It’s the 3rd weekend in a row now that I’ve been met by this flooded torrent in place of what is normally a gentle, babbling brook. Out walking in the countryside, there’s a lot of wet lying fields for the middle of October. The figures don’t really do it justice but we are certainly getting some serious rain, not in gentle dollops but 15-20 mm in a few hours. The strange thing is a couple of hours later and all the roads were dry because we still have temperature and therefore E.T to dry things out.
Nothing compared to Japan though where Typhoon Hagibis brought 939.5 mm (37 inches) over a 24-hour period. It is difficult to imagine the effect of that volume of rainfall in a U.K or Irish scenario.
Whilst out mountain biking yesterday I came across a Range Rover whose driver thought that it would be a good idea to attempt a local river crossing despite the fact that it was in flood. There he was up to his dashboard in flooded water, inside and outside of the car…not the greatest of ideas I thought as I cycled over a footbridge next to him. (I didn’t think it pertinent or fair to take a picture)
With out further ado I’ll take a look at what this week and next has in store as we continue our march through October.
General Weather Situation
So Monday starts off dull and calm in this next of the woods but we have two weather systems bringing rain to the U.K and Ireland. One is across most of Ireland save the east coast of Leinster and the other pushing up from The Bay of Biscay and already covering an area from Exeter to The Wash. Both rain fronts are associated with the same low pressure system and through the course of the day they will slowly edge northwards so for The Midlands, South Wales and north of England, you may be dry now but it is heading your way I am afraid. For most of Ireland it looks like a total washout today with consistently bad weather with heavy rain throughout the day. Scotland will see that rain over Ireland push into the west of the country and later this evening into central areas but the east and north-east of Scotland should stay dry. Little point in forecasting wind direction because with the low pressure over Ireland we will see great variability in direction, but overall winds will be light to moderate, freshening as we go through the day. Temperature-wise, pretty much par for the course now with 11-13°C across the U.K and Ireland.
Onto Tuesday and overnight that low pressure spins off into The North Sea to give us a pretty dry picture to start the day thankfully. Just a risk of some showers across The South West and east of Ireland. Enjoy it while you can though because by late afternoon another thick band of heavy rain is set to swing in from The Atlantic and slowly push eastwards across Ireland. This does mean that for the bulk of the U.K, Tuesday will end up being largely dry as this rain won’t impact until later in the day. Some showers may break out later in the afternoon across central areas of England whilst the rain will slowly move across Ireland, clearing the west later into the evening. So a largely dry day for the U.K and really Ireland as the rain isn’t set to arrive till late in the afternoon / dusk. Slightly better temperatures for the U.K pushing up to 15°C but under that cloud and rain expect 11-13°C again.
So by mid-week the boot is on the other foot as that rain is projected to clear most of Ireland by dawn on Wednesday but overnight it has moved across The Irish Sea into the west of the U.K, Wales and The South West and stretches in a line up to the tip of Scotland. Through the course of the morning this rain front will edge eastwards into The Midlands, northern England and central areas clearing the west as it does so. Ireland will start dry but by late-morning you’ll see more in the way of showers pushing into western coasts. That rain keeps moving eastwards so by lunchtime it should have cleared Wales and the western coasts and moved into central and eastern areas finally clearing the eastern coastline of the U.K by dusk. So a dry (ish) day for Ireland, a wet start for the west but clearing through the day and a wet one for central and eastern areas. Similar temperatures to earlier in the week with a moderate to strong south / south-westerly wind in situ.
Onto Thursday and that rain is but a distant memory heading over to the continent, unfortunately absence doesn’t make the heart grow fonder in this case because yet another Atlantic low pressure system is on its way as the Meteoblue clip above shows. So as you can see Thursday will already see a freshening wind across Ireland and showers for the west quickly pushing across country during the first part of the morning. Those freshening winds and showers will also affect Wales, The South Coast and the western coastline of the U.K. This low though is tracking slowly north-east so whilst Ireland is the firing line we may see the bulk of showers across the U.K confined to the south and west with fewer showers pushing inland. This could easily change as I type this on a Monday morning but currently the further east you are across the U.K, the drier you’ll likely to stay. So a wet day for Ireland, Wales, The South West and western / southern coasts with plenty of showers rattling in on that strong to moderate south-westerly wind. Again similar temperatures to the rest of the week 11-13°C.
Overnight into Friday and that low is still off the north-west coast of Ireland so expect another day of sunshine and showers for Ireland and the western coastline of the U.K. We will also keep the strong south-westerly wind and are likely to see showers push further inland across England and Scotland through the course of Friday morning. Again though the bulk of those showers will be across Ireland, Wales, The South West and western coasts stretching all the way up to Scotland where we may see more push inland because of the proximity of the low pressure. So a sunshine and showers day with windy and unsettled conditions but as mentioned earlier if you get a gap between the showers, things will soon dry down. Temperatures remain consistently low double figures – mid-teens.
With such an unsettled week, does the weekend look to follow the same pattern or will we get a breather ?
Saturday will see that very slow-moving low centred over the north of Ireland so that means a continuation of a strong south-westerly air stream / sunshine and showers theme for the start of the day. During the morning we are set to see the showers merge across Ireland, Wales, The South West and western coasts and this rain will push inland as showers through the 2nd part of Saturday. For Scotland we look to start off showery but then later in the morning those showers will consolidate to longer spells of rain for western and central areas.
