Melissa forms in Caribbean, forecast to intensify and stall over exceptionally warm water

The easterly wave that I mentioned in the posts on October 13 and again on October 15 finally made it into the Caribbean on Sunday and then was upgraded to Tropical Storm Melissa on Tuesday morning. It is located in the central Caribbean Sea, south of Hispaniola and just north of Venezuela.

Melissa is the 13th named storm of the season, and formed just four days ahead of the climatological date of 13th named storm formation.

The storm is forecast to gradually strengthen in the coming days, but also slow down to a crawl as it loses steering currents. And any time there is a forecast involving weak steering currents, there is an exceptional amount of uncertainty. Of course, the "cone of uncertainty" can't actually capture that because it's the same size for all storms all year long -- so on the map below, you need to mentally inflate the later days of the cone in this case. [see "Cone of Uncertainty" Update & Refresher]

If we take a look at some ensembles, we get a sense of the range of possibilities that helped to inform the NHC forecast shown above.  Some members track it across the Caribbean toward Central America, while others show a stall followed by a sharp turn to the north. Several others linger somewhere in between the two.  Any track forecast more than a few days out has very low confidence.  These ensemble members' tracks are shown out to one week (October 28)... American model on the left, European in the middle, and Google Deepmind on the right.

NHC is leaning slightly toward the north turn scenario, and has issued a tropical storm watch for Jamaica and a hurricane watch for Haiti's Tiburon Peninsula. Certainly anyone in the western Caribbean should be paying close attention to this... and if the lingering lasts longer and it drifts further west then a turn to the north eventually happens, it's not out of the realm of possibility that Florida will need to be on alert -- but not yet.

Quite a number of the ensemble members indicate Melissa becoming a strong hurricane in the coming week, while others keep it very weak -- again, huge uncertainty. One element that looks much more certain is flooding rainfall across the Greater Antilles, particularly Haiti and the Dominican Republic.

The ocean heat content is exceptionally high for this time of year across much of the Caribbean, so even a stalled storm will not be able to upwell cooler water from below. The Caribbean is famously an endless fuel source for hurricanes, and these huge anomalies only boost that further.

https://bmcnoldy.earth.miami.edu/tropics/sectors/

If the forecast scenario of an "M" storm in October cruising into the Caribbean, stalling, and turning north as a major hurricane seems familiar to you, it should: this outcome would be remarkably similar to what we saw with Matthew in 2016:

Track of Hurricane Matthew (2016)

... and also Hurricane Hazel in October 1954:

Track of Hurricane Hazel (1954)

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