightly to the west. Over time, that high pressure system may shift east a bit to focus more over Florida or the Bahamas. This could open the door to more of a northwest or northerly motion into the Gulf from this system.

The upper air pattern will favor a westerly and perhaps eventually a northwesterly motion to this system in the Caribbean. (Tropical Tidbits)

You may look at that outcome and say, “Oh no, here we go again.” But the situation in November is generally much different than that of October. While the Gulf is generally warmer than normal, it has cooled a good deal in the last month.

The Gulf has cooled off a good deal over the last 30 days. (StormVista Weather Models)

So we aren’t dealing with the precursor setup that we were with Helene or Milton. Secondly, wind shear tends to be quite aggressive in November. The forecast of wind shear in the northern and western Gulf is quite significant next week, with high shear in those locations.

A lot of wind shear separates a potential disturbance in the southern Gulf or northwest Caribbean from the U.S. Mainland. (Tropical Tidbits)

That said, any kind of development is worth noting, particularly for folks in Mexico (the Yucatan), Cuba, Jamaica, or the Cayman Islands. And I would encourage those areas to watch this system closely, especially given that the Caribbean remains very warm and has barely cooled off in the last 30 days. For folks in the U.S., this is unlikely to cause major heartburn, but it probably remains worth watching at least until we have a better sense of how things will unfold. For now, it remains nothing of serious concern for the Gulf Coast.

More this weekend.

Caribbean development odds around 50-50 over the next week, as we look to open November on an active note

Headlines

  • Tropical development odds are close to 50/50 in the Caribbean over the next week.
  • Initially, if anything develops, it is unlikely to move a whole lot, rather just sitting over the Caribbean.
  • Eventually, we may see a slow west or west-northwest movement.
  • Interests from Central America through the Caribbean should monitor updates on this.

Apologies for the lack of post yesterday, but I was preoccupied with some other things most of the day. Let’s get into things this morning.

The NHC gives the western and central Caribbean about a 40 percent chance of development over the next week. (NOAA NHC)

Eyes on the western or central Caribbean

Development odds are officially up to about 40 percent now in the Caribbean over the next week, as it appears we will enter a somewhat more active period in the tropics for November. The first thing I think we can say with some confidence this week is that this is not going to be a quick process. If this develops into an organized tropical system, it will take its time. The most likely outcome is that whatever forms here is likely to kind of fester for several days before trying to develop. We can sort of see the beginnings of stuff over the Caribbean this morning.

Far from organization, what we have in the Caribbean are a couple “blobs” of thunderstorms around the periphery. Over time, we’ll see a slow focus toward more storms in the central or wester Caribbean. (Weathernerds.org)

We’ve got nascent thunderstorms all around the periphery of the Caribbean right now. But over time, we will probably see more thunderstorms focus themselves in the central or western Caribbean. This is what could fester its way into development this weekend or early next week.

What will probably end up happening is over the next week or so, we see this begin to pop up and fester in the Caribbean. Heading into the late weekend, high pressure over Florida and the Gulf and a second high pressure system just east of the islands will impart opposite movement on the disturbance, which basically cancels out. The steering currents shift to near zero. In other words, what starts to develop in the Caribbean will be unlikely to move a whole lot initially.

A map of the situation about 20,000 feet up on Sunday. Whatever tries to form in the Caribbean will likely only move very slowly, if much at all. (Tropical Tidbits)

Over time, high pressure in the Gulf will probably stay in place, while high pressure east of the islands weakens. This may allow for a very slow northwest or west movement within the Caribbean next week. Exactly what this means is somewhat unclear at this point but we have several days to watch this. I don’t believe we will see any marked organization of anything until at least Sunday or Monday. For now at least, I would not be too worried about this in the United States, but interests from Central America across the Caribbean should be checking back in with their sources every day or two for updates on this. We will obviously keep watching.

More to come tomorrow.

Beyond this area, there is not a whole lot to focus on at this point.