October 16th, 2023

Hi All,

Last week when I was typing this blog, the outside temperature was sitting at 17°C and heading towards the early twenties. This week it is struggling to get above 2°C with the 2nd frost of the year clearly visible.

What a change in the weather we have experienced over the last 3 days.

The change happened on Friday afternoon as this snip from a nearby Davis weather station shows, with a near 10°C drop in a matter of hours as the jet stream position dropped south and colder air pushed down from the north west.

If ever there was a more defining point in time, when summer finished and autumn / winter started I would be surprised to see it.

This trend to warmer autumn temperatures has caught nature on the hop as only a few days ago I was seeing so many Red Admiral butterflies, one of the winners of climate change here in the U.K. I wonder how many are now using the northerly airstream to head off to warmer climes ?

Normally at this time of year we are welcoming in hordes of Scandinavian Redwings and Fieldfares that have crossed The North Sea to feed on our burgeoning berry crop. In fact, typically from mid-September you can hear them travelling at night above you. I went out last night and apart from coming face to face with a fox that nipped into my garden to partake of the Hedgehog food, the sky was clear and quiet. Those thrushes are staying over in Scandinavia and Russia later and later into the year as their autumn warms as well.

Maybe at the end of this week, they will hitch a ride over because we have a spell of prevailing easterlies coming up courtesy of a Bay of Biscay low pressure system that is projected to bring an extremely wet and windy second part of the week / weekend. This slow-moving low pressure system could potentially bring a months worth of rain to the southern half of England over the course of 3-4 days.

Last week, I had the pleasure of attending and speaking at the Lawn Tennis Seminar at The All England Tennis Club, Wimbledon. It was fascinating to understand the pressure on grass courts during the tennis season, both here and abroad and the threat of other surfaces replacing grass. When you consider that in the hotter summers like 2022 and 2018, the baseline temperature on Centre Court can be over 40°C, well north of the temperature that Lolium perenne is comfortable, you can understand the demands on the groundstaff, both here and at the various venues on the run up to the finals.

It was a great experience for me and I thank Neil, Mark, John and staff for the invite and hospitality. A thanks too, to the lads from Ilkley, Frinton-on-Sea, Felixstowe and Cromer tennis for the banter, it was a good craic.

Swiftly onto the weather now, as I have an appointment with 'The Blond Assassin' this afternoon at Nottingham Hospital. My name for my Pain Management Consultant who will be administering my twice-yearly ultrasound-guided injection into my ruined right shoulder. Oh Joy.

So what has the week in store for us...?

General Weather Situation - w/c 16th October, 2023

Well, definitely a week of two halves this week as we will see some milder air push in mid-week as the rain arrives and then see temperatures drop back during the weekend to the seasonal average.

As I sit typing this now, the low pressure system that is going to bring all of that rain is sitting off Portugal as this satellite image shows courtesy of meteoblue.com.

So Monday we have a quiet and dry start to the week for pretty much all areas, dull, cloudy and cool with light winds. Enjoy this because it is all downhill from here. So a dry Monday is followed by a change day as that low pressure pushes up towards the U.K and will bring rain to the south west of England and Ireland during Tuesday morning. The first tranche of this rain will push over Ireland on Tuesday and bring heavy rain to the south coast in particular. For the U.K, we will see some rain across The South West and south coast of England, but Tuesday will be a largely dry day, brighter with some sunshine and milder, with temperatures in the low to mid-teens as a freshening easterly wind enters our weather picture.

That rain over Ireland will stay in situ overnight into Wednesday, so that means some very high localised rainfall totals and flooding is likely. A new rain front will push into The South West and South Wales during the course of Wednesday morning and push north bringing heavy rain to South Wales and along the south coast. That rain across Ireland will finally start to move north and west into the north west of England and western Scotland during the course of Wednesday afternoon. This band of heavy rain will slowly move north into The Midlands and northern England later on Wednesday evening and it'll start to clear the south of Ireland finally. It'll be much milder on Wednesday with a very strong easterly / south easterly wind.

Thursday morning sees that band of heavy rain across the far north of England and pushing into Scotland with some heavy rain for the east. Further south a drier start before the next swirl of rain showers pushes into the south coast of Ireland and England. So Thursday is more showery with some drier interludes but cloudy and mild with temperatures in the mid to high teens, urged on by a strong southerly wind.

