June 22nd

Hi All,

After bemoaning the general lack of rainfall here in Leicestershire during last week’s blog, Market Harborough was the recipient of 3 thunderstorms in a row last week. Each an evening event that gave the rowdy, non socially-distancing teenagers in the park behind me a real soaking and sent them scattering for home. How I laughed my nads off, I don’t think anyone has taught them how to time thunder following lightning and therefore understand that a storm is getting closer.  Sadly, they’ll be back this week as we have something of a mini-heatwave on the way 🙁

The lightning storms were particularly impressive, some really lovely patterns in the sky. Helen, a good friend of my significant other, took these mega pictures of a storm over Atherstone (Midlands), thanks for letting me use them Helen, they’re great 🙂

So our monthly rainfall total stood at 18 mm to date last Monday and now sits at 76 mm, with the last rainfall 5 mm yesterday morning, enough to give my boat a thorough dowsing at Eyebrook. Thursday’s potentially unreliable continental rain was actually extremely well-behaved and gave the south of the country a 20-25 mm hit across the whole day, nice steady rainfall, excellent.

We will need it though, because this week we see a hot air plume pushing up from Africa and this will drive temperatures into the upper twenties and bring with it 30 mm or more of E.T for the southern half of England and Wales. Further north, low pressure will be in attendance so Scotland will pick up plenty more rain this week. It is interesting that the jet stream pattern changed on the 2nd of June and that pattern has stayed in situ for 3 weeks now. This week’s hot air peak looks like being a blip because the GFS data is suggesting a thundery breakdown at the end of the week, so get your camera ready again Helen :).

I don’t know about you but I love rainfall in the summer, I love the smell, how everything responds and feels fresh, it’s like having a cool shower after a long, hot run, invigorating 🙂

OK, onto this week’s weather and what we have in store.

GFS220620_Predicted150620

GFS220620_Actual

General Weather Situation

Above are two outputs from the GFS (Global Forecasting System), the one on the top is the predicted orientation of high and low pressure systems and temperature  made by the GFS system last Monday, the one on the bottom is the actual sitting here today. Not bad eh and that’s why I place good store in their forecasting system and am consistently grateful that unlike ECMWF, GFS allow public access to this data, so I can put together this blog 🙂

So Monday as you can see creates the theme for the week, a northerly low pressure system and a very warm front pushing up from Africa. This will gives us a pronounced north-south / west-east divide in terms of the weather. From the off we will see showers across the north west of Ireland pushing north east into the north west of England and west of Scotland and later into central and eastern parts. Further south and east we have a nice sunny start to the day with a gentle to moderate breeze. The dividing line between areas receiving the showers looks to be around Preston, Lancs, so north of that looks unsettled today, further south dry, sunny and pleasant with the odd shower tracking into Wales. Ireland will see most of the rain across the north west but there is also a heavy looking number affecting Kerry as I speak and that’ll track north and east through this morning so showers further south as well for Ireland. Some of that rain over the north west of Ireland could be potentially heavy later this afternoon, the same for the west of Scotland. So Monday is cooler and unsettled for Ireland, Scotland and the north of England (north of The Pennines ish) vs. warm, dry and sunny in the south. Temperature-wise that translates to 15-16°C for the west and north, 20-22°C for the south. Winds will be light to moderate and from the south west (for the south) but it’ll be windier across the north west and Scotland.

Tuesday sees that low pressure continue to affect the north and north west with a band of rain sitting diagonally (/) across Central Ireland from the off. This will stay in situ for most of the day and won’t move further east because it is being buffered by that strengthening high pressure system over the U.K. So the west and north west of Ireland looks to be wet and this will also straddle The Irish Midlands. This band of rain will extend across The Irish Sea into Scotland with all but the east and north east in for another wet day. Further south we have temperature building as that hot air plume pushes up into central and southern areas of the U.K. We are set to have bright sunshine with a pretty high U.V rating so if you’re working outside remember to slap on the factor 30 and if you are like me, folically-challenged, wear a hat !

Bright, warm and sunny then is the forecast for Tuesday for the southern half of the U.K, with temperatures pushing up into the mid to high twenties accompanied by a moderate southerly wind.

For Ireland and Scotland, it’ll be similar temperatures to Monday, that is 16-18°C with a stronger south westerly wind.

