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  • Writer's pictureMark Hunt

January 3rd / 4th, 2023 !

Hi All,

Well Happy New Year and all that....the exclamation mark is to verify to myself that it's now 2023 and I actually remembered :)

We are only on our 3rd day of the year and already meteorologists are saying this will be our warmest year ever and the more 'creative' ones are claiming there's a second 'Beast from the East' on the radar for Mid-Jan, with air mass over The North Pole looking likely to undergo Sudden Stratospheric Warming. (SSW)

An SSW event can lead to the formation of an Omega Block and at this time of year such an event is normally associated with northerly and / or easterly cold air, ala Winter 2010, 2013, etc. There is a great explanation of what constitutes a SSW on The Met Office's website here .

As I sit here typing this blog on a very wet Tuesday morning and look at the GFS output, personally I can't see an Omega Blocking event on the cards, but it's worth keeping an eye on.

What I can see though is one almighty deep Atlantic low pressure with some pretty cold air and packed isobars associated with it heading our way.

955 millibars is a pretty intense, low pressure system and I'm guessing this was the culprit behind the USA's weather bomb event prior to and over Christmas. As a matter of interest, the lowest air pressure ever measured across the U.K was courtesy of 'Cyclone Dirk' (now that's a far better naming system than the one we have now) in 1886, which took the barometer down to 936.4 hPa (1 hPa = 1 mb by the way).

The GFS output below (courtesy of is for Saturday into Sunday and for sure it looks a wild one. Not a 'Best from the East', more like a 'Pest from the West' !

So let's put some flesh on the bones of our weather picture.

Now before I do I should say my blogs during January won't always be on a Monday because I have a pretty full diary of weather station installations to do and some exhibitions to fit in as well, culminating with BTME 2023, where Prodata Weather Systems will I am pleased to say, have a stand. So January will be a bit hit and miss on the days that I publish the blog and maybe a little shorter than usual because of time constraints, however I will do my best as usual to keep you guys informed on all things meteorological and agronomic.

General Weather Situation - w/c 03-01-23

So this week we have a very strong westerly airflow across the U.K & Ireland and that means it'll be windy, mild and pretty wet on occasion, starting today where we have bands of rain pushing across the U.K and Ireland. Last night the skies were clear and so many will start today with a light ground frost before milder, wetter air arrives and the temperature rapidly climbs to 12°C across Ireland, England and Wales and a couple of degrees down on that across Scotland. That rain will hang around all day and it's best to flick on your rain radar app and see what's coming your way. Later tonight we will see some heavier rain across Wales, the north west of England and then Scotland. Some of the latter will fall as snow across elevation.

By Wednesday, most of the rain will have cleared through but they'll still be showers across western-facing coasts and Northern Ireland to boot. Some of these will cross The Irish Sea into Scotland later but on the whole Wednesday will be a drier day, but a very windy and mild one. Temperatures will remain in the low double figures for England, Ireland and Wales and again, a few degrees down on that for Scotland. The feature of the day will be the wind though.

Moving onto Thursday and we look to have another pretty dry day again across England and Wales. Ireland will see some heavier rain for the north west and some lighter stuff along the southern and eastern coasts. This rain front will push into The North West and the south and west of Scotland from lunchtime, preceded by lighter showers. Further south as intimated above, it'll be a mainly dry day until well after dusk when rain will push into The South West and Wales and track across country overnight. Remaining mild with temperatures just tipping into double figures and with a lighter south westerly wind compared to earlier in the week.

Friday sees the first effect of that intense low pressure come into play as this graphic from shows with an arm of rain extending towards Ireland on Friday afternoon.

So Friday will see a west-east divide with Ireland picking up some heavy rain from lunchtime onwards and accompanied by strong winds as well. Across The Irish Sea, it'll be a mainly dry day and a cooler one as well as we sit in a temporary hiatus between one low pressure system and another. So 7-8°C I'd say with a bit of winter sunshine as well and moderate to blustery south westerly wind. That rain front will push across Ireland and into the west of the U.K later on Friday night and then move across overnight into Saturday morning. So we could see some heavy downpours on Saturday morning from The Midlands south (though this might change yet). Ireland will see its weather clear on Saturday, just in time for the next front to push into the west later in the day, with more rain for the west of the U.K at the same time. So Saturday night sees some really strong winds and some very wet weather across all parts of the U.K, before it breaks down to showers on Sunday morning. So, very windy overnight and into Sunday with rain likely early a.m. and temperatures on the cooler side of 7-8°C. Hang onto your hats folks !

