Sort of a two-part blog this week as I started writing it on Monday and hopefully I’ve finished it on Tuesday, both times in Huntingdon’s finest Costa Coffee 🙂
I was tempted to add an April fool’s joke in yesterday about Brexit but sadly our parliament is full of April fools and I for one think Guy Fawkes was a visionary 🙂
Two weeks now since the last rain with some significant temperature and E.T closing off the end of March 2019. Enough to get many of us irrigating or at least thinking about it, and when you look at the moisture loss you can see why…Despite these warm temperatures, March 2019 won’t check out as a particularly warm month because although we had some nice day time temperatures, we picked up a good number of grass frosts as well and that pattern will continue into early April.
Nature though is in full swing, summer migrants are still arriving (still yet to see a Swallow though) and 3 of my Hedgehogs are out of hibernation and already working on their July brood if you get my drift. This week is going to be a bit chilly for them and a reminder that April in the UK and Ireland can serve up any type of weather and often does….
If you do a lot of driving like me you’ll have noticed over the last 7-10 days or so that the edges of roads, motorways are lined by a white flower right along the salt line margin of the road. This is called Danish Sea Scurvy, one of the most successful Danish invaders of this country (after the Vikings of course) . I’ve written about it before but it fascinates me as it is a halophyte (salt-tolerant plant species) and has therefore adapted to live in the high salt environment on the edge of roads where the salt spread reaches. It’s also interesting because it is a great example of predicting flowering by GDD. This species begins to flower around 100GDD from Jan 1st and when you see it, you can rest assured that the emergence of the annual Poa annua biotype seedhead isn’t far behind 🙂
Ok tempus fugit my friends so I better get cracking with how this week’s weather looks….
General Weather Situation
So last week I predicted that our high pressure situation would start to break down from Tuesday and that’s what we are going to see, so thanks to Meteocentre.com for being a reliable supplier of GFS weather forecasting output after Unisys did a corporate update to their weather information that rendered it as much use as a chocolate fireguard. Funny enough Weather Underground have just updated their PWSN web offering to an immeasurably worse version. Think these guys should get out of their office more and understand who uses their service and why….0/10 for effort…
So Tuesday starts with a much more unsettled picture as a rain front sinks south and east to bring rain into the north of England and Midlands through Tuesday morning. The same happens across The Irish Sea with a mix of wintry showers and rain from the off, initially for Connacht and Munster but soon pushing south and east across country to affect all areas. By early afternoon, this rain band should be clear of western coasts and will now be affecting the south and east of the U.K with Ireland seeing a general mix of showers across the whole country. Scotland will see isolated showers, wintry across north-western coasts with some pushing inland through the afternoon. For the 2nd half of the day then a much more showery, unsettled outlook for all areas with blustery showers, some of them wintry for all areas of the U.K and Ireland. Feeling nippier with a moderate to strong north-westerly wind keeping temperatures down in the high single figures, low double figures with significant windchill.
Wednesday sees another mixed day with sunshine and showers likely for Scotland, the north and west of Ireland and the north-east coast of England as rafts of showers, some of them wintry move south and east into central England later. Another cold start with ground frost likely if skies are clear overnight. So an unsettled day, plenty of sunshine though between the showers away from western and northern regions but there’s a suggestion later in the afternoon that more consolidated rain / wintry showers will sink south and east into central and eastern England. Cold again in that north / north-westerly wind with temperatures similar to Tuesday.
Onto Thursday and another unsettled day for Scotland, the north of England, north Wales and The Midlands as wintry showers push south and east through the day. Ireland should miss the majority of these until later in the afternoon when a mix of rain and wintry showers pushes into the north and west and moves south. At present it looks like most areas will see some showers on Thursday but south of the M25, the frequency should lessen to just the odd interloper. Again feeling really nippy even though the wind will swing round more to the west through the day, with temperatures lucky to break into double digits.