It’s easier to sum up Wednesday and Thursday’s weather together because the pattern is fixed. You can see above in the GFS output above that the heat plume extends up from Africa right up into Scandinavia and Russia. The south and east of England picks up the hottest weather, slightly cooler across Wales, whereas Ireland and Scotland stay unsettled through Wednesday but with an ever-increasingly dry picture. So still expect to see some showers across Ireland and the west of Scotland on Wednesday with these tending to become more Scotland-only on Thursday. Temperatures here will climb into the high teens / low twenties through Wednesday into Thursday. Further south that heat plume will push temperatures up into the thirties for the south of England through Wednesday and Thursday, accompanied by light winds. Night temperatures will also stay up so it’ll feel sticky, particular on Thursday night.

As we get to Friday the weather looks to change with an increasing risk of thunder storms in the west and north with overnight rain pushing into the west on Thursday night / Friday morning. So the outlook for the end of the week is for that Atlantic low pressure system to finally win the day and that’ll push the heat eastwards onto the continent and allow showers to push in across Ireland, Scotland, The South West of England and Wales through the course of Friday morning. Some of these showers will be accompanied by thunderstorms as moist air meets heat. Further south and east, Friday looks to start off similar to Wednesday and Thursday, bright and hot, but that low pressure will increase cloud cover and from Friday afternoon onwards increase the risk of a thundery breakdown through Friday evening. So wet for the west and north on Friday with again the bulk of the rain for Scotland in the north and central areas. Ireland looks to see rain throughout the day, maybe drying out a tad later into Friday. Needless to say some of the rain overnight on Friday could be torrential accompanying those thunderstorms.

So how does the weekend look ?

Well Saturday doesn’t look too bad but you will notice the change in temperature, down a good 8 degrees on Friday across England with much fresher air pushing in, still pleasant mind temperature-wise. Saturday will see showers across the north west of Ireland and the west of Scotland with England and Wales looking to stay dry and pleasantly warm. Sunday sees overnight rain crossing Ireland and pushing across The Irish Sea into Wales and The South West during the morning. As we progress through Sunday we see more rain but this time from the continent push into the east of England on Sunday afternoon, evening, so a much more showery picture overall on Sunday. Temperature-wise a return to high teens for all areas on Sunday with strong to moderate south westerly winds.

Weather Outlook

So next week starts off with a very different weather picture to this week. We have the start of a trough pattern re-developing after this week’s interloper. This trough is predicted by GFS to last most of the week and as you can see, it’ll stream in north westerly winds which means a potentially cooler and fresher end to June. As we progress through the week, high pressure nudges into Ireland and the south / west of the U.K bringing warmer temperatures and lighter winds. This warm ridge of high pressure looks to strengthen through next weekend to bring a pleasant start to July. At this stage I think we we will see this kind of pattern, i.e a cooler, fresher and unsettled phase, then a settled warmer phase and then back again. Going into July no one weather pattern is dominating and the jet stream is sitting sort of mid-country which means it doesn’t ‘allow’ low pressure or high pressure to dominate for long.

Putting a bit more detail on it, Monday looks to start next week unsettled with rain across most areas. This unsettled theme continues through to Thursday as that north west air stream pushes showers down central and eastern U.K. The west looks potentially drier next week than the east through the 1st part of next week. As we approach the end of next week, the showers die down across the U.K, although there’s still a threat of rain for Ireland at the end of next week. Still a risk of rain on Saturday but Sunday looks good before that new low pressure is projected to arrive w/c July 6th. Now that’s a long way away weather-wise, so as always in my caveat-laden forecasting world, we will see 🙂

Agronomic Notes

Disease activity

Last week’s rainfall coupled with some high humidity produced a continuation of the disease pressure we saw at the end of the previous week.

Thankfully in terms of Microdochium, we also saw a reciprocal increase in grass growth so the worst of any scarring was soon grown out. I was chatting to Paul in  Business Support about this one and we both agreed it would be interesting to know at what point the grass growth rate needs to be at to counteract the effects of Microdochium nivale. Of course there are so many variables mixed in with this agronomically, not least nutrition, time of year, light levels, PGR usage, etc we then agreed that its a subject in itself and one best left to cleverer people at a later date with more time on their hands :).