Weather Outlook - w/c 09-01-23

So after a pretty turbulent week wind and rain-wise, what is the outlook as we cast our eyes forward towards the middle of the month ?

Can we see an Omega Block on the cards ?

Well the short answer is no I can't as things stand now meteorologically.

So next week looks like following a similar pattern to this week as the animated GIF's indicate above. So we start next week, with that low pressure still affecting our weather, so that means very windy and showery as well, with the predominance of the rain across the west and north. I expect it to remain reasonably mild as well with temperatures gracing double figures across the south and west. Tuesday sees a brief hiatus as one low pressure exits stage right and another one lines up behind it. So a bit drier on Tuesday but then Wednesday sees more heavy rain and strong winds push across the U.K & Ireland. As we approach the end of next week, there's a lot of disparity between the models. Some are pointing to the arrival of a southern-biased low pressure system that will bring strong winds and heavy rain across the south of Ireland and U.K. Others suggest high pressure will push up warmer air towards the south of the U.K and Ireland and this will vector the wetter weather further north. Still windy from the west, but it could be very mild across the south through the weekend after next.

'Mystic Megging' it, I think we are currently in a run of a strong jet stream and this will continue to push Atlantic low pressure systems across the U.K & Ireland. So I'd favour the outlook to continue unsettled, windy and occasionally mild, but we will see.

Agromonic Notes

OK, so I thought I'd have a bit of a look back on 2022 in general using some Davis Weather Station data in order to give me E.T and Smith Kerns values as well. In the coming weeks I'm going to break this down into 3-month segments and discuss the climate and agronomic decisions we make for each of these segments of the year. It should be an interesting exercise. Now I don't have a complete set of 2022 data from locations in Ireland, Wales or Northern England but it's coming.

So, the first data I am presenting is the yearly summary from a month by month basis of the rainfall, E.T and soil moisture surplus / deficit (SMS / SMD) for 3 locations. These are Sevenoaks, Thame and Dumbarton.

I think the results are very interesting. (but then I am sad :) )

Starting off with the monthly rainfall VS. E.T scenario for the 3 locations, we can see that both southern England locations go into a pronounced soil moisture deficit situation during April, with much higher moisture loss by evapotranspiration than is compensated for by rainfall. This of course means there's a need to irrigate much earlier in the year than we are used to doing as that surface begins to dry out. It doesn't mean that we have to irrigate because it's warm and dry because that's rarely the case in April nowadays, it is more often cold and dry. This deficit then extended from April to the end of August, with a wetter May in the Sevenoaks location helping somewhat.

We know of course that 2022 featured our 2nd hot and dry summer in the last 4 years and this affected large areas of the U.K and Ireland. What it also means is that plant stress starts in April across the southern half of the U.K and that diseases linked to plant stress are more likely to be prevalent earlier in the year going forwards because of this. Here I am thinking specifically of Anthracnose and Dollar Spot.

Now the rains did arrive in September and in some locations they have gone a long way to redressing the drought imbalance created in the summer of 2022, however if you look to parts of Suffolk, Essex and Norfolk, this is still not the case with yearly rainfall totals less than 400 mm and E.T levels over 600 mm, so there's still a deficit scenario present as we enter 2023 in some parts of the U.K. I will be summarising the countrywide situation for both the U.K & Ireland in a later blog so keep those 2022 rainfall stats coming. The above picture shows the same area of Rutland Water, roughly two months apart. You can see how much the water level has risen, but it still has some way to go.

Compare that with our Scottish location and you can see how rainfall / E.T across the north of the U.K follows a very different pattern with October through to February as the heavy rain months. The E.T levels aren't as high as we go through the year, so the stress levels aren't as high. There is also more consistent rainfall through the year than there is further south but that brings with it a different agronomic challenge. Monthly rainfall totals do however hide dry periods of weather and Scotland often has a much warmer and drier May compared to locations further south and west.

I think this is a similar pattern to what we would see across the west of Ireland, however the east coast is much drier for both Ireland and Scotland. So it's worth me pointing out that if I presented the E.T / rainfall stats for say Fife in Scotland, they'd be markedly different.

