cieldumort
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A wave that has recently entered the far eastern Tropical Atlantic well south-southeast of the Cabo Verde Islands is more likely than not to track underneath a building area of high pressure left in the wake of a recurving Lorenzo and potentially track much farther west and develop in the Atlantic basin than most have done this year.
Conditions for development in the Main Development Region (MDR) this week and into next look markedly more favorable than they have throughout the bulk of this season, with abundant instability, rising motion, less dry air, and a forecast of less shear.
Despite it being mid-October, this year, like last, is trending back-loaded. If conditions for this wave play out as forecast, it could become a named storm approaching the Caribbean later this week into next. As such, we are starting a Lounge on this disturbance at this time.
No Invest tag yet and not yet mentioned in the
More details to come
This wave, now nearing the Caribbean, has been Invest tagged 98L today and the title has been updated accordingly.
2025-10-18 12:00 11.7N 49.9W 30 KTS
Ciel
Edited by cieldumort (Sat Oct 18 2025 01:02 PM)
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Owlguin
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Thanks. Both main models seem to be picking up on this and developing it into a pretty strong storm. Plenty of time to see how that plays out.
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TanukiMario
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Thanks. I'll be following this one.
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cieldumort
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10-15-0z model runs out to 180 hours (7.5 days)
Models are increasingly holding off development of this wave until it just approaches, and more so, already well into, the Caribbean, sometime next week.
In sharing these, it is worth noting that 2025 has been a very challenging year for the models and forecasters, so much should be taken with a helping of salt.
Of all the models, the Google DeepMind GDM-FNV3 (Google Deep Mind's newest ensemble machine learning weather model, optimized for cyclones) has really been outstanding in terms of track and intensity for certain, and a cursory glance at how it has handled issues of TC genesis/no genesis, also a very good performance. At the other end, the has spun out so many phantom Caribbean TCs (usually of the CAG variety) this year, it is seriously at risk of becoming the little boy that cried wolf for when one actually does form, eventually, some month, some year, maybe this, maybe next.
All in all, this is a strong signal for TC genesis in the Caribbean by the middle of next week. TCs that are in the Caribbean nearly always make a landfall, and often more than once. Additionally, this part of the basin has not yet been tapped of its potential, with very warm waters extending to exceptional depths.
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MikeC
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Mixed model support on this system, worth following, but odds and climatology are still stacked against anything developing, or if it does staying away from any major landfall events. Key indicators, consistency in ensembles (particularly euro and google deep mind) and it's ensembles are showing lots of development potential, but the others aren't. Something may happen, but those in the Caribbean, Central America and the Yucatan Peninsula seem to be the most likely ones in the long range.
I.e. monitor, but not really concerned.
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CFHC
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puts it over Haiti as a major. Euro and Google put it into Central America then bends back over Florida from the west coast in about 2 weeks.
Not too concerned yet, but in monitor mode.
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Robert
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...
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cieldumort
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Possibly the best model ensemble this year is the Google DeepMind, and it is not a bad one to give some credence to for as far out as 10 days.
Today's most recent 240 hour (10 day) outlook from the DeepMind continues to show a sizeable number of its ensemble members developing this wave in the Caribbean, with most of these then also showing a near collapse of steering currents, with the forecast future cyclone meandering about for a bit. Beyond ten days this model does show more of them moving the system, but beyond ten days is also pushing the capabilities even for this excellent model.
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cieldumort
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A collection of 10/17/0z globals out at 168 hours (a week out) from initialization strongly suggests development is possible if not likely in the Caribbean, with earlier development favoring a stronger-sooner cyclone that runs into the eastern Greater Antilles, heading, presumably, out to sea, whereas a delayed-weaker system might head for the western Caribbean, ultimately of concern for other locations.
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cieldumort
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Tonight's 0z hurricane models seem to be losing the vortex, if they even capture one. This could be one of the rare times where the globals do a better job, at least for now. All models should perform much better once recon missions begin, but so far, none have been tasked.
Looking at tonight's 0z "Big Three" globals ten days out highlights the unanimity of the globals that 98 will develop once in the Caribbean. From there, where it goes, is far less certain. Should 98L find itself in the central to western Caribbean mid/late next week, steering currents could even collapse.
