After an extremely dry last half of March and most of April I was actually looking forward to a weekend of rain, such is the mindset of those who work in the turfgrass industry.
A week of warm weather previous to that with high daily E.T’s had put grass on the back foot and Poa annua into seedhead mode. On Saturday we were initially promised 9mm, then 7mm, then 4mm and we ended up with 0.70mm 🙁
I must have worn out the refresh button on my NetWeather Extra V8 Rain Radar as I watched a big mass of rain sit over North Wales and Cheshire (34mm for the latter eh Mikey) and instead of it pushing inland to The Midlands, it just stayed there, it didn’t move all day, despite the fact it was blowing a houlie and freezing for an end of April day. So for the rainfall losers who bemoaned that fact on Twitter over the weekend, you have my sympathies. The transition from a warm peak to a cool trough was quite dramatic temperature-wise and had many reaching for their recently discarded winter layers as we struggled to hit even double figure temperatures on Saturday, tricky times indeed.
So do we have anymore rain on the horizon ?
General Weather Situation
Well Monday starts off looking pretty misty, dull and overcast for many but it’s an west- east divide with a chunk of rain sitting over The Irish Sea, just nicking the north-east coast of Ireland and extending down through Wales into The South West of England. As we go through the early afternoon this band of rain will push slowly westwards into the east and north-west of Ireland, drying up in the west of England and Wales. Away from this band of rain we look set for a pretty settled and dry day, if a little dull with reasonable temperatures pushing up into the mid-teens. Maybe the east and north-east of Scotland will see some good spells of sunshine but everywhere else these will be limited. Winds will be light and easterly.
Overnight into Tuesday and we see a rain front from an Atlantic low pressure system push into the west of Ireland and by dawn this rain will cover the whole of the Ireland. Away from this rain we will see a much brighter start on Tuesday aside from western coasts where cloud from that Atlantic front will build. By the afternoon this rain will be clearing Ireland from the west and pushing into the south-west / north-west of Scotland. Elsewhere we look to stay dry and warm with temperatures climbing towards the high teens in the south of England, but 3-4°C lower than this for Ireland and Scotland under that cloud cover and rain. Winds will be light to moderate and from the south.
Onto Wednesday and that band of rain overnight has consolidated and moved eastwards so by dawn it’ll be affecting the whole western coastline of the U.K from The South West, through Wales, The Lakes and right up to north-west Scotland. Through the course of Wednesday this front will push eastwards across Scotland and the north of England. During the early afternoon, another rain front will push into the west of Ireland and move eastwards across the country during the 2nd part of the day. The southerly rain front over the U.K is projected to stall and make slow progress with not a lot of rain for The Midlands / south of England I’m afraid. So a duller day on Wednesday with more in the way of cloud from that front and the chance of rain for many north of The Midlands. Temperature-wise, we are down in the mid-teens with that cloud cover so 13-15°C is likely. The best chance of seeing the sun will be across the east of England.
Onto Thursday and that unsettled picture sees rain crossing The Midlands overnight and by dawn it’ll be sitting over East Anglia. More rain is also projected for the west of Ireland, west Wales and western / central Scotland from the off on Thursday, and it is likely to be the wettest day of the week. Through Thursday morning we will see that rain consolidate over Ireland and the north and west of England pushing into all areas through the second half of the day. For the drier southern counties, this is our best chance of rain this week thankfully I’ll be sitting in a strategy meeting so unable to see the outcome 🙂 By late afternoon, Ireland should be drying out except for the east of Leinster where that rain will linger. Notable not only for rain on Thursday but a freshening north-westerly wind which will push this rain southwards and introduce a much cooler feel to the weather with temperatures struggling to get much above double figures so expect 11-12°C as typical, maybe slight warmer for Scotland.
Closing out the week on Friday we have that overnight rain largely cleared the U.K and Ireland. I say largely because there’s a likelihood of some rain still lingering over the north of England and this is projected to push down into The Midlands through the early part of Friday. A real north -south divide on Friday as Scotland and the far north of England looks to have a sunny and pleasant start to the day whereas from the north of England down it’ll be dull and with a risk of showers. Ireland looks dull but dry. So a dull and showery forecast for the southern half of the U.K and Wales, drier for the north though later some rain and wintry showers is forecast for the north-east of Scotland. It will feel raw though for early May in the U.K with a moderate to strong northerly wind imparting significant windchill. As we close out the day that cloud cover will break and temperatures will climb a little into the other side of double figures, still cool though for early May. Even after dusk we may see some of those showers consolidating over southern England.
After an unsettled end to the week, the weekend looks more promising as high pressure takes over with a largely dry outlook with plenty of sunshine and rising temperatures through the weekend with Sunday / Monday, the warmer days of the mix. This switch to high pressure though will bring a return to frosts as we begin May so if you’re out first thing wrap up well. It’s a Bank holiday for the U.K and Bank Holiday Monday looks to be fine and dry with long spells of hazy sunshine and not bad mid-teen temperatures. The only fly in the ointment will be for Scotland and the north of England where rain preceded by cloud will push in through Monday morning and drift south through the day down into The Peak District by close of play probably.
