March 20th, 2023

Hi All,

As I type this on a gloomy Monday morning, the rain is hammering down (again) and we are rapidly playing catch up on what was our driest February since the 1930's in some locations.

Without a doubt we need this rain but as I drove over the flooded River Welland yesterday, barely contained within its banks, I wondered at the scenario where in a few months time our industry, the water companies et all will be bemoaning the lack of water available as we effectively 'waste' what we have.

You have to wonder at system where we predictably (reasonably) go from a scenario of surplus to deficit every year and yet knowing this, we do very little about changing it. Every time we announce plans to build new reservoirs, they are opposed by the NIMBY brigade. The east of England particularly is crying out for more water capacity with annual rainfall levels sometimes under 400mm and annual E.T levels sometimes double that. The warning signs are already there (https://www.bbc.co.uk/news/science-environment-64966953)

General Weather Situation - w/c 20th March

So as discussed in previous blogs, the movement of the jet stream further south has allowed a succession of Atlantic low pressure systems to push over the U.K & Ireland. Is this set to continue or do we have a drier interlude on the cards ?

Well as you can see from the animated GIF's above, we look to be set in a pattern of successive low pressure systems right through to the end of March with perhaps a drier interlude then for a time. The GIF's from tropicaltidbits.com also show that colder air is very much still in the general weather picture and this I think is related to the Sudden Stratospheric Warming event that took places in the third week of February.

The reason why this continues to be significant when we have a run of westerly low pressures relates to wind direction. The first thing you must understand is that the winds associated with a low pressure system in the northern hemisphere rotate anti-clockwise. As a low pressure system approaches our shores from The Atlantic, we invariably receive milder air from the south west / west on its leading edge, dependent on the position of the low pressure from a north / south perspective. As it departs east, it then draws down northerly air on its trailing edge. Normally the winds are stronger as the low pressure approaches with densely-packed isobars and lighter as it departs. This isn't always the case but it tends to be.

I have tried to explain this in the graphic below ;

Last week I was over in the west of Ireland installing Davis weather stations and I was fortunate to visit the very picturesque Co. Sligo Golf Club with the imposing terrain of BenBulben in the background. My thanks to Mark Millar and the club for their hospitality. As I struggled to keep feeling in my finger tips in the negative wind chill, I wondered how that beautiful mountain affected the local weather and particularly rainfall. This is the grey area of forecasts where a local feature like a hill, water course, area of woodland and the like will affect how the weather 'happens' at ground level. It is one of the principle reasons why forecasts are 'wrong' when it comes to wind direction, cloud cover and the like.....local factors result in local weather.

So if you're looking at the images above and I have managed to communicate my point properly, you will have surmised that this week's weather is characterised by strong winds, mild temperatures, frequent rainfall and then concludes with a cooler temperatures at the end of the weekend.

So Monday is characterised by an approaching low pressure system and frequent rain across the west of Ireland and the U.K, with showers pushing across through the day. The wettest places look like being Ireland, the west of Wales, the north west of England and south west of Scotland. Temperatures will be mild around 12-14°C. Tuesday offers a bit of respite with those showers or heavier spells of rain declining in intensity. So a drier day on Tuesday, still some showers around but it is only a brief hiatus before a deep Atlantic low pressure system makes landfall across the west of Ireland on Tuesday afternoon. So heavy rain moving eastwards across Ireland later in the day and this will cross The Irish Sea on Tuesday evening reaching western coasts of the U.K later. Similar temperatures to Monday, maybe a little cooler as those winds really ramp up to gale force in places.

The only advantage of very strong winds is that it does move low pressure systems over the U.K & Ireland quickly and so by Wednesday, it'll be exiting stage left towards Scandinavia, leaving behind a raft of showers across Ireland and the U.K. Some of these will turn wintry across the Highlands of Scotland. Scotland will see a lot of rain during the day, Ireland close behind and then the west coast of the U.K, Wales and the like as well. Further inland we will see sunshine and showers but it will be very windy with gusts over 30mph.

Thursday sees again more rain pushing across the U.K and Ireland. This rain will move north east across Ireland, the south east of England and Wales during the day. Plenty of showers inland as well with the odd sunny interval and again a strong, south westerly wind, maybe a touch gentler than on Wednesday. Temperatures will remain on the mild side with Scotland a little cooler down at 10°C.

