I think the map below explains the weather story for March very well.
Access it from The Met Office website here
The negative North Atlantic Oscillation (NAO) which caused (and continues to do so) the jet stream to sit lower than normal allowed low pressure after low pressure to affect the U.K, hence the heavy rainfall. Coupled with the predominantly easterly wind aspect, we can see the result in terms of rainfall distribution, it has a pronounced eastern bias.
The bad news for us is that the jet stream is still sitting low and the NAO is still the wrong side of where we need it to be. The indications up to the middle of April point towards another strong negative dip so in my books it looks like more of the same I am afraid in terms of rainfall.
On the flip side we have seen much better temperatures over the last week and that has at least allowed some growth. In fact there’s been more GDD across the U.K over the last week than we had in 3 weeks during March and that rise in temperature will help a little in terms of faster drying of the turf surface. Yes I know I’m trying to put a positive spin on it when a lot of surfaces remain saturated but that’s just me 🙂
General Weather Situation
So we start the week with a dull and pretty dry picture on Monday save for a raft of showers that is working along the Dorset coast. With an easterly wind in situ these showers will move west across Wiltshire and into The South West through the course of the day. Elsewhere we have plenty of cloud cover that will eventually break across the east coast, north-west England and Leinster to reveal some patchy sunshine. As we close out the morning, that rain across The South West will push north and eastwards into South and mid-Wales and later The Midlands. At the same time we see another strong rain front push into the south-west of Ireland. Through the course of Monday night that rain will edge eastwards to cover most of the south and central regions of the U.K, pushing up into northern England by dawn on Tuesday. A north-east / easterly wind will keep temperatures down to low double figures, so maybe 11-12°C for the U.K and Ireland.
So a very wet start to Tuesday beckons for England and Wales and also for the east and west of Ireland as a band of rain is set to lie horizontally over the country. South of this band you’ll be dry and dull though. As we go through the morning rush hour, the band of rain over England and Wales tracks northwards clearing the south and south-east of England as it does so. The reason I haven’t mentioned Scotland yet is because you’ll be dry and dull through Tuesday but expect that southerly band of rain from northern England to push into north and east Scotland during Tuesday afternoon. As we go through the afternoon the rain over Ireland, Wales and England begins to dissipate and we may even see some spells of sunshine break through as it does so. Still plenty of rain showers around though it has to be said. Where that sun breaks through it may just lift the temperature up from 11°C to 13°C in places as we close out Tuesday, cooler in Scotland mind.
Onto Wednesday and a much better day with a pretty dry picture, save for the risk of showers over Northern England. Plenty of cloud initially but this will clear from the south and south-east to give long spells of sunshine and rising temperatures pushing up into the mid-teens during the day. More in the way of thicker cloud for the north of England and Scotland in particular means that temperatures will sit a good bit lower and struggle to break out of single figures. Ireland should almost mirror England, with a dull start and the cloud cover breaking across the south-east during the morning and clearing northwards. A lighter easterly wind will allow a much milder feel to temperatures.
Thursday sees the effect of the east wind come into play as a bank of thick cloud is pushed in off The North Sea. This will bring rain to the east / north east from first off pushing north and westwards during the morning into The Borders and North East Scotland. South of this band of thick could we will see a dull, dry start with cloud breaking across The South West and east of Ireland to reveal hazy sunshine. Through the late morning there’s a risk of a narrow band of rain running along the south coast westwards, some of this may be heavy across The Isle of Wight and Hampshire, rain shadow or no rain shadow 🙂 During the course of Thursday evening this rain pushes into The South West from the east and may be heavy in places. Further north we see that rain peter out and be replaced by a bank of thick cloud so nothing great about the temperatures here. 9-10°C under that cloud and 13-14°C further south, so a real north-south divide. Winds will be easterly swinging round to the south east at close of play.
