June 26th, 2023

Hi All,

Back from a lovely break on the beautiful North Norfolk coastline. This picture was taken on Thornham beach looking across The Wash towards Lincolnshire. That rain in the far distance looked to me to be 5-10 miles away but when I looked on the radar, the storm was actually 50 miles away centred over Lincoln !!

We had some massive downpours last week with 30-35mm measured and some seriously high rain rate figures. Nowadays I think rain rate is more of an important parameter than just rainfall itself because it is the rate that rain is falling that overwhelms drainage systems, washes out bunkers and causes flooding, albeit temporary in nature.

The storm we had here in Market Harborough last week flooded our roads to the point where people had to be rescued in cars caught in flash flooding. Downloading some data from a local Davis weather station showed we hit 256.8mm per hour rain rate at the storms peak which equates to 10" per hour. Bearing in mind violent rain is classified as over 50mm per hour (2" per hour), you can see how the characteristic of rainfall has changed and our industry has to change to accommodate it.

Onto our current weather...

General Weather Situation - w/c 26th June, 2023

As you can see from the animated GIF above courtesy of tropicaltidbits.com, we have a rarity of late, an Atlantic low pressure system in charge this week. The arrival of this low pressure system into our weather mix has had the effect of nudging the jet stream (and the heat) further south. So this means the week will be characterised by a cooler, fresher feel to the weather, significantly lower day and night temperatures (a blessing) and some rain. Now since it is an Atlantic low pressure, this means the majority of the rain will be in the west, north west and north, however some showers will move further inland on occasion this week.

So for Monday, a largely dry day with a strong to moderate westerly wind and a smattering of showers pushing in across Wales, The South West and North West. A big change in temperature, some 10°C lower than yesterday and less humid as well means it should be easier to get some kip this week (some hope with me)

With the rain (and therefore cloud) more likely to affect the west, north west and north, we can expect a temperature differential from 17-18°C for Scotland (with 10-12°C at night) vs. 19-22°C for Ireland and Wales (with 11-15°C at night) and then 20-24°C for central England (with 12-15°C at night). The east will probably be the warmest areas but how nice to lose those easterly / north easterly winds for awhile.

Tuesday sees a band of rain move across the northern half of Ireland overnight and into Scotland and northern England. Some of these showers may dip a toe down into the north Midlands during the day. Further south, it is likely to be drier and warmer. Wednesday sees some potentially heavier rain move into the south west of Ireland early in the morning and then move across country with some welcome rain for the east of Ireland before departing east across The Irish Sea into North Wales, north west England and Scotland during late morning and extending into the afternoon. We may see some showers further south and into East Anglia later but don't hold your breath.

Thursday looks a drier day, except for some showers across the north west of Scotland during the day which will consolidate into longer spells of rain across The Highlands and north east of Scotland. Thursday will see that wind swing round temporarily to the north before switching back to the west for Friday and the remainder of the week. Friday sees a cloudier day for most of us with frequent showers crossing Ireland and the west / north west and north of the U.K before these consolidate into longer spells of rain overnight into Saturday. Some of these showers will have a more southerly intent as well.

This will set up a wet start to Saturday for Ireland and most of the U.K, except the southern coastline. These showers will quickly clear Ireland and the west as they move east across the U.K clearing the majority of the U.K by Saturday afternoon. I say most because some rain will linger across the north west of Scotland. Sunday sees a continuation of this rain across northern coasts of the U.K and Ireland with some showers across western areas through the course of the day. On the whole though, Sunday will be a drier day away from western coasts and that rain across the north of Ireland and Scotland. Temperature-wise, as I have written above, cooler across Scotland and the west, with the best temperatures across Central England.

Weather Outlook - w/c 3rd July, 2023

Well this week's weather has helped re-adjust the position of the jet stream pushing it further south and for the time-being keeping the heat away. The projected GIF for next Monday (shown above) indicates we will remain in a cooler, more unsettled westerly airstream for the start of next week, so I expect a similar temperature regime to this week. Low pressure is sitting off the north west of the U.K looks set to dominate our weather for the start of July. Cool (for July) and unsettled is the MO then. So wet and windy and not just for the north and west next week. There's more chance of rain further south and across the east with bands crossing from later on Monday into Tuesday and carrying on all week really until we reach the weekend. Just at the end of next week, we may have a drier interlude before a more southern-biased, low pressure pops up to the west of Cornwall. Now there is plenty of time for this to change but we look to have a more southerly-biased jet stream for the time-being so no heat records just yet. I for one welcome this weather.

