October 3rd

Hi All,

As we edge into October and after a very wet end to last week it is tempting to think the summer drought is behind us.

The image above is from Grafham Reservoir near Huntingdon. This time last year I would have been standing up to my waist in water on the left of the picture, bank fishing. Today it is a 300m walk to the waters edge. A bit later in the blog I'll be doing my usual round up of U.K and Irish locations to see where we are with rainfall but the message in the southern half of the U.K at least is that we still have a long way to go.

September's monthly rainfall total, though welcome is barely higher than September's monthly E.T total, suggesting nearly as much has been evaporated as has fallen.

Scratch away the damp surface and 10-15mm down the soil is bone dry.

A few weeks back I mentioned finding dead and dying birds on the Llyn peninisular in North Wales due to the highly infectious H5N1 Bird Flu. Back home here in Leicestershire, Bird flu is silently going about its deadly business. Swans, Geese, Ducks and recently a Barn Owl have all been found dead at my local fishery. It really is so sad to see nature in this way and entirely due to the actions of man. I watched a dog pick up a dead carcass on the shore at the weekend and then run back to its owner, probably slobbering all over the place. We aren't making it difficult to jump species are we ?

OK, onto the weather and let us see what we have in store for this week and next week possibly....

General Weather Situation - w/c 3rd October

So there are two features of the weather this week and as usual they are connected.

Firstly, we will have some strong winds and secondly they'll be from the south west and so mild and warm. A good drying week which after the deluge (for some) at the end of last week means the predominance of worm casts will dry up and be easy to brush away without smearing the surface. It also means that we will have a dry leaf so nice dry cuts and low disease pressure.

Rainfall-wise , with a south west wind vectoring rain north east across the U.K and Ireland it means that the west and north will be the recipient of much of the rain this week until the latter part of the weekend when we have a more southerly low pressure system waiting in the wings to tilt the wind round to the north west and push significant rain further south.

So the first part of this week looks pretty wet and windy for Ireland, Scotland and really the northern half of the U.K, including North Wales as well, as we see successive rain fronts pushed in from The Atlantic. These will attempt to move south through the day but will fizzle out as they do so, so not much appreciable rain for the southern half of the country, just showers really. Tuesday in particular looks very wet all round for the afore-mentioned areas. As stated above it will warm in that wind with high teen temperatures for Ireland, Wales and England, nudging up into the low twenties I'd say across the south of England. Scotland will be low to mid-teens as they pick up the majority of rainfall and cloud cover.

The second half of the week sees things settle down a bit in terms of rainfall but north western coasts will still see heavy showers and the wind will maintain its strength particularly towards the end of the week. As we approach the weekend we see a southerly-based low pressure push rain across Ireland on Sunday and this rain will have more of a southerly bias moving across the southern half of the U.K later on Sunday and into the start of next week.

General Weather Situation - w/c 10th October

Well you can see from animated GIFS above courtesy of www.tropicaltidbits.com that we have a very unsettled week on the cards next week and it will be associated with two prominent features. Firstly, the wind direction will shift round to north westerly late on Sunday / early on Monday next week so that means a cooler theme to next week and it'll push successive bands of rain in from the north west and down across The Midlands and the south of the U.K starting early on Monday morning and continuing through the week with next Wednesday and Friday looking wet. Later in the week, more wind and rain and possibly even cooler temperatures as the wind swings round to northerly.

So next week looks at this stage to be dominated by successive low pressure systems with a more southerly bias and plenty of rain associated with it.

Agronomic Notes

Since this is my first blog of October, it is traditional of me to look back on September as a month from a GDD / G.P / Rainfall perspective.

First up we will look at GDD from our default Thame location in Oxfordshire.

GDD Summary - September 2023 - Thame, Oxford

So September came in around 253 GDD for the entire month which ranks it sort of mid-table compared to other Septembers. Interestingly it is almost identical to the two other recent dry summer years of 2020 and 2018 (253 & 249 respectively)

With August coming in at the highest GDD level we have recorded (397) since 2005 courtesy of the mid-month heatwave and July as well near the top, it means September total GDD y.t.d (1764) is tracking right towards the top end of the cumulative y.t.d totals and again uncannily similar to 2020 and 2018 over the same time period (1754 & 1752 respectively). Is there a pattern building here ?

