Powerful hurricane IRMA set to strike the north-eastern Caribbean Islands

Monday 4th September 2017

Disturbance Thirty Four is still inching its way west across the far south of the Bay of Campeche. Whilst this is still being held in place by a strong frontal boundary, even within its limited range of motion, environmental conditions are improving for development and there is a slim chance of this deepening into a weak tropical storm. Nonetheless, wind shear and dry air should keep this fairly well suppressed and neither intensity nor breadth should cause any angst over a wide area before it beaches in southern Mexico towards the end of the week.

Strengthening category three Hurricane IRMA is now around 550 miles east of the Leeward Islands headed west-sou'west at 12 knots with a current hurricane severity index rating of 23 out of a possible 50 (9 for size and 11 for intensity), producing 105 to 125 knot winds which is bad enough, but a predicted peak passing over or close to the northernmost islands of the Caribbean on Wednesday of 37 (18 for size - almost double - and 19 for intensity) with tropical storm force winds over a potential 220 mile radius will produce destructive wind and torrential rain over a wide area. IRMA will be a very powerful hurricane indeed when it reaches the Caribbean. There is still much uncertainty thereafter but respected commentators have all edged a little further west with their predicted tracks overnight. We can almost dismiss the best option, an early curve into the Atlantic now and whilst those with interests in the Bahamas, Florida, and south-eastern continental United States need to monitor this storm closely, we are seeing more tracks heading towards Cuba before a turn to the north.

Disturbance Thirty Seven is now about midway between the Cape Verde Islands and the Leeward Islands, westbound at 12 knots and is becoming a little better organised. This should start nudging to the north of the convergence zone over the next day or so before turning north-west. Most commentators are ignoring this but I still have a cautious hunch that it may need watching as it approaches the Caribbean later this week.

Another grisly day at sea in the west central tropical Atlantic and storm cones aloft over the north-eastern Caribbean.