Overnight into Friday and that wind has done a 180° transition to easterlies and so you might expect that to mean it’ll feel even cooler but actually no, Friday will see a milder day with temperatures up into low double figures for many. That easterly wind will push showers across The South West, Wales and into Leinster through the morning / afternoon and again these will fall as sleet and snow over elevation. Through the 2nd half of the afternoon these showers over Leinster will move westwards into Munster and later, Connacht. Away from this rain front Friday looks for many a lovely, dry and sunny day with better temperatures despite the moderate to strong easterly wind.
Onto the weekend and with an east wind in situ I’d be expecting it to be a dull, drab and cool one but I’d be wrong. That’s because the source of the east / south-east wind is from southern Europe and so we can expect much milder temperatures than we are currently experiencing this Tuesday morning. So Saturday and Sunday look like starting off dull with plenty of cloud cover but through the morning the cloud will thin and the sun will break through to reveal a nice 2nd half to the day. Sunday is likely to be duller for longer particularly across the south and east of England but through the late morning that bank of cloud will sink south into southern England and thin as it does so. Ireland looks to have an not so bad weekend after rain clears south and west from Leinster through Saturday morning. Scotland and Wales look to have a similar weekend to England with some scattered showers around early on Saturday but warming up nicely (esp for South Wales) on Saturday to the mid to high teens. So double-digit, low teen temperatures this coming weekend, enjoy.
OK, so how does next week look from a weather perspective ?
Well ‘pretty unsettled’ I’d say after a kind of hiatus on Monday when we start with gentle winds and reasonably dry. We have a couple of Atlantic depressions heading our way, the first will make landfall across Ireland on Monday morning and this will quickly cross The Irish Sea overnight into Tuesday bringing a south-westerly airflow and rain with reasonably strong winds. A likely sunshine and showers scenario continues through Wednesday and Thursday before a large, deep Atlantic depression pitches up in time for the weekend when I expect to see more strong winds, mild temperatures and plenty of rain. So if it all falls into place we can expect sunshine and showers next week in-between longer spells of rain. Crucially though, good growing weather.
OK, better late than never we look back at March 2019 and what was essentially a month of two halves for some locations in terms of growth and rainfall.
March 2019 – Monthly GDD – Thame Location
So for this location March came in at a pretty miserable total GDD of 60, which although 3x higher than March 2018, it’s probably half of the GDD of a strong growing month and average really growth-wise. It now bears little resemblance to 2017 from a total GDD perspective as you’ll see below, but we are in a much better place than last year and that needs to be remembered.
Y.T.D 2019 GDD – Thame Location
From a yearly progression till the end of March we aren’t really setting any records as you can see from the chart above. Sure we are well ahead of 2018 (it would be difficult not to be, it has to be said) but I’d argue that spring is no longer ahead of ‘normal’ and is definitely not early despite Radio 4’s pronouncement this morning when they ran a feature on nature and how spring is getting earlier. It is a gradual, slow spring in my mind and if I look ahead to April I see that trend continuing, nothing too radical temperature-wise and apart from the low temperature blip this week, reasonably good growing weather.
Let’s look at our U.K and Irish locations from a GDD and rainfall perspective.
March 2019 – GDD & Rainfall U.K Locations
A lot of variability in March 2019 both in terms of rainfall and GDD with Okehampton continuing its ‘Valentia of the south west’ impersonation (sorry Pete) in terms of rainfall. You can see again that The Midlands and east of the country were dry for March with York coming in as the driest location at 29.8mm. Now we know March was a month of two halves, the first cool and wet and the second, warm and dry, but this description really only fitted the southern half of the U.K because the north of England and Scotland endured a cooler and wetter 2nd half of the month. This can clearly be seen from the Fife location which comes in at 92mm of rainfall (that’s a lot of rain for Fife) but only 43.4 GDD, similar to York and Okehampton.
March 2019 – GDD & Rainfall Irish Locations
This pattern of significant variability in terms of rainfall and growth is also present in the Irish data with the north-west, south and west locations coming in with lower GDD and higher rainfall, compared to the easterly locations which saw less rainfall and more growth.