Despite the 'warm' GDD stats, September 2022 was definitely a month of two halves from a growth perspective in the U.K, as you can see from the daily Growth Potential graphs below ;

All the above U.K locations follow a pretty similar pattern - A warm first part of September with optimum growth conditions and then on the 16th, there's a pronounced dip as cooler air and rain arrive before picking up again and then dropping off a cliff at the end of the month. The growth conditions in the last week of September were particularly poor with not only cold nights but not particularly warm days either and it was dry. Dry cold for me is the pits. Interestingly the coolest location with the lowest growth potential stats was Guildford in Surrey.

That cold end to the month put recovery from aeration, summer disease scars, etc on hold somewhat and has led to much slower germination from overseeding.

Cold and dry are the worst combination for turfgrass and usually not an issue in September but here in England certainly the end of the month served us up a largely dormant grass plant (due to the sudden dip in temperatures) that was dry as well. In this case, lack of irrigation and rainfall wasn't an issue because the plant wasn't growing anyway !

I mentioned earlier that September's rainfall had been counteracted by September's E.T, so I thought I'd substantiate that statement with some data. I'm glad I did because although reasonably accurate, it wasn't wholly accurate. I should have known when discussing any topic featuring rainfall !!! (groan)

So we have 2 locations who had more E.T than rainfall in September, Northampton and Milton Keynes which kind of points the finger towards The Midlands still being very dry and here in Market Harborough I'd reinforce that statement. We are so dry still and the local reservoirs, so low.

On the flipside of that coin, Dumbarton up in Scotland showed the largest surplus of rainfall vs. E.T and next up was Guildford, at the other end of the country !

Such are the vagaries of rainfall.

On average, most locations showed a 15-20mm rainfall surplus in September vs. E.T which though welcome, isn't about to change the underlying deficit any time soon. Way back in 1976 when we had the drought, we followed that by 4 successive months, Sept-Dec of 110mm + rainfall in the south of England. So far then we are off to a slow start in terms of summer drought rectification. As my school reports often said, C-, more effort required here....:) (largely as a result of gazing out of the window and wanting to go fishing I'd say)

So September was a month of two halves here in the U.K, how did it shape up across The Irish Sea ?

Well we can see first off it was significantly wetter across the whole of Ireland and although a pain, I suspect that rain was very much welcomed in terms of recovery from the summer, aeration and overseeded areas. (You might not agree if you live / work in Kerry but you are still probably on a high after the All-Ireland in the summer !!!)

Monthly totals don't tell the whole story though because the rainfall was very much condensed into a short period of time, a feature I think of today's rainfall events. So if I take Kerry where we have 175.8mm for the month, the pattern across the month tells a different story with a run of dry and cooler days in the middle of the month. This pattern got more pronounced as you went from west to east with Dublin and Wexford very dry mid-month before some significant rainfall events in the last week.

Growth-wise in Ireland, September marked a pretty good month with similar monthly G.P totals to the U.K and that is because although they both experienced a mid-month dip, the end of the month was much milder in the west across Ireland than it was for the central and southern regions of the U.K, which picked up that very cool north easterly wind.

I am struck with just how similar the Irish total G.P totals are y.t.d between the many locations. This isn't normal for Ireland and reflects how the weather has been dominated by the warm summer that all areas experienced.

Looking ahead in general - U.K & Ireland

Now the outlook for this week is better with south westerly winds bringing moisture and warmth, with much better overnight temperatures as well. I can though see another dip next week as we get that wind change round to the north west and north. So we will see a growth pick up I think, nothing too radical as G.P's are only going to be 0.5 - 0.6 on a daily basis. With warmer days and nights and an ever-present wind, it will be a good drying week as well which should help get some dry cuts in and the plant tidied up before what could be an unsettled week, next week. Disease pressure should be low if the wind maintains a dry leaf at your location.

OK, that's me for this week, a lot of stats I know but then looking back helps us to look forward IMHO.

All the best.

Mark Hunt