Busy day aloft but no threat
General overview Wednesday 9th September 2015 from west to east
Over the past few days, some modellers have been punting a tropical depression or storm piping up in the western Gulf of Mexico early next week. The basis for this is a new disturbance starting to take shape in the extreme western Gulf of Mexico along the coast of Mexico which has now been designated disturbance thirty nine - a little prematurely in my view, as the disturbance has not formed yet. Nonetheless when/if the system moves out over the Gulf waters, it may have a chance of developing into a tropical depression or storm early next week. A weather eye needed on this.
Disturbance thirty seven is centred somewhere close to the north of the Netherlands Antilles and moving west at 15 knots. Development is not expected as it tracks across the southern Caribbean over the next couple of days.
Disturbance thirty six has deepened and become tropical depression eight. Situated a couple of hundred miles north of Bermuda, this is stationary but will begin to move north later today. Upper-level wind shear over the area is keeping the associated squalls east of the centre with little change in strength expected until the shear decreases. It will be a tropical storm later today then pass near Nova Scotia and Newfoundland late Friday and early Saturday, becoming an extra-tropical low shortly after passing Newfoundland. Locally heavy rain and gusty winds could impact southeastern Newfoundland on Saturday morning, but most of the wind and rain will be over water east of the centre.
Disturbance forty is a new weak system about a day east of the Leeward Islands, moving west at 12 knots. The disturbance is not expected to develop but will bring strong thunderstorms, gusty winds, and locally heavy rain to the Windward Islands and Trinidad and Tobago over the next 24 to 36 hours. Whatever is left of GRACE is moving quickly west with only poorly organised low-level circulation and sporadic thunderstorm activity. It is expected that GRACE will be a remnant low in 24 to 36 hours and be an open wave when it crosses the Leeward Islands into the eastern Caribbean Sea early on Friday. Any impact to the islands will be minor.
Disturbance thirty eight is a day west of the Cape Verde Islands and is moving westward at 12 knots. Development is not expected. The next tropical wave is expected to emerge off the coast of Africa late Thursday or Friday. Conditions are favourable for this to develop but unlikely to break into the Caribbean of it survives the crossing.