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  • Writer's pictureMark Hunt

April 11th, 2023

Hi All,


A month or so ago I did a talk at a BIGGA regional seminar and someone asked me if April showers were a thing of the past and I said that they were less and less likely. Well the last week and parts of the Easter bank holiday reminded us that April showers are very much still a part of our weather.


The unsettled theme will continue through this week but there is a drier and potentially much warmer spell of weather on the cards. I know some of you guys courses and pitches are wet but I can't help thinking that every drop of rain we get now will help us at a later date when the tables are turned and we need the rain.


The way our weather goes nowadays we are just as likely for it to stop raining and then not rain again for an extended period of time. Mark my words we could easily be irrigating before the month is out.....


A.I, A.I 🥱🤔


I was listening to a debate on the present and possible future role of A.I the other day and particularly the piece of software called Chat-gpt (read about it here).


The official description of Chat-gpt is ;


ChatGPT is an AI-powered language model developed by OpenAI. It has been trained on a massive amount of text data from the internet and can generate human-like text responses to a given prompt. It can answer questions, converse on a variety of topics, and generate creative writing pieces..........


It intrigued me and especially when the following evening I watched Terminator on the telly, a portent of things to come maybe from an A.I perspective ?


So, next week I have decided to ask Chat-gpt to produce text for this blog by posing the following question ;


"Produce a weekly blog that predicts local and national weather forecasts across the U.K & Ireland with an agronomic slant on turfgrass management. Key words that must be featured are Growth-degree-days, Growth Potential, Poa annua seedhead development, Hedgehogs, Fly fishing and dealing with golf club members"


I promise to print whatever it produces 😋



General Weather Situation - w.c 11th April


So this week is in two parts, starting with low pressure sitting out in The Atlantic pushing in across Ireland today (Tuesday) and then crossing the U.K over the next two days. Behind it we have another low pressure stacking up and then we will see quite a change.


So for Tuesday a dry, sunny and cold start for the U.K, but Ireland is already seeing a raft of showers and heavier rain pushing across the country with the main rain front arriving into Kerry this morning and currently moving across the southern half of the country. This rain band will then push into The South West and Wales before moving across the rest of the U.K in the second part of Tuesday and into the evening. This rain will be accompanied by strong south westerly winds. Temperatures will sit around 12-14°C, but you'll notice a sharp dip during the rain. So a dry start but rain coming in during the 2nd part of the day, with the heaviest rain across the north west of England and south west of Scotland. Some of the Scottish rain will fall as sleet and snow over The Highlands.


For Wednesday we have a re-run with the low pressure swirling around to bring a second front into the west of Ireland by dawn. Scotland and the west coast of the U.K will see a continuation of showers with some of them wintry across high ground. During the morning that rain will push into the west of Ireland, but also across Wales and The South West and then move eastwards. So dry initially but more rain pushing into central and eastern areas during the second part of the day, commencing from the west. The rain should clear Ireland during the evening but we will still see rain across the west of the U.K into Wednesday night. The winds will be very strong and although they are from the south west, they originate from the north, so Wednesday will be a cool one with temperatures in the high single figures., maybe nudging 10°C.


Thursday sees those strong westerly winds continue but it'll be a much drier day on the whole save for a raft of showers stretching from The Humber north west into the south west of Scotland. So drier on the whole but still very windy from the west though that wind will dissipate during the second part of the day. With lighter winds, temperatures will recover towards 10-12°C. I should also say that with the cloud cover associated with the rain for the first part of the week, we should be frost-free.


Friday sees the second low pressure system push into the south west of Ireland and England overnight but it will not encroach any further than the south coast before slinking off eastwards into the south and west of England. By dawn it'll be across The South West and Wales and then move into central / southern half of the U.K during the morning. By the afternoon, it'll be across all of the U.K, but also now affecting eastern counties of Ireland. The heaviest rain will be across central areas. With light westerly winds, this rain will be slow moving and so totals may be high. It'll also be a cool day with temperatures again in the 8-10°C region. Ireland will be drier across the west and south, with rain across the east, but this will clear during the evening.


The change in our weather comes into play during the first part of the weekend with high pressure nudging up from the south. This will push further rain more north and provide a drier interlude. So a nice weekend is on the cards with plenty of sunshine, lighter winds and dry across all areas. Ireland will see a weak rain front cross overnight to leave a legacy of showers on Sunday which will slowly dissipate. With cloud cover we should be frost-free and temperatures will climb into the 13-15°C range by Sunday. What's not to like ?


Weather Outlook - w/c 17th April


So how do we look for next week, more rain or is this dry coming weekend a marker for the rest of April ?


Well next week is looking pretty dry starting with pleasantly light southerly winds and plenty of sunshine. Through into Tuesday we start to pick up some warmer temperatures and light easterly / south easterly winds and I expect mid to high teens are likely. South easterly becomes the dominant wind direction for the rest of the week with pleasant temperatures. I think it'll be warm enough to negate any frosts. As we approach the end of next week, low pressure down in The Bay of Biscay could potentially create some unsettled weather for the south of England and Ireland maybe. This threat continues through into Friday and the weekend. Much depends on the location and behaviour of that low pressure system but for most of the week, it'll be lovely weather, so enjoy.


Agronomic Notes


So since we are already into the second week of the month, I better have a look back at March to see what it gave us across the U.K & Ireland starting with our default location. Before I start I'd just like to say thanks to everyone for either sending me their data or allowing me access to their Davis weather station data, it makes doing this so much easier.


