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  • Writer's pictureMark Hunt

January 29th, 2024

Updated: Feb 12

Already I am typing the last blog of January, 'tempus fugit' and all that.

First up, many thanks to everyone that dropped by for a chat at BTME 2024. It was a great show for Peter Palmer and I with plenty to follow up on. 😊

I managed my usual visit to Betty's and regretted jumping on the scales when I got home for sure. Fat Rascal's and all that !

Onto the weather.....

Yesterday, the news was full of a new record temperature for January in the U.K and perhaps surprisingly (or not surprisingly as you'll read) the record was set in the Scottish Highlands in a place called Kinlochewe, an hours drive from Inverness. Many places in the north west Scottish highlands recorded temperatures close to the 19.6°C and some of our Davis weather stations were actually higher than this.

Before you run to the hills (or away from them 😊) the record temperature was set as a result of a 'Foehn wind', a fact that some media broadcasters neglected to mention.

Now I first heard about a Foehn wind (pronounced 'Fern' although everyone seems to say it different !) on my travels to Switzerland, visiting Bernie and Tobias at Fenaco, Winterthur. Both mentioned about a specific wind that caused high temperatures and a drying effect on the leeward side of a mountain.

Foehn winds are a fascinating phenomenon, because they graphically illustrate the effect of local topography (in this case a mountain range) on rainfall, cloud cover and temperature. The high temperatures on the leeward side of a mountain range are a result of (word of the day warning) Adiabatic processes, namely condensation of water vapour into rain on the windward side of a mountain, which releases latent heat energy due to the conversion of a gas to a liquid. This warmed column of air then descends down the leeward side and warms due to compression on the way down. As the air cools on the windward side it does so at a rate of 0.6°C per 100m of altitude gained but on the leeward side, the opposite is true and the descending wind warms by 1.0°C per 100m altitude lost, hence the warmer temperature here.

We thus have a significant temperature differential between the cool /wet, windward side of a mountain and the dry / warm, leeward side. The record of 19.6°C was recorded on the leeward side. Last night I made the other half sit through a number of YouTube videos 😉 on Foehn winds and we decided that this one gave the best explanation, you can find it here. Foehn winds occur all over the world and are famous meteorologically with names like Chinook and 'Snow Eater'

Now the chances are you don't live close to a Foehn wind location but it is very likely that your site and the weather / climate it 'experiences' is impacted by local topography. An effect that is independent of a weather forecast. This could be a hill, a forest, thermal updrafts from heated concrete and buildings (in a town / city), light soil types that cool down and heat up very quickly. All of these contribute to your local climate in some shape or form.

So we are mild at the end of January and reasonably dry in some parts of the U.K & Ireland (disregarding a rain front that is currently sitting over the north of England / southern Scotland today) courtesy of that Omega blocking event I highlighted last week. (Image from

So will it last and give us a dry start to February as intimated last week ?

General Weather Situation - w/c 29-01-24

So we start the week mild and in some places very wet due to a weather front that crossed Ireland on Sunday and is now crossing northern England and The Borders today. Away from this rain, it is a balmy 13.5°C as I sit and type this and spring is seemingly in the air. The Snowdrops, Cellandines and Daffodils think so anyway !

So for the coming week we have high pressure to the south of us ushering up warm, mild and humid air battling it out with cold, wet and windy weather to the north. This means we will see a sunshine and showers type spell of weather for the U.K & Ireland, with reasonably mild days alternating with cooler nights if the skies clear overnight.

It is quite a complicated mix of weather this week with both warm and cold air masses and conflicting wind directions. This makes it tricky to forecast.

Taking up the plot from overnight Monday into Tuesday and that rain front should slowly clear away from eastern coasts, departing The North East last, just after the morning rush hour on Tuesday. Thereafter Tuesday looks a fine and dry day with varying amounts of cloud cover and temperature. The west will see a cool, dry and bright start to the day after an overnight ground frost and the only fly in the weather ointment will be more in the way of cloud cover for north west Scotland, thick enough for a bit of drizzle. A bit of a Dreich one in places there I think !

