TS Sean develops some thunderstorms, forecasts to weaken

Tropical Storm Sean has also built some new thunderstorms tonight but still forecast to weaken

TS Sean develops some thunderstorms, forecasts to weaken
TS Sean develops some thunderstorms, forecasts to weaken

Caribbean: Tropical Storm Sean has also built some new thunderstorms tonight but still forecast to weaken. Recent models increasingly show it moving W or even WSW then its low pressure or trough remnant affect the Leewards.

94L a large tropical wave/low pressure in the east Atlantic is building a larger area of strong thunderstorms tonight but circulation is not as strong yet. The last 8pm NHC update has 40% chance of development in 48 hours and 80% in 7 days.

In the 8am Friday morning Euro ensembles there were less possible tracks in the southern islands and it has generally 2 groups of tracks; 1 around north Windwards to Leewards and another set over water just east of the Leewards.

The difference seems to depend on how soon and strongly the tracks develop, which make some gain latitude and feel the pull of passing mid-latitude troughs whilst weaker. Tonight’s 8pm GFS main model is similar and keeps a strongly developed 94L far east and north.

The slower to develop tracks feel the high pressure more and move more W-WNW into islands. The 8pm Fri main model tracks are mainly moving 94L possible center WNW towards the central to north Lesser Antilles.

94L is a low pressure with noticeable spin centered near 9.3N 28.5W. Gradual development is expected the next 2-3 days, NHC has high chance 70% [mow 80% in 2pm update]. By early next week, conditions become more favorable, and more steady development is expected.

A tropical depression can form by early to middle of next week as it moves west. Further development is shown by models mid to late week as it moves west or WNW over the tropical Atlantic and potentially into the islands or just north.

Thurs morning and night models were consistently developing 94L by Mon-Wed and taking it either intro the islands by Friday to Saturday or passing north of the islands.

The Euro(ECENS) model ensembles, show a mix of possible tracks that are strong to weaker but majority move into the Lesser Antilles. A few move more WNW then NW which are very strong scenarios.

The GFS(GEFS) ensembles have more scenarios that develop strong early and these possible tracks go more WNW then NW with some weaker developing late near the southern islands then moving northwest.

So far the GEFS model tracks this Fri morning are a bit more west than before but most moving WNW to NW indicating more gradual development, slower movement.

Tropical Storm Sean is weak and forecast to weaken more as it heads WNW. Eventually models show weakening to a trough that may bring some moisture to the islands next week