1st March

Hi All,

Well it is the 1st of March and the weekend gone certainly felt like better times are round the corner with some lovely warm sunshine.

Wandering into town for my early morning Flat White, I was looking up at our local church steeple for the sole resident, female Peregrine when another person gauged the direction of my stare and dutifully informed me that there wasn’t one anymore but two :).

This passer by turned out to be a BTO (British Trust for Ornithology) regular and Peregrine aficionado and she promptly informed me that they had been eating Teal (duck) for breakfast judging by the remnants scattered around the place. I took a really poor picture but you can probably just make out the two birds (circled). Apparently the other one is a male. We now have a growing number of Peregrine Falcons occupying our churches and cathedrals in Leicestershire and Rutland. Brill is all I can say, great to see some parts of nature recovering.

Clear blue skies and warm sunshine are such a tonic for the sole and it was great to see so many people outdoors enjoying themselves. Difficult to believe that only two weeks ago we were sitting under snow and ice and the thaw hadn’t started yet.

Not great growing weather though because here we have had 3 hard frosts on the bounce down to -3°C, so even though we were warm in the day, we won’t have seen the benefit in grass growth. I’ll look a bit more at that later in the blog.

We are dry though and that’s great and much-needed. Walking yesterday you could see / feel how the soil has started to dry out in the surface, the ditches were running clear and the countryside was slowly starting to emerge from a cold and wet winter. I could even hear plenty of Sky Larks.

So how are we set for the coming week as I look out of the window at a cold and foggy start to the day ?

General Weather Situation

Short on time today (as usual) so let’s get stuck in.

Well Monday, Tuesday and Wednesday I’ll take together because for once across the U.K & Ireland (as you can see from the GFS output above), we have very similar weather conditions. Now it doesn’t happen very often but for me writing a weather blog, it is welcome. So Monday looks to have early low cloud / fog in a lot of areas but with an easterly wind it is more likely to affect eastern and central areas of the U.K and Ireland as The North Sea pushes some cool ‘Haar’ in for us. The further west you are, the more chance you’ll be starting brighter or the fog will clear quicker but looking at some webcams for Wales and Dublin, it looks like most of us have got cloud / fog to start the week. Obviously this will make it cooler than of late with that easterly wind pegging back the temperatures despite sunshine breaking through during the afternoon. This seems to be the pattern on both days with the positive flipside that cloud cover should prevent a frost, however it will likely give us heavy dew.

So Monday and Tuesday look like low cloud / fog to start the day with sunshine breaking through and pushing temperatures up to 10-12°C in places. Those unlucky enough to have cloud cover all day may be more like 6-8°C. Onto Wednesday and there’s a subtle change as a Bay of Biscay low pressure sneaks up from the south to bring more in the way of cloud cover and also the risk of some rain. Wind-wise we will have a light to moderate easterly wind on Monday, backing off to much lighter winds for Tuesday and Wednesday.

Wednesday morning sees more in the way of cloud around and light winds so a pretty dull , cool Wednesday is on the cards for the U.K & Ireland. As we approach the end of the afternoon we will see the wind swing round from easterly to south westerly and that’ll push in some rain to the south west of England, the south and south east of Ireland.

Overnight into Thursday this rain will slowly move north and east into South and West Wales so by the time we get to dawn on Thursday we will have some showers moving up from The Severn Estuary into western and central England. At the same time we may see showers moving up from Wexford to Leinster. Nothing too heavy hopefully, just some showers. So Thursday should be mainly dry for the U.K & Ireland, except for the areas affected by those slow-moving showers. During Thursday afternoon those showers look to become more widespread across The South West, Wales, West Midlands and pushing up into the north of England / Peak District area and they’ll move east later reaching East Anglia and The South East. Duller across the south and west on Thursday due to this weather front but Scotland looks to have another dry day with good spells of sunshine, so that’s a bonus.

Closing out the week on Friday and most of those showers have cleared the east coast and are away to the continent. Friday looks to end the week brighter but cooler due to a more pronounced north east wind. Now this may rattle in the odd shower from The Wash and Humber Estuaries but most areas look to be dry, cool and sunny on Friday with a much brighter start to the day than earlier in the week. Those clearing skies at night may mean we return to ground frosts overnight Thursday into Friday dependent on cloud cover in your vicinity. Right at the end of the day we may see some showers tickle the toes of Kerry as we approach dusk. Temperature-wise, I’d say 6-8°C is likely with that strong north easterly wind.

