MARIA making landfall in Puerto Rico

Wednesday 20th September 2017

Dry air has started to enter the convergence zone from the Sahara. It is quite extraordinary for wisps of high altitude sandy air to reach the Leeward Islands at this stage of the season and this almost certainly the forward scout for a major ingress of sand into the food chain. Welcome news for the Leeward Islands and indeed may be the precursor for an early end to the Atlantic production line. One or two European modellers are even pulling the shutters down on the Atlantic, although I'd be hesitant to back that in entirety. This is not however an early end to the season by any means, just a shift in risk areas. Out to the west, eastern Pacific temperatures are falling and we would appear to be entering into a La Nina pattern a little earlier than expected. Sea water temperatures in the eastern Pacific are below normal and above normal in the Caribbean and Gulf of Mexico and in addition, a monsoon trough seems to be forming in the far south west Caribbean. These conditions give us warm water and moisture, both positives for intense storm development. Storms which fire up in this area typically head north-nor'east towards Florida, or curve north west into the Gulf of Mexico. A continuing barrage of cold fronts is likely to keep storms away from the Gulf for the time being, aside from brief dashes across the bay of Campeche. Make of this what you will, but I wouldn't be booking a holiday in Florida yet. If these conditions persist, and despite my allergy to long range forecasts, I believe they will, the other high risk area is likely to be the eastern seaboard although steering currents at this time of the season tend to push cyclones seaward.

Today, from west to east,
Weakening tropical storm JOSE is now 170 miles south of Nantucket and moving to the northeast at 8 knots with maximum winds of 65 knots. The storm is expected to slow down and stumble about off the coast of the north-eastern seaboard over the coming weekend but it is unlikely that JOSE will have any real impact ashore now Hurricane MARIA is making landfall now in eastern Puerto Rico just north of Yabucoa as it moves to the northwest at 8 knots with an HSI rating of 33 out of 50 (11 for size and 22 for intensity). This had an eye-wall replacement wobble overnight which took the edge off the cyclone as it hit the beach but winds touching a terrifying 170 knots are still being reported offshore and full warnings are in place for catastrophic damage. Interaction with Puerto Rico and a glancing blow at the Dominican Republic will change the shape of this storm which is likely to widen from its current tropical storm windfield radius of 140 to 200 miles as it reintensifies. After passing north of the Dominican Republic and close east of the Turks and Caicos Islands on Friday, the forward track is still a matter of unresolved speculation but most models have inched west - only tens of miles - albeit still on a northerly track, and a passage between the eastern seaboard and Bermuda is still the firm favourite.

The remnants of tropical depression LEE are centred around midway between the Caribbean and the Africa coast moving harmlessly to the northwest at 8 knots. Despite the imminent onrush of sand, LEE has organised a little overnight and may reactivate briefly but without any impact on land.

Disturbance Forty Two is centred around three days west of the Cape Verde Islands. This is dashing west-nor'west at an impressive albeit pointless 23 knots which may outrun the sand invasion but will limit any chances of maturing.

Stand by for severe hurricane impact in Puerto Rico and the Dominican Republic.