Well, I’ll kick off this week’s blog by humbly accepting the prize for smug, amateur meteorologist, April 2021. Now I could go into Ted Crilly – Golden Cleric speech mode but knowing this industry as I do, it won’t be very long before I am unceremoniously dumped back down to earth with a bump, so I’ll enjoy it while I can. I am of course referring to the fact that we have rain arriving for some locations this week but more importantly this brief rain event will open the way to a subtle change in the weather patterns and the prospect of more to come. Nothing dramatic but promising. What I can’t see yet is any significant heat which means we will definitely go into the first week of May behind on Poa seeding for the first time that I can remember (I’m sure Angus and his team are delighted though with The British Masters on the 9th May !! 🙂
The general weather picture and the way weather systems are both orientated and moving on the jet stream is unprecedented for this time of year in my limited meteorological experience. You can see from the graphic above, there is no strong westerly airflow, instead the jet stream is broken up, segmented and much lower than normal with a westerly slant to it south of Spain and Portugal. So it is lying really far south and it is weak which is allowing cold air from the east and north to dominate and it is effectively blocking warm air movement.
General Weather Situation
So as we can see from the graphic above, we have two low pressure systems on the chart, one over Scotland which is heading south and one over The Bay of Biscay which is heading north. Over the course of this week these will bring rain to the party for some, but more importantly it’ll set the scene up for a little more later. So starting off Monday that rain is firmly camped as the NetWeather radar shows across Scotland and during the day it’ll very slowly edge south and eastwards into The Borders overnight pushing cloud ahead of it. So for the rest of the U.K and Ireland, expect another dry, cool day with plenty of cloud cover initially. The sun will poke through but we will still have that chilly easterly wind that seems to have been around for absolutely ages. So cool and dull with some sunny intervals sums up Monday but getting a little warmer in the afternoon so 13-14°C looks to be on the cards for the U.K & Ireland.
Tuesday sees that low pressure edging south so that means showers for Scotland and the north east of England from the off, dry elsewhere. As we go through the morning which starts dull and cool but probably frost-free because of the cloud cover, we see a raft of showers populate the weather picture across the north and north west of Ireland, Scotland and northern England by lunchtime. These showers will then edge southwards during the course of Tuesday afternoon / evening. Tricky to say but I’ll wager that most of Ireland gets a drop, the east of England and then into more central and western parts overnight into Wednesday. With a low heading southwards, it is kind of a waste of time predicting wind direction because it’ll be different for all of you. Westerly at the base of the low, easterly at the top and somewhere in-between, in-between 🙂 !!! Similar temperatures to Monday 13-14°C for England and Wales but I think cooler for Ireland and Scotland with 10-11°C more likely in a strong north easterly wind.
Wednesday morning sees that rain across Wales and The South West with some wintry showers over elevation and also the same for the north east of Scotland. This southerly rain will consolidate across the southern half of England and Wales through the course of Tuesday morning and it could stay all day for Wales and the west. Tricky to say how far south and east it’ll extend to. Elsewhere it’ll be a day of sunny intervals and some cloud cover with a strong north easterly wind cooling things down for most areas as that rain departs the south west of England on Wednesday evening. Still some showers around over the north east of Scotland, some of these will be wintry in nature. So a cooler day for everyone I think with that north east wind firmly in situ and 10-12°C on the cards.
Thursday sees us back to cool and dry for the most part after a possible ground frost but they’ll still be some wintry showers pushing down the north east coast of Scotland and England during the morning. Ireland will also see some showers across the north and north east as well and these will head down the east coast through the course of the morning. Through the second part of the day we will see those showers increase in number and frequency across Ireland, Scotland and the north of England. Elsewhere a cool and dry day with some sunshine but also a strong north easterly wind pegging back those temperatures to high single figures, so chilly.
Finishing off the week we have another cold night with clear skies meaning some of us will pick up our umpteenth ground frost in April. Bright, cold and sunny to start the day, I’ll be getting my second AZ jab first thing Friday morning. I joked last time that being half Danish, half of me didn’t want it, so the lady asked me which of my arms was English and which Danish ?
We settled for the left one but I did find her quite intimidating 🙂
So after a bright and sunny start we will see a recommencement of showers down the north east / east coast of Ireland and Scotland with some of them pushing south into north east England, Wales and across The South West. These will increase in frequency as we go through Friday afternoon sinking south as they do so. Lighter winds on Friday but they’ll be more northerly in nature so remaining cool with similar temperatures to Thursday.