Closing out the week on Friday and overnight we see that band of heavy rain over The South West and Wales extend into Leinster and Connacht bringing the risk of heavy rain here. Likewise we see thicker cloud over the south and central parts of England on Friday and so a dull and potentially damp start here too. This time the north of England and Scotland gets the better start with sunny intervals breaking through a clearing cloud base but it won’t last long as more cloud pushes in from The North Sea on a south-easterly wind bringing rain to the north of England and Scotland for the second part of the day. This will clear from the south mind. For the south and central regions which had that thicker cloud and early rain you’ll see it clear during the afternoon to finish pretty nice really with hazy sunshine and warming temperatures.
So how does the weekend look ?
Saturday looks potentially pretty good at this stage with a warm, sunny day for most of England and Scotland at least. There’s a threat of some rain for The South West and South Wales possibly but plenty of time for this to change yet. Ireland looks to have a dry Saturday morning but there’s a threat of rain for the east for the 2nd part of the day I’m afraid 🙁 With those rising temperatures we could see some snap showers associated with thunder across the U.K later on Saturday afternoon. Mid to high teens for England on Saturday, cooler across the west with that cloud cover and for Scotland, but low teens here and dry crucially. Sunday looks similar, more cloud cover about though and heavier showers running up from The South West up the west coast. There’s also a rain risk for the east coast of Ireland as well. Some of these showers may extend into The Midlands during Sunday afternoon. Winds will swing round from the south east to more westerly on Sunday and I’d expect temperatures to stay in the mid-teens for Central England and low teens elsewhere. So a bit more unsettled on Sunday but remaining mild.
So the outlook for next week is I’m afraid a continuation of unsettled conditions with a deep Atlantic low pressure developing from mid-week onwards and set to give us some heavy rain for the 2nd part of the week and extending into next weekend possibly. As you can see from the Unisys graphics above, the orientation of the low is more south-westerly so perhaps reversing the easterly trends of late. If I try to pick some crumbs of positivity, I’d say it will remain mild with a south-westerly / southerly airstream but we really don’t need any more rain as we all know.
Until I see a change in the weather I will keep churning out comparisons with prior years because I think they’re helpful in understanding exactly where we are.
Now I got this idea from Rob Hay at Northampton County who kindly forwards his weather data to me. (Thanks Rob)
His contention is that 2018 is closely following 2016 in terms of growth and rainfall patterns and we know that in both years we had late SSW events so there’s some logic there. I happen to think he is right.
I plotted out his data and expressed it as Cumulative Growth Potential comparing 2013, 2016 and 2018, when we had SSW events, with 2017 when we didn’t.
Here’s how it looks….
So you can see from the data that all SSW-affected springs show lower (and slower) growth levels compared to 2017, when we had a decent spring with no SSW.
Broadly-speaking, 2018 is tracking mid-way between 2016 and 2013 in terms of cumulative growth and roughly 25 days behind 2017 (as of 08/04/18). The gap has closed a bit because we have had some growth over the last week or so.
The other interesting parameter that Rob documented was rainfall, so here’s the same graph as above but looking at cumulative rainfall.
So you can see from the above that a SSW event doesn’t necessarily mean we will pick up high levels of rainfall as a result because in 2013 we had lower rainfall than 2018, beset by a pattern of cold, dry easterlies. If you look at 2018 and 2016 though, the rainfall total to date is very similar though the pattern is different.
So we continue to track behind 2017 in terms of growth and a long way ahead in terms of rainfall. That trend will I am afraid continue through the next 10-14 days by the look of it with further high rainfall predicted. As a reminder, April 2016 finished off cold and dry in the last week with night frosts but come the end of the 1st week of May we had a massive growth flush.
Warming air means higher E.T rates and quicker drying
I am determined to keep positive despite how the weather looks and one point I’d like to emphasise is the effect of that warmer air coming into play. As we progress through April and pick up warmer day temperatures it means we also get higher evapotranspiration and that means surfaces dry down quicker.
If I look at the stats over the last week from The Oxfordshire, they received 17.4mm of rainfall but crucially 13mm of E.T so some of that rainfall effect was negated by evaporation. Now the further north you go, the lower the E.T and I accept it isn’t the case for everyone, but warmer air dries surfaces quicker so I’d like to think we will dry down quicker as we go through April.
Where is Poa annua in all of this in terms of seedheads ?
