Weather thoughts/forecasts from me

Tag: Rain

The wettest start to October for several decades.

It has been an incredibly wet start to October here in CS England with many places reaching well over 60 mm of rain within the first 2/3 days of the month. Many official stations are over 60% of their monthly average already this month with some such as Benson at 126% with a monthly total standing at 86 mm.

Roger Brugge’s automated rainfall average map for stations in the UK at 06:00 UTC on the 4th of October.

It is not often that you see Central Southern England at the forefront of most of the rain. with Reading recording the second wettest 48 hour period on record with 83.2 mm, stretching all the way back to 1908.

Here in Herne Bay, the first 4 days of October have been wetter than every month’s monthly rainfall total apart from February. This year truly has been filled with dry to wet flips. For instance, an incredibly dry Spring led to the very wet & thundery start to Summer. Some have attributed these dramatic flips to our ever-changing climate.

The monthly rainfall totals from my weather station this month so far at 16:00 UTC on 04/10/2020.
109.5% of the monthly average

I also recorded the wettest day for many years with 37.31 mm of rain falling within 24 hours on Friday the 2nd.

AWS rain readings from 00:00 – 23:59 on the 2nd of October.


Manual rain gauge measurement at midnight on Saturday the 3rd of October showing the amount of rain fallen in a 24 hour period.

The South is an incredibly dry climate year-round so rainfall totals like this from one or two low-pressure systems within days are unprecedented & don’t happen often like this. You’d normally expect to see such high rain totals at the start of the month in the North, not in the center of the South.

Rainfall - October average: 1981-2010

October’s average rainfall from the Met Office.

The start of October’s synoptic setup has been much like last year with a southerly jetstream & low pressure in full force, dumping over 100 mm at Manston. Last year was just not so wet.

October 2019 monthly rainfall map from the Met Office, showing much of the South within 100 mm.

The main cause of this was the continuous rainfall from Storm Alex after which a low-pressure system formed in France, bringing weather fronts to the UK which very much halted over the UK for a long period of time, adding onto the already wet period & totals just rising & rising, well into 50/60mm.

Storm Alex hanging out in the channel & just into France on Friday started off the rainfall & it just kept on going & going & going. You can see below see an occluded front sat over the South precluding the arrival of other occluded fronts & troughs, bringing continuous endless rain from nearby France into the UK, as Storm Alex moved slightly north into the Channel.

Synoptic analysis from the Met Office at 00:00 UTC on Friday the 2nd of October.

Rainfall radar at 00:00 UTC, showing the rainfall from France slowly moving North into the UK, bringing a good amount of rain.

Rainfall totals were already well into their 30/40 mm range in many places on Friday evening with no end in sight for the rain to be seen as it just kept on coming & coming from nearby France.

The 18:00 UTC synoptic analysis from the Met Office does show this pretty well with three different weather fronts interlinked over Central Southern England, bringing copious, non-stopping rainfall.

The 18:00 UTC synoptic analysis map from the Met Office.

Rainfall radar at 18:00 UTC on Friday the 2nd of October with weather fronts.

As Storm Alex pulled away south during the night, a new low-pressure system formed in Northern France & further helped these interlinked cold & warm fronts stall over Central Southern England. These, in turn, allowed the rain totals to further build & build with many places into the 50/60 mm range from the two days.

The 06:00 UTC synoptic analysis map from the Met Office on the 3rd of October.

Rainfall radar at 06:00 UTC on the 3rd of October with weather fronts drawn on.

Radar estimates at 12:00 UTC on Saturday show the true extent of how wet it had been with many areas into 50 mm of rain combined from both days totals. Many areas had been stuck under the rain for many, many hours.

Radar estimated 24-hour rainfall totals at 12:00 UTC on Saturday the 3rd of October.

The rain then moved west & stalled for a brief period in the SW & into Wales in the afternoon, bringing rainfall of well over 30 mm widely. As the evening started, this rain started to move ESE incredibly slowly, intensifying as it went.

The synoptic analysis map from the Met Office at 18:00 UTC on Saturday the 3rd of October.

Rainfall radar at 18:00 UTC on Saturday the 3rd of October with weather fronts drawn on.

Rainfall radar at 19:45 UTC on Saturday the 3rd of October.

This culmination of events eventually leads to some places receiving well over two inches of rain in one day & nearly an inch of rain overnight on top of that. This brings many places up to well over 70/80 mm recorded within the first days of October & places many stations well into their monthly averages.

