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  • Writer's pictureMark Hunt

March 14th - Weatherblog

Hi All,

Well a number of you fed back that the font I'm using was hard to see so I've played around in Wix Editor and hopefully this one will be alot easier in future. Part of the learning process for me after years of Wordpress.


If you take a look at the animated GIF's below you can see we have a nice piece of weather coming our way as continental high pressure is set to build through the early part of this week. Not optimum for grass growth (more on that later), but at least we can dry-down and we have some good light levels for that bentgrass 😎

Talking about light, I've been doing some work with the Sunseeker App lately and it reminded me what a cracking app it is.

I took this image last Sunday (7th March) whilst out walking around Rutland Water's lovely peninsular using the Sunseeker app.


Sunseeker displays the arc of the sun on the day you take the picture against a backdrop of the arc of the sun at the winter, spring and summer solstice. (You can just see the red line at the top right of the image, that's the position of the sun at the summer solstice)


The light blue arc shows the suns direction of travel on the day of the winter solstice (21-12-21) and you can see it sets around 16:00hrs. On the day I took the photo, you can see the higher arc in yellow and how much higher the sun is in the sky now vs. December and how much later (around 2hrs) it now sets.


Sunseeker also lets you change the date and see the effect on the suns arc (so you can see during what time period you'll get maximum sunlight at your location) and it also allows you to take a map picture as well looking down on your location with the suns arc overlaid.


So here is some output from my location in Market Harborough from 22-12-21 and today and you may get an inkling why I said last week it's such a rubbish place to try and grow grass on my back lawn :)


Originally developed for the solar industry to assess the viability of solar panels on buildings and the like, Sunseeker has a good number of practical features that are useful for the turf manager and particularly for those managing in shade.


Onto the weather......


GFS Output courtesy of Tropicaltidbits.com

So for Monday we can see we have a bit of an east-west divide with high pressure building from the continent but also a sneaky low pressure sitting just off the north west of Scotland. Currently this is bringing rain to the top half of Ireland and during the morning this rain will move across The Irish Sea and into the west of Scotland and north west of England. There's also some rogue showers hovering around the south coast of England. Through the second half of the day those northerly showers will push eastwards into Central Scotland and northern England clearing Ireland as they do so. Away from the rain, Wales and most of England will have a lovely day after a ground frost in places and temperatures will push up towards 12-13°C, in a much lighter south westerly wind.


Onto Tuesday and overnight an extended rain band does its best to push into the west and north west of Ireland but that continental high pressure is building and so it'll only make slow progress with showers across Connacht and Donegal. The northern end of this rain front will also push rain into The Western Isles and the west of Scotland, but again it'll make slow progress. Away from this western band of rain, England and Wales and most of Scotland look set for another lovely start though again a chilly one. Bright sunshine for the morning but during the afternoon cloud will build from the west as that rain band begins to make progress across Ireland and into the west of Scotland. By dusk it'll be into the east of Ireland and the west side of Scotland. So away from this, another lovely dry day with temperatures pushing up into mid-teens and light winds from the south west. Cooler over Scotland with more in the way of cloud cover and temperatures just pushing into double figures.


Mid-week beckons and dawn on Wednesday sees that rain front fizzling out somewhat but still likely to bring rain to the south west of Scotland and south east of Ireland. At the same time we will see some showers across the south and south east of England. Through the morning the remainder of this rain and cloud will clear Ireland from the west to leave a sunnier second half of the day, however, across The Irish Sea we will see lines of showers across Wales, the south of England, Midlands and northern England, with Scotland mainly dry. Through the afternoon these bands of showers will consolidate into heavier rain across the north of England and The Midlands moving eastwards and clearing into The North Sea overnight. Still mild but around 11-12°C with that cloud cover and rain.


Onto Thursday and overnight that rain has cleared eastward into The North Sea but already there's some more fronts pushing into the west and south west of Ireland just in time for the rush hour at Waterville :) Some of this rain will also push into The Western Isles. Away from this though across most of England and Wales, it'll be a beautiful sunny day after another cold start which will verge on a ground frost in sheltered areas. Not a cloud in the sky type of day, just what we needed. It won't be a splitting the stones jobbie though because a feature of Thursday will be the strengthening wind from the north east which will cool things down a tad and keep the temperature around the 11-12°C mark. That wind across Scotland will be strong to gale force at times and it'll rattle some chilly showers in from the west through the day although these will mainly be confined to western coasts. Ireland should dry up through the day as those showers push eastwards into northern England during the afternoon. Not a bad day by any counts but don't expect the grass to jump out of the ground with that north east wind chill. Be mindful as well that a north easterly wind direction always has the potential to throw some showers in from The Wash.


