After a chilly, but mainly dry weekend, (except I think for parts of Scotland) it truly feels like autumn has set in and predictably talk turns to the winter ahead and the re-emergence of the ‘Beast from the East’ in some tabloids. You may remember me talking about the increased potential for a harder winter this year due to a low-lying jet stream that will allow colder air to come in. Well just to show that very little in life and not much in meteorology goes to plan, I see the projection over the coming week is for the jet stream to swing really high and that’ll allow high pressure to fill in the void and sit over the U.K. It won’t be a warm high though because of the direction of the wind and the presence of cold air spilling in over the continent to give them a first taste of winter. So this week I confidently predict you’ll be digging out the buffs and the thicker fleeces in readiness for the winter ahead 🙁
So how are we looking for the coming week ?
General Weather Situation
Well for most we have a dry, settled, cool but bright day following on from a misty start to the day, but in the north east of Scotland we still have a vestige of that rain lingering and during the morning this will push south down into The Borders and later on, northern England and the north Midlands possibly to bring some light rain to some areas. After some early drizzle over northwest Connacht it looks like a nice pleasant autumn day for Ireland and pretty much all of Wales and the south west, southern and central England. There will be spells of nice sunshine and out of the wind it’ll feel pleasant. There is of course a ‘but’ to this dry scenario and this concerns the temperature. It’ll feel chilly because the light to moderate wind will have a northern component and depending on where you sit, it may be north east or straight north, but it will keep temperatures down in the low double figures for many. Night time temperatures through the coming week are likely to be low single figures so there’s a chance of mist and fog early doors and a risk of a light ground frost in rural areas.
Moving onto Tuesday and we still have some rain lingering over north east England and The Borders but this will gradually dissipate through the course of the morning. The wind will pick up a pronounced north east orientation and that will introduce our old friend ‘Haar’ onto the scene so Tuesday looks to be a good deal cloudier and therefore duller across the U.K, with perhaps the best chance of sunshine over Wales, westerly coasts and possibly Ireland where it also looks set for a dry, autumnal day. Temperatures will be a degree or two down on Monday due to the cloud cover. The wind will be fresher for Tuesday and that will keep the temperature pinned down.
Overnight into Wednesday and a similar day to Tuesday is on the cards with that north east wind continuing to spill in cloud from The North Sea. There’s also the chance of some of that cloud being thick enough for rain along eastern coasts and the coast of the south east of England. Elsewhere it’ll be dull, cool and with some drizzle amongst the thicker cloud base. That moderate north easterly wind will continue to peg back temperatures so a cooler day again for mid-week with temperatures barely making it into double figures. Those thicker winter fleeces will come out of the cupboards for sure this week 🙂
Onto Thursday and a changing wind direction for some will push rain into north western Scotland and Ireland through the morning and this will push south and east through the day. At the same time we have some more rain pushing over from the continent and that may mean some light showers for the eastern coast of England through the morning. The wind will be all over the place depending on your location, varying from north west over Ireland, south east over Scotland and turning through the day to northerly for England and Wales. No surprise then that we have another chilly, dull day on the cards for England and Wales, but a milder one for Ireland and Scotland with that change in the wind direction so here temperatures may just make it into the low teens (Gosh Golly say one and all)
Closing out what will be a dull, cool unspectacular week we have more of the same unfortunately. That rain over Scotland and Ireland should have all but fizzled out, maybe some drizzle remaining, but for eastern and central counties of England we will again see some very thick cloud courtesy of The North Sea and this is likely to bring light rain and drizzle for some areas here. Through the course of the day this cloud cover will push west so extending the areas affected by the lower temperatures and drizzle. Further north we may see some gaps in the cloud for northern England and Scotland with that rare feature, the sun, visible at times. Under the cloud it’ll remain dull and cool, but in the sunshine temperatures will lift a little. Ireland looks to have a similar day, with dense cloud cover across eastern counties but some chance of breaks in this for the west. Again that wind will be northerly / north easterly and so keeping the lid on any semblance of decent temperatures.