Agronomic Notes

June has been a brutal month for managing irrigation and moisture loss

That may seem a statement of the exceedingly obvious but it is worth looking at some of the stats we have recorded across the U.K and Ireland this June.

First up though one of the climatic parameters other than E.T that has made June tricky to manage from an irrigation perspective has been the ever-present north easterly - easterly wind direction. North easterly winds tend to maintain their strength into the evening and night and that means they affect coverage from an irrigation perspective more so than westerly winds I believe.

Below is the wind speed vs. wind direction readout over a 24-hour period from a Davis Vantage Pro2 weather station (sorry it is a lot of data) on not the windiest day we have had in June. You can see that although the wind speed reaches a maximum during the day (14:00) , it still continues into the evening and night with similar strength gusts up until 02:00. This affects irrigation coverage and particularly if you have an old system with not enough heads per green and / or poor pump pressure.

So during June we didn't just have to contend with high moisture loss as you'll see shortly from some stats I have collated but overnight irrigation efficiency was poor in terms of coverage with some areas received too much water and others not enough due to the uncanny 5 week spell of dominant north easterly / northerly winds. Having an accurate picture of soil moisture levels was therefore key and making up for the shortfall with hand watering, a must.

Probably the highest E.T June I can remember.....

As we approach the end of the month, no doubt the media will be full of hottest, driest June quotations but for me I'll be focussing on what affects turfgrass health the most during the summer and that's E.T. "Probably the highest E.T June I can remember" translates into "Probably the highest stress June I can remember from a grass plant's perspective..."

Yesterday, we hit the highest E.T reading of the year so far, not surprising with air temperatures tipping 31.8°C at this location (East of England) and some strong winds. I did see 7mm + E.T loss yesterday on some locations....

It is interesting, not so long ago, an air temperature in the low thirties would have had the tabloids in 'Summer Meltdown' headline mode. Now it passes with scarcely a mention. 40°C is the new benchmark it seems......

The cumulative effect of the lack of rainfall during June and the high E.T levels has led to some significant soil moisture deficit scenarios.

Here's some examples for June up until and including June 25th ;

.........................................................................

Rainfall (in mm) Evapotranspiration (in mm)

Limerick 105.4 90.09

Bristol 25.2 83.72

Thame 20.4 111.18

Milton Keynes 15.8 98.68

Bury St Edmunds 15.6 107.24

Scarborough 26.8 99.16

Dumbarton 75 87.33

.........................................................................

If we pick one of these locations (Thame, U.K), chart out the daily E.T levels (above) and put a line across at 4mm per day which I use a marker for plant stress, you can see on how many days we exceeded this marker. It is actually 18 days out of the 25 we measured. Now with cooler temperatures and higher humidity, we should see less E.T going forward but with a strong - moderate westerly wind forecast, it'll still be significant I think. (above 4mm per day on occasion)

So the take home is that plant stress levels have been high throughout June and we need to factor this into our agronomic plan going forward

Now you may have been lucky enough to receive some of those downpours last week and if you are also sussed enough to have a good wetting agent program in place, some of that rain may have penetrated the surface organic matter layer and done some good. That said, the majority will have run off due to the hydrophobic nature of the afore-mentioned organic matter layer. (see image above)

Two Potential Anthracnose triggers in June 2023 for most areas of the U.K & Ireland

Featured above is the Prodata Reports Agronomic report for June 2023 so far from the same location.

I have highlighted some specific numbers in the maximum air temperature column and Smith Kerns Dollar Spot Probability. On the latter, you can clearly see two peaks during June, one from the 11th - 15th June and the other from the 20th - 25th June, with probabilities touching 40%. During these periods we also had maximum air temperature's exceeding 25°C, so I think it is likely that one or both of them tripped Anthracnose trigger territory. With high enough temperatures, high humidity and rainfall, we can expect to see plenty of summer fungal disease activity with Fairy Ring, Take All and Waitea Patch (the latter wholly dependent on moisture). July would be early for Anthracnose but mid-June is an earlier-than-usual trigger time, so we will see.

It's not all doom and gloom, just keeping the plant ticking over nutrient-wise, minimising plant stress from a biostimulant, surfactant and agronomic perspective and being sensible with cultural work are the bedrock practices of summer turf management in the U.K & Ireland. I am often amazed how well grass as a plant stands up to this level of stress from a climatic perspective and that's without factoring in foot traffic and human wear and tear.

OK, that's me for this week, enjoy the cooler temperatures..

All the best.

Mark Hunt