20th November, 2023

Hi All,

A short blog this week because I'm nipping off for a few days R&R.

Looking at the forecast for Market Harborough, this is the 1st week in a long time when there isn't a deluge or two within the 7-day outlook accompanied by plenty of showers, so we have a drier interlude as originally forecast a couple of weeks ago, hallelujah !

Last week, I attended an AEM webinar on the weather outlook for winter 2023/24 for the U.S. The relevance for me is that we share the same polar jet stream, so its behaviour over there is often a pretext for what we see days later across the U.K & Ireland. The webinar was given by 4 meteorologists and discussed the effects of the El Niño event currently underway on the prognosis for U.S weather and the behaviour of the jet stream. I asked the panel how confident they were in modelling of the jet stream and how far away they could detect a blocking event and their collective answer was interesting. 10 days was their view and during that time if the signal held, then confidence increased.

The relevance for our industry is that's probably the most notice we are likely to get of an extreme weather event. These tend to occur during blocking events, whether that be slow-moving low pressure systems delivering excessive rainfall and rain rates, or high pressure systems and summer heatwaves. It is also the likely limit for any disease prediction model. Consider that......

The meteorologists felt that this winter could deliver some colder air peaks pushing south across the U.S and a continuing trend for wetter weather across the southern states of Texas and Florida. So if you're thinking of a nice winter break to Florida, take your wet weather gear !

"I smell Winter...."

The above is a lyric from a cracking tune by The Housemartins and is very apt I think.

Looking at the forecast for this week and beyond as temperatures are due to take a significant hike downwards as the wind shifts more northerly later in the week. As the GIF above from tropicaltidbits.com shows for the start of this week, we currently have a low pressure system sitting over us and this will still bring showers across all areas today with some heavier rain across South Wales and norther eastern Scotland.

As this low pressure moves off eastwards overnight, we have a blocking ridge of high pressure forming and that will serve to provide us some drier and colder weather for the week ahead.

By mid-week you can clearly see the change in the weather picture as that high pressure peak pushes up from southern Europe and vectors the colder, wetter weather north. Now you can see that there is some heat associated with this high pressure and it is this fact that I drew attention to last week from a disease pressure perspective. Before the temperatures drop down later this week, we will be in for some mild, humid air which will of course promote disease activity.

So there's your 10-day disease pressure warning in action, there and then.....

Some mild nights this week following on from the mild nights over the weekend. As I type this, we are sitting at 8.4°C with 94% humidity, that's great conditions for disease development. I'd pick out overnight Wednesday night into Thursday as another potential peak, thereafter we drop colder as the disease pressure should decline.

By Friday you can see why we will be in for some colder temperatures as the leading edge of a huge and cold, easterly low pressure system vectors down some strong northerly winds across the U.K, in particular the eastern half of the country. It may be cold enough to see the odd sleet shower associated with this system across eastern coasts from Friday onwards. As we go through the weekend, we will see the wind become more north westerly in nature and this could pull down more cloud and some showers into Scotland and the north west of England, particularly off the Mersey Estuary. So I expect 6-7°C to be the top temperature with 2-3°C overnight and the risk of some ground frost though with the change of wind direction, the protective cloud cover may negate this.

Weather Outlook - w/c 27th November

So next week we start the week cold and chilly with that north / north westerly wind in situ. We will have a weak high pressure system in charge but as you can see from the GIF above, we will be sandwiched between two low pressure systems. The one sitting out to the north west of Scotland is likely to feed moisture into our weather dynamic next week, So we won't be completely dry, I can already see rain projected early in the week and towards the end of next week, moving west to east across Ireland and the U.K. The rain later next week may be heavy as yet another slow-moving system pushes in. Currently it is tracking northerly, so Scotland could be front and centre unfortunately after just recovering from the effects of Storm Babet.

At the end of next week the wind will change from northerly to south westerly ushering in milder air to the southern half of the U.K and Ireland, so maybe a change to more unsettled weather further south as well, accompanied by some very strong winds.

OK, that's it for me, I have just time to nip some clothes into a case, 4 back copies of New Scientist that I need to get up to speed with and I am out of here. Betty's here I come. Hopefully back to a normal blog next week, wrap up well this week !

All the best.

Mark Hunt