So there has been a trend for the coming week's unsettled spell to be relatively short-lived with high pressure quickly reasserting itself somewhere close to Ireland but as it's more than 5 days out, there is obviously going to be some uncertainty and disagreement on the placement of the high which is vital to seeing where gets the chance of sunshine and what the temperatures will be like.
Latest ECM shows an area of high pressure over us and pushing to the northeast drawing in an easterly flow though starting off as a cool northerly flow meaning it'd be cold at first but as the high would stick around for a few days, it would get relatively warmer with the land warming up by the strong May sunshine.
This pattern is somewhat similar to the Easter period but high pressure is a bit further north as low pressure is rather deep in the North Atlantic out to the west of Ireland. Whether this would be a cut off low where the low undercuts to Iberia like those that did during Easter or not, would be important for the high to develop over us and be a blocked pattern or migrate northwards and form another northern blocking anticyclone like this coming week.
ECM clusters have not updated since Friday evening so these are the ECM 12z clusters from Friday. Full agreement at t216 that some sort of ridge will build into the country from the south but centred well to our south and deep low pressure in the Atlantic Ocean. This would be dry but cloudy I would have thought with southwesterly to westerly winds being the dominance.
Things started differing a few days after on these clusters with 4 different placements of the high pressure.
Scenario #1 shows one similar to t216 but the high is further north so more of a chance of sunny spells particularly in the sunny southeast as the moisture layered southwesterlies are pushed northwards with the jet stream.
Scenario #2 shows high pressure blocking to our north with a little ridge coming through the country into Iberia. This would be a bit more unsettled as the high is too far north to really take over the pattern and the low pressure is too close to the west for comfort. Looks sort of similar to mid-April, the period just before Easter.
Scenario #3 shows a large area of high pressure centred right over top of us. This is the best case scenario if you want dry and fine weather. It would be initially cool at first due to the northerly flow from a few days before but it would become gradually warmer and warmer as the strong May sun shines.
Scenario #4 shows high pressure just to the east of the UK with low pressure in the Atlantic. This would result in long fetched southerly to southwesterly winds I would have thought which would be cloudy and humid - warmest conditions in the east of the country.
Latest GFS is very similar to the ECM with a northerly flow at first veering to easterly but high pressure building through the country (although later in FI builds the high as a northern blocking feature essentially repeating the coming week's pattern).
Overall, looks like the unsettled spell will be short-lived with an area of high pressure building in by the end of the second week of May but staying cool for a time with temperatures gradually warming up a little.
Long way out so pinch of salt as ever with FI.