March 2023 and Y.T.D GDD - The Oxfordshire Golf Club, Thame


So March 2023 came in pretty much on average, not the coldest, not the warmest, but middle of the road temperature-wise. Bearing in mind we started March with conditions like this (thanks Kim!) as the SSW event gave us a very cold start to the month ;

It suggests a month of two halves and that's certainly what it was. Looking at the cumulative GDD, we came in at 138.3 at the end of March 2023 vs. 119.9 the year before, so we were ahead of last year temperature-wise and towards the warmer side of previous years, due mainly to a milder January in 2023 vs. 2022. I'll be looking at where we are now approaching the middle of April later in the blog.


Monthly Growth Potential & Rainfall totals - U.K locations - March 2023


Looking at the Growth Potential for March 2023, the range is from 3.77 (Dumbarton) up to 8.35 (Guildford), with the latter no doubt warmed by the close proximity of the M25 / A3 !!.

There are some low figures amongst then notably Milton Keynes, Brands Hatch and Pinner and that is the effect of elevation as all of these weather stations are at sites that have a significant elevation effect. You are looking at 20-25% less Growth Potential on these sites vs. the norm. Just imagine a golfer plays a lower elevation course and then one of the upper elevation courses, the latter will be behind from a growth perspective, but does he / she takes this into account before making a judgement ? Nah....



From a rainfall perspective, March definitely played catch up when it came to y.t.d rainfall totals. After such a dry February, the media was already predicting a summer drought, then it started raining / sleeting / snowing on the 6th of March and pretty much didn't stop for the month. If you look at a location like Flempton, near Bury St Edmunds, their annual rainfall being in the east of England is typically 400mm and they had 91mm in March !


The highest rainfall totals for the y.t.d are at opposite ends of the country reflecting the fact that the south west of England is first in the firing line for much of the rainfall we get and Scotland always picks up north easterly-orientated rainfall. The oddity if you can call it that in March, was that central and eastern areas also picked up significant rain (sometimes more than northern England if you look at the totals) and that is because a lot of the low pressure systems emanated to the south of the U.K, rather than the middle / north. March was a very wet month for sure, but one I think we will ultimately be grateful of in a few months time maybe ?


Monthly Growth Potential & Rainfall totals - Irish locations - March 2023



From an Irish perspective, March was pretty similar temperature-wise to the U.K, with a range from 5.8 (Ballyhaise, Claremorris, Cork) to 7.9 (perennially mild Valentia). As we shall see later, the growth in March followed the same pattern, a cold start courtesy of the SSW event and then better growth from the middle of the month till the end before dropping back in early April.



Looking at the March rainfall totals across Ireland, there are some shockers (aside from the perennially wet Valentia), with Cork the second wettest location y.t.d. Now I know there's a lot of rivalry between the two cities of Cork and Dublin but when you compare rainfall at the end of March, Cork is 2x Dublin and that makes life difficult if you are maintaining golf or pitches. The two driest locations are the coastal ones of Bray and Killiney and that's because they are the last place the rainfall reaches before heading out into The Irish Sea and they are protected by hills / mountains so a lot of the rain falls windward of their location and not leeward.


Again local factors / topography significantly affect local rainfall and these must always be considered alongside a standard weather forecast.


Y.T.D GDD and projections by end of w/c 17th April.....


So I know a lot of you track your PGR applications using GDD rather than G.P, so I thought I would plot out y.t.d GDD in daily and cumulative form and add the projected GDD taking us up to the end of next week.


The reason why I wanted to include the projected GDD is that temperatures are forecast to rise significantly from the weekend and through next week so after a reluctant start to April we will see a significant growth flush. It will also take us through the commencement date for the perennial Poa annua seedhead flush, which is earlier than normal.


So if you are looking to apply a PGR to hold back growth, then the early part of next week is key in my mind. Not just because of the GDD timing but also because with light winds and warmer temperatures, you will have good spraying conditions and good uptake of the PGR into the plant, which is absolutely key to getting a good end result. Right GDD, but cool temps = unpredictable outcomes.


I have plotted the data from The Oxfordshire because firstly I simply don't have the time to do a round Robin across the U.K and Ireland (which I did) but also because having worked with Sean longer than I can remember, I know how the Poa annua biotypes on his site behave vs. GDD. This won't be the same for Cork or Guildford, but what it does show is the pattern of GDD and cumulative GDD coming up.


Fail to plan, plan to fail is a suitable phrase for the next week or so :)



Above is the daily GDD from the start of the year and as you can see we had a mild start to January and some growth days in February. March and April has been typically up and down, but look at the far right of the graph, there's a clear upward growth progression with some high (for this time of year) daily GDD. It is those days that will rapidly accumulate GDD. We should also remember that with March being such a wet month, having growth and not being able to get a machine out to cut it has been a pain, especially on fairways and cut rough. Trust me though, you want it cut before mid-week, next week if you can !


You can see this on the cumulative GDD graph below, remembering that a flat shape to the graph means no daily GDD and therefore no growth. A steep incline means good consecutive GDD and hence daily growth.



So on the graph above we can see that we hit the commencement of the annual Poa biotype seeding (130GDD at this site) around the 29th of March and the perennial Poa biotype seeding (180 GDD at this site) is projected for the 17th of April. That's two weeks earlier than normal.


Now I know not everyone has the resource / time / inclination (delete where applicable) to record, track and work with GDD or G.P, but the above to me is why it is useful feature in turfgrass management. You may think different, I don't....


Ok, my head is buzzing, lots of figures, can't wait for the Chat-gpt exercise next week :)


Take care and enjoy the better temperatures after the cool and unsettled period this week and get them shorts out !


Marky Mark Hunt




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