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As always when Invest is on the road to the Caribbean arc with a high risk of reinforcement, the craziest rumors start to run on social networks and on WhatsApp groups. I read today that the nhc reportedly declared that a Category 5 hurricane would pass over the Caribbean arc within a week. I advise people who wrote this to go back and take English lessons because they obviously have big translation gaps ... nhc having absolutely NOT announced such a thing !!
The reality tonight is that we don't know much more about this disturbance than last night. It is still in an area of very dry air and with a lot of sand which has been blocking its reinforcement for 2 days by preventing it from properly organizing. The question is how long this situation will last and what will be its ability to withstand the ingestion of dry air over this period. As you can see, the longer it will last, the better… for us! Especially since the current phase of the MJO (Madden Jullian Oscillation, which is an atmospheric phenomenon much faster than ENSO) is currently positive over the Atlantic, which has the effect of “boosting” convection in water that is already extremely hot.
At the moment 92L is moving faster (18 kts) than the dry air zone to its north. It is therefore anticipated by models and forecasters that over the next few hours it will be able to exceed this zone and find much more favorable conditions. Hence the forecast of nhc which gradually increases the risk at 48 hours. It should still be borne in mind that this risk of strengthening is for the moment for a tropical depression. The nhc does not speak at present of storm or hurricane but of a risk of classification in depression only.
Moreover, forecasting models have largely adjusted the evolution of this system before the West Indies since yesterday. The GFS who had a very aggressive prediction of a 970 system hPa on the north of the West Indies last night is now on 990 hPa north of the arc. Same for the SHIPS which in terms of intensity has reduced its forecast and now forecast a Category 1 (and this is a model that very often overestimates the intensity at sea level).
We now have 2 conflicting hypotheses.
A group of models whoseECMWF extension which anticipates a good storm on the northern half of the arc (and they have been in this position for 3 days) and another group whose GFS which predicts a slightly more powerful system passing a little north of the arc, but this group is more unstable in its prediction which makes this option less clear at the moment.
We are a little less than 120 hours from the possible passage on the West Indies. We are slowly entering the forecast period where we will be able to have a little more confidence in it. The model releases tomorrow noon will probably start to be more consensual and give us a little more tangible information.
For the moment we have to watch this closely and wait another 24 hours to get a more precise idea. If it is classified as a low by tomorrow evening and quickly strengthens into a storm, then it will be time to worry a little if its trajectory forecast were to cross the West Indies. We're not there yet.
To follow the live quantified evolution of Invest 92L is HERE.
Image credits; Tropical tidbits, NHC / Noaa, UW-CIMSS