Closing out the week on Friday and a clear weather picture for all of the U.K & Ireland from the get go. Those cool winds from the north east will swing round to the east and lighten a touch, especially over Ireland and Scotland and this will allow temperatures to nudge up towards 13-14°C. Lots of sunshine, some cloud but otherwise a beautiful spring day. End of.


The outlook for the weekend is promising to say the least with lots of sunshine for all of the U.K & Ireland. Maybe a bit more cloud up the north east coast initially on Saturday but a lovely day for sure and the same on Sunday. Those winds will continue to swing round to a more south westerly aspect over the course of the weekend and that'll allow temperatures to push up to the mid-teens in places. Cracking.


Weather Outlook


So as we start next week, the weather map is dominated by high pressure systems with one over the continent and a new one pushing in from The Atlantic. That said, to the north west we have a cold Atlantic low pressure system and this looks set to influence the first half of next weeks weather.


So for Monday we see rain feed down into the gap between the two high pressure systems and this will cross Ireland and push down across the west / south west of England and Wales. More rain on Tuesday, initially for Scotland, but this will again push down on northerly winds across the U.K through the course of Tuesday, so I think maybe a little chillier and some wintry showers over elevation. From Wednesday the high pressure to the south of Ireland is projected to continue to build and this will push any rain away from the U.K, so I think a drier 2nd half of the week, next week although still with a threat of rain and wintry showers across the north of Scotland.


Agronomic Notes


At first sight, a forecast with not too much rain and plenty of sunshine would be considered good news for our industry. In some ways it certainly is because we need a chance to dry out and an elevation in the DLI levels (Daily Light Intervals) will be much needed on Poa / bent greens.


This is the point in the year when the balance begins to tip away from Poa annua towards bentgrass as light levels pick up and we dry down. The bent responds and the Poa hunkers down in the sward not wanting to budge.


Being dry, bright and sunny and warmish around the middle of the day and afternoon, it is assumed by many that this type of weather, that is to say, Spring high pressure systems are good for the grass growth, but in reality they aren't really and here's why...


It's all about night temperature...


If you look at the Meteoturf graphic below for the coming week for air temperature at 2m height in my location, The Andes-style profile says it all !


What we see is lovely daytime temperatures but cool night ones and it is the latter that does the damage in terms of low-cutting-height grass growth. I make that distinction because higher-height-of-cut turf doesn't have the same suppressive effect. Maybe because the greater leaf surface area facilitates more effective photosynthesis which in turn means more energy produced and available to power growth. Whatever the reason it works opposite to close mown greens height turf and that's why a hypothetical members lawn cut at 50mm plus behaves very differently from a golf green per see. Not too mention the 1,000's of feet the latter has and the former doesn't of course !


Good growth in the spring is all about night air temperature and its affect on both the air and soil temperature.


I picked two days over the last week to illustrate this...


The first on the 8th of March had a cold night preceding it and the second example on the 10th of March had a very mild night. The 8th of March is going to be reasonably representative of this week in terms of night and day temperature fluctuation. So I took the hourly minimum and maximum air temperature and converted it into Growth Potential by using the equation we are all familiar with. For those unfamiliar with Growth Potential, I've included an explanation regarding Growth Potential below which you can download here


So here is the theoretical Growth Potential on the 8th of March with the cold overnight temperatures and bear in mind that anything G.P-wise over 0.4 at this time of year should yield plant growth provided the other factors (nutrition, light, water, etc) are in place.

Looking at the hourly Growth Potential we can see that it only exceeds 0.4 from 14:00 - 17: 00 so realistically the plant will be growing well for about 3 hours of the day even though the maximum temperature was 12°C. The reason for the tardy growth curve is that overnight the air temperature dropped to 1.2°C.


Let's look at the example from the 10th of March when we had much warmer overnight temperatures.


A very different kettle of fish in terms of Growth Potential with readings exceeding the good growth threshold at 09:00 am and carrying on till midnight. So that's 15 hours of good potential growth when night time temperatures are mild vs. 3 hours when they are cold.


So don't expect greens growth to fly out of the ground this week just because we have some nice middle of the day temperatures. We will get growth for sure (on outfield) and especially root growth (because the grass plant isn't partitioning growth just towards new shoot growth) so for once it'll work well with March and earlier aeration but recovery will be slow at this stage.


OK that's me for another week, enjoy the sunshine and let's think about those that can't because of the awful situation not a thousand miles from here. A line from William Butler Yeat's poem 'The Stolen Child' comes to mind...."While the world is full of troubles and anxious in its sleep"....Indeed we are.


All the best.


Mark Hunt






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