March 4th, 2024

Hi All,

Got up early yesterday to go fish a very flooded, River Trent before the season finishes in mid-March. As I drove across the countryside, the temperature dropped to -4°C at one stage, that's chilly for March. It stayed foggy and dull most of the day by the river, the cold air trapped in the valley, dull enough even for Tawny Owls to call all through the day. About 3'ish the sun broke through and it was lovely.

Downstream, I watched a cloud slowly form, courtesy of I think, Staythorpe Power Station. It formed into a lovely distinctive anvil shape, just like a warm air updraft in the summer that seeds a thunderstorm. The flat shape at the top of the cloud is caused by a layer of warmer, more dense air preventing the warm, condensing air rising higher, so it flattens out.

You don't often see evidence of these different layers of cooler and warmer air but clouds are the give-away. So we have a layer of cool air sitting over the river, warm air from the power station cools as it is emitted into this layer and water vapour condenses to form a cloud. As this rises it then runs into an upper layer of warmer denser air formed by heat from the sun and cannot rise any further, so flattens out into the distinctive anvil shape. A chap walking past me whilst I was fishing said "It looks like a big Elephant's head !"........😀

Now there's a lot going on weather-wise currently as we tip-toe into March after our very wet and mild start to the year, more on that later.

Image courtesy of Netweather.tv read the full article here

Over the weekend I was looking at the tropicaltidbits.com output for the next 10-14 days and noticed how the jet stream was reversing from the usual west-east to an east-west direction. I have seen this before when we have a Sudden Stratospheric Warming (SSW) and sure enough on clicking Netweather.tv, I saw the article above which suggests one is likely to occur. You can read about the science behind it in the article but the practical part is that we sometimes see a run of northerly / easterly winds associated with a SSW event and this can lead to an influx of colder air.

So that's the meteorological debate going on at the moment, will March be a cold one due to a SSW ?

General Weather Situation

So this blog starts on Tuesday as I know by the time you'll read it Monday will have gone or nearly gone !

This week we are transitioning from low pressure to a ridge of high pressure as correctly predicted a week ago (smug award). So overnight into Tuesday, we will see the rain front that pushed into the south west of England and east coast of Ireland on Monday clear the north east of England by dawn on Tuesday. At the same time, we will see a pulse of rain (possibly heavy) move into Connacht on Tuesday morning. That rain will move across Northern Ireland and into the north west of Scotland during the day. Further south and east in the UK, we look to have a nice day with light winds and temperatures climbing into double figures and with more cloud cover overnight, less risk of ground frost. Just on wind direction, Ireland and Scotland will see a transition straight into easterlies, that swing to easterlies will happen later in the week further south. Sunshine and showers for Ireland across the south and west and across western Scotland but feeling pleasant in the sunshine.

Wednesday sees that ridge of high pressure strengthen and that'll provide a protective shield to Atlantic low pressure systems. So Wednesday see's a much nicer day, drier, yes I said drier for most areas. There will be an Atlantic front trying to push into the south and west of Ireland through the morning and we will see showers or longer spells of rain for the west and south. Away from this rain, the U.K should have a nice day, with plenty of sunshine and temperatures pushing just into double figures, may be a little warmer for Ireland. The wind will be southerly swinging round to the south east as it edges towards a final destination of easterly by Thursday.

So by Thursday morning we see easterlies setting the scene and that means more in the way of cloud cover pushing in off The North Sea. That wind and cloud cover will cap off temperatures below double figures for England and Scotland, especially for North Sea coasts, but further west across Wales and Ireland, you should see more in the way of sunshine and it'll be a little warmer. Dry again though and that must be welcomed. That cloud cover should keep us frost-free.

Friday sees a very similar weather picture with easterly winds dominating, dry and reasonably warm, maybe edging up a little over Thursday into double figures. Plenty of winter sunshine and feeling pleasant away from that easterly wind.