Thankfully, this rainfall does not look to return for a little while with signs of returning sunshine next weekend & into next week but still under the 13°C maximums with below average temperatures. At least the sun’s returning!


GFS pressure ensemble showing a rise in pressure over the next week.

ECMWF chart for Tuesday the 13th of October.

Enjoy the rest of your Sunday!


Rain, rain go away, come back another day!

The tradition of a wet & blustery October has returned once again this year with a good few inches of rain being dumped over the next few days & into early next week. October is traditionally the wettest month on average so it is no surprise that true gloom & doom has arrived.

It is all to do with pesky low pressure & the jetstream being ‘meridional’ & diving south, introducing colder air & sending the track of low pressure directly overhead, compared to the usual route to the north of the UK.

Storm Alex

Storm Alex arrived late last night with satellite & observation indications of a sting jet forming on its western bank.

It underwent rapid cyclogenesis as it neared an amplified part of the jetstream, allowing the rapid deepening to happen & causing a nasty, powerful low-pressure system to arise.

The Met Office had identified it as a Stage II Shapiro-Keyser cyclone. Shapiro-Keyser cyclones are known to possibly create sting jets. A sting jet is a rapidly descending localised area of cold air inside a cyclone. Dry air rapidly rushes into the cyclone,  otherwise known as a dry intrusion & as a strong flow of cold air forms inside the cyclone, the precipitation from the cold conveyor evaporates & cools. This all happens way up into the air around 3/4 km up & because the colder air is denser, it rapidly descends to the surface, causing a narrow space of accelerated air, forming a jet. These can cause wind gusts of well over 100 mph.


A visual diagram of the aforementioned sting jet.

It is dubbed a sting jet due to the scorpion tail look it takes on satellite imagery with a notable cloud head curling into the tail.

They are the main cause of the tremendous winds seen in the Great Storm of 1987, causing widespread damage across the south, which was completely unforecast & unexpected.

The same was seen last night with a notable cloud head curling into the scorpion’s tail & water vapour satellite imagery showed drier air rushing into it.

Image Image

Ground observations from Belle-île-en-mer, an island off the coast of Brittany confirmed some suspicions of a sting jet with a gust of 115.6 mph just after 11 pm UK Time. This beat the previous record there from the Great Storm of 1987 which was 162 km/h (100.6 mph). Luckily, gusts of near that magnitude were only recorded in that one spot & elsewhere got nowhere near such speeds. It does go to show the magnitude of these storms when an amplified jetstream is involved!


The aforementioned wind gust can be seen to the bottom left of the image.

Why am I telling you all this?

This storm is the reason we all are currently getting bathed in rainwater. The nature of the storm is that it has hung around in the Channel & is slowly backing down south into France currently.

This is the perfect combination for the rain to simply just keep on coming & coming with flooding already being seen in places such as Southampton, in which a primary school has been flooded from the amount of rain that has fallen.


NW Europe Radar Still at 05:30 UTC, showing the outer rain bands of the low-pressure system heading towards the UK.

Rainfall radar estimates as of 17:00 show that many places, especially in Hampshire & Sussex have been hit the worst with an inch to two inches of rain falling within the last 24 hours. A yellow weather warning is out for the South East as well as an amber stretching from Dorset into Wales.

This is set to continue for the next days as a copy-cat system reappears from the depths of Storm Alex, bringing more rain to the UK & in turn more chances of flooding. More details are below!

Rainfall estimations using radar observations from 01/10/2020 16:00 UTC – 02/10/2020 16:00 UTC

Manual rain gauge showcasing the 25 mm of rain (an inch) that has fallen over the last 24 hours.
(01/10/2020 16:30 UTC – 02/10/2020 16:30 UTC)

What is this new low-pressure system?

It is a new system that spawns off the other one as its brother in crime & brings the weather fronts along with it. It brings rain tomorrow morning & that rain moves a little before eventually stalling in the afternoon.

The wind gusts in this low-pressure system aren’t anything to take of note; the rain is.

Met Office FAX showing the new low-pressure system & the stalling weather front forecast for tomorrow afternoon.

The stalling weather front as a result of a weather front from a new low-pressure system in France can be seen here.

The main thing is certain, however, Hampshire & Dorset into Somerset are the ones most at risk of being completely stuck under a deluge of rain. No-one knows the one spot that is going to get the most but a deluge is certainly coming.

It’s a mixed bag but it is certain that this weekend is a washout before better conditions start to arise mid-next week with the sun returning for a little bit!

Enjoy your weekend everyone & stay safe!


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