June 15th

Hi All,

There has been some beautiful cloudscapes around of late with the combination of warm temperatures and building humidity. The cloud in the centre of this picture, (took while I was heading out for a lovely evening session on the beautiful Eyebrook reservoir) is already building and gathering energy. Summer thunderstorms though are not without their frustrations as you watch them appear, dump their payload and disappear within miles of your site, while you sit dry as a bone. That was the case this weekend, some places got a good drop and some stayed dry. I remember Karl at Meteoblue saying to me that summer rain was much harder to forecast accurately. I noticed the familiar tracking of storms along motorway networks over the weekend, particularly along the M5 and M4. A clear indication, if any were needed, of life returning to ‘normal’ with traffic building up again on our road systems. Ho hum.

Without further ado, let us see what’s in store for the weather this week and next. What is going to win the battle, a high pressure peak or a low pressure trough ?

General Weather Situation

As the GFS output shows above we start the week with the same low pressure we had last week. This low pressure tracked in from the north last week, moved south of the U.K to the top of Portugal and then turned round again and tracked back up into the south of the U.K over the weekend. It is typical low pressure behaviour in a trough pattern, moving vertically north to south but not horizontally, west to east. Sadly for me here in Market Harborough, we got very little rainfall from it, but others did. Month to date we are sitting on 15.6 mm, I know other places who got that amount of rain in one shower 🙁

So Monday starts off with a largely dry picture after the early morning mist burns off but with low pressure close there’s always likely to be rain around somewhere. Currently the projection is for some sharp showers to kick off over Mid / North Wales around lunchtime and these may consolidate into longer spells of rain for this area and the north west of England. The same across The Irish Sea for the north west of Ireland. I can also see a re-run of the weekend where we will see some showers build over southern England and The Midlands, but you’re far better clicking on your radar than me predicting where and when. By early evening these showers look to consolidate into more widespread rain over the southern half of the U.K and extending northward up into the west coast of Scotland. I’d say the rain will be more west and central ly-focussed across the U.K & Ireland, but don’t place too much store in that. Universally pleasant with temperatures into the low twenties for all areas. Winds will be light and from the south east / east. As will be the case throughout this week, some of the storms may be accompanied by thunder and lightning.

Onto Tuesday and ‘the glorious 16th’, so called because it marks the first day of the fishing season on inland rivers in the U.K. As a wee nipper I used to spend many a restless night anxiously waiting for this day,  before heading off to the local brook, canal or carp pond, fishing rod strapped to the crossbar of my pushbike to ply my wares with a smile on my face and a life devoid of responsibility. Happy days 🙂

So overnight that low pressure sinks south dragging the rain away with it, though you may still see some showers across Wales and the west of Scotland. Through the morning those showers will build again along the west coastline of the U.K and extend inland, though the east looks like it’ll miss most of them. For Ireland it’s the other way round with the showers building in central and eastern areas through the morning. Through the course of the afternoon, these showers will drift eastwards into central and eastern areas of the U.K, whilst the rain consolidates across Ireland in all areas bar the west coast. As we go through the evening those showers will dissipate. Similar temperatures to Monday in the light easterly winds, low twenties being the order of the day and maybe a degree or two lower over Ireland with the thicker cloud mass and rain.

Mid-week beckons and overnight that rain has fizzled out over most of the U.K and Ireland but it’ll persist across the west of Scotland. Through the morning, yes you guessed it, we will see more rain build across the west and move north and east consolidating as it does so through the late morning / early afternoon. Ireland looks to stay largely dry, except the south east across Wexford and Cork. Some of this rain may extend along the coast to west Cork and northwards into South Leinster. So another day of rain building in the west, tracking north and eastwards but rarely troubling eastern coasts, the same for Scotland. Similar temperatures to Tuesday, low twenties for the U.K, high teens for Ireland, accompanied by light easterly winds.

Onto Thursday and here we see that unreliable weather feature, continental rainfall, make an appearance. This is projected to build across France during Thursday morning and push into the south east of England, extending across the south of the U.K into Wales by dawn. Through the morning we see continual showers pass along this route, primarily south of The Wash, so that means the north of England, Scotland and Ireland look to start dry on Thursday. Later in the afternoon we see this rain consolidate and spread northwards, with some showers making the trip across the Irish Sea into the east of Ireland. Cooler on Thursday as the wind swings round to the north and picks up pace. This will pull in some cloud cover and drop the temperature down into the mid-high teens. As we approach dusk, that rain will push south out of central areas and across the south coast of England.

Friday and we still see that low pressure stubbornly refusing to depart the scene. As such on Friday it’ll pull in showers across the south of England, Wales and The Midlands from the off. Through the rest of the day this pattern continues with some of the showers consolidating to heavier bouts of rainfall across the west and Wales. They’ll be some showers across the north of England and Scotland but these will be largely few and far between. Some of these will push into the north of Leinster and Northern Ireland during the 2nd half of the day. Winds will be lighter than Thursday, but still from the north so temperatures will pick up a bit into the high teens and low twenties again.

