So we have had a proper taste of winter over the last few days with some very cold winds, overnight frost and the first proper snow showers for Scotland and Northumberland.
So is this a portent for the start of another 2010 / 12 winter ?
Last week at Saltex I had plenty of questions on that front and the honest answer is we simply do not know. For sure though we have a very different jet stream pattern compared to last year.
The image bottom left is the pattern of the jet stream on the 10th November, 2015. It has the familar ‘L’ shape which means it is flowing strongly across the Atlantic and pushing weather systems across so we were wet and mild.
The image bottom right is very different, much more fragmented, still with the vague ‘L’ shape but above it we have fragmented currents across Northern Scandinavia and Russia. So in my books there is a greater chance of colder weather this November but remember November 2015 was one of the mildest on record so maybe what we’re likely to see is a return to a ‘normal’ November with night frosts and a colder, more northerly wind direction. What I do know is that winter has started early across Scandinavia and Russia with snow already on the ground in the latter and currently 3-4 weeks earlier than usual.
If I had a choice though I’d take colder and possibly drier than wet and mild any day of the week.
So after a cold blast how are we looking this week ?
General Weather Situation
Well Monday looks like a quiet start to the week (as predicted last week) because it is a changeover day between a northerly low and a westerly low. So that means lighter winds today, plenty of dry weather around and sunshine. There is a risk of the odd shower along the north east coast of England and perhaps the far extreme south east coast as well, but on the whole we look dry for Monday. Although the winds will be lighter than of late, they’ll still be moderate to gusty in places and from the north so that means a chilly day for all with high single figures the order of the day temperature-wise.
Moving onto Tuesday and after a widespread frost, we have the beginning of that change from the west I’m afraid as a band of rain pushes into the west of Ireland in time for the daybreak and this rapidly crosses the country through the morning reaching Leinster and east Munster by mid-morning latest. For the U.K we have another dry start with the exception of some snow showers working along the north east coast of England. By lunchtime this milder, wetter air from the west is beginning to meet the colder continental air and that means it will fall as snow initially over Scotland and the north west of England, though Ireland will just have a very wet day, fullstop. Some of that snowfall will be heavy. As we close out Tuesday that rain is into all western parts of the U.K and falling as snow along a central strip from Scotland down to the North Midlands as it butts up against a colder airstream.
Overnight into Wednesday that rain becomes locally heavy across the south west and South Wales as it pushes eastwards clearing Ireland. It will continue to meet that colder continental air though so a high risk of snow all the way down from Scotland to Birmingham with northern, central and eastern areas the most likely to be hit as over western areas it’ll turn to rain. So starting off Wednesday morning we have a dry picture for Ireland thankfully and that rain will feature in a vertical strip stretching from Inverness to The Isle of Wight. On the eastern perimeter of that strip it’ll be falling as snow so a high risk of snow through Wednesday morning for Scotland, the North of England extending as far down as The Wash possibly. As we move through Wednesday that threat decreases as the rain sinks south into south eastern England leaving behind it another cold day with high single figures the best you’re likely to get as the wind remains from the north west.
For Thursday we see a change as the wind begins to swing round to the west so immediately it’ll feel a little milder maybe even breaking double figures in places. (A Gosh Golly Moment!) That milder westerly airstream only means one thing though at this time of year as showers are likely to push in overnight to the western coast of the U.K and inland through Thursday morning. Ireland looks to be mainly dry after overnight rain but perhaps they’ll be showers over Leinster through the latter part of the day. Those U.K showers look to die out by the afternoon to leave a milder feel to the weather and it’ll be dry. Scotland though will see a continuation of wintry showers across the north west through the 2nd half of Thursday. So not a bad day all in all, milder in that westerly wind for sure.
Closing out the week on Friday, we have the arrival of a much heavier, second band of rain into Ireland and southern Scotland, The Borders and the north west / north of England by daybreak . This will quickly push east covering most of the U.K by late morning with the exception of the north of Scotland which appears to miss the worst. If anything, Friday afternoon looks even heavier rain-wise than the morning in particular across the western coast of Ireland, the south west of England and Wales. During Friday evening this rain pushes east and south clearing the north of England leaving it and Scotland, dry. What a difference in temperature though as it’ll be dig out the shorts time again on my Friday night cycle with increasing temperatures as we go through the 2nd part of the day as the wind swings temporarily from the south west. That means low to mid-teens in the south of England on Friday night and low teens through the day. Cooler though for Scotland with just double figures I think. For Ireland and The Midlands of England I think we will be low double figures.
Looking onto the all-important weekend and the outlook is ‘mixed’. Saturday looks to be a north-south divide with Scotland and the north of England dry whilst an area of thick cloud and rain hangs over Ireland, Wales and England. As we progress through the day, the wind swings round to the north west and pushes more rain through so I think Saturday looks like being mild and wet initially changing to a more showery outlook thereafter. Winds will be strong and from the west / north west. Sunday looks the drier day of the weekend I think but still you’re likely to see some showers rattled across on a strong wind which comes increasingly from the north, so much cooler on Sunday as we return to single figure daytime temperatures.
