December 17th

Hi All,

The last blog of 2018 for me and how the year has flown by.

It started as you’ll no doubt remember by me waffling on about a Sudden Stratospheric Warming Event (SSW) back in late January after an unremarkable start to the year.  The SSW occurred around the 12th of February and this spun our prevailing winds round to easterly from the 21st of February, pretty much to the middle of April. We endured a really cold March / April period as a result.

Well the meteorologists are at it again, with a SSW event predicted to occur around Christmas Day.

In layman’s terms (i.e mine), an SSW is a sudden warming of the air miles up in the stratosphere (10-50km above us) with temperatures rising by up to 50°C over a short period. Now at this stage it doesn’t affect our weather at lower altitudes but it is how the SSW breaks down that can. In certain circumstances the breakdown of the SSW can permeate down through the Stratosphere into the Troposphere (lower altitude) where our weather systems occur and reverse the orientation of the sub-polar jet stream. This as you’ll know flows ordinarily from west to east but a breakdown of the SSW can split / weaken this flow and in some cases even reverse it to easterly. There are lots of variables as usual that come into play, not least the magnitude of the SSW. The one earlier this year was significant and this one is looking similar in intensity so there’s a chance we could see an easterly flow / very cold weather coming in for the end of December / start of January. Too late to earn me a Paddy Power White Christmas win though I think (Bah bah humbug)

There’s a good explanation by the Met Office of what an SSW actually is here

Just picked up a tweet from James Warner that confirms the above…

Reproduced by kind permission of James Warner

Onto the weather for the time-being…

General Weather Situation

So you may have noticed over the 2nd part of the weekend that the wind turned round from the Baltic east to a slightly milder south-westerly. This heralded the change to a westerly airflow and some milder, wetter and at times, windier weather. So although Monday is starting calm it won’t be long before rain pushes into Kerry and marks the start of what will be a pretty wet week for Ireland I’m afraid. This rain is set to move across Ireland during the course of the morning. The U.K on the flip side will be calm, dry and settled, one of the few spray days of the week I think. By dusk the rain will push into The South West and West Wales and then move slowly eastwards, fizzling out as it does. This is just the first skirmish though because by mid-evening, another front of much heavier rain will be into the west of Ireland and this could bring some flooding along the southern coast of Ireland with heavy rain predicted for Kerry, Cork and Wexford I think. So Monday (away from the Irish rain) will be a nice, settled day with temperatures up in the 8-9°C range and moderate to strong winds. Ireland will be milder with 11-12°C and stronger winds.

Tuesday kicks off with that heavy rain front over much of Ireland though clearing the west. During the morning it’ll be into the west coast of the U.K and then it’ll move slowly eastwards bringing heavier rain with it and maybe not reaching East Anglia till dusk clearing Ireland as it does so. So for Ireland once that rain clears it’ll be a pleasant day, more so in the west though with temperatures up around 8-9°C. Summing up for the U.K, a dull, cloudy day with a strong to gale force southerly wind in situ and rain pushing in across Wales, Scotland, England from the west through the day reaching eastern parts late in the day. Temperature-wise, similar to Monday at 8-10°C.

Overnight into Wednesday and by dawn that rain should have cleared off into The North Sea leaving a dry start for the U.K and Ireland. That said it won’t be long before another rain front pushes into the west of Ireland and moves eastwards through the morning. We may also see some rain across the south-east of England from dawn onwards. That rain over Ireland quickly clears from the west to bring showers to the west coast of England, Wales and Scotland for the 2nd half of the day with the latter falling as wintry showers over The Highlands. At this stage it looks like the bulk of these showers will be confined to western areas but later into Wednesday evening we will see a new rain front across Ireland. Feeling a little cooler across all areas with temperatures a degree or two down on Tuesday and a strong to moderate south-westerly wind in situ.

