UK Weather - Autumn 2024

[Simon Culling]

A change of season to Autumn here in the Northern Hemisphere and it looks like we will be hanging onto summer temperatures but with a spattering of warm rain at times. It was mild overnight here in Tiverton and the minimum for Sunday 1st September was 16°C, but it is cloudy. We are now in a continental airflow and this looks like persisting with winds from an easterly quarter for the forthcoming week. This type of weather can be difficult to forecast as areas of rain and/or showers can develop almost anywhere and not just on any fronts that might be present. With low pressure to the SW of the UK and slowly moving N/NE over us during the week, it will be rather humid and variable in terms of weather and the radar will need to be watched if venturing out to get some idea of where the rain is or might be!

The Met Office 3-month forecast for Autumn was released a few days ago and it is a probability based system which is currently favouring a milder season than normal and probably a little wetter and windier. Below is their summary page.

The post contains public sector information licensed under the Open Government Licence v1.0

[Simon Culling]

It was warm again over more eastern parts of England on Sunday 1st September with 30°C reached at a few stations in and around London and as far north as Cambridge. Since then, it has gradually become more unsettled with rain/showers at times as the warm and muggy air persists. With high pressure to the NE of the UK (over NW Russia) and low pressure just to our SW, we will see an east to south east flow for a couple of days and this is coming off a still hot continent. There looks likely to be around 30-50mm of rain quite widely over southern England + Wales in the next two days with up to 75mm where any heavy rain/thunderstorms develop. In other words, many parts in this area could see nearly a month worth of rain before the first week has ended. At the moment (11am Thurs 5th Sept) the rain has just begun here in Tiverton and the forecast suggests this will continue until tomorrow afternoon. After the coming weekend, when we will see more showers, it looks to turn rather chilly as the flow switches more northerly.

One thing of note in the last week was the occurrence of a dew point of 20°C at a number of Met Office sites on the afternoon and early evening of Sunday 1st September. This does not happen regularly in the UK, especially in the Autumn - albeit only half a day in. The highest figure I could find was 20.2°C at Herstmonceaux (in E Sussex) at 12Z. The air temperature was 26.5°C at the time which gives a humidity of 68%.

[Simon Culling]

We have had a wet few days across much of England + Wales as the low to our SW continually pushed fronts and troughs north across the UK in its circulation. With the air coming from the south and being warm and humid, there have been quite a few thunderstorms in many places, but we seem to have missed all the electricals here in Devon - just hours and hours of rain. Generally across much of England + Wales, around 20-40mm has fallen, but some areas have seen more than 100-150mm in the first nine days of the month of September.

It has also been warm and especially the further north you go with Western Scotland having its warmest + sunniest weather of the year. The temperature reached 27.6°C at Brigton in Dumfries & Galloway on 6th September (highest for the year for Scotland) and many sites in central + western Scotland also recorded their warmest day of the year.

Today (Tues 10th Sept) we have a cold front sweeping south and this will introduce much colder weather to all of the UK for the rest of the week with a little snow to the tops of the Scottish mountains. Many houses in the UK will be switching their central heating on in the next day or so - let's hope the utility companies are ready for the surge in demand for both gas + electricity.

The CET for September was 16.7°C (+3.2°C) up to the 9th and the EWR was 38mm up to the 8th which is 50% of the monthly average of 76mm. The positive temperature anomaly will fall quickly in the next few days.

[spwill]

The current run of the ECMWF has warmer air mass over the UK next week than over Italy, amazing. See if this holds in the models.
It is currently snowing on the high villages of the Dolomites, Italy.

[Simon Culling]

Thanks spwill. The current model runs still show high pressure dominating the UK from the coming weekend and through most of next week with some quite warm weather next week - models suggest 23/24°C for SE England for a couple of days.

This will be a complete contrast to the current weather regime and a welcome improvement in terms of the change to drier and warmer weather. The last few days have been very chilly here in the UK for the first half of September with frost being recorded at quite a few sites. This morning (13th Sept) the temperature fell to -3°C in parts of Scotland + northern England. We even had a slight ground frost here in Tiverton with an overnight low of +3°C with frost visible on some of the shed + house roofs.

The tops of the Scottish mountains have seen a covering of snow as well although this is not a rare occurrence in September per se, but it is a little early this year. See BBC article:

https://www.bbc.co.uk/news/articles/cd6y1lgdp8go

[Simon Culling]

As spwill highlighted last week, after the early cold snap it has warmed up a bit in the UK as we are dominated by high pressure. The weather improved from Friday onwards and we have been dry since then with a reasonable amount of sunshine. The nights have remained rather chilly for the time of the year, but the days have been getting progressively warmer and we reached 20°C here in Tiverton yesterday (Mon 16th Sept) after the stubborn morning Sc cleared.

Looking ahead, we should see out most of the week with dry + mostly sunny weather and still on the warm side, but there are now suggestions of heavy showers for Fri/Sat as the easterly flow sees a few troughs move out of Europe and cross the UK from the east.

The main action weatherwise in this part of the globe is in central and eastern Europe where a stubborn low (called Boris, ironically) has given copious amounts of rain over the last week with resultant flooding and fatalities. The chart below is a satellite estimate of the rainfall between 9th and 15th of September and there has been more since then. Some of the ground based measurements are in the 5-600mm range.

https://www.bbc.co.uk/news/articles/c5yjjqyv84eo

[Orion]

A mile-long tornado swept through Aldershot on Friday, damaging properties and felling trees.

The extreme weather event caused no injuries as it twisted through the Hampshire town at noon on Friday, according to the local council.

