FI Charts ( T120+ onwards) Spring / Summer 2019 **READ MOD NOTE IN FIRST POST**

ECM a bit of a cold outlier but funny all the same and with NAO and AO forecast to go Negative we could get a nice Easterly, just a pity it isn't January!!

tanko wrote: »

How is the weather for the week from Monday April 15th looking at this stage?

How's it looking +10 days in advance? You won't get an accurate answer.

Gonzo wrote: »

easterlies in May are rarely warm, often cool along eastern areas. Most Mays we get this with Leinster struggling to get into double figures while the west get's close to or above 20C.

Rarely warm, in the east!

I'll happily take an easterly in the west!

That kind of scenario reminds me a lot of early October 2016 when there was a narrow but intense band of rain which got stuck to the extreme west of the country throughout on the 3rd and Scandinavian blocking was forming to our east. The block would win the battle.

Models have trended relatively drier (much more so for the UK as Ireland still gets some outbreaks of rain and mainly cloudy skies I would have thought) and warmer overnight and this morning with easterly winds still ongoing even into mid-week.

Obviously some uncertainty indicated here by these big changes.

Trough centred more out west and less deep too.

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.

ECM 12z operational run was a big outlier in FI in its ensembles. Clusters updated for the 0z run from this morning and they support ridging through the country but with the initial northerly flow, the air mass will be cool under the high. Sunny spells would moderate the cool air mass somewhat I would imagine.

GFS 12z pumping up a very warm run this evening with the UK & Ireland just missing out on the northerly flow around the 12th which goes into Scandinavia as high pressure builds over us and just to our east allowing the winds to turn into the south. Just goes to show ya how much can change with small differences in positioning of pressure systems.

Looks almost record breaking-like over Iberia. Would be a big change from early May.





Reasonable support within the GEFS at the same time (which is kinda surprising as this is quite a new scenario) for some sort of southerly to southeasterly wind (although not full on as the operational run suggests) to become established with the centre of high pressure building just to the east of the UK.

GFS OP is one of the warmest members as you'd imagine with such a warm run so not quite as warm with the GEFS mean but the 10c isotherm (which it does show) over Ireland is very good for May.



Will see if the ECM latches on to this scenario and show a similar position change in the northerly wind with Ireland just missing it. ECM clusters from this morning's 0z all very indicative of high pressure over top of us at the same time frame as the GFS above. Not quite a southerly flow though as it's not to the east of the UK.

wing52 wrote: »

Too early for a spanish plume from that, sryan?

GFS OP did show some charts that I would characterise of a spanish plume yes which would be mad given it's May. One point in its run, it tries to get close to the pattern of late May last year and May 2017 too when there was a southerly flow (and 27c) followed by thundery rain for some. Long way out though and a rather warm outlier.

ECM 12z is now cutting off that northerly flow for Ireland with warmer air filtering up from the south this time next week on its run. High pressure establishing to the east and ridging over us. Not as warm as the GFS.



ICON was similar to the GFS. I won't even describe the GEM of what it showed for the UK .

pad199207 wrote: »

May last year? Thundery rain ?

It was the best lightning storm witnessed in this country for quite a number of years.

I said May 2017 for the thundery rain.

The pattern on some charts of the GFS in FI were reminiscent or somewhat similar to late May last year when that lightning show occurred. Low pressure over the Bay of Biscay with southeasterly winds feeding in continental air and temperatures getting above 20c widely. Talking two weeks away though!