Two disturbances merging in the NE Caribbean
General overview 1400z 3rd September 2013
Disturbance forty is currently over the Leeward Islands, westbound but at little more than walking speed. There is no doubt that disturbance forty seven, approaching fast from astern at around 12 knots will merge with and absorb this system over the next 24 hours. The combined system is then expected to move to the west-nor'west, passing south of Puerto Rico tomorrow and toward the Dominican Republic on Thursday. Thereafter, a turn to the north is expected. This would result in a track through the south eastern Bahamas. There is little or no wind shear to spoil this party, but there is a band of dry air between Haiti and Anguilla which would put development chances at around 50/50. If this does deepen and strengthen, it is likely to head for the eastern seaboard of the continental United States but any further speculation would be premature. Irrespective of development, this will bring rain across the entire north-east Caribbean, heavy in places.
Disturbance forty six is still ashore but has a very respectable windfield as it approaches the Bay of Campeche where it will go seaborne again later today. However, aerial imagery shows some strong wind shear coming off the Mexican coast - albeit likely to be over in the next day or so. This may allow the disturbance to slowly develop as it moves in the general direction of mainland Mexico however, this is not expected to move into the central or northern Gulf of Mexico.
It is fortunate that disturbance forty four has dissipated as the greyhound analogy was running thin.
A new non-canine disturbance – tagged forty eight has launched from the African coast and is just passing the Cape Verde Islands, headed west-nor'west at 7 knots. The disturbance is showing signs of organisation, however, it is moving toward an area of less favourable environmental conditions. Early days, though.