So onto the coming weekend and Saturday looks like continuing the cool and unsettled theme with plenty of sunshine, a north easterly wind and some showers across the U.K and Ireland pushing in from the north east. With cool temperatures some of those showers will be wintry in nature over higher ground. More in the way of sunshine for central and western areas, cloudier across the east. Sunday looks like being a similar affair, duller initially but with the sun breaking through across the west. Now we have a potential fly in the ointment on Sunday with that low pressure looking to make a possible reappearance across the south east / east of England. At the same time we have an Atlantic low (well it’s the Bay of Biscay one that has edged north and west) pushing rain showers across Ireland. So a sunshine and showers jobbie for the U.K & Ireland on Sunday with more in the way of showers across the east. With light westerly winds it’ll feel a little milder on Sunday when the sun comes out 🙂
As I mentioned right at the start of this blog, the rain event this week will serve as a trigger to a subtle change in weather patterns and that’ll allow low pressure systems to feature in the forecast for the start of May as you can see from the projected graphic below ;
So we start next week with low pressure, (yes low pressure) to the west of Ireland. This will in turn pull cool air down from Russia, Scandinavia so the start of next week looks both cool and unsettled. Rain then for Ireland on Monday and this system will push eastwards bringing rain and cool temperatures across the southern half of the U.K during Tuesday and Wednesday. Although the low pressure has a southerly bias, Scotland and the north of England will also see some rain through this period. As that low developes it’ll drag in some very strong north easterly winds and heavy rain for the south eastern side of the U.K on Wednesday / Thursday. Now there’s two things we should focus on next week. The first is of course the arrival of rain for many areas after a first dab this week. The second is that the weather picture will mean more in the way of cloud so that’ll mean an end to night frosts for awhile and some better growth I think even though we won’t have much in the way of warmth. I have a hunch that this may arrive later next weekend / week after as a new low pressure pushes in and pulls in rain but also a south easterly airstream. Happy Days if that one proves right.
So if I pull down some stats from our Great Dunmow weather station over in the east of England we can all see what a challenging month April has been to manage turf in terms of drying out for one thing. 75 mm of evapotranspiration with some days hitting > 4.0 mm of moisture lost per day, now that’s pretty extreme for April in anyone’s books. The argument about irrigation and not irrigating is I think superfluous when you see these stats. The fact is if you don’t want to encourage all the negatives associated with plant stress, you have to water. I ran a readout from a Soil Scout probe buried at 25mm depth which details soil temperature, moisture and salinity and this highlighted the lack of cooling of the rootzone after irrigation had been applied. See below…..
So I think that debate should be consigned to the bin once and for all.
Lack of growth….
As I mentioned in earlier versions of this blog, I feel April 2021 will go down as one of the coolest April’s on record and certainly one of the driest.
The media will get hold of it soon once they finished with Boris, Dominic and the latest heat plume that won’t be arriving this week (They must be on something).
Now this lack of growth is both a blessing and a burden because it means outfield areas which are usually enjoying their spring flush won’t be doing anything of the sort so maintenance in these areas is easier. That said if you need recovery from insect and / or worm cast damage, then you could have had an easier spring than this one. The same goes for recovery from March aeration, it isn’t happening at the moment and when you look at the temperature stats above, it isn’t surprising. Here in Market Harborough, I counted 17 frosts so far this month, others I know have had more.
It’s unprecedented (that word again) and although some parts of the day are warm, we know cold nights greatly curtail the ability of the grass plant to grow (especially Poa annua)
So we can see from the log of growth potential at our Great Dunmow site above that not one day has registered so far as a good spring day for growth. So it won’t surprise you to know that the April will I think go down as one of the lowest from a G.P / GDD month and we should be able to see quite how it stacks up next week when I get round to doing an April monthly summary from the sites all over the U.K & Ireland. From a GDD perspective, this site finished March at 103.3 cumulative from Jan 1st using a 6°C base.
So where is it likely to be at the end of April ?
So on this site we will look to end April at 130 GDD for the year which puts us firmly in Poa annua var. annua seedhead production but a good way behind the Poa annua var reptans seedhead production point which tends to get into its stride around 180 GDD. So the seedheads in the image below are mainly a result of the annua Poa biotype seeding and as you can see, yet to extend fully on the panicle.
Now normally we’d see an immediate uplift in growth in early May, sometimes we go from nothing to flat out in the course of 24 hours but it won’t be the case this year. On this site I expect us to be around 147 GDD by the end of the first week in May which still leaves us short of the main Poa seedhead flush, maybe the 2nd or 3rd week of May seems more like it this year ?
So I don’t think I’d be reaching for a can of any PGR just yet and if you’ve already applied any type of PGR this year then maybe you need to ask yourself why when Mother Nature has given you it for free unless of course you are looking to hold back outfield and other vigorous turf areas in anticipation of a growth flush sometime in May. Good thinking that.
To me this sort of weather plays to light rate, immediately-available foliars, managing soil moisture effectively with hand watering and soil surfactants and keeping the plant happy and healthy from a biostimulant perspective. We aren’t out of the woods quite yet but I’d hope some milder night temperatures and moisture next week in particular will gradually ease up the growth rate on fine turf and outfield alike without it going into flat-out mode. Can’t be bad…..
All the best for the coming week…