So Monday looks to be largely warm and dry for England, Wales and Ireland but as we move through the 2nd half of the day we will see rain and cloud push into Scotland and the west of Ireland and the wind freshen and swing south-westerly. This change marks the arrival of not one but two low pressure systems sitting out west of the U.K. Initially these will drive wind and rain into the west and north of the U.K whilst high pressure still sits over the south of England but through the 2nd part of Tuesday, the more southerly of the low pressure systems will bring its influence to bear pushing rain and cooler weather into central parts of the U.K. So the 2nd part of next week looks cool, wet and windy for all areas but of course we have the usual caveat about a longer-term forecast. My hunch is that the low pressure systems will indeed dominate because there’s two of them and only one high in their way.
If you’ve been religiously filling in one of our GDD / G.P spreadsheets you’ll find a useful tab called ‘charts’ on it which should give you plenty of useful data. It is divided into seasons so below is output from a Birmingham location (thanks Jonathan) for nearly the first 4 months of this year..
I think it summarises very well our spring or one might think, our lack of spring. March you can see gave very little good growth, 4 days actually which is only one more than February ! We can see for April the arrival of the very warm temperature quite clearly but of course it coincided with a period of no rainfall so unless you had irrigation to areas it provided little benefit.
This lack of strong growth has meant persistent Microdochium nivale symptoms, ok not aggressive Microdochium, but it’s there nonetheless in the sward, small copper blotches dotted across the profile. This continued growth of disease is due to mild night temperatures and the presence of dew. Tuesday and Wednesday this week may be significant for disease development along the lines mentioned above. Once we hit the weekend though, it’ll drop away as colder nights come into the picture.
We have to consider the role of E.T more…
For many in the dry south of the U.K, the second half of April put Poa annua on its backside whilst bentgrass grew quite happily. The stats below show the main issue…
The period from the 18th April provided no rain and high daily E.T and that knocked Poa annua back into dormancy so we saw very little growth on Poa-dominated greens and undoubtedly this period led to a switch from leaf to seedhead production.
I think E.T remains one of the parameters that is least-measured in a turfgrass scenario, it’s also one of the hardest to obtain data on as most personal weather stations that upload data to the net don’t measure E.T, so getting historical data is difficult. When we have a period of high E.T, the grass plant undergoes physiological changes to preserve water loss and these changes can limit uptake of nutrient or more precisely uptake efficiency. It kind of closes down the hatches so you don’t really see a great deal of response from foliar applications during this period, be that nitrogen or iron for that matter.
A lot of times when people report to me that they haven’t seen a green up from a foliar iron application it is because the grass plant isn’t receptive in terms of uptake and that can be due to low soil moisture, cold temperature desiccation or as we experienced at the end of April, high temperature desiccation.
During the period from the 18th to the 26th of April we lost 29.2mm of moisture by E.T, that’s over 1″ of rainfall equivalent. Now of course we don’t irrigate at 100% E.T, normally we might be replace 50-60% of E.T loss by irrigation but on that basis we’d still need to replace 14.6mm of moisture @ 50% E.T replacement.
So how much did you irrigate during that period from a mm perspective ?
Of course moisture meters can help us manage soil moisture levels but it is important to realise that spring desiccation tends to be isolated to the top 12.5 -25.0mm of the profile and often we are reading deeper than this from a probe depth perspective.
How is 2019 shaping up from a GDD perspective ?
2019 to me is a strange year from a turfgrass perspective, we had a very warm start during the 2nd half of February but after that it has kind of proceeded in dribs and drabs with no really strong weather pattern dominating other than it has been very dry for many areas south of The Peak District.
If you look at the GDD stats, 2019 comes out as a middle of the road year so far, warmer than the SSW-affected years but behind the 2 best growing years we have had recently, 2017 and 2014. At the location above we passed the point for perennial biotype seedhead formation on the 23rd April, a week earlier than normal and right in the middle of the run of dry, warm weather with high daily E.T so that is why we are seeing Poa annua switch to seedhead mode.
Just to continue the theme on the above graph I have highlighted the period at the end of April / beginning of May and you can see in 4 years out of the last 7, the GDD graph flattens out for awhile before picking up strongly as we get into mid-May. This flat section of the graph corresponds to slow growth and more often than not, night frosts which depress the daily GDD (and G.P for that matter). 2019 will do the same, flattening off at the end of this week before picking up again as the night temperatures recover during the mid-part of next week.
A return to night frosts….
So we can see some good growth this week before we drop off a cliff from with another Baltic end to the week and frost at the weekend. The saving grace is that at least we won’t experience a surge of growth over the Bank holiday and a mountain of clippings.
Next week’s blog will be on Tuesday because of the Bank Holiday and I’ll be doing my normal monthly review.
Till then all the best.