Well usually what we see in the spring is that the annual biotype of Poa annua begins to seed at around 100 cumulative GDD from Jan 1st. If I pick the data from Northampton, they’re up at 82 come yesterday so a little way off. That said they were only at 62 at the end of March so have packed on 20GDD in the last week. That means if we continue this trend we will see the annual Poa biotype seeding in greens in a week or so for The Midlands and given the fact it’s been warmer down south, you’ll already be seeing it.
The perennial biotype seeds later in the spring and typically anywhere from 180 cumulative GDD so we are a long way off that at present.
I haven’t had the opportunity to strip down any Poa plants of late and have a look (a great way to pass time if you are exceptionally sad like me) but I wouldn’t expect to see much at current GDD levels.
Just as an aside, if the perennial Poa annua at Augusta (perish the thought) seeded at a similar GDD point, the seedhead flush there would have been around mid-February !
Following Rob’s line of thought that we are tracking similar to 2016 in terms of GDD and rainfall, the Poa annua seedhead flush started on 7th May, 2016 looking back at my records. It was the week when we went from a G.P of 0.25 to 1.0 in a matter of two days, with Poa seeding profusely and clippings around our ankles !
With the milder weather and high humidity of last week comes Microdochium nivale with plenty of reports of disease activity out there last week. Looking back at the data from my little Netatmo Weather Station, I recorded a period of 34 hours between the 2nd and 3rd of April when the humidity and air temperature were above the threshold for Microdochium activity, so it is not surprising that we are seeing disease activity. Thankfully though with those same temperatures comes growth and that means we are at least able to grow the effects of the disease out of the sward.
Linking your Netatmo Weather Station with Weather Underground
Now I know quite a lot of people have gone out and purchased one of the above weather stations after reading my blog. I should point out there is no commercial connection between myself and Netatmo and therefore you won’t see me retiring to a life of fly fishing and mountain biking just yet….:)
I have though found it a cracking piece of kit so far in terms of weather monitoring but to the contrary I have also found The Netatmo dashboard quite limiting in terms of the ability to look back at historical data.
I thought I’d got round this when I found out you could link your Netatmo Weather Station to the Weather Underground (WU) – Personal Weather Station Network (PWS).
When you do so you can spot your weather station on their map, click on it and look at your data. My weather station is 1of 5 in Market Harborough as you can see on the Weather Underground (WU) map below.
Now I am not going to go into how you link your Netatmo with WU because I don’t think the software marriage between the two of them is very robust. I encountered a number of instances when the WU map said my Netatmo wasn’t reporting data to WU when it was working fine, but the link between them wasn’t so I ended up with missing data, sometimes for days.
I then happened upon another solution using software from a company called Meteoware Plus. They offer the ability to look at your weather data from your Netatmo in a fancy dashboard set up which is nice but their ace card is that they also offer the ability to link your Netatmo PWS with WU, if you click here
It’s really simple to do once you enter your Netatmo login details and within an hour or so you’ll see your data featuring on the WU map. It transmits your PWS data every 15-20 mins or so and you can click on a log (shown above) to check that your weather station is uploading data.
So what’s the advantage of sending your weather data to the WU site ?
Well if you click on your weather station you can put in custom historical dates and it will pull up your data in either graphical or table form. Here’s my March summary…
So you can easily take this data and fill in your GDD / G.P spreadsheet, rainfall and the like. What’s more WU have a map of PWS’s all over the world so you could say hypothetically click on a weather station next to Augusta and look at their weather or anywhere really where there’s a PWS indicated.
Now the idea of a PWS Network is pretty recent so don’t expect to find years worth of data, also sometimes there are gaps in the data if the weather station wasn’t maintained, battery went flat, WiFi broke down or the software between the two didn’t work for while.
Now I don’t claim to be an expert on this so please don’t email me asking ‘x’, ‘y’ and ‘z’ because I probably won’t have the answer, I’m simply relating my experience so far with my own PWS and data usage / availability.
Ok that’s it for this week, it must be a record for me to finish this blog it on the day I actually started it 🙂
All the best for the coming week.