The outlook for the weekend should be pretty good particularly across the U.K. We still have high pressure in charge so I think that means a cold frosty start to Saturday but with long spells of sunshine from the off. Ireland may just see some showers trying to push into the south west and west but these look to be largely kept at bay by that continental high pressure system. So cold, bright and frosty on Saturday with temperatures probably again sitting around 6-8°C, with light winds. Ireland will see some moderate southerlies so maybe a tad warmer there. Sunday sees that rain front move across Ireland overnight and push up into the north west of England, south west and west of Scotland, with some of the showers turning wintry over elevation. Sunshine and showers for Ireland, rain for the north west of the U.K, but calm, dry and settled for Wales and most of England away from western coasts.

Weather Outlook

So looking at the GFS output above for next Monday, you can see we have a kind of squashed high pressure scenario developing with low pressure sitting out in The Atlantic and over the northern continent. The current projections are for high pressure to move aside in the early part of next week and allow an Atlantic airflow to push across with south westerly winds coming back into dominance. Ireland should see the change in wind direction during the latter part of the weekend / Monday morning. The first low pressure that’s likely to swing our way next week looks quite northerly-biased so I’d expect to see rain into the north west of Scotland on Monday and this will be joined by a more concentrated front pushing across Ireland and all of the U.K during Tuesday accompanied by some strong westerly winds. I expect this rain front to push through on Tuesday but we will see another one following close behind so a bit of a repeat for Wednesday. Strong winds and rain. Thursday and Friday look to be more sunshine and showers with the bulk of the showers running across Ireland and onto the western coastline of the U.K. That’s the way we look set with a sunshine and showers theme extending into next weekend. Staying on the cool side despite the change in wind direction because these low pressures are northerly in nature and so pull down winds / temperature from Greenland and Iceland. So I would say 7-10°C at a guess but with less risk of night frosts.

Looking slightly further ahead (always dangerous) we look to pick up a milder airstream from the middle of March onwards and that to me should signal the start of good growing weather with better day and night temperatures. Now a lot can change between now and then so we will see but that would be a nice prelude to a return to golf in late March / April.

Agronomic Notes

Next week I’ll do a proper summary of February, 2021 when I get all of the data in but it looks again like an up and down month dependent on your location in the U.K & Ireland.

One area I wanted to focus on is growth prospects and the fact that if you haven’t had it already, you’re bound to get the question phrased something like this….”Hasn’t the weather been beautiful, I expect the golf course is in prime condition !”

This obviously follows the time-honoured pattern of a certain fraction of all membership, players and the like living their life in a hermetically-sealed environment (well I suppose there’s a good reason to this year !) but the reality is now the sun is out, there’s no reason in their minds not to expect a top of the range golf course, sports ground, be it what you may. That’s of course conveniently forgetting the small matter of furlough, reduced staffing and budgets. And that only two weeks ago from today we were contemplating a fast thaw and emerging from ice and snow :). It’s analogous to me walzing along to my local Trout fishery and expecting it to be gin clear at the start of the season despite a very wet winter and start to the year. It isn’t going to happen.

Now when we have a run of cold nights and warm days like we have had and so so typical of our traditional spring weather in the U.K & Ireland, it is worth understanding how much growth we can expect and why…

Growth Potential across a 24-hour period

I looked a a couple of locations this weekend, picking Saturday as a test day. In one location we had an overnight frost followed by sunshine, the other some cloud cover that kept the temperature just above freezing overnight.

Here’s how the air temperature looked in location 1 – Thame, U.K.

Now this is a notoriously cold location in the winter and spring geographically and often produces some of the coldest night temperatures in Central England.

Hourly Air Temperature – 27/02/21 – Thame, Oxfordshire, U.K

So you can see a hard overnight frost occurred on the 27th, with temperatures dipping to -2°C just after dawn and then rising quickly with clear skies and good levels of sunshine to hit a maximum of 11.1°C at 15:00. So when we have a day like this we know that growth will be limited by the very cold overnight temperature, but how limited ?

