Two weak disturbances and further speculation

General overview 1600z 6th August 2013

Disturbance twenty nine is centred around 380 miles north east of the Virgin Islands and is moving to the west-nor' west at 20 knots. This ground speed prevents low pressure cells from forming any meaningful heat transfer relationships with warm seawater thus no tropical development is expected. In any event, there is still some upper level shear from a busy frontal system aloft, which will also serve to stifle cyclonic development.

Disturbance thirty has formed about one day's steaming east of the Windward Islands, which is a typical breeding ground at this stage in the season. In this case, it is a rather weak system which is moving west and 12 knots. Squalls associated with this are displaced to the east of the nominal centre of circulation which indicates upper level shear, and usually prevents vertical convection currents from forming. No significant tropical development is expected other than squally weather across the Windward Islands tomorrow.

The huddled modellers are still talking up a disturbance forming in the next couple of days in the eastern Gulf of Mexico, in the wake of a retreating front, and still expecting this to be weak and to head west towards Texas. I still have a sailor's healthy cynicism about the accuracy of modelled cyclone predictions where, at the moment, there is only still, fresh air and the odd seagull, but it won't be the first time I've been caught out.

Stand easy. 

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