Closing out the week on Friday, we have more of the same with plenty of rain around across all areas, particularly Ireland, western coasts, you get the picture. That strong south westerly wind will persist blowing to gale force in exposed locations and temperatures will remain in the 10-12°C sort of range. Wet, wild and windy with the odd sunny interval inland seems to be the theme for the week.

That theme continues into Saturday with more rain for Ireland, the south west of England, Wales and the west coast of Scotland from the off before moving inland across all areas through the day. There's some very heavy rain looking to follow later in the evening into The South West, Wales and the like before again moving inland overnight into all areas. Ireland should miss the bulk of this. Remaining very windy from the south west with mild temperatures. Sunday looks a drier day after that rain has moved away during the morning, though it may take its time to move from the north west and northern England. As we go through the day, the low pressure moves across The North Sea and as the second image above shows, it'll pull down northerly winds later in the day and drop temperatures as well.

Weather Outlook - w/c 27th March

The longer-term GFS forecast looks to be more of the same I am afraid because the jet stream is remaining stubbornly low, so I think next week we will see a colder start to the week with light winds and possibly an overnight frost. The first part of the week will be cool with northerly winds and then the wind will swing round to the south west. The week will then become increasingly wetter with Wednesday looking like the wettest day with strong winds and rain and a little milder for a time before the winds shift round to the north west and bring temperatures down a tad. The closing part of the week looks like being sunshine and showers, cooler with winds from the north west. As that low pressure departs on Thursday we may see a temporary, dry hiatus with lighter winds and possibly another overnight frost for some. As I sit here now there doesn't seem to be an end to this pattern of weather. Previously I had thought the end of the month would bring some warmth and drier weather but currently this isn't the case :(

Agronomic Notes

First up I thought I'd have a look at how the rainfall is shaping up this year so far across a number of locations. Now I accept there is always regional variation but this is just to give a flavour of how different areas are or aren't getting a March top up vs. a dry February.

You clearly see how locations across the eastern side of the U.K are drier overall and how the west and south west are picking up plenty of March rainfall. The two driest locations are Bury St Edmunds in East Anglia and Scarborough. The driest Irish location is Dublin by some margin, again an easterly location comes to play here. Remembering that we have a pretty unsettled forecast for the remainder of this month, it seems likely to me that the rain we missed in February will be replaced by a very wet March for many. Although this is what we needed it does cause an issue in terms of abstraction because some licenses are worked on the calendar and not the flow rate / level of the water course that you are abstracting from :(

Agronomic Implications

A wet March has some significant ramifications for turfgrass management.

Fortunately, the second half of March is looking to be milder than the first half which means we are picking up a small amount of growth as the unsettled weather means more cloud cover, a predominantly south westerly wind and higher night temperatures. In turn this means that we are putting on some nice GDD / GP and therefore growth providing continued recovery from February aeration, disease scarring, etc.

A knock on effect from having better night time temperatures and rain that is falling from warmer air is that the soil temperature has picked up nicely from 4-5°C a week ago to 8-9°C this week. This means more microbial activity, better germination and growth. If you look at the scenario I discussed last week, that of dormant seeding, you could expect to see the fruition from your efforts popping up this week. Those of you that were lucky enough to aerate during the drier conditions of February must be quietly smug, knowing you are well on the way to recovery and if you overseeded at the same time, starting to see the benefits. I 100% understand it wasn't / isn't for everyone but it clearly highlights why thinking out of the box and ignoring the calendar is a great adaptive strategy.

Some negatives of an increasing soil temperature mean we will likely see more grub activity whether that be Leatherjackets or Bibionids. Corvid species like Crow and Rook have young in the nest and Badgers / Foxes are more active as well, so this means the potential for more damage is likely I am afraid.

Finally if you are looking to add nutrition, a preventative fungicide, wetting agent and biostimulant anytime soon, the clear lack of spray days is an issue and will remain so I am afraid because of the current weather pattern. Certainly any nutrition has to be granular-orientated for the time-being.

Ok, that's me for now, I have a Teams meeting to jump onto, so tempus fugit and all that....

All the best.

Mark Hunt

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