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.
It’s been a very wet 24 hour’s down here in Devon, although there seems to be a curious mismatch between the estimates of what the radar saw (fig 1), and the rainfall that found its way into the gauges of the AWS at all the various SYNOP stations across the country (fig 2). Capel Curig just 2mm? The river Culm has certainly burst its banks locally and flooded all the water meadows that surround it.
Locally in Bradninch I only measured just over 19 mm in the 24 hours, but Exeter had almost 30 mm, and Dunkeswell close to 40 mm, so either the rainfall was very sporadic, or I’ve still got a spider’s web in my AWS connected to my tipping bucket.
The sheltering effect of Dartmoor seems to have had a long reach if you look at the estimated 24 hour rainfall totals for yesterday from the weather radar network. Conversely the funneling effect of the Bristol Channel, and the resultant large rainfall totals across south Wales, with a finger of higher totals extending northeast towards the Wash was also evident (fig 1).
You would have expected the upper winds to be from around 220° which they were from the 2317 UTC ascent from Camborne (fig 2).
Hill fog and periods of heavy rain and drizzle made this a very nasty kind of day down here in the southwest, especially along the south coast, hopefully things will improve tomorrow.
There’s no quicker way to strip snow of high ground than a combination of mild air and heavy rain. The rivers must be in spate after a rapid thaw of the snow on Dartmoor and Exmoor brought about this way overnight by a band of heavy early morning showers tracking N’NE across the southwest (fig 1).
The cold air is still hanging on for dear life further north, so there’s quite a temperature contrast in this 09 UTC chart (fig 2). The Met Office analysis for 06 UTC reckon the rain is from an occlusion.
Well, what I thought might happen has happened. I can’t remember seeing a red warning for snow being issued by the Met Office before so this could be a first for the central belt of Scotland (fig 1).
I’ll be my usual picky self and say that they should have extended that red warning southward to include most of the east coast down to Berwick-on-Tweed by the looks of the latest radar images. There are some red pixels mixed up in the intensities that extend over most of the Cheviot’s (fig 2), certainly a day to be staying at home round the fire, and not out on the A1 which almost certainly will get blocked later today, I feel sorry for the hill farmer whose sheep are out in it.
The Met Office may have purposely forgotten to issue a strong wind warning for Philine yesterday, but the NWP model must have been indicating some heavy rain for Northern Ireland so they did issue a yellow warning of heavy rain for the province (fig 2). As you can see there was indeed some intense heavy rain, with rainfall rates of over 32 mm per hour at 1810 UTC (fig 1) close to where low Philine was developing a discrete centre. This shows you just how good the NWP models can be.
Weather Radar Estimates
As far as I can see from my estimates from weather radar images there was a largish area with totals in excess of 50 mm for the period 10-1200 to 11-0845 (fig 3).
Evidence from the rainfall gauge
It’s clear from the gauge network totals for the 24 hours ending 06 UTC (fig 4) that the weather radar may have been over doing the intensity of yesterday rain for some reason. The freezing level was low enough for the rain to be falling as snow down to low levels ~2500 feet, so the white intensities (fig 1) could have been some form of bright banding effect.
The warning itself was just about perfect for Northern Ireland, but there were even higher totals across northwest England and southwest Scotland that didn’t get a mention.