There’s some big differences between locations that are pretty close to each other as well with Donabate to Bray, probably just over 20 miles distance between them as the Seagull flies but 43% more GDD at the former vs. the latter. The same distance probably between Donabate and Casement (Dublin) but nearly double the monthly GDD. It just shows how measuring your own data and creating your own stats for your location is important when it comes to this day and age where venues are compared over social media on a day-to-day basis.
How are we faring GDD-wise 2019 vs. 2018 vs. 2017 ?
You can see for our Thame location how 2019 fits right between the disastrously slow spring of 2018 and the belter of 2017. From a GDD perspective we are close to a month ahead of last year but two weeks behind 2017.
It’s been dry as well….
There’s been a lot of discussion on social media regarding the merits and pitfalls of watering in early spring, using cold water, dropping the soil temperature and the like and of course it isn’t a one size hat fits all discussion. The north, west and north-west of the U.K would have no such requirements because their rainfall levels have been higher and E.T levels lower. The same with Ireland, across the west, north-west and south-east there’s been plenty of rain but further up the east coast of Leinster, the end of March dry spell mirrored some areas of the U.K.
Now it’s a complex picture and there are many variables, not least rootzone characteristics, site dynamics (in terms of wind and therefore exposure levels) before we even mention the weather itself and rainfall.
I took data from two sites, one at Thame, in the middle of England representing a dry and exposed site with little cover and therefore a high susceptibility to drying out. The other at Norwich, representing a site with lots of tree cover, less exposed to the wind and actually a wetter site than Thame as it turns out.
I graphed out daily rainfall, E.T and looked at the potential moisture surplus or deficit across a month. Now of course this is where rootzone characteristics comes into play because high sand content rootzones will not hold all the moisture that comes the way of rainfall or irrigation, whereas a higher loam / clay content rootzone will hold more. We also have another variable, that of organic matter levels in the surface, but let’s assume the rootzones are similar for the sake of this exercise.
Here’s how the rainfall vs. E.T dynamic pans out for both sites…
At the Thame location we see that the end of the month is dry and due to the exposed nature of the site, the daily E.T ramps up till it reaches a maximum of 5.1mm loss on the 30th of March, now I can tell you that is a very high figure for the spring. You can see after the rain stops in the middle of the month, the moisture surplus is reduced till it goes into deficit by the 30th of March.
At the Norwich location, they have slightly more rain over the month, but due to the nature of the site, significantly lower E.T loss and so they never go into moisture deficit. Their highest E.T day is 50% lower than Thame.
Now I accept the above comparison is an over-simplification because the rootzone will not retain all of that moisture, some will undoubtedly drain through, especially with a high sand content. If we were talking loam / clay outfields though, we would expect more moisture to be retained and in this case, the Norwich example to not require irrigation through March, whereas the Thame location would probably be under moisture deficit.
The differentiating factor between the two sites is actually the daily E.T level and at any location, this will definitely be one of the primary considerations with respect to irrigation. I’d suggest on a high E.T day when you are losing 3-5mm of moisture, it will soon become apparent that irrigation is required to prevent plant wilt and desiccation. The modern usage of moisture meters helps massively in this thought process. We must remember though that we are sampling moisture levels at the end of the probe depth only, not along the whole probe, so it is quite feasible for moisture levels to be much lower nearer the surface and especially when that surface profile is dominated by organic matter. Glenn Kirby over at Syngenta is doing some interesting work in this area. My problem is as ever the sheer number of variables impacting this ‘should I water, should I not debate’ but one things for sure, you cannot generalise between sites as my examples above highlight.
Many people have hand watered at the end of March and if you look at a day when we have 5.1mm of E.T loss, 17mph winds and a maximum temperature of 17°C, it is easy to understand why. Like I often say, the calendar is irrelevant, what the turf is telling you is not.
All the best and sorry for the late arrival of this blog, entirely my fault…