OK, let's look at some more stats for the same locations on a month-by-month basis, this time I'm focussing on monthly growth potential (G.P), the number of frost days and peak Smith Kern (SK) figures to give an idea as to what months peak disease pressure appears.

So, let's talk frost patterns first.

The data from all of the locations I looked at show the same pattern and its one that is repeated all across the Northern Hemisphere I think. In earlier times, we saw frosts commence in October and extend through the winter till March. The frost dynamic has now shifted, I believe because of climate change. They now start later but critically I think, they finish later which means growth in the spring is harder to come by than it perhaps used to be. And yet this is when we schedule in aeration, some of it super-aggressive. You have to ask yourselves why ?

Look at the monthly G.P totals at any of the 3 locations from January through to May. Remember that the total potential G.P figure is usually either 30 - 31 (dependent on the number of days in the month and excepting February of course). So if we pick March as a month, the total G.P at any of the locations is below 7.0 (the actual figures for the 3 locations above are 6.54, 6.61 and 4.76 respectively). There's 31 days in March, so the total potential G.P is 31 x 1.0 (optimum daily G.P = 1) = 31. So as a % for the 3 locations the potential monthly G.P is 21%, 21% and 15% respectively. That is not a lot of growth for the grass plant in terms of recovery.

So, if you have an aeration week booked in March and you use large diameter hollow cores, Graden or deep scarify, I think you are very unlikely to see recovery before May. Firstly because of the lack of temperature and therefore growth potential and secondly because we also know the likelihood is that grass plant growth will become moisture-limited as we move into April due to high E.T levels.

Let me make it clear, I'm not saying no spring aeration, I am saying 'pick your fights wisely'.

So compact vertidraining, solid tining and smaller diameter hollow coring are probably more pertinent aeration practices. Now it's true they don't remove much (enough) surface organic matter, so we then have to look at periods of the year when we have good (reliable) G.P and (hopefully) moisture. That is why more clubs aerate in August and September. Recovery is quicker and you can take more O.M out effectively. I could also mention the fact that having holes open in March and April is also a calling card for Leatherjacket issues.

Spring vertidraining is for me one of the most important practices that we should look to achieve because it sets the stage for better root development and that means we are creating a grass plant that is more able to withstand drought stress. I have to thank Mark Todd from The Wildernesse (👍) for sending me in some of the best photos from an aeration perspective. The one below shows the benefit of vertidraining on summer plant stress. Spot the areas vertidrained and not vertidrained in the image below ;

Adapting to our changing climate is key and spring aeration for me is a clear case of understanding the weather trends and working with them rather than against.

For many years I've also been suggesting aerating earlier in the year.

Take today, it is currently 12°C outside. Soil moisture is abundant (maybe a bit too abundant) but let's say you were able to get out onto your surfaces and aerate this week. Why wouldn't you ?....You are giving the grass plant 4 months head start to develop roots and recover before we hit plant stress in April and every time we get a mild spell in January and February, you'll get recovery. Now I 100% accept that many facilities will be far too wet to undertake aeration this week and in some cases it would be counter-productive to attempt to do so, but if the opportunity arises, it should be taken, regardless of the date on the calendar. In my experience, the grass plant doesn't read them too well you know :)

Disease Activity

Again looking at the graphs above, I have highlighted the maximum Smith Kerns Probability reading month by month from the 3 locations I have covered.

Here I think you can see an interesting trend.

Every location has very similar readings on a month by month basis, despite the fact that they are separated by some 400 miles as the crow flies. That is why we are seeing diseases like Dollar Spot push further and further north during late summer and early autumn when the dews arrive in earnest. Each of the 3 locations above is affected in a similar fashion by these columns of warm, humid air that push up from southern Europe across the U.K & Ireland during Omega blocking events. They may last longer in the south of England but the magnitude of their effect is very similar regardless of latitude.

This disease pressure is extending later into the year and in fact 2022 was an oddity in some ways because December had an unusually prolonged cold snap with frost. This occurred on all locations and dropped our disease pressure away to practically nothing. In other years we have had a pronounced disease pressure peak between Christmas and New Year. Not in 2022 and we have that to be grateful for.

OK, that's me for this week, sorry the blog is out on a Wednesday, but our web hosting site went belly up late morning yesterday so I turned off the pc and got on with some more productive work :)

All the best.

Mark Hunt

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