10/19/0z EURO, CANADIAN, AMERICAN out to 240 hours
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CFHC
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System looks impressive on satellite this morning, but not really fully organized. This setup has the potential for the low level area outrunning the convection to the west, and you wind up with a huge convective area moving to the north without a low center. With the models (Still) split on how this winds up I think that's fairly likely.
Right now the lower level area is on the west end of the convection, not really aligned, but not completely out of the way. recon will help determine it when that heads out tomorrow.
However, not before it actually develops, and those in the Caribbean would see impacts regardless.
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cieldumort
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We now have several recon missions to look forward to that have been tasked. Data assimilation has been a little wanting with this wave, especially considering we have not had a single recon mission into it yet. Its track across the islands did add some extra information as to its structure we did not have before, but all in all, I do not have a high level of confidence in the models with what they have had to work with thus far. This is a tricky set up in a tricky year, also with the introduction of several new models, some better than others, but also with drawbacks.
Going with what we have to work with so far, which isn't all that much compared to the usual, I am still going to toss out my personal best guess for 98L's lifetime maximum intensity, something I try to do as a little academic exercise with systems likely to impact land. This is not to forecast their maximum intensity at landfall, however.
Best guess for 98L's lifetime maximum intensity
Disturbance/No-TC (Current status) 1%
Tropical Depression <39 MPH 2%
Tropical Storm 40-50 MPH 3%
Mid/High-end Tropical Storm 60-70 MPH 10%
Cat 1 Hurricane 12%
Cat 2 Hurricane 16%
Cat 3 Hurricane 21%
Cat 4 Hurricane 22%
Cat 5 Hurricane 13%
In summary, I think the chance 98L becomes a Tropical Cyclone is 99%, a Hurricane 84%, a Major Hurricane 56%
This opinion is of lower than usual confidence. Limiting factors to higher confidence: Potential land interaction/s, nearby dry air, mis-analyzed shear, lack of recon missions. Will update later after flights.
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TanukiMario
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Now that the and the are coming closer in agreement over the north then northeast turn into the Atlantic, it would seem the most likely scenario is through Cuba and FL is off the hook? I'll admit last week I was getting Hurricane David vibes... especially since I have a trip to the DR planned during the forecast window.
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cieldumort
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Quote:
Now that the and the are coming closer in agreement over the north then northeast turn into the Atlantic, it would seem the most likely scenario is through Cuba and FL is off the hook? I'll admit last week I was getting Hurricane David vibes... especially since I have a trip to the DR planned during the forecast window.
Personally, I'm not confident in model forecast tracks given the propensity for the LLC to want to establish itself a bit south, at least so far, and that we have not had a single recon mission in there yet. Track forecast should become more trustworthy after tomorrow (after data from multiple missions comes in). If 98L/Melissa-to-be misses the first trof exit out (E Cuba/DR/PR), there's that very legitimate risk that it lollygags around in the western Caribbean, and fine-turning how the next exit window turns out, this far out, is just too uncertain. Extra days delay is more time for steering currents to change
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cieldumort
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Now that hurricane models and intensity models are no longer hallucinating the demise of 98L and are actively expecting a coherent vortex, they are starting to become more reliable. The most recent 0z runs out are way up from where they were just 24-48 hours ago, when many saw nothing. Most now foresee a hurricane.
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MikeC
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The system's low level wave axis is still too elongated, recon tomorrow will help determine what the state of 98L is.
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cieldumort
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Looking at the Google AI ensembles, both the most recent FNV3 and GENC suites have eased up on crossing Hispaniola, with several more members stalling, then looping back around towards the west. GENCs deepen slower overall than the FNV3s, but this can probably be explained by the fact that the FNV3 is specifically designed to forecast tropical cyclones, whereas GENC is a general purpose weather model.
Both 18Z AI model members that take 98/Melissa back towards the west largely ramp her up into a Major, except for some of the early landfalls.
18z FNV3
18z GENC
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MikeC
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Best to do nwcasting, the system is beginning to consolidate a center, but trough axis is still a bit elongated and sticks from the tip of Venezeula up to north of Aruba, where that area is likely to be the ultimate center. Models do not have a good feel for the setup right now, I think the is too far off where the center is.
Counter to development is a pretty strong jet, which could expose the center. (Shear) And also mid level dry air to the west of it. So it's at least capped in the near term.
Recon is sorely needed here.
Edited by CFHC (Tue Oct 21 2025 09:15 AM)
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