The Tornado and Storm Research Organisation (Torro), a privately supported research body specialising in severe convective weather in Britain and Ireland, tracked the length of the tornado’s movement to be 1.2 miles (2km) long.

Despite its size, the tornado was preliminarily classed as a T1 or T2 tornado by a Torro investigator, making it relatively minor.

A Hampshire and Isle of Wight fire and rescue service spokesperson said: “Firefighters were part of a joint response at an incident in Aldershot yesterday after a number of properties and trees were damaged in strong winds.

“Crews from Rushmoor and Surrey fire and rescue service were first called shortly after midday and worked closely with partner agencies to make the scene safe.”

Rushmoor borough council said: “There was a weather event in Cadnam Close, Aldershot, which caused damage to two blocks of flats and brought down several trees.

“Luckily, no one was injured.

“Damage to property has also been reported nearby in Lower Farnham Road, Osprey Gardens, Basing Drive, Andover Way, Ayling Lane, Sandown Crescent and Boxalls Lane.

“We are now working closely with all of our partner agencies to make the scene safe.”

The senior BBC Weather presenter Alexis Green said: “The UK, on average, has close to 30 tornadoes per year, although this varies year on year, so they are part of our climate.
“They are rare at any one location, though.

“Today’s event was associated with the active thunderstorms in southern areas.”

Alex Baker, the MP for Aldershot, posted on X: “I’ve been out talking to residents whose homes were damaged.

“Thank you, Rushmoor fire brigade, the teams from Vivid Homes, and everyone else who came out to help with the cleanup. It was a great community effort.”

Link includes brief video:

https://www.theguardian.com/uk-news/202 ... -and-trees

[Simon Culling]

Thanks for posting this report, Orion. There was indeed a tornado in the Hampshire town of Aldershot just after midday on Friday 20th September. This occurred in a synoptic setup not normally associated with tornadoes in the UK, but the ground survey has confirmed this event was indeed a tornado. This TN moved from SE to NW rather than the much more normal SW to NE. Damage was fairly limited, but it would not have been a nice experience being caught up in it.

The attached tweet has a video of a group of people who were either on the fringe of the tornado or had it pass over the top of them - they were in Tice Meadows, which is on the southern fringe of the town. They appear to have been located close to the start of the visible effecrs of the tornado on the ground. The other video on this tweet is a doorbell cam which also recorded the tornado.

https://x.com/davidcissbury/status/1837221726918259093

[Simon Culling]

The past weekend and into Monday (21-23 Sept) was very wet over England and Wales and particularly in the south and east Midlands with quite a few sites reporting 100mm+ rainfall for these two days. With a flabby area of low pressure anchored to our SW, lots of troughs and fronts pushed N/NW over England with a lot of the rainfall developing in situ over the country and in some places there were a series of pulses of continuous heavy rain with quite a bit of thunderstorm activity thrown in for good measure - there were even at least three small tornadoes on Sunday afternoon to add to the mix.

The chart below is a radar rain derived map for the two rainfall days of Saturday + Sunday (21st/22nd Sept) and gives an idea of the wide extent of the area affected by heavy rain. There was quite a bit of flooding as can be seen from the BBC report. As a comparison we had only around 15-20mm here in Tiverton, so no flooding for us.

The road shown on the A421 between Milton Keynes and Bedford (which I traversed quite a few times when I lived up there) has only been open about 5-6 years and the water under the bridge was estimated at 8-10ft. There was either a design fault here or the local council have not been maintaining the drains.

https://www.bbc.co.uk/news/articles/c4gq4qw7q48o

[Simon Culling]

The wet weather has continued with rain and/or showers every day, although much of the flooding has now subsided. September will turn out to be a very wet month for England + Wales but not so much for Scotland. The forecast does not bring much releif with heavy rain and stronger winds due Sunday as the jet stream remains close to the UK. With the totals predicted for later in the weekend, it is likely that there will be more flooding as the ground is saturated at the monent. As the BBC article shows, travel has been interrupted by all this rain.

https://www.bbc.co.uk/news/articles/cp3w4kp3ne2o

As well as the rain, there have been a number of weak tornadoes in the last week as well as quite a few funnel clouds observed. There are some signs in the models of the weather quietening down as we move into early October - but no signs of any late warmth.

The CET for September was 14.6°C (+1.1°C) up to the 26th and the EWR was a whopping 128mm also up to the 26th which is 168% of the monthly average. The highest ever figure for September is 189.5mm set in 1918 but I doubt if we will beat this number in 2024. Data goes back to 1767.

[Simon Culling]

We have had a bit of a break in the rain in the last couple of days, but the weather is turning more unsettled this evening (Sat 5th Oct) as a front moves across the UK from the west, and the more disturbed theme looks set to continue for much of the coming week. There has been much speculation as to the track of Hurricane Kirk, which reached cat 4 status in the mid-Atlantic a few days ago, and whether it will come towards us, but it now looks like it will move eastwards across France rather than directly hit the UK. Even without this system it looks like being an unsettled week ahead here in the UK with rain and/or showers most days, and turning colder by the end of the week as the flow switches to more of a NW or N.

The final CET for September was 14.0°C (+0.5°C) and the final EWR was 154mm which is 202% of the monthly average. Attached is the Met Office summary for September 2024 which was a very wet month for England + Wales - indeed six Midland counties had their wettest on record in a series that has now been extended back to 1836. The stark diffence between the south and north of the UK can be seen in the map in the Met Office article - indeed, the northern half of the UK was drier than average in September. Temperatures were very close to average, but it was a dull month except for Western Scotland.

https://www.metoffice.gov.uk/about-us/n ... -september