All eyes on a promising new system in the southern Caribbean

General overview 1400z 12th August 2013

Disturbance thirty one is ashore now in Mexico and off our radar.

A new disturbance – thirty three – has appeared in the southern Caribbean, centred around Curacao in the Netherlands Antilles, it is headed west at 15 knots. At present, this is little more than an open wave with no appreciable surface circulation or inspiring cloud systems attached to it, although there are scattered thunderstorms blooming around a nominal centre, which shows some thirst for vertical convection. Frontal activity over the southern US has created a complex web of upper level shear over the past few weeks, which has stifled attempts at convection. This line of fronts has shifted to the latitude of the Great Lakes now, and air aloft over the Gulf is now vulnerably still and may have created a hole for disturbance thirty three to develop. High pressure and a donkey's breakfast of monsoonal winds over Colombia is likely to turn thirty three towards the north west where warm fertile waters await. If this does occur, then conditions are right for this system to develop and begin strengthening as it approaches the Yucatan peninsular and the Gulf of Mexico.

Arguments for developing are tranquil upper air and warm water. Arguments against are residual upper level shear – albeit reduced over the past few days – and excessive ground speed. Cyclones love warm water and still air but need to proceed at a sensible pace to gain most benefit. There is a possibility that this system may make a rush for the Gulf. Modellers are divided over track – some opting for Bay of Campeche, which would mean a short lived spell in the Gulf – whilst others have placed a flag in eastern Texas/southern Louisiana for landfall. Early days, but worth watching.

Disturbance thirty two in the eastern Atlantic is still struggling to cope with dry Saharan air. As things stand, this is unlikely to develop.

Stand easy.