GERT weakening after violent night
Thursday 17th August 2017
We described Hurricane GERT as a nasty little bruiser yesterday, but by night it became a violent thug. This hit a hurricane severity index rating of 23 last night (13 for size and 10 for intensity) with sustained wind speeds of 105 knots. This was the most powerful storm of the season to date. Aside from a stiff breeze and swell around Newfoundland, there was no impact ashore but a long sleepless night at sea. Hurricane GERT is traversing cold water now and weakening quickly, some 330 miles south east of Newfoundland. This will weaken quickly now as it accelerates north east.
To the south, four disturbances are on the Transatlantic production line, two with development potential. Starting in the west, Disturbance Thirty Three is crossing the Virgin Islands now, causing rain and the odd roll of thunder in scattered squalls. Conditions ahead are not particularly favourable for storm development so we can expect a weakened system to track west-nor'west over the next few days, bringing enhanced thunderstorm activity to the Bahamas by tomorrow morning and to south Florida and the eastern Gulf of Mexico over the weekend.
Disturbance Thirty is now centred around 475 miles east of the Leeward Island moving west at 18 knots. This is quite weak but aerial imagery does show some signs of showers and thunderstorms and a window of opportunity exists ahead for development. At best this will cause heavy rainfall and fresh winds across the southern Leeward and northern Windward Islands beginning tonight but could form a brief, week tropical storm. Conditions in the western Caribbean are improving for storm development so we would need to watch this as it heads that way.
Disturbance Thirty One is now around 600 miles north-nor'west of the mouth of the Amazon, headed west-nor'west at 21 knots. This looks set to dodge the Caribbean. Aerial imagery shows some squalls and is producing some organisation. Conditions ahead are improving slightly for development and this has the ingredients for a weak tropical storm as it passes the north east Caribbean on Sunday and may need watching from the viewpoint of the Bahamas and eastern seaboard.
Disturbance Thirty Two is just passing south of the Cape Verde Islands, westbound at 18 knots: Dry air awaits, so a little early to make any forecast.
Another uncomfortable night ahead in the North Atlantic otherwise stand easy.