With two weather systems competing, the wind between them will be funnelled through so Ireland and Scotland will notice some strong winds on Wednesday and Friday. After a dry day on Tuesday, Wednesday sees a rain front push into the north west of Ireland and Scotland and push south and east across Ireland, the north of England and Wales later in the day. As it does so, it fizzles out. So wet for Ireland and Scotland, a dry start but wetter later for North Wales and the north of England and dry for the south and east. Cooler on Wednesday with a much fresher wind, especially aligned with that rainfall. So whereas we would be 10-12°C for England, Wales and Ireland on Tuesday (Scotland much cooler at 7-9°C), Wednesday sees temperatures just up in the high single figures after a cold start with ground frost.

Thursday sees that rain fizzle out overnight across the southern half of the U.K and for nearly all of the U.K & Ireland, it'll be dry, bright and sunny and remaining on the cool side. Just a weak rain front skimming the far north of Scotland, the only blemish. Plenty of solar radiation round on Thursday as that sun beams down 😎

Closing out the week on Friday and those milder temperatures reappear along with a strong south westerly wind. Dry again on the whole with just a weak rain front affecting the western coast of Scotland and the north west coast of Ireland later in the day. More cloud cover will keep the temperature up into the teens in places despite a very strong wind, especially across the west and north.

The outlook for the weekend is again largely dry, especially for England and Wales. Remaining mild with a south westerly wind in situ and a pretty dry outlook for Saturday other than some rain across The Mersey estuary and North Wales, some of these showers may push inland later. On Sunday we will see a rain front push into Scotland overnight with this moisture turning to snow at elevation as the lower air temperatures impact here. Later in the day, rain arrives into the north west of Ireland and moves eastwards across The Irish Sea. Away from this, we look to be dry and mild on Saturday and Sunday further south, with strengthening winds on Sunday. Temperatures should be double figures for Ireland, Wales and England and just shy of them for Scotland.

Weather Outlook - w/c 05-02-24

So after a not so bad end to January and start of February, how long are we going to hang onto our mainly dry weather outlook ?

Next week starts off with a noticeable shift in the wind direction to northerly, so first up we will see temperatures drop away from the weekend with a return to ground frosts I think. Some rain around at the beginning of the week as well, falling as wintry showers over elevation. The north winds are a result of the leading edge of a high pressure system and that is good news because it means currently the outlook for next week is cool and dry. Just what we need I think. Those cooler northerly winds should run through to mid-week whereupon they will swing round to a more westerly direction, increasing the temperature and the wind strength. Those strengthening winds will signal change as the jet stream drops, high pressure exits stage right and a cold, northerly low pressure looks to interject from the end of next week / weekend. At the same time we will become more unsettled so I think that could mean wintry showers and snow making a return towards the end of next week and affecting the north of the country first. Currently the projection is for much colder air to interject from around the 9th, 10th of February and for this to last up to the middle of the month. So we may possibly have a finite window to get stuff done.

Agronomic Notes

Using that weather window...

Many years ago I was chewing the cud with some superintendents and we discussed the merits of out of season aeration work. At that time it was more typical to slit and / or vertidrain post Christmas, but to go out and remove organic matter by hollow coring, nah.....One of these afore-mentioned now religiously sends me a photo of their 'spring renovation' in late January / February. This years effort dropped into my inbox today and is shown above, thanks Mark for brightening up my day and boy did it need brightening up !

Then people started experimenting, doing the odd green, maybe their worst greens organic matter-wise and the feedback was good. Nice recovery, box ticked when it came to taking out O.M (if necessary that is) and a good time before the season started in earnest and that old expectation button got turned up prior to The Masters.