So how does the weekend look ?

Well the GFS output above shows the potential story of the weekend with a big Atlantic low pressure trying to push in and that diminishing low sitting over the southern half of the U.K.

So for Saturday, the longest day of the year,  it looks like we will be mainly dry save for some showers popping up during the 2nd half of the day across the U.K & Ireland. As that low approaches, the winds will swing round to the south west and freshen across Ireland later on Saturday but for the U.K, they’ll remain light. At this stage the main rain front is due to make landfall around dusk on Saturday night along the western coast of Ireland and overnight it’ll push eastwards across Ireland and into the west of the U.K. So Sunday looks to see the winds swing round to the south west across the west of England, Wales and Scotland as rain pushes in. Central and eastern areas will remain bright and sunny but cloud will build from the west. At this stage, the first front of rain doesn’t look to progress much eastwards before fizzling out, so mainly dry for central and eastern areas.  Winds looks to be fresh to moderate from the south west with similar temperatures to the end of the week, high teens to low twenties.

Weather Outlook

So we start next week finely balanced with an area of high pressure sitting across Spain, Portugal and France and low pressure to the north west of Ireland. Now I know enough about these scenarios to say that either one could easily win the day with heat pushing up from the start of next week or that low pressure pushing in. Both the GFS and ECMWF suggest that high pressure will win the day with the latter showing some significant heat building next week. GFS suggest heat but not as intense. As it stands now it looks like the early part of next week will be dry and warm though Ireland could still pick up rain from that low pressure system on Tuesday. The ECMWF output for next Wednesday is shown below. If they’re right that’ll be temperatures in the mid to high twenties I would say.

The real question concerns the 2nd part of next week when a more southerly low is projected by GFS to nudge the high pressure onto the continent and allow rain to move in from The Atlantic for the 2nd half of the week. So if we go with the GFS projections we have a dry, settled and warm first part of the week followed by a fresher, cooler and unsettled second part. Again we see a distinct difference between the European ECMWF model and the U.S GFS model in terms of 7-10 day projections.

Agronomic Notes

Disease Spike

Last week I commented that the end of the week and the coming weekend would represent a significant spike in disease pressure as moist air arrived with higher night temperatures.

Below is a snap shot of the disease pressure predicted for this period last week on a fairly open site using the algorithms I’m working on with my ever-suffering colleague, Paul Vipond, in Business Support 🙂

It is clear to see the increasing pressure through Thursday, Friday and Saturday last week.

This spike really applied to Microdochium nivale but also to some of the other diseases that we see at this time including Red Thread and Fairy Rings.

If ever there were diseases that like humidity and temperature, it is these three and if we were on the continent it would be joined by Dollar Spot.

Here’s a pic I took on Thursday whilst looking at a tee complex that sits out of the wind and therefore builds humidity.

This particular tee was just at the end of its nutrition so the combination of slow growth rate and building climatic drivers enhanced the disease pressure for Red Thread in this instance.

I’ve had plenty of feedback over the weekend about increased disease pressure particularly from Microdochium but also Fairy Rings and Red Thread but the former doesn’t appear to have done much damage to the sward. This is undoubtedly because not only did we experience an increase in disease pressure, the arrival of rain to most places also kicked off a surge of growth. So we had the dynamic of the plant growing faster than the disease in many (but not all) instances.

You can see the climatic drivers and the increase in growth in the following graphs from Sevenoaks, U.K.

So the diary of events went like this ;

On the 9 / 10th of June, we started building humidity and night time temperature which resulted in an increase in dew formation / plant leaf wetness. These were the drivers for disease development. Initially we saw significant disease pressure / evidence on the 10th of June particularly because the level of growth was slow as the overnight temperature remained cold. From the 10th onwards, we saw higher night time temperatures dove-tailed with elevated humidity and extended periods of plant leaf wetness, all strong drivers for disease development, however we also saw a big spike upwards in growth potential, increasing from 44% of optimum to 69% of optimum between the 10th and 11th of June. This upward growth trend continued with a further increase to 89% of optimum on the 12th of June and then 100% of optimum on the 13th. So although the climatic drivers were promoting strong disease development, they were also promoting strong growth and so that’s why in many cases we saw the disease grow out.

The exception to this rule would be on surfaces that were under strong growth regulation and here for me is a lesson for the autumn / winter.

If we regulate our grass late into the autumn so we slow down its growth rate (with the intention of increasing the longevity of a fungicide maybe?), we will definitely (in my mind) increase the severity of disease because it is not growing out as fast. Now sometimes I’d admit, the climate acts as its own PGR and there’s absolutely nothing we can do about it, but it does make you think doesn’t it ?

Looking ahead we look to maintain our high disease pressure this week until we pull in those fresher winds at the weekend so best keep an eye on this one.

Short but hopefully informative blog, lots to do this week.

All the best.

Mark Hunt