Thursday sees the low pressure firmly over the U.K so expect another wet start to the day but it should clear eastwards through the early morning fizzling out as it does so. By mid-morning we have another front of heavy rain associated with that low pushing into the south-west of Ireland. This will move across Ireland through the morning and make landfall across The South West, South Wales and the south coast by late morning and then push up across England and Wales during the early evening. Scotland may see a similar pattern with some wintry showers early doors before these become localised over The Highlands leaving thick cloud behind. The rain from the south will arrive with you overnight in the wee hours me laddie. Again we are stuck around the 8-9°C mark this week but Thursday sees the winds strengthen again and swing in from the south-west.

Friday may see a cooler start to the day across the south of England if cloud clears overnight on Thursday. We will still have a vestige of that rain across the north and north-east of England and some of it may be wintry in nature across The Pennines. Right from the off at daybreak we will see more rain across the south / south-west of Ireland and this will push north and west into mid / north Wales by late morning. Away from this rain front, the rest of the U.K looks to have a dry, if cool start to Friday. Through the afternoon though we will see the cloud thicken and that westerly rain track easterly from Wales into the north Midlands and north of England. Scotland will still pick up some showers chiefly across the north and west with these falling as snow across The Highlands. A mucky day really with some showers also moving along the south coast of England and lots of cloud about as well. Temperature-wise, I should sound like a stuck needle by now, a heady, yes you guessed it, 8°C. Another feature of Friday will be strengthening winds from the west reaching strong to gales force for the 2nd part of the day across the U.K and there from the off for Ireland.

Ok into the last weekend before Christmas and shopping bedlam 🙂

Saturday looks like having a dull and unsettled start to the weekend with plenty of showers around across the west and north, though Ireland looks to start dry. A better 2nd half of the day for England with the cloud thinning and sun breaking through across The South East and East later. Sunday looks like seeing more heavy rain push into the west of Ireland and move eastwards with much milder air as well. This will probably reach The South West and Wales overnight into Sunday so a wet start to the day for the west of the U.K before this rain moves eastwards through the morning into all areas. So Sunday looks to be the wetter day of the weekend, a good day for wrapping presents, writing Christmas cards for neighbours you’ve forgotten and the like. A much milder day on Sunday with 11-12°C typical for Ireland and England and again very windy from the south west with gale force winds.

Weather Outlook

OK onto the crucial Christmas period forecast and what the weather has in store. Will I lose my White Christmas Paddy Power bet for the 4th year in a row and return my overall balance into deficit. Living proof that gambling seldom pays 🙂

So Christmas Eve looks to start off very wet and windy, particularly for the west and south with some strong winds as well accompanying that rain. For the 2nd half of the day that rain pushes away and the wind swings round more northerly and drops away so a bit cooler for what will be the start of my Christmas celebration (Having a Danish Mother and English Father pays dividends at Christmas because they celebrate on different days 🙂 )

Now the buggeration factor if you wanted a White Christmas is that the change of wind direction to northerly signals the approach of an Atlantic high pressure which I think will give us a dry and settled Christmas period with 8-9°C during the day and maybe frost, fog at night. Definitely no sign of snow.We see some nice winter sun though so ideal to walk off the excess of calories and vent (ahem).

Now of course I started this blog with the warning of a SSW event so I’m pretty sceptical of anything beyond the 10-day forecast I’ve presented you with. It really depends on how this breaks down for the early part of January but I think the run up to The New Year will be dominated by high pressure and settled weather on the whole with maybe some rain / wintry showers for the far north and west between Christmas and The New Year.

Agronomic Notes

2019 GDD / G.P Spreadsheet

As 2019 approaches Paul and I have been working hard on an improved version going forward.

One of the areas I find on my travels that needs improvement is the consistency of disease recording so for 2019 we have added these columns onto the GDD / G.P spreadsheet.This will let you get a clear view of when disease was active and you can then assess both the contributing weather conditions and the efficacy of your respective applications going forward.

