Wat betreft de Invest in the Atlantic:
quote:
David vs. Goliath? 96L fights the El Niño factor
As of 2:00 pm EDT Monday, Invest 96L was located near 10°N and 31°W, moving west at about 10 mph. Located along a broad monsoon trough that coincides with the Intertropical Convergence Zone, 96L remains only loosely organized, with a large but unconsolidated area of showers and thunderstorms. Vertical wind shear is light (less than 10 knots), and 96L will encounter warmer sea-surface temperatures as it moves west-northwest (up to 28°C, or 82°F, by later this week), so the large-scale conditions favor gradual strengthening. The National Hurricane Center has been increasing the odds that 96L will develop: in its 8:00 am and 2:00 pm EDT updates, NHC gave the system a 50% chance of becoming a tropical depression in the next 48 hours and a 70% chance over the next 5 days. The RAMMB/CIRA Tropical Genesis Index is also maintaining high odds for development. Among the favored models for intensity, the 1200 GMT Monday runs of the statistics-based LGEM and SHIPS models, which rely heavily on climatology, bring 96L to Category 2 strength by Thursday. The dynamics-based HWRF and GFDL models, which simulate tropical systems within nested high-resolution grids, diverge on the future of 96L. The HWRF develops 96L into a Category 1 hurricane by Thursday, while the GFDL fails to develop 96L significantly. As we discussed in last week’s post on tropical cyclone modeling, HWRF features a dramatic increase in resolution this year, so it will be interesting to see if it correctly pegs the fate of 96L.
While it seems that 96L has a reasonable shot at becoming a tropical storm (which would be named Danny), it also faces some obstacles. Foremost is a huge area of dry air and Saharan dust that extends across the tropical Atlantic just north of 96L's path. As the system grows in size and strength, it would become more likely to ingest some of the dry, dusty air, which would hinder shower and thunderstorm activity. 96L may also encounter an increasing amount of vertical wind shear as it approaches the longitude of the Leeward and Windward Islands this weekend, assuming it survives up to that point. Over the northern Caribbean, shear has actually lessened from the near-record values observed earlier this summer, although shear values of 20 to 40 knots continue to prevail across the southern Caribbean. The ever-strengthening El Niño favors westerly wind at upper levels across this region, though it's possible that the relative lull in shear over the northern Caribbean will continue as 96L approaches. A weak upper-level low is forecast to become pinched off near the Bahamas, south of a building ridge over the northwest Atlantic; this low could become a growing influence on 96L's track and intensity as it moves west of longitude 60°W.