Overnight into Friday, those showers will consolidate into heavier rain across the north of England / Ireland and across Scotland. By Friday morning the rain will be across the northern Midlands and northern half of the U.K and Ireland and it'll be drier further south until further rain arrives later on Friday to the south. Ireland will stay mainly dry apart from rain across western coasts. A little cooler on Friday as that wind swings round to the east again with temperatures in the low to mid-teens.

Now what you will see this week on your forecasts is the rainfall totals changing daily as we get closer to the end of the week as we get a better idea of where it is heading, when.

By the weekend that low pressure will be pushing eastwards across The North Sea and as it butts up against cooler air on the continent, it may fall as snow, some of it heavy. So Saturday looks showery across the southern half of the U.K, drier further north and across the west / Ireland. Much, much cooler as that wind swings round to the north east, so we head down into single figures for most areas struggling to hit 10°C. Overnight into Sunday, we will see some showers across the south east and east of England and during the course of the day these will head northwards up the eastern coast through the course of the evening. So drier and cooler away from these eastern-focussed showers but with a biting north easterly wind on Saturday, swinging round to the south west on Sunday, which means slightly milder and slightly sunnier on Sunday, with the best weather in the west.

Weather Outlook - w/c 23rd Octboer, 2023

So we start next week with a low-lying jet stream and colder air out in The Atlantic to the north west. We also have another Bay of Biscay low pressure system lying in wait. This sets a potentially pretty unsettled picture in my mind for the start of next week.

Unsettled next week it will be, with a strong south westerly wind, so that means milder air will push in through next week accompanied by a lot of rain. Monday looks like being the driest and calmest day of the week, next week before that Atlantic low pressure pushes in, flips the wind to the south west and pushes rain into Ireland overnight into Tuesday and across the U.K. The rest of next week looks very wet and very windy with a brief cooler interlude at the end of the week as the wind swings more north westerly, before heading back to the south west again next weekend with more rain.

Taking into account this week's anticipated rainfall, the second half of October looks particularly wet and windy at times with some milder air in place briefly this week and most of next.

Agronomic Notes

First up, let's look at the change in weather that occurred at the end of last week courtesy of some Davis Weather Station data from Sevenoaks, Kent. I have charted above, air and soil temperature (at 100mm) and you can see (hopefully) that along with a pronounced air temperature drop, we lost about 5°C soil temperature over the course of 24 hours as that colder rain fell and pushed the temperature down. So if you have overseeded late, that will put a temporary delay on germination. I say temporary because I think the milder, wetter air this week and particularly next week will push the soil temperature back up again, so all is not lost.

Button down areas with a PGR ?

The problem we face front and centre is the volume and frequency of rainfall projected over the next 7-10 days so for me if I had the budget and resources I would be buttoning down any hard to cut, known wetter areas on my facility with a PGR and iron tankmix (no fertiliser) so that I didn't have the dilemma of having to go out and cut grass in very wet ground conditions and create a lot of mess. One can also imagine that worm casting during this period will be a problem because the soil temperature will come up from this week's low as the warmer air and milder rain will influence it.

So nipping these areas down with a plant growth regulator and iron (to keep colour but not generate growth) seems to me like a good idea given the forecast in front of us.

Disease pressure

After a pretty brutal summer disease pressure-wise courtesy of the warm, wet and humid air we received, this autumn has continued that trend. Peaking on the 11th of September for all of our locations, we have seen a continuation of this disease pressure in the first half of October, with a further peak of Ireland / Scotland on the 9th of October and England on the 14th of October. The good news as you can see from the far right of the graph is that this pressure is now heading downwards with the sudden loss of air temperature we have experienced of late.

This also means growth rates will have dropped as well, but as hinted above, the milder air mid-week, this week and next week will see the Growth Potential recover to I think 0.5-0.6.

Image courtesy of Kate Entwistle, The Turf Disease Centre

Microdochium Spores don't like rain......

So to finish on a positive note with decreasing disease pressure, I would single out the next 7-10 days of rainfall as further decreasing the risk of Microdochium thereafter.

Why ?

Microdochium spores (not the fungus, the spores) don't like sitting wet and cold, it decreases their viability dramatically. So with high levels of spores from the summer and autumn sitting in your turfgrass canopy, the upside to what on the face of it looks like being a run of pretty dire, wet weather is that it will decrease spore viability for later in the autumn / winter, particularly on areas that hold moisture (push up greens).

So hold that thought this week and next as the rain hammers down :)

All the best.

Mark Hunt