Hi All,

Two days late this week with my blog due to the Bank Holiday here and work commitments.

Speaking of which wasn’t it a cracking Bank Holiday with some truly beautiful weather and very high temperatures capped I think with an early May Bank Holiday record measured at RAF Northolt at 28.7°C.

Got in some lovely walks including this one around Rutland with Eyebrook reservoir in the distance, scene of a lot of my fly fishing and one of the most-used reservoirs by the Lancaster’s of 617 Dambuster Squadron for practice in WWII. Along with the good weather came two new residents to my newly revamped garden. Last year I moved house and inherited a ‘modern style’ garden complete with decking, patios and mostly hard surface areas. A lot of work, 11 mt of vegetable topsoil later and a second mortgage spent with RHS Wisley and my local plant nursery, The Plant Man and it’s now naturalising well as a shade garden. Lot’s of log features, ferns and the like have encouraged a number of bird species to frequent (A Blackcap this week was a new visitor) and last week after making a number of 13cm x 13cm holes in gates, fences (my neighbours love me) and the like (earlier in the year), I was joined by 2 Hedgehogs that I feed nightly, cracking.

Ok enough of me, onto the weather and as you all probably know, our high pressure scenario is due to come to an end today / tomorrow with the arrival of a cool, Atlantic low.

The GIF below from Unisys Weather captures the scenario well.

Image courtesy of Unisys Weather

General Weather Situation

So today we see the beginning of the change to a more unsettled and cooler outlook with the influence of the above low pressure being felt first across Ireland and the west of the U.K during Wednesday. This process starts with a bad of rain due to push into the west of Ireland around now (7 a.m.) and move quickly eastwards across the country through the morning reaching the east of Ireland / west coastline of the U.K by early / mid-afternoon. Away from this impending rain front we have a lovely dry and settled start to the day after a cool night and very heavy dew. Cloud cover with build across The South West and Wales through the morning in advance of this rain front and this cloud will extend eastwards through the afternoon by which time we will see rain into the west of Scotland, Wales and the north-west of England. By late afternoon the west of Ireland will begin to clear that rain and the sun will break through but further east that rain front will be across western coasts and the middle of the country reaching eastern areas overnight into Thursday. Feeling a good bit cooler than of late with Ireland in the low teens and central and southern areas in the mid to high teens I think. Scotland with a bank of thicker cloud will be similar to Ireland down in the low teens after some lovely weather of late. Winds will be light to moderate westerly / north-westerly.

Onto Thursday (I must say I like 3-day blog weeks :)) and that rain is projected to clear the rest of the U.K overnight leaving behind a vestige of showers across north-west Scotland. They’ll continue to be some light rain showers across the western coastline of Scotland through the morning but these will eventually dissipate. Elsewhere after overnight rain we will see a bright start to the day in central and eastern regions and not a bad day with plenty of sunshine for the U.K and Ireland, mixed cloud cover and temperatures pushing up into the low to mid-teens in that sunshine. Winds will be moderate north westerlies, weakening as the day goes on to leave most areas with a calm, dry and sunny end to the day.

Closing out the shortened week on Friday we see the next chapter of that low pressure play out with a heavy band of rain moving into the west of Ireland in the early hours of Friday morning bringing heavy rain to Kerry I think. This front will be slow-moving and so the rainfall totals associated with it will be a good bit higher than the one on Wednesday.  East of that impending rain, the U.K will enjoy a dull, cloudy and dry start to Friday as cloud cover pushed in front of that low pressure tends to dominate the weather picture. That band of rain will stay over Ireland throughout Friday slowly moving eastwards and not clearing the west of Ireland till last afternoon / early evening by which time it’ll be approaching The South West.

So you can probably guess that Saturday’s outlook for the U.K is unsettled with that band of rain crossing The Irish Sea late on Friday night to give heavy bursts of rain overnight for Wales before clearing east into The Midlands and north of England through Saturday morning. At this stage it looks like the south-east of England will miss the worst of it but I think we will see heavier rain for North Wales, north-west England and the west of Scotland through the first part of Saturday. That rain looks to concentrate across Central Scotland through Saturday to give some pretty hefty daily rainfall totals I’m afraid. By Saturday afternoon we will see a band of showers crossing Ireland and a clearing picture across the southern half of the U.K with some showers later for The South West and Wales. Cooler in that rain with temperatures in the low double figures across Ireland, Wales and Scotland, perhaps a degree or two higher for Central England. Winds will be westerly veering south-westerly and then northerly for Sunday which will drop temperatures a degree or two. Sunday looks the better day of the weekend, still with the threat of rain across the south-east of Munster during the morning but elsewhere plenty of sunshine and some hazy cloud cover. That change in wind direction will usher in some thicker cloud for north-east / eastern coasts on Sunday with some of that cloud thick enough to give rain along its leading edge. So sunnier and brighter the further west you go on Sunday with similar temperatures to Saturday.

Weather Outlook

Actually next week doesn’t look too bad I’d say with low pressure influencing our weather early in the week bringing a sunshine and showers-type scenario to the U.K and Ireland with more threat of rain I think across Ireland, the north-west of England and Scotland on Tuesday / Wednesday a.m. With a westerly airflow in situ we will pick up some milder air and a return to more normal temperatures for this time of year, mid to high teens I think will be the order of the day. Towards the end of the week there’s a suggestion of a new low pressure coming in which will bring more rain to Ireland and the southern half of the U.K but that’s a good way away at present so let’s hope it doesn’t happen.

