Curse of the black pearl

Figure 1

The models captured the development of the low called Pearl very well as it deepened and tracked E’NE, and it’s all set to spoil the rest of the weekend with its rain and cloud especially across the southeast of the country. The low almost seems to be developing a black pearl like centre as it spirals round just southwest of the Scillies but that’s probably my over active imagination (fig 1).

Estimated rainfall totals since 18 UTC yesterday are starting to mount up across the southwest, with the first lime green pixels appearing over the Lizard and Bodmin moor (32-40 mm), I’m not sure whats wrong with the radar across the Celtic Sea though (fig 2).

Figure 2

“Tomorrow is a dry fine day for most of us, there is a risk of a shower”

Good old David Braine, we’ve had more showers first thing this morning (fig 1) than we saw all day yesterday!

Figure 1

Hopefully I can get the washing hung out by the end of the morning as the showers finally die out and the upper cloud from low Pearl rushes in this afternoon. I guessed at the central pressure of 1016 hPa, but I can see that the pressure has just started to fall at weather buoy ‘Pap’ so Pearl has engaged the jet stream (fig 2).

Figure 2

Wall to wall sunshine in Scotland

If you’ve ever read a sunshine card from a Campbell–Stokes sunshine recorder then you’ll probably like this image generated by my SYNOP application. It takes the sunshine reported each hour throughout the day and generates a pseudo mega sunshine trace for all 50 odd SYNOP sunshine reporting stations in the UK (fig 1). I’ve even tried to match the colour of the chart to match that of the sunshine card from memory, but I may not have got the shade quite right.

Figure 1

What today’s mega sunshine card shows is that its been overcast and dull across many parts of the country except the north and west of Scotland and the southwest England, in fact in the Northern Isles the sunshine has been from dawn till dusk by the look of the pseudo trace. The low total from Camborne was a bit of a surprise, but that must have been the convective infill that produced the thunderstorm over west Dartmoor, which produced totals of over 32 mm if my weather radar estimates are to be believed (fig 2).

Figure 2

Today’s poor forecasts

It’s difficult to pin these two organisations down when it comes to verifying just how accurate their maximum temperature forecasts are. But the Met Office model is already one up after yesterday, so I thought I’d just see how they did today.

Figure 1 – Courtesy of the BBC and the Met Office

Here are the actual temperatures at 1600 BST today which I mark 76% to the Met Office. The forecast for London was really dreadful from both models, obviously they expected the stratus to clear but it didn’t. I can’t understand why MeteoGroup have labels for both Glasgow and Edinburgh, but only one temperature, and for which city it’s for. If anything MeteoGroup should have had the edge because the actual and forecast temperatures are both for 1600 BST, but that didn’t stop the Met Office taking a two nil lead.

It wasn’t only temperature that caught out both the Met Office and MeteoGroup today, there was also an area of heavy rainfall that extended across Humberside into Yorkshire during the afternoon that escaped both models. I watched the rolling news on the BBC news during the afternoon and I think even worse than the poor forecast was that the presenter never seemed to noticed that it was happening at all, let alone bothering mention it or show a real-time weather radar image. It reminded me of the taped forecast given by Michael Fish as the Boscastle flash floods was in progress in 2004. I can’t see why the Met Office have bothered to update their weather radar network when no one seems to look at it. Here’s the BBC forecast for the east Midland’s from yesterday evening (fig 2).

Figure 2 – Courtesy of the BBC

Overnight thunderstorms

Figure 1 – Courtesy of Blitzortung (10 Apr 1800 -11 Apr 0600)

There was some pretty heavy rain for a time overnight here in mid-Devon, but none of the overnight thunderstorms (fig 1) seemed to have survived the trip over the cold sea from Belgium and the Netherlands though. We certainly didn’t need any additional rainfall in our part of the world as the ground is already fully saturated.

Figure 2
Figure 3

The sky won’t rain and the sun won’t shine

Apologies to the Eagles and adjusting a line from the lyrics of their song Desperado for my title, but they seemed to be a fitting description for the weather this Sunday morning across our part of Devon. The laser CBR at Exeter airport says that the layer of alto-stratus across eastern Devon is at 14,ooo feet (fig 2), as the rain across Dorset is marching steadily north-northeast, and the edge to the medium level cloud is quite stark across west Devon, most of Cornwall look to be having a lovely morning.

Yesterdays unexpected snow

Figure 1

My estimates of the 24 hour precipitation totals up to 06 UTC this morning may appear to have been a little high for Liscombe (fig 1 & 2), but at this resolution, you only need to be a pixel or two out to make a big difference – well that’s my excuse anyway.

Figure 2

But apart from yesterday being such a cold and miserable day in east Devon and west Somerset, the wet snow that fell for much of the afternoon made it rather unusual too. Here are the plotted observations for Dunkeswell in Devon (fig 3), the snow started here at 13 UTC, perversely the warmest time of the day, and lasted until 17 UTC, before milder air from the northwest lifted temperatures and turned it to rain.

Figure 3

Full marks to the Met Office about yesterdays warning for heavy rain in this part of the world, especially Exmoor (fig 4).

Figure 4 – Courtesy of the Met Office

I think the widespread nature of the wet snow falling across lower lying parts east Devon and west Somerset yesterday afternoon caught them out though. The photo of the snow at Christ Cross above Silverton yesterday afternoon is rather appropriate taken as it was on Good Friday (fig 5)

Figure 5 – Courtesy of Warren ‘Weatherman’ Radmore

Intense rain NE Scotland

Figure 1

An area of heavy rain has developed in the last hour over northeast Scotland (fig 1). It doesn’t get much more intense that 16-32 mm per hour, well actually it does, the pixels turn white with intensities of 32 mm per hour and higher. According to the UKMO analysis it looks like it’s a very active bent back occlusion that’s behind it (fig 2).

I did notice that the rain never even got a mention in the BBC weather at 12.58 pm, although we did get Sarah Keith-Lucas showing us a couple of  nice pictures, one by Geoff of Histon in Cambrideshire, and the other by Alan in Topsham in Devon!

Figure 2

The Cherbourg dangler

Figure 1 – Courtesy of the Met Office

We’ve had around 5 cm of fresh snow this morning here in mid-Devon to add to the 5 cm or so that we got overnight, in a spell of moderate snow that’s now moving away W’NW across Devon. There’s an interesting convergence line that’s pluming a line of showers northwest across the Channel from the Cherbourg peninsula towards Devon. At the moment that looks like it might keep the snow falling in this part of the world for the rest of the afternoon, as the latest models suggest it will. I saw this type of convergence happen in an easterly from Cherbourg that affected Guernsey in the last cold spell, but this is a new direction for me.