Nowadays if resource and ground conditions allow, aeration in January and February is more and more popular and rightly so I believe. Traditionally the time for spring aeration is March / April but it can be an exceedingly tricky time of year to grow grass. It is more often the case than not, that our spring weather features an Omega or Diffluent Blocking Event which means a spell of cold and dry weather with late frosts. These make the opportunities to grow grass especially limited. Now 2023 threw us a curve ball with an exceptionally dry (and mild on occasion) February followed by a cold and wet March. Not the norm in my books and unlikely to be repeated.

So last night I thought I'd collate some growth potential (G.P) figures for 2023 using 4 locations across the U.K. Next week I will do the same for Ireland. So I have charted out the monthly growth potential from January to December from 4 locations across the U.K, here's how they looked ;

So we can notice a number of features from this chart.

First up, the south west of England warms up faster than the east and north, no great surprises there and for sure next week's Irish data will look the same. The second is the lack of difference between the north of England and the east for most of the year, from a monthly G.P perspective. That surprised me. The last and relevant to the above discussion, there is not a massive difference between the total G.P for January and February vs. March. Yes, March is higher, but not by much and the same goes for April as well in 3 out of the 4 locations.

So let us imagine you aerated this week, the end of January in Suffolk in 2023. By the end of March you'd have had a total G.P of 4.28 (Feb) +6.89 (March) = 11.69, good enough to provide recovery in my books from a reasonably-sized hollow core. If you look at the G.P for March / April and worked on the same amount of G.P, aerating at the beginning of March, you probably wouldn't have got to the same G.P figure (11.69) till the middle / end of April. That is also based on the assumption that moisture conditions were forthcoming for March and particularly April. The other difference that can't be stressed enough is that expectation levels in January / February are so much lower than March / April from golfer and management alike. This time of year people are just glad to get out and play, it's a bonus if the course is good as well. Come March and April that is a very different scenario.

Just to show that it isn't all plain sailing doing early season aeration and there is another side to the coin weather-wise, it can look like this ! That said, it still got done and it still recovered well before the spring season commenced in earnest.

Above is a chart showing daily Growth Potential for 2023 from one of the locations documented above. If you look at the beginning of the year, you can see those early season growth spikes which provide recovery from early season aeration. You can also see the very up and down nature of April from a growth perspective and the fact that we don't get consistently good growth in the U.K till May and sometimes the end of May. June, July, August and September were the growth months last year and the season extended well into October. It is no wonder that it was difficult on occasion to keep greens speed when the daily G.P was at or close to 1.0 (in other words optimum) day in and day out.

Organic matter levels going up ?

Speaking to a number of superintendents last week at the BTME show, it seems like a lot of organic matter levels have increased year-on-year despite good levels of aeration and topdressing. When you look at the type of growing season we had, the fact that moisture availability was constant all through the summer and into the autumn and so growth wasn't moisture-limited, it probably isn't a surprise. Dove-tail that with the very wet back end of the year with water-logged rootzones, low oxygen status and therefore (possibly) sub-optimal microbial decomposition and it make sense that we may see an increase. Dr James Beard always used to say that you shouldn't aerate and topdress the same amount every year. In a good growth year like we had in 2023, it follows that you would have had to topdress more to dilute the organic matter created or of course fertilised less if you were measuring clipping volume.

Without a doubt things have moved when we factor in growth clipping volume alongside Growth Potential using the Growth Ratio equation, as discussed by Micah Woods (here) and Jason Haines (here). When we consider the Growth Ratio we are looking at the relationship between the Growth Potential and turf clipping volume to fine tune both nitrogen and PGR inputs. It is a very interesting concept and one I need to apply myself to understand fully. (I am old you know so be patient 🙂)

For sure we need to change our input levels (nitrogen, GDD, etc) every year dependent on what Mother Nature throws at us, what the data suggests and what we observe / measure at our facility from a plant growth perspective.

Marrying them together is key in my mind, thinking out of the box and putting the calendar in the bin !

All the best.

Mark Hunt

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