Agronomic Notes

As this is my first blog of May, we have the opportunity to look back on April and the year to date.

April 2018 GDD – Thame Location

The GDD total for April came in at 99.5 which represents not a bad growing month however as more detailed analysis below will show it was a topsy-turvy one from this perspective.

In isolation April provided nearly double the amount of growth we had in January, February and March combined and 5 times the growth of March alone, illustrating just what a crappy month March 2018 was.

Cumulatively for the year, 2018 is unsurprisingly classified as an under-performer, GDD-wise, with a running total till the end of April of 156.5. It does indeed share a good deal of similarities with the other SSW-affected years of 2010 (159.5), 2013 (119) and 2016 (137.5) in having a low spring total.

In comparison with last year, 2018 y.t.d has recorded nearly 50% less GDD for the first four months.

GDD Comparison – April 2018 – U.K Locations

Firstly, a quick word of thanks for the growing number of people sending me in data on a monthly basis, many thanks, still short though for Wales, the north-west, north-east and Scotland though.

So analysis of the U.K locations shows a very variable GDD picture with our east of Scotland location running at nearly half the GDD of our Devon location !

Fortunately for Fife the same can be said for the rainfall total which goes some way to compensate I think…:)

In general The Midlands comes out favourably with higher GDD totals than most locations further south which must be a first I reckon. Rainfall-wise a good deal of similarity with 75mm looking to be about average for the month.

You can download this chart here ;

GDD Comparison – April 2018 – Irish Locations

A much cooler April for Ireland compared to the U.K sites and I’d say the western side of Ireland looks milder to me than the east or south.

That said there was a really significant flip side to this coin when it came to rainfall and so I’m sure the lads in Kerry, Mayo, Sligo, Clare and the like will be tutting and rolling their eyes to the sky at my stats above showing rainfall and E.T loss for the Thame location and wishing it was them. I had to create a different graph for the Ireland locations simply to fit on the rainfall totals for Valentia, Cork and Limerick, with the latter exceeding 10 inches of rainfall during April.

Of that total, nearly half of it came on the days of the 6th and 16th of April, with > 40mm of rainfall in a day measured at a number of locations across Ireland on the same dates. So it’s no wonder it was milder as well because the low pressure associated with that rainfall will have pulled in milder air, little compensation I know so I’ll shut up about it now.

You can download the above chart here ;

April 2018 in more detail…

Ok I cheated a bit here because I’ve added on the first 8 days in May as well to illustrate the growth peaks and troughs we have experienced over the last 5 weeks…

Again emphasising the worth of tracking growth patterns using GDD / G.P we can see the two significant peaks in growth that we have experienced during April and the early part of May.

Now in other years we would be bemoaning the growth peaks for too much grass, clipping yield, etc but after the memories of March 2018, I didn’t hear one peep of protest 🙂

Those 5 days of growth during mid-April transformed many a lagging-behind turf surface, be that a golf green, winter tee, cricket outfield, square and football pitch alike and brought a smile to many a strained face as an aside (including my own it has to be said 🙂 )

Following that though we dropped off a cliff with those cold, dull days of late April representing minimal growth and reflecting poor uptake conditions as well. Plenty of sites marched right up to Poa seedhead development at this point and although seedheads weren’t visible on the turf surface, the Poa plant had already flicked a switch away from leaf / root growth towards seedhead development. So associated with this spell of cold weather also came a Poa plant going off colour and with a reduced growth rate to boot that wasn’t keen on responding to nutrient, iron or PGR inputs.

Thankfully we turned a corner when we turned the page of the calendar over to May as the graph above illustrates with a welcome rise in temperatures and grass growth although in central and southern England, the temperature got high enough to put Poa annua under stress.

Looking at the first 8 days of May, here’s how the rainfall and E.T levels panned out at the same location…

So the combined E.T loss was 25.9mm with 7.6mm of rain to compensate but that still left this location -18.3mm, which is significant over such a short period.

Now a lot of you will be reading this and remarking how this chap can’t seriously be moaning about things drying out when the site has only just become workable and of course I’m not.

I’m just making the point that at some locations, the grass plant went under pretty severe stress over the last week or so and in the case of Poa annua this will have driven the seedhead process forward significantly.

I got asked recently what drives the seedhead process for Poa annua and if the factors differ between the Poa annua annual and perennial biotypes ?

Honestly that’s too good a question for me (another way of saying I’m not clever enough to answer it in I suppose 😛 ) but I would say this. Elevated stress periods,  particularly high temperature and the reciprocating lack of moisture will cause nitrogen uptake to drop in the Poa annua plant and this I believe is a major contributory factor to seedhead development and expression. Run your plants too low on N and expect to see a continued seedhead flush. Now I’m not saying lash on N, you should know by now that isn’t my bag, it’s a question of balance, (isn’t it always) keeping the plant healthy and not over / under-fed.

O.K that’s it for this week, hopefully we will be back to Monday as the blog day next week and in the meantime I wish you all the best for the rest of this week.

Mark Hunt