February 13th, 2023

Hi All,

Well we are already approaching the middle of February and sitting here now in Market Harborough, we are 28 days since the last rain, a really strange stat to be trotting out in mid-February. Add to that we still sit under a divided jet stream and you have to wonder quite what is going on with the weather ?

Sudden Stratospheric Warming Event

Looking at the GFS and ECMWF projections, they hover between more of the same and a breakdown of the blocking pattern on a daily basis which says to me, there's a lot of uncertainty attached to the current weather situation. Dovetail this uncertainty with a renewal of the 'Beast from the East' (BFTE) type trash that our tabloids issue forth and is it any wonder people are confused !

One subject that I have talked about before is a Sudden Stratospheric Warming (SSW) event. One is occurring now over the North Pole currently and this event can result in a reversal of the normally westerly flow of the jet stream. Every time it's announced that a SSW is taking place, the tabloids dust off their BFTE story. Now you can read about the exact mechanics of this here, but in essence a SSW event can precede cold weather and easterlies, but it doesn't always happen. The key word in the last sentence is can, it isn't will. The last SSW that affected our weather occurred in late February / early March 2018, so later I'll take a look back at this from an agronomic perspective and discuss the potential implications at ground level.

General Weather Situation - 13-02-23

Aside from the SSW event high up in the Stratosphere, there's two aspects to our weather down in the Troposphere that will impact us. First up, we have some really mild air this week coming in with temperatures reaching the teens across Ireland, Wales and the south of England. Secondly, we have some rain that will push through under the main blocking peak we have currently in place. This rain will be heaviest in the north and north west, with Scotland on the receiving end again I am afraid.

So Monday looks to start off dull but later we will see some sunshine and temperatures will climb into low double figures. Dry for all areas I think, with a gentle southerly wind making things feel nice and pleasant really. Tuesday follows a similar pattern, except for the west coast of Ireland and Scotland, where we may see some showers on and off through the day as a weak rain front tries to push in. Away from this, another mild, pleasant and dry day for the bulk of Ireland, Wales, England and Scotland. The first appreciable rain for awhile (away from Scotland and N.Ireland that is) is set to make landfall across the west of Ireland overnight into Wednesday. This rain will then move eastwards clearing the west by the Fanore rush hour (😊), but the east coast will have a wet morning, as will the west coast of Scotland. Later, this rain band will push into The South West, Wales, the north west of England and south west Scotland, but as it moves eastwards, it'll fizzle out. Away from this rain band across the south and east of England, it'll be another dry day and will feel appreciably milder, with temperatures in the south pushing towards 13°C.

No sooner than one rain front has moved across Ireland than another one arrives early on Wednesday evening into the south west of Ireland. This front will clear Ireland overnight and bring rain into western coasts in time for Thursday morning, with some heavier rain across the north of England up to The Borders. It'll break down into a showery outlook for the morning as it moves eastwards across the south of England but some areas will remain dry. A drier day for Scotland and Ireland once that front moves through across the latter early doors. The wind will swing round to the west on Thursday and pick up in strength. Later on Thursday, we will see a new rain front push into Northern Ireland, the north west of England and western Scotland. This will be heavy in nature and may fall as wintry showers over The Highlands. Friday sees those winds ramp up and swing round to the north west, but despite this it'll remain in the early teens across Ireland, Wales and the southern half of the U.K. Another dry and sunny day with more cloud cover over the west heralding the arrival of more rain for the north of Ireland and west of Scotland later.

The outlook for the weekend looks 'mixed' because the change in wind direction will push that northerly rain down across the U.K on Saturday morning, so we might start off damp in places and although it'll swing back to a more westerly, it'll feel cooler on Saturday. So remaining breezy and unsettled for most areas on Saturday though Ireland should stay pretty dry. More showers across all areas on Sunday but these will fizzle out as we go through the day. Cooler on Sunday with a northerly wind in situ, but bright and breezy.

Weather Outlook - w/c 20-02-23

So after a brief incursion of rain, next Monday looks pretty much a dead ringer to this Monday, last Monday and the Monday before that. So high pressure sitting over the U.K & Ireland. There is though a subtle shift next week, as the jet stream looks to be shifting slightly further south which means we will see more unsettled and cooler weather impacting. as we go through next week, starting as usual in the north of the U.K.

One of the aspects you'll notice is the strength of the wind which will ramp up I think as we go through towards the end of the week. This change heralds the arrival of an Atlantic low the weekend after next, so windy, unsettled and wet is likely if everything pans out by the time we reach the end of the month.

Up until the end of next week though, we look to be reasonably dry (save for some rain moving down the east of the country from the north on Tuesday) and settled before things break down at the end of the week. Thereafter ? Well that's Mystic Meg territory well and truly, but my hunch is we will move into March on a cool note.

Agronomic Notes

When you look at the weather we have had since the start of this year, it has definitely been a case of limited opportunities for growth and whereas normally a winter granular will have kept things looking shipshape, the lack of rain since mid-January has kept a lot of granular fertiliser in the shed.

The above graphs are from my default location at Thame, Oxfordshire, but aside from the north of Ireland and Scotland, I think they're quite representative. Some brief mild interludes, cold and frosty in-between and a very sharp cut off rainfall-wise once we got past mid-January.

I have projected the temperatures for this week and converted them into daily G.P on the graph above (together with rainfall) and you can see we have another growth window appearing which will suit a light foliar feed whilst air temperatures are pushing into double figures. A little rain around possibly for the south of England, but I don't see it amounting to much.

Further west for Wales and Ireland, the greater level of cloud cover will mean overnight temperatures will hold up higher than they will for England and Scotland, so you'll see more in the way of a growth spike this week and of course more rain being further west. This means a granular could come into the equation because the rain signal is stronger than it is for England. That is a really good growth spike for this time of year.

Sudden Stratospheric Warming Event - Spring 2018

Earlier in my blog I discussed the SSW event that is currently taking place and the potential for it to influence our weather in a negative fashion. The last one that did was back in the early spring / late winter (who can tell these days ?) of 2018, so I took some of Sean's data from back then and graphed it out below ;

You can see in late February, 2018 that we immediately went into a period of frost and the wind direction I can tell you was indeed easterly. In early March, this became north easterly, except for a brief period of westerlies around the middle of the month which brought milder weather. We remained much cooler than usual with east / north easterly winds throughout the second part of the month.

The absence of good growth days is clear to see with in fact more growth in January than March that year. So that's what a SSW event can do to our weather if the weather high up in the Stratosphere couples with the Troposphere after a SSW event. There's no guarantee that it will, but it is worth keeping an eye on. As a matter of interest, it continued to stay cool (and on the dry side) through to the middle of April 2018, when we suddenly got some warmth and rain. Bingo !

I draw attention to this for a couple of reasons.

Firstly, knowing about the likelihood of a SSW and then following its effect or non-effect on our weather should equip you better to make management decisions when it comes to the spring. There's simply no point in carrying on in isolation of the weather and then bitching about it when it hasn't played ball with your objectives simply because you didn't change and / or adapt. The smarter play is to work with it, not against it.

Flexibility to change isn't one of our great strong points I think when I look at the structure of our industry and the way decisions at club level are sometimes made. Pigeon-holing aeration weeks in the calendar between fixtures are all well and good but if they are not achievable sometimes because the weather isn't playing ball, then we have to adapt and think out of the box rather than consigning them to the rubbish bin. Aeration is the foundation of our IPM and just like us, the grass plant needs oxygen to breath.

The more pics like this that I see in January and February, the happier I am.....(thanks MT)

All the best.

Mark Hunt