Onto the all important weekend and any chance of a change in the fixed, dull, cool pattern ? In a word….no with what looks to be a dull cool Saturday with plenty of cloud cover for eastern and central areas of the U.K. The west and north again may have the best chance of seeing the sun on Saturday, but it looks a dull and cool one for Ireland as well, though the cloud will break late in the day. Sunday looks a little more promising with more in the way of sunshine for most areas, but with that north easterly wind still calling the shots, it’ll only feel a little milder, possibly climbing into double figures for Central England and maybe a degree or two higher in the west.
With a week of high pressure, cool and dull weather under our belt by next Monday, is there any sign of the high moving off and bringing in some milder temperatures ? No there isn’t. So for next week it looks like high pressure will again sit over the U.K and we will have cool winds particularly for the early part of the week before it settles down and brings us quieter autumn weather towards the end of the week. So another dry week to come next week, maybe more in the way of sunshine from mid-week, next week onwards, as we lose that north easterly wind direction and the associated Haar. Temperatures are projected to be low double figures during the day so remaining cool.
If you look at the Unisys-animated GIF at the top of the page I’d like to draw your attention to the mass of cold air that is projected to come down into Scandinavia and Central Europe during next week. Now in my books it’s very early to see cold air that far south and it does set up the possibility of some colder, more wintry weather earlier than normal for us depending on the jet stream orientation.
Disease Pressure – Some better news…
With the arrival of cooler and settled conditions with less risk of morning dew because of the wind direction I’d expect disease pressure to drop from last week’s high pressure spike that I discussed a week ago. The 48 hour period from Sunday 4th October through to Tuesday 6th October represented quite some disease pressure as you can see from the image below.
What this is showing is that the coolest it got all night going from Monday into Tuesday was 14.5°C and that was at 7 a.m. Throughout the night the air temperature sat between 15 and 16°C, which is ideal for disease development. In addition we had rainfall and so a very moist atmosphere with the humidity sitting close to and exceeding 98% during the same period.
We are therefore looking at two key drivers here, one is temperature and the other is leaf wetness, the latter is critical as it facilitates fungal mycelial growth across a leaf surface and into the leaf itself.
So if you did see significant disease development through Sunday to late Tuesday, you can now see why….
A poor uptake week coming up…
During the above disease period the Growth Potential reached 0.8 or 80% of the theoretical maximum possible so the grass plant was also growing strongly. Compare that with this week’s projected Growth Potential and you can see the average daily growth potential is close to 0.15 or 15% for the week coming up, a fraction of what was occurring only 7 days ago !
So this means we have a grass plant that is only growing at a very slow rate because of the cooler days we have in store this week. Couple that with lower light levels due to increasing cloud cover and I think you can see the plant isn’t going to be up to much in terms of growth, nutrient or fungicidal A.I uptake. So if you’re spraying this week, don’t expect much to happen fast because the plant will be very slow to react to either a nutrient input and / or a pesticidal one. Today and tomorrow probably represent the best days for uptake, but it’s marginal to say the least. Yet again it shows why knowing the Growth Potential on your site, seeing how it’s likely to sit in the coming week and then making management decisions on the back of it are integral to good agronomics.
I am aware some of you are aerating this coming week (against your better judgement I appreciate sometimes) and I wanted to continue on the theme of graphing out the likely growth attainable as a % of the maximum Growth Potential over a 7 day period. I’ve included the projected maximum and minimum air temperatures over the next 7 days so you can see how much of a drop they will be this week in terms of growth and therefore plant uptake.
So you can see for the coming week the projected growth is 8% of the theoretical maximum compared to 28% last week so we have a growth reduction of nearly 72% compared to last week.
To put that into perspective in terms of potential recovery, if we aerated a month ago and say it took 14 days for the surfaces to recover, it’s likely to take 8 times longer if the temperatures stay as they are now to get the same recover, in other words a very long time. I appreciate there is the matter of fixtures, revenue and agronomics to try and balance, but I’m merely pointing out that with every week that goes past mid-September, your recovery time increases markedly, particularly once you’re into October.
Now all this may change and we may get the traditional warm end to October / start to November that we’ve had in 5 years out of the last 7, but somehow I don’t think so this year with that cold air mass sitting over Europe.
Wrap up well and all the best.