Well surprise surprise, the weather models fail to agree yet again on the outlook for next week but I’ll be going with the Unisys intepretation as they got this week bang on.
So next Monday looks quiet and cool after the strong northerly winds of Sunday, so dry possibly with overnight frost and likely foggy / misty I think. As we move into Tuesday we see a strong northerly low pressure pushing up the wind strength from the north so windy but crucially from the west from Tuesday onwards with less wind further south and pretty dry except for some showers over Scotland. As we get to Wednesday we see that low sink south so the wind swings round to the north west and we lose some degrees temperature-wise. This change also increases the risk that some of that northerly rain will sink south as well so a higher risk of rain for England from mid-week, next week. Closing out next week I think we will see that northerly low push slowly down so increasingly colder from the north and the risk of wintry showers increasing over Scotland and the north of England as we progress towards the end of next week. Windy with it as well. This is the main bone of contention climatically, i.e will the cold low sink south or be kept northwards by a developing high. My hunch is the former so we’ll see this time next week.
It’s the first week of the month so that means a review of GDD data from the Thame location, thanks to Wendy for sorting this as usual 🙂
So for October 2016, we can see a monthly GDD total of 134.5, which is low for the month and compares very similarly to some other years when we had colder winters such as October 2010 at 132.5 and October 2012 at 128.5.
A word of caution though as last October was only 147 and then we went on to have the mildest November and December months on record so as an indicator to colder winters we will have to reserve judgement. We can though see why October 2016 wasn’t an aggressive disease month on the whole because a mild October would have a GDD figure over 200.
If we split October down in more detail and feature 3 different locations, we see a pattern of a dry, cool month with 3 pronounced peaks in disease activity.
If you look at the start of the month we see high G.P readings for the south west of England and Ireland and a quick increase for Bristol as well then things settle down and the G.P is low for the U.K sites, but remain high for Ireland. Again mid-month there’s an increase in G.P readings which coincides with milder, wetter air so we have higher air temperatures and moisture and that spells disease.
Finally the strongest disease pressure in October 2016 was at the end of the month. You can see the increase first in Dublin and then mirrored by the U.K locations as milder, south / south westerly air brought warm air temperatures. This culminated in the Devon locaiton running at a G.P of 0.9 one day from the end of October, so that means the grass is growing at 90% of its optimum ! Of course it would be fascinating to mirror the G.P of grass with the G.P of a disease pathogen so we can see what the optimum temperature is for disease growth and when it truly stops.
Coming up to the present day we have had a very fast transition from high disease pressure at the end of October, beginning of November to very low disease pressure currently because of the rapid cooling winds and drop in air / soil temperature. Prior to this though we saw Microdochium nivale forming bunch mycelium on the tips of grass similar in appearance I think of Pink Snow Mold.
This disease is on a Rye / Fescue mix rather than Poa and shows how aggressive disease activity was at the beginning of last week. Sad to say it was on my front lawn and yes I know I need to get my blade sharpened. Makes a great trial site though, very cheap and convenient like 🙂
The coming week..
Onto this week’s outlook and you can see that blast of a milder, south westerly airstream will provide an increase in G.P over Saturday. Coupled with moisture at the end of the week this means we are likely to see a short period of high disease pressure over the weekend, especially in the south of England.
What you may see then is the classic re-occurrence of a disease outbreak around the edge of an existing scar rather than new sites of innoculation. We have covered this before but the rationale is that the highest disease population lives on the edge of a Microdochium nivale scar and so when conditions conspire to cause an increase in pathogen population growth we see this area showing symptoms of disease more quickly. It’s also this area where you are asking the most of any fungicide application because the disease population is often developing at a faster rate than the fungicide can hold it back.
Iprodione – where are we at ?
Last week I talked about the loss of pesticides from our market and mentioned Iprodione as one of the active ingredients on the list. It’s clear from the amount of comments / emails and texts buzzing around that we have a confused picture surrounding this active ingredient currently.
So what is the latest official statement ?
Well looking at the CRD website, the latest amendment was published on the 9th of September, 2016 and reads ;
AMENDMENT OF PLANT PROTECTION PRODUCTS
IN THE UNITED KINGDOM
PLANT PROTECTION PRODUCTS REGULATION (EC) No 1107/2009
Amendment Notice – Extension to Expiry Dates – Iprodione
Date of issue: 9 September 2016
This authorisation ends:
(a) 31 October 2018 except as set out in (b) and (c) below:
(b) 30 April 2019 for sale and distribution of existing stocks by any persons
(c) 30 April 2020 for the disposal, storage and use of existing stocks
The expiry dates of the authorisations for the plant protection products listed in the Amendment Table have been amended to the above dates.
So if you take this as gospel, end-users will have up until April, 2020 to use up stocks of Iprodione in the amenity market.
Now before we all breath a collective sigh of relief, this isn’t written in stone, things change in the regulatory world and seldom for the better, so I must stress this is the current status of this active ingredient. Think of it as the best case scenario but not the most likely.
Ok that’s it for this week, lot’s to do, talks to write and a long journey down to Cornwall awaits.
All the best.