I did expect to say ‘well done’ to the Met Office concerning the yellow warning for heavy rain (that they had adjusted southward) from storm Aileen, which looked like it had covered the wettest areas across Northern Ireland, southwest Scotland and the northwest of England (fig 1). But I found from my estimates of accumulation from the weather radar, that the heaviest rain had turned out to be in the Grampian region of northeast Scotland, with estimates for Fochabers of around 40 mm in the 18 hours between 18 UTC on the 12th to 12 UTC on the 13th. The Met Office did issue a late yellow alert for the area, but as they don’t have any form of archive for warnings, it’s impossible to say when it was issued. The rain certainly came out of left field and caught them on the hop, as most eyes were fixed further south on storm Aileen, it looks like it may well have been the results of some embedded instability, as there a few SFERICs on the archived chart from Blitzortung.
I can’t see much wrong with the forecast charts from either the UKMO or the GFS (figs 2 & 3) when compared with the 00 UTC plotted chart for 13th. It may have been that there was not just enough oomph in Aileen to produce more of an impact, or maybe the explosive development started just a little bit too late and further east. Having said that pressure did fall by around 20 hPa across northern England in 10 hours during Tuesday afternoon and Evening.
As most of you know the Met Office belatedly got round to naming Sebastian (as the rest of Europe know it) storm Aileen on Tuesday. Personally I think they would gain more attention, and a bit more prestige if they had named it on Sunday, rather than waiting till just 12 hours before its first impact. Fourteen of the eighteen storm force gusts occurred outside the amber area, and at least four stations reported storm force gusts that weren’t even in the yellow area (fig 1). The highest gust that I saw from a SYNOP station not surprisingly occurred at the Mumbles lighthouse in South Wales, but the 63 mph gust at Heathrow was a bit more of a surprise. I read on Twitter that the Needles battery on the Isle of Wight had a gust to 83 mph, which again is not surprising as there was a westerly gale force nine running along the English Channel. I always suspected that the yellow warning area for strong winds should have included the whole of southern England (fig 2), so overall not a great result for the Met Office as far as the wind warnings were concerned, although Aileen certainly did bring down a lot of twigs and some larger branches where we were in Berkshire yesterday.
I still can’t quite understand why much of the southwest has been left out of the yellow alert for strong winds from storm Aileen (fig 3). At 19 UTC Plymouth was the windiest place in WMO block #03 (fig 2), almost gale force eight, meaning 33 knots with gusts to 48 knots, that’s storm 10 (55 mph). I would have thought that the gradient will tighten even more as Aileen tracks across the Irish sea and North Wales later tonight. There have been large pressure falls of almost 10 hPa in three hours across Ireland, but generally the falls have not been as large as I’d expected.
The rainfall since 06 UTC is starting to mount up, with the Northwest of Ireland seeing quite a bit again, with estimated totals from the weather radar of 40-50 mm over higher ground (fig 4).
As predicted on Sunday, tonight’s developing low that zips across the country, has been finally named Aileen by the Met Office (fig 1). It has looked on the cards for the last couple of days, but the Met Office have been in their usual indecisive state of mind about whether to give it a name. I did joke in an earlier post today, that giving it a name, might give people the wrong impression about the source of the storm, which I’m sure the media will immediately link with the recent hurricane activity in the Caribbean, perhaps even with the long-lost remains of ex-Hurricane Harvey!
Although they have now extended their yellow warning area for strong wind further south (fig 1), I still think it’s not far south enough, trees are in full leaf and this could bring a lot of branches and boughs down. The same goes for the amber area, which again is a little too far north, if you believe the latest GFS run. I will make my usual plea at this point to the Met Office – please, please release the NWP model that you produce to the citizens of the UK who pay for it.
The GFS model was correct when it had the tightest gradient from storm Sebastian at midnight tonight further south, across most of England and Wales south of 54° north. It’s a subtle change between todays T+24 (fig 1) and yesterdays T+48 from the Met Office (fig 2).
Here’s the latest GFS solution, with the tightest gradient at midnight south of 53° north.
The low being a little further south of course changes the position of the occlusion, and the area that will see the heaviest of the rain. That yellow warning for heavy rain has now been moved south and extended (fig 4).
The only thing left that they have to do now is to extend the area of strongest winds further south, Oh I nearly forgot, and decide if they should call it Aileen or leave it at Sebastian. In light of recent tropical cyclone activities, and not wanting to cause any mass panic amongst the populace, naming it Aileen seems unlikely now, but what if Sebastian has more fire in its belly than they think?
I see that the Met Office have just issued a yellow warnings for strong winds for Monday across the southwest of England, but the gradient on Tuesday evening when the next low breezes in looks even tighter in the latest GFS model run, maybe this is storm Aileen, and the first storm of the 2017-18 season?
If anything the Met Office model seems to have the low (981 hPa) a little more intense and deeper than the ~984 hPa of the GFS.
Apologies for the title of this one, but I thought that I would get in before the Daily Express did!
Large 24 hour rainfall totals have been recorded across the northeast of both England and Scotland in the last 24 hours ending 06 UTC, and it’s still raining in Northeast Scotland. There is the odd white pixels in my estimates from the weather radar south of Nairn, which indicate accumulations in excess of 150 mm (fig 1), so I expect that the rivers Spey, Findhorn and Nairn are all now in full spate after the deluge of the last 36 hours. Wettest from the observations was Loftus in North Yorkshire, with 58.2 mm in the 24 hours (fig 2), Edinburgh wasn’t far behind with 48.6 mm.
The inset observation grid are the last 24 hours observations from Lossiemouth, overlaid on a map of 24 hour rainfall totals (fig 3).
The heavy rain brought down the freezing level overnight as well, so the very tops of the Cairngorms could have seen some of this rain fall as snow, that combined with a 50 knot mean northwesterly might put a hold on your plans to knock of a few Munros in the area today (fig 4). The Met Office were too frit to call this storm Fleur, but the Berlin Meteorological Institute ended up naming this particular vortex Ingraban, either way this vortex continues to play havoc with flaming June.
I see the upper cloud from the next feature as got well into Ireland now (fig 5), and looking at the forecast from the GFS model, it looks like Thursday and Saturday will be wet again, in many areas, particularly the further northwest that you are in the country. After the weekend though, things look like they start to settle down, and next week we may well see the return of flaming June.
The vigorous low that’s forecast for Monday now looks like it will track across Cornwall and Devon, up through the Midlands before exiting the east coast of England via the Wash, that’s according to the latest run of the GFS model (fig 1).
In the southwest, there will be a spell of 12 hours of strong southerlies ahead of the low during Monday [5th June], the winds will then veer round in the early evening, as the low tracks rather smartly northeastward, and blow hard right through the night and for most of Tuesday [6th June] from the west or northwest. The lowest pressure that I can see for the centre of the low from the forecast frames is around 985 hPa at 00 UTC on Tuesday. As usual with the Met Office, we are limited to the old fax charts when it come to looking at their NWP output, so below is their T+72 offering (fig 2) for Tuesday at 06 UTC, whatever happened to summer?
It will be interesting to see just how this one pans out, for the moment the media don’t seem to have caught on to the story. I also wonder if the Met Office would make an exception for such an unusually vigorous low in early June, and give the low a name? I think Fleur, would be a very appropriate name for a Summer storm like this.