The dynamic I’m referring to is this one :

Grass growth rate > Microdochioum nivale population growth rate = No scarring

Grass growth rate < Microdochium nivale population growth rate = scarring

……………………….

It wasn’t just Microdochium that was doing the roads last week and the week before., the increase in humidity I discussed in last week’s blog set off some of the more humidity-related diseases, like Fairy Rings, Thatch Fungus, Red Thread, Dollar Spot and Etiolated Growth. So if you’re seeing some different looking patches on the odd green, you are probably not alone.

Looking ahead to this week, the split forecast in terms of Ireland, the far north of England and Scotland picking up mild and wet weather means you’ll have a continuation of Microdochium nivale pressure this week with Tuesday and Wednesday looking quite high in this respect. As we get into the 2nd half of the week, this pressure reduces for you. For the southern half of the U.K and including Wales, I think Microdochium pressure should drop off this week but the high temperatures and very high predicted E.T levels will bring other issues and that’s what I’m going to talk about next.

Soil moisture status

Now this of course will vary a lot depending on how much rain you have received over the last 20 days since the dry spell broke but I thought I’d carry on my earlier exercise where I compared spring 2018 with spring 2020 from a soil moisture deficit perspective.

So up until yesterday, this is how the stats look ;

So you can see that in 2018, we were already embarked on that run of 8-10 weeks of continually high temperature and E.T. For this spring and now summer, you will remember (hopefully) from when I last did this that we are actually a good way ahead of that year from a moisture deficit perspective. At the end of May 2020, we were -191 mm in deficit vs. only -20 mm for the same period in 2018 (March 1st to the end of May)

Looking at the chart above you can see the arrival of rainfall has flattened off the soil moisture deficit graph and in fact reduced the deficit to a small degree. Now The Oxfordshire is one of the drier places in the U.K, for instance their monthly rainfall is only 47.8 mm, whereas ours here is 70 mm +, courtesy of picking up some big storms last week.

So up until yesterday, this is how it looks when we directly compare both years…

Versus 2018 the results are interesting. So from the end of May till June 21st, the soil moisture deficit had increased from -20 mm to – 84.4 mm in 2018, whereas for the same period this year, it has only grown from -191 mm to – 202.7 mm. The fact remains that we are still a lot drier going into the main two months of summer this year than we were in 2018 and with the excessive amount of new developments springing up everywhere, the requirement for water is higher.

If this government had its backside in gear and actually planned ahead rather than doing everything for the here and now, it might have considered where the water was going to come from to service the demand from all these new developments. It seems utterly ludicrous to me to have the 5 wettest months most can remember over the winter of 2019 / 20 and then in the next breath talk about water shortages. Build some more reservoirs and sort the problem, I can think of a few places that would be considerably improved by incorporation into a reservoir 🙂

I digress (as usual)

This week’s big learn…

So this week we have some pretty serious heat coming into play and with that heat will come significant E.T.

Above is the Meteoturf for my Market Harborough location and if you look on Wednesday and Thursday we are scheduled to hit 6 mm daily E.T loss, now that is the highest I think I can remember seeing in a Meteoturf prediction. You should also note that the Growth Potential for those two days drops from close on optimum to just over 80% of optimum. What this means is that the heat is high enough to cause some grass species to shut down and in particular Poa annua.

So it should serve as a warning if your Meteoturf is looking like this that growth will drop off, the grass plant will be under quite severe short-term stress and your irrigation demand will also be significant until the weather breaks. So I would planning to prioritise my wetting agent and biostimulant usage this week, hold off on things like selective herbicide, iron applications and not to put too high a nutrition /PGR loading on the grass plant, particularly if you’re managing Poa annua-dominated surfaces. Cultural work like grooming, verticutting should also take a back seat if you have it planned for later this week to give the plant a chance to cope with what is a pretty high E.T stress. Fortunately this is just a short-term blip and if everything pans out properly you should be back to normal service next week with the anticipated breakdown and cooler air stream 🙂

That said, it looks like the soil moisture deficit will increase by 30 mm with the forecasted E.T for this week 🙁

OK, tempus fugit my friends, I have to get cracking on the in-tray again and as importantly fill up the Suet feeder, as I can hear two Great Spotted Woodpeckers in attendance and they can’t be kept waiting 🙂

All the best….

Mark Hunt