At mid day today, a cell of high pressure will be centred near the Azores with a ridge axis to extend from this high to the north east across Charcot into Pazenn and west Biscay. Low pressure areas are centred over western France and Spain with a weak front across eastern Biscay into NW Spain. Another area of low pressure is centred near southern Ireland with an Atlantic frontal system moving in across Altair and Faraday. This moves into western Romeo and western Charcot on Tuesday morning.
Tuesday high pressure areas will be centred just east of the Azores with another cell in Biscay. These will weaken as the frontal system continues moving east across Romeo, Charcot and Pazenn. Low pressure will be centred near SW Spain with thermal troughing across Portugal. A cold pool of air aloft around Cape Verdi will produce showers with some of these possible across parts of Josephine. This cold pool also develops low pressure by Tuesday 0600 just to the east of Cape Verdi.

At mid day today, an area of low pressure, 1000mb, is to be centred west of Ireland near 52N and 22W. This will be a semi-stationary weather feature over the next 24 hours then it drifts towards Ireland and weakens. A weak front extends across Brest to near the NW tip of Spain then across southern Charcot and Josephine. A cell of high pressure is now centred near 41N 37W and dominates the Azores.

5 Day weather forecast for Ponta Delgada to Lagos and UK.  Departing Saturday 13 June

Forecaster: Simon Keeling, sail@weatherweb.net

Issued: 1000 Friday 12/6/09 All times UTC. Wind speeds in knots.

Note: The forecast now represents the region within approximately 50nm of the line from 38:20N 31:30W through to the finish at 28:30N 28:37W.

Situation at 06UTC Saturday 6 June 2009 with forecast to 24UTC

Eastern centre of the Azores high near 34:00N 35:00W with ridge to 33:00N 25:00W. New low centred near 44:30N 35:00W and is expected to move very rapidly to 44:30N 27:00W by 1800UTC.

Situation at 06UTC Sunday 31 May 2009 with forecast to 24UTC

Situation at 06UTC Friday 29 May 2009 with forecast to 24UTC Intense low near 42:00N 45:00W with developing cold front from low to 38:30N 53:00W. Low expected to be near 41:30N 39:00W at 1800UTC with front to 37:30N 50:30W. Ridge 32:00N 50:00W to high near 35:00N 40:03W to 39:30N 32:00W moving to lie east-west along 32N by 1800UTC.

Situation at 06UTC Tuesday 26 May 2009 with forecast to 24UTC

Ridge lies from 31:30N 57:30W to 35:00N 49:00W to 36:00N 46:00W where it ends. Light and variable winds extend 60nm either side of the ridge axis but tend southerly near 46W. Ridge moving southwards during the day. Cut off low centred near 30:00N 49:30W with a trough to 36:00N 46:00W where it hits the ridge. Northerly winds 10/15 knots to the west of the trough but tending light and variable west of 54:00W. S to SSE winds 10/15 knots to the east of the trough. Winds lighter near the trough itself.

The difficult weather conditions for the trip towards the Azores are set to continue for another 3 days. At the current time there is a high pressure system centred near 37:30N 63W with the ridge still oriented from the west to the east. The low mentioned yesterday has now largely dissipated but a poorly structured trough remains in the central North Atlantic Ocean. The winds between these two systems are swinging to moderate to fresh ENE winds. These unfavourable trade winds look like continuing for the next 2-3 days.

The latest developments with the weather pattern continue to be generally unfavourable for the trip to the Azores. There is a 1027hPa high pressure system centred near 37:30N 67W with an east-west oriented ridge axis. The remains of a cut off low pressure system lies near 28:30N 55:00W and is moving only slowly. This is producing a fresh northeasterly wind between the two weather systems. These trade winds look like continuing for the next 3-4 days, although they are expected to weaken as a weak frontal system moves past to the north of the fleet, bringing westerly winds as far south as around 36:30N during Monday. The best strategy appears to be to gradually ease northwards as fluctuations in the trade winds permit as the longer range forecasts are for frontal systems to gradually move into the region north of 37N which should gradually assist the fleet for the second part of the trip towards the Azores.

The final yachts on the run in to Bermuda are likely to have quite showery weather as the main band of showers, with isolated thunderstorms, is now approaching Bermuda from the northwest. Ahead of this band are scattered showers with one or two thunderstorms also about. There are reasonably large breaks between these pre-frontal showers. Short lived but strong gusts are likely with the heavier showers. The band of showers should extend southwards through the tail end of the fleet during the next 24 hours. The NNE wind change is also now well past Bermuda and is likely to be past the southernmost yacht in the fleet by the time this forecast is issued. The wind direction should swing towards the northeast during the next 24 hours and the speeds, initially a little fickle near the change, should firm up into the 16/20 knot range on Thursday.

The fleet remaining at sea are now all between the ridge axis to the south and the frontal system to the north of Bermuda. The frontal system has developed a double cloud line structure which indicates the wind change is likely to go through as two separate changes. The first change is expected close to 00UTC on Wednesday as a swing of the winds from the WSW around to just north of a westerly. The second change, now likely around 0200UTC Wednesday, should quickly turn the winds through NNW to a northerly. Some gusty winds are likely with the lines of showers but the northerly behind the second change is looking a little weaker than it did earlier, most likely settling down after some initial variability into the 13/18 knot range. Winds should hold NNE behind the change for much of Wednesday, gradually shifting towards the northeast, particularly after 1800UTC. The showers now look like lingering across the Bermuda region for much of Wednesday.

Most of the fleet is now crossing the ridge, which is around 28:30N at the moment, and heading towards a slow moving cold frontal system that is currently at around 33:30N. There are a couple of cloud lines starting to form south of the cold front and a few showers are likely to form over the final 60nm into Bermuda after 1800UTC today. The frontal wind change now looks like holding off until around 0400UTC on Wednesday as a low developing to the north of the frontal system should slow its southward progress. This low is expected to move quickly away to the east and should not directly affect Bermuda or the fleet. However, the low’s development is expected to slow the rate at which the winds behind the frontal wind change turn towards the northeast with winds most likely to hold northerly to NNE behind the change for much of Wednesday.

The weather pattern along the route to Bermuda continues to be controlled be an east-west oriented ridge currently lying along 29:00N but expected to shift south to along 28:30N by Monday 00UTC. The southward shift of the ridge will be caused by a weakening cold front that is expected to push towards Bermuda during Tuesday. Current indications are that the frontal line will stall close to Bermuda with a couple of weak lows forming on the frontal line – one to the west of the island and a second to the east. This is likely to produce greater variability in the winds near Bermuda on Wednesday but at this stage the winds do not look like being very strong near Bermuda.