Yep you guessed it….11-13°C 🙂
Sunday sees that low finally move through and so we will see a drop in the winds and a change in wind direction to northerly / north-easterly, so that means a cooler day on Sunday. Still some showers around mind across the south and west of England and Wales and these could push inland later on Sunday, so not a dry day by any means. Ireland looks to be largely dry, notably cooler but still with the threat of showers across the north and south-west. Temperatures a degree or two down on the norm so just nudging into double figures but as we go through the day, the winds look to strengthen from the north-west and that’ll keep temperatures down.
I think sometime at the end of September i mentioned that it seemed like the floodgates had opened when the jet stream finally dipped south after a dry September and allowed low after Atlantic low to push in and bring us wet, mild and unsettled conditions.
So far that pattern has remained pretty much set for the last 3 weeks or so.
Well next week looks at present to see a continuation of that pattern as a very deep Atlantic low pressure system with very strong winds associated with it is due to push in from Tuesday after a calmer, drier day on Monday. So stronger winds and showers from Tuesday initially across the west but pushing across the U.K through the day. By Wednesday we see heavier rain push across the southern half of the U.K from the south before more heavy rain for Ireland and the remainder of the U.K on Thursday accompanied by strong winds. This pattern continues on Friday but there is a change in the air if the projections are true with high pressure establishing over the continent and forcing that rain initially across Ireland but then clearing from the south. This drier weather will also pull up warmer winds from the south so it could mean another balmy end to October and not for the first time. That said it is a long way away yet so we will see.
Wet and windy weather provides leaf dry down opportunities…
Now I know the latest run of weather has significant drawbacks from a practical perspective with lots of areas waterlogged and courses closed on heavy ground sites but it is also ‘tending’ to provide lower than normal disease pressure for this time of the autumn.
Normally I’d be approaching this time with concern because for the last 3-4 years the middle of October has seen significant disease pressure. This was normally due to a period of weather with light winds, high humidity / overnight temperatures and a prolonged duration of plant leaf wetness. Currently we have the opposite i.e high winds, heavy rainfall but still with mild temperatures.
One of things that has struck me recently is how quickly areas dry down during such weather because we still have high enough air temperature to generate sufficient E.T to dry down the grass plant leaf.
I downloaded some data that highlighted this point quite neatly…(well I think so anyway 🙂 )
So here is a diary of a day in 1-hour segments from 11/10/19 00:00 – 12/10/19 00:00.
The top graph shows hourly E.T, the middle rainfall and the bottom leaf wetness….
You can see how quickly the leaf dries down when the rain stops provided there is sufficient E.T to achieve this….Within 15 minutes of the rain stopping the leaf wetness has decreased by 30% and within an hour it is practically dry during a morning rainfall event. The same scenario in the afternoon gives even quicker dry down with the leaf not fully wetting up because the E.T was at its highest. In this scenario within 30 minutes of the rainfall stopping the leaf was dry.
So from a Microdochium nivale perspective I think it isn’t easy for the fungus to develop when the leaf is wetting and drying down consistently because of the weather conditions generating E.T. Of course as we go further into the winter we will see less and less E.T as the ambient temperature drops. You’ll notice this on the roads as they wetter for longer finally reaching a point when they don’t dry out over a 24-hour period. For now though as we are right in the sweet spot of Microdochium nivale activity I’d take these dry-down periods any day of the week and the wet and windy weather that accompanies it over calm, humid muggy weather.
Microdochium nivale pressure
This doesn’t mean we are devoid of a threat from this perspective because as one weather front moves through, there is a period between when the winds drop, the humidity and air temperature are high and the grass plant leaf stays wet. This is the danger period and of course it is a more significant danger in a sheltered, shaded environment with poor air flow, lower E.T and slower dry down of the leaf.
So currently we are seeing short-term spikes in disease activity as disease pressure rises between weather fronts before dropping down again as the next bout of wet and windy weather pushes through.
Here’s how the intensity chart looks for the 3 locations I used a few weeks back using an ‘open’ and ‘sheltered’ green scenario commencing on the 1st Sept and up to the current day.
The other important feature to consider is the consistent growth during October which hopefully is already well underway in growing any early autumn disease scars out.
You can see this clearly in the Growth Potential chart below…
Even last week we were hitting G.P figures of 0.8 here in The Midlands which means very good growth, maybe a pain to cut in these prolonged periods of wetness but good for growing out scars and for germinating / establishing seed after the dry September many of us have endured.
Looking ahead this week we can see the cooler day temperatures are knocking back the G.P to 0.4-0.5 and once the winds change round to northerly over the weekend it drops further still.
My concern is the longer-term forecast for warm high pressure to establish towards the end of this month. This could (and it is only a ‘could at the moment) result in some pretty aggressive disease activity especially if it is difficult to get a spray window beforehand.
You could be forgiven in thinking Microdochium nivale is the only disease out there such is my focus most autumn’s however I’m also seeing lots of Fairy Ring, Etiolated growth at present as the combination of warm soil and rainfall stimulate fungal activity. Plenty of Red Thread as well on rye / fescue swards and still there’s some lingering Anthracnose from the summer now manifesting itself as basal rot.
OK that’s me for another week…
All the best..