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

Despite the cold weekend spring sprung last week!

Figure 1

Despite the last record couple of cold days in Central England, I reckon that the average number of degree days between the winter solstice and the vernal equinox was exceeded on the 14th of March this year (fig 1).

This normally would make the first day of spring around a week early, but because springs have been occurring earlier on average (20 days earlier than in 1772 and now around the 11th of March each year), 2018 was around three days late this year, it was also the latest spring to have occurred since 2013.

I personally think that using degree days like this is a crude but effective way of coming up with a date for the start of spring, let me know if you have a better idea.

Coldest 18th March since 1853

Figure 1 – Data courtesy of the Met Office

Yesterday, the 18th of March 2018 was the coldest for that particular day  in March since 1853. That’s according to the latest provisional Central England mean temperatures released from the Met Office (fig 1). The maximum for Sunday was 0.6°C and the minimum -2.2°C, and the mean of -0.8°C, was almost 6.6°C lower than the 1961-1990 long-term average of 5.8°C.

Figure 2 – Data courtesy of the Met Office

Only four other years have reported negative mean temperatures for the 18th of March (fig 2 & 3) in the daily mean CET series that started in 1772, they were 1900, 1853, 1814 and 1812.

Figure 3 – Data courtesy of the Met Office

Don’t forget that you can keep an eye on the latest daily CET values here

Looking at the observations for yesterday and the reported 06 to 18 UTC maximum temperature (fig 4), many stations across central England and Wales had sub-zero maximums, in fact at a number of stations, the temperature has remained below zero the whole weekend, which just two days from the vernal equinox is highly unusual.

Figure 4 – Maximum temperatures 18 March 2018

I think the thermograph for the last few days from Rothamsted in Hertfordshire gives a good account of how quickly the cold snap set in last Friday, and just how cold the last 48 hours have been across the country (fig 5).

Figure 5

Large temperature swings – Gravesend 13.5°C colder than yesterday

Figure 1

The temperature at Gravesend yesterday was 13.6°C at 12 UTC, and today at the same time it was just 0.1°C, which makes it 13.5°C colder. To be honest there are a good number of stations which are 10°C or colder than they were 24 hours ago, and I’ve outlined them on the chart (fig 1). You can of course get large variations in temperature in the late winter and early spring, but today’s must take some beating, and looking at the latest NWP it looks like there may be more large swings in temperature in the coming week.

What a diff’rence a day makes

It’s time to roll out that old cliché blog title that I’ve used a number of times before from that old Dinah Washington song – what a difference a day makes, 24 little hours you know the rest, because temperatures in eastern parts of the country are between 4 and 8°C lower at 06 UTC this morning than they were at the same time yesterday. I think it’ll be even more interesting to compare today’s maximum with yesterday’s, so keep posted and tell all your friends.

Retrospective on the last cold spell from the Met Office

Figure 1 – Courtesy of the Met Office

The climate team at the Met Office have been working overtime and have produced a report detailing the events of the recent cold spell which as you know started on Sunday the 25th of February and lasted to following Saturday the 3rd of March 2018.

Figure 2 – Courtesy of the Met Office
Figure 3 – Courtesy of the Met Office

I’m not certain if the snow depths in this chart (fig 3) are particularly accurate from what I saw locally here in our part of Devon – 0 cm really? They would have been better using the snow depths reported from their WOW network, which for some reason known unto themselves you can’t plot on a chart.

Hurricane force winds on top of the blue hill

Figure 1

Hurricane force winds on top of Cairngorm this morning, where the winds is meaning 77 knots (113 mph) and gusting to 98 knots (120 mph) at 10 UTC, that’s close to category two hurricane strength, and that’s a ten-minute and not a two-minute mean. The wind has been slowly backing over the last couple of days, and with the air temperature currently at -3.7°C that means a wicked wind chill equivalent of -17.2° for any poor sod who’s daft enough to be up there at the moment.

Figure 2

Rapid thaw on Dartmoor and Exmoor

Figure 1

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).

Figure 2

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.

Figure 3 – Courtesy of the Met Office

Coldest March day since 1878

After reporting yesterday that we’ve just experienced the coldest 28th of February since 1785 in Central England, it now transpires that the first of March provisionally has the lowest mean temperature for that day since 1785 (fig 1), and additionally was the coldest day (lowest maximum of -0.8°C) for any March day since 1878.

Figure 1

The last seven days have been cold, but they still only rank 6th in the all time coldest weeks (23rd February – 1st March) since 1772 (fig 2). So if you think the mean of -0.5°C for the last seven days has been cold, the -2.56°C of 1947 was a magnitude colder. It’s very rare these days to see any new extreme minimum records broken, but setting three records in two days isn’t bad going!

Figure 2

Don’t forget you can keep up to date with the latest daily temperatures in Central England by using the interactive graph on my Meteograph website.