A tale of too lows

Figure 1 – Courtesy of the Met Office

It seems to me to be a tale of two lows, tonight’s rather interestingly, some may say bizarrely, hasn’t attracted any warnings for heavy rain so far from the Met Office (fig 1), but they have already issued an early warning for the possibilities of heavy rain for the low that will affect southeast England later on Sunday. Depending on what NWP model you look at the accumulations for Friday don’t look particularly that heavy (fig 2), but I wouldn’t have thought it would have hurt to have issued a blanket yellow warning for southern and central areas for 15 to 25 mm locally 40 mm, but what do I know. I suppose they still have time to do it but it’s cutting it a bit fine.

Figure 2 – Courtesy of www.wxcharts.eu

Tomorrow’s low

Figure 1 – GFS (1) ECMWF (2) UKMO (3)

It’s interesting to see how the three main NWP models handle tomorrows low and the heavy rain it introduces across the country (fig 1). The Met Office take the main thrust of the rain north into Ireland, whilst the GFS and the ECMWF are in no doubt that the action will be centred much further east over southwest Wales. I think the UKMO model looks out of step with the other models on this one, time will tell.

One of the tricks of the trade as a weather presenter when you want to be as vague as possible about the timing of rainfall events like this, is to leave of the exact time in the graphics, so it’s good to see that Aidan McGivern has picked this one up and is now ready to move on to the next chapter (fig 2).

Figure 2 – BBC (1) Met Office (2)

As well as this cyclonic development on Friday another low threatens to spoil the weather in the southeast of England during Sunday. It’s amazing just how the weather likes to dish out bad weather in as fair a manner as possible isn’t it?

Another cold end to a month looms

Figure 1 – Courtesy of www.wxcharts.eu

It seems that we have been caught in a cycle of cold end to months recently. First there was February, then March and now April. That’s according to the latest run of the GFS model, which indicates that the end of April and beginning of May will be changeable and often cyclonic, with winds in the east or northeast, the anomalous warm start to spring of last week will have retreated to the continent, but even here the warm air will be gradually pushed back further east.

Figure 2 – Courtesy of the Met Office

This afternoon’s rain across the southwest

Figure 1

A lovely solar halo this morning here in mid-Devon which is the old weather lore precursor for rain in 6 to 9 hours, so I’m curious about just how fast the rain will spread across the southwest of England this afternoon, so here are the latest forecasts as of 09 UTC this Easter Sunday morning as a reminder.

Figure 1 – Courtesy of www.wxcharts.eu, BBC and the Met Office

Well all the models were much too slow in bringing the rain northeast across the southwest peninsula, and the BBC and Met Office forecasts weren’t much better either. If you look at the 15 UTC weather radar the rain had extended as far as Somerset (fig 2), nothing spectacularly wrong perhaps, only out by a couple of hours or so, but the various forecasts that I took a snapshot of (fig 1) were only for six hours ahead and should have been spot on. At least the old weather saying about solar halos still works!

Figure 3

Brightening up from the west

Figure 1

Not a lot going on at the moment weather wise across the British Isles, but hopefully it should brighten up in many places today from the west on the passage of this frontal system (fig 1). I did notice that there’s been another minor SSW event that looks to have occurred just before the equinox (fig 2).

Figure 2 – Courtesy of the CPD at the JMA

That, along with some wild NWP output, is what probably led to all those stories of a snowy Easter, stories which now seem to have been summarily dropped like a hot potato. Having said that the models do take each successive Atlantic low a little further south into Biscay as the week progresses leaving the country in an easterly, anticyclonic in the north and cyclonic in the south, so it look’s odds on that’ll it will be a cold Easter (fig 3).

Figure 3 – Courtesy of www.wxcharts.eu

Cold start to spring

I am reliably informed that the spring vernal equinox will occur at precisely 1615 UTC today this 20th day of March 2018, but the weather is in a fickle mood at the moment, and spring, well at least the start of it, looks like it will be a cold affair in our part of the world. The Met Office in their extended outlook till the middle of April (fig 1) is being its usual unequivocal self about the possibility.

Figure 1 – Courtesy of the Met Office

In line with that outlook, the GFS model for April 1st (fig 2) is forecasting a northerly outbreak which is not at all unusual for spring across the British Isles.

Figure 2 – Courtesy of www.wxcharts.eu

Cold springs are somewhat of a rare commodity these days, and the last one to produce negative anomalies in Central England was back in 2013 (fig 3), and in the last 30 year there have only been three cold springs (2013, 1996 and 1991).

Figure 3

Sunday looks interesting

Figure 1 – Courtesy of the Met Office (Sunday 12 UTC)

I did say last Sunday in the article return of the easterlies that it was still in the land of science fiction, well the models look to have been spot on even at T+168. The Met Office have a discrete centre of 1002 hPa on the low that seems to form on the northern edge of a warm trough that’s moving westward across France for 12 UTC on Sunday (fig 1). None of the other models, apart from the French ARPEGE seem to have pressure as low as that across the Channel on Sunday (fig 2), although it’s difficult to synchronise the validity time. It’s still 72 hours away, and we are now close to the vernal equinox, but this situation has the potential to cause a lot of disruption, especially if snow falls in the overnight period.

Figure 2 – Courtesy of www.wxcharts.eu

Today’s 06 UTC (Friday) from the GFS has a similar feel to it at T+42 (fig 3).

Figure 3 – Courtesy of www.wxcharts.eu

Return of the easterlies

Figure 1 – Courtesy of www.wxcharts.eu

Still out there in the realms of science fiction land I know, but the last few runs of the GFS model have had pressure building strongly across Scandinavia later this week that pushes low pressure further south into central France, leaving the UK in another easterly air stream by next weekend and just in time for the vernal equinox and the real start of spring (fig 1).

A spot of déjà vu in the southwest this morning

A very similar sunny start to the day in the southwest of England (fig 1) when compared to yesterday (fig 2), with another curl of cloud over eastern districts.

Figure 1
Figure 2

It’s certainly cyclonic and very changeable at the moment, and still cold enough to produce snow further north especially over higher ground (fig 3).

Figure 3

March has certainly come in like a lion this year, and Monday looks like it could end up being quite stormy across southern areas if this GFS forecast comes off (fig 4).

Figure 4