So I calculated the Growth Potential each hour by averaging the low and high temperature points across the hour and converted them into Growth Potential.

Here’s how it came out ;

Hourly Growth Potential – 27/02/21 – Thame, Oxfordshire, U.K

If we take a Growth Potential = 0.4 as a good mark of growth in a spring season, we can see that we reached this mark around about midday and stayed above it till 16:00 before dropping away sharply.

So we can conclude in a day when the minimum air temperature was -2.1°C and the maximum 11.1°C, the grass plant would have grown appreciably for a 4-hour period over a 24-hour day. Interestingly the calculated Growth Potential for the 24-hour period was 0.13, which we know is pretty low. So even though we had a really nice late morning to mid-afternoon period, the actual benefit of such a lovely spring day from a grass plant’s perspective was an ability to develop shoot growth for 4 hours of that day.

I looked at another location on the same day, 27-02-21, where low cloud cover avoided a frosty start to the day and repeated the same exercise.

This particular weather station transmits data every 15 minutes so the time interval is a bit different but more precise.

15 minute Average Air Temperature – 27/02/21 – Great Dunmow, Essex, U.K

So in this location you can see the air temperature stayed above freezing (just) overnight, dropping perilously close just after dawn but then rose strongly to hit a peak of 12.6°C at 13:45.

So milder at night and warmer during the day. Here’s how the calculated Growth Potential looks using average temperature every 15 minutes…

15 Minute Average Growth Potential – 27/02/21 – Great Dunmow, Essex

So in this example we see that the Growth Potential reaches the 0.4 benchmark around 11:45 and stayed above it till 17:00, so that means 5 hours 15 minutes of reasonable Growth Potential across a 24-hour period. A good hour and 15 minutes longer than the first location because of the lack of night frost. Even then we are talking about less than 25% of the 24-hour period though and for this day the Growth Potential calculated out as 0.18, so nothing special.

So when we look at these typical spring days when we have good periods of sunshine and nice temperatures from midday, we know that the potential for the plant to grow strongly is unlikely given the slow start to the day and the very fast drop-off as the sun sinks lower on the horizon.

Now in a shady environment you can expect the peak period for growth to be even shorter.

Better light levels….

One of the clear benefits (that won’t be as prevalent this week unfortunately) of those lovely spring days is increasing light levels. Plants only absorb a part of the total light spectrum, this is known as PAR – (Photosynthetically Active Radiation) and it sits between 400 – 700 nm wavelengths, corresponding to the blue, red  and green light portions of the spectrum. There is a rough conversion from Solar Radiation (measured in watts per m2) to PAR, but to measure it exactly you need a PAR sensor. Most weather stations come equipped with Solar Radiation and U.V Radiation sensors, but just a word to the wise, if you see a cheap one on Ebay and the like, it’s usually because it doesn’t feature a Solar Radiation sensor. These typically cost £200 + for a Davis Vantage Pro and alongside measuring Solar Radiation, they are also used to calculate Evapotranspiration (E.T), so pretty essential. They don’t tend to come equipped with PAR sensors as these are equally costly. So the data I am showing below denotes total Solar Radiation of which the grass plant will absorb a part of this in order to photosynthesise, make energy and grow.

Below is a chart of total Solar Radiation per day since January 2021 at a location in Kent ;

As you can hopefully see, we are on a steadily increasing trend with longer day light hours and stronger sunlight. Typically at the height of summer, we can measure over 3500 watts per m2 per day, so currently we are only at about 13% of optimum in terms of a broad definition of Solar Radiation (of course when we receive very high levels of Solar Radiation, some of this will be U.V light and potentially damaging).

We are though heading the right way and for grass plants that respond well to sunlight (bentgrass and ryegrass to name but two), you will start to see a growth response from the aggregated benefit of drying down soils (more oxygen), increasing temperature and increasing PAR light levels.

Now for the week ahead some of those those benefits won’t be that obvious because we are staying on the cool side and duller but let’s hope as we move further into March we start to see them accumulate 🙂

All the best, stay safe and healthy

Mark Hunt