The outlook for the weekend looks like continuing this reasonably dry and mild weather picture away that is from North Sea coasts. That said, we have a low pressure system edging just south of the U.K and that'll push rain along the south coast of the U.K and Ireland. Away from this, there will be plenty of sunshine but there will be some showers on Saturday and Sunday across The South West and along the south coast. These showers may edge inland on Sunday reaching The Midlands. So mainly dry, still with those easterlies in situ, edging north easterly later on Sunday as the trailing edge of that low pressure ushers in more easterlies / north easterlies.

Weather Outlook

Not a bad week this week, what does next week look like ?

Well, next week looks like being cold with a continuation of that easterly wind pattern at least for Monday and Tuesday. Monday looks like being particularly cold in this respect as the wind takes on a more north easterly aspect. There could be some wintry showers ushering off The North Sea for coastal areas in particular across eastern coasts.

Tuesday sees a deep Atlantic low pressure system push into Ireland and as it does so it'll swing the wind round to the south and usher in milder air, so Tuesday will see the Ireland and the west, wet and mild, and the east remaining cold with rain arriving later in the day. This may just turn to wintry showers when it hits the colder air mass across the east of England. One to watch.

Thereafter the week descends into an all to familiar I am afraid, mild, windy and unsettled pattern before potentially clearing by the weekend after next.

Agronomic Notes

So just look at that February 2024 GDD number from our default location in Thame, U.K.......77.2 total GDD (using 6°C Base Temperature) for the month of February.

To put that into perspective, the average from Feb 2005 - Feb 2023 was just 26.05 GDD !

We have had colder March and April's from a GDD perspective !

Normally when we are talking climate records, we just shade the previous record, but measuring GDD, February 2024 was nearly 3x higher, that is a game changer.

February 2024, was the warmest ever for England and Wales and second warmest ever for the U.K as a whole. 7 stations in Ireland reported their warmest ever February according to Met Éireann, 5 of them in the south west of the country.

The cumulative GDD of 114.2 measured to the end of February 2024 at our default location, last year was recorded on the 23rd of March. So from a GDD perspective vs. 2023, we are over 3 weeks ahead. Staggering really when you consider it.

if you graphed out cumulative GDD for 2024 vs. 2023, this is how it would look ;

I am staggered at such a difference, I really am.

My case study location in Kent reported surfaces pretty much there and just a light dressing required to get 100% recovery from their end of January aeration. This is how the cumulative G.P looks year-on-year.

One caveat is the fact that we are now facing a run of easterlies. Usually an easterly at this time of year is a chilly one, so maybe we won't continue to pack on GDD, G.P for the 1st part of the month. Last March you can see it was also cold for the 1st part of the month (shallow upward gradient = little growth) so maybe we will follow a similar pattern in 2024 ?

It ain't half been wet....

It would be remiss of me to compare Jan-Feb '24 vs. Jan-Feb '23 without putting up some rainfall statistics. It is difficult to quantify the effect that this winter's rainfall has had on ground conditions, revenue and hey, moral, but here goes.

Some pretty amazing numbers for the U.K and some very clear evidence that the rainfall patterns have not conformed to past climate prediction models, where they predicted the west and the north automatically receive the most rainfall. In the U.K, yes there is a clear west-east difference, but areas in the south, central and east of England saw some massive differences 2024 vs. 2023 and significant rainfall.

Ireland saw some massive differences year-on-year.

Yes, Valentia came out wettest but look at Cork and Johnstown Castle. They followed the same pattern as seen last autumn with significantly higher amounts of rainfall for Wexford and Cork.

As discussed before, the low-lying (southerly) position of the jet stream allowed Atlantic low pressure systems to affect areas on the south east and south of Ireland and the southern half of the U.K. So, it isn't just the shape of a blocking event formed when the jet stream loses momentum and forms into a characteristic peak or trough pattern. It is also pertinent where the blocking event occurs from a longitude / latitude-wise.

With blocking events entering into the meteorological discussion for March 2024, it'll be interesting to see the result.

All the best.

Mark Hunt