We have also been working on some background charts that collate the data you’re entering and summarise it, so you have some meaningful stats at the end of the year. The data is on the tab called “Charts” at the end of the sequence of monthly spreadsheets.

In theory the charts self-populate as you enter the data into your normal monthly spreadsheet so at the end of the year you’ll have a full set. This I think is particularly pertinent going forward with the weather and our industry being what / where it is.

I have included images below of some of the charts to give you a teaser as I’ve been doing it with my own weather station data in 2018.

The above documents the growth as denoted by Growth Potential through the year. You can see how low March and April 2018 were compared to May because of the cold spring (SSW-related). You can also see the reduction in the monthly G.P for July due to the excessive heat pushing the average day temperature above the optimum for cool season grass growth.

This chart records dry day / wet day and frost day statistics and should be particularly useful. The December entry is still ongoing obviously so don’t worry about the numbers there because the default is for a frost day and it only changes as you enter the data.When it comes to discussing playability I would think the number of wet days may be particularly beneficial for those in the west, north-west and north 🙂

Some of you may have to change the scale on your site for the monthly rainfall total but you can also see what a dry location Market Harborough is with only 424.8mm to date, not a stat I’m comfortable with going into 2019 🙁

When did the good consistent growth start this spring ?

Well around the 15th of April at my location which incidentally compared to the 23rd of February in 2017, some 8 weeks difference !

Some big depressions on the G.P chart at the bottom as high heat levels suppressed growth and in theory we entered Anthracnose territory as early as the 1st week of May at this location.

Now we didn’t actually see as much Anthracnose as I was predicting in the summer of 2018 and there is a very straight-forward reason for this, humidity or more precisely, the lack of humidity. Summer 2018 was as we know an exceptionally dry one and without that plant leaf wetness, Anthracnose as a fungus couldn’t develop. When the rains came in the third week of August, we then saw significant Anthracnose and that continued through the autumn and even now we see some signs of Basal Rot on greens in small, defined areas.

This worksheet is intended to provide more data to you guys to support your management decisions be it disease, aeration, drainage-related, whatever works at your end.

The only thing I’d ask is that you don’t forward your spreadsheet to any of my crappy competitors who use a Rank Xerox machine as their R&D dept. Many thanks 🙂

I hope you find it useful. You should be able to download it here

Disease Activity

Going forward into the Christmas period it looks like Santa has one last unwelcome surprise from a Microdochium perspective with a peak predicted in disease activity on Christmas Eve (sorry the scale is tricky to read) as we transfer over from the mild low pressure to the cooler high pressure. I would predict that this is because we will have a reduction in wind coming into Christmas Eve / Christmas Day and that will cause dew to form over Christmas morning and increase disease activity. Certainly our models are predicting significant dew formation.

Sorry to be the bearer of bad news particularly when finding spray windows for the north and west this week will be particularly tricky. I know quite a lot of guys are out today even though we are getting a late air frost in order to get an application down. The good news is once we are past this peak I think activity will drop markedly from late December and that should be that until the spring whenever that is 🙂 ! ???

So this marks my final blog of 2018.

I’d like to say a special thank you to everyone that has diligently sent their weather data to me at the end of every month, posted comments and feedback and generally kept me motivated enough to plant my backside on a well-worn office chair early on a Monday morning and start typing. You are stars.

I wish you all a great, relaxing break after what has been after all a testing year, some good R&R and hopefully we will all touch base in 2019 to start it all again 🙂

All the best.

Mark Hunt

 

 

 

3 thoughts on “December 17th

  1. Adi Porter

    I’ll echo that Mark, you have a good break and hopefully Santa will bring you enough motivation to continue your blogs throughout 2019.
    Regards
    Adi

    Reply
  2. Finbarr o mahony

    Hi mark
    Great work all year as always in preparing the weekly weather blogs for everyone. Have a great Xmas
    Regards finbarr

    Reply

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