Atlantic influences and is it going to rain?
Blog by Jo Farrow
Issued: 20th September 2021 14:10

Atlantic influences and is it going to rain?

September so far has been warmer than average and also had a lot of dry days. This followed a drier than average August across much of Britain. There have been a few notable individual wet days such as Tuesday 14th when it rained for most of the day over eastern England, particularly counties around The Wash. Cambridge recorded just over 50mm (2") of rain in a day. This is close to the whole month September average. Also yesterday, Sunday 19th produced some heavy, thundery downpours, again for eastern England. Haverhill reporting 65mm.

heavy rain Haverhill but dry august UK 2021

“Up to Sept 14th rainfall totals for the first half of September are below 50% of the long-term average (LTA) for all regions as a result of the dry weather at the beginning of the month. “ Env. Agency England

However high pressure has dominated our UK weather with a warm southerly flow for a time, dry weather and a lot of sunshine. Looking at the monthly rainfall figures as a percentage of the full monthly averages, Manston and Bournemouth have only seen around 5% up to the 19th, Boscombe Down, Middle Wallop and Carlisle around 13% but in Essex and Norfolk the totals are already over 110%. We are about two-thirds of the way through September, so around 64% of the month's time gone.

Environment agency

In the first week of September, “All the sites we report on in north England are now below normal or lower with the River Lune now exceptionally low for the time of year. “ Env. Agency

Arable farmers in Scotland have reported favourable conditions for this year’s harvest, and an earlier than usual finish. With low levels of moisture, drying costs were down although everything else seemed to be more expensive. At times with the light winds under high pressure the early morning dampness or fog was annoying but the winter drilling is now underway and looking for some rain soon.

ECMWF low pressure

This season’s Storm Names were issued at the start of September, but all looked quiet for several weeks. Low pressures are going to trouble north-western parts of the UK with gales forecast later in the week but with high pressure building in, this deflects the worst of the winds closer to Iceland then Scandinavia. It is the Autumn Equinox midweek, and the Jetstream looks to be celebrating with a powering up.

Atlantic jetstream

Low pressures, affecting at least the northern third of the UK, seem to multiply later this week and into the start of next week. This means rain for Scotland, particauly in the north and west, parts of Northern Ireland and NW England, mainly Cumbria. To the south and east much of England and Wales it looks to stay dry even through the weekend. Although there will be rain for western shores by then

No major tropical influences for NW Europe with Tropical Storm Peter and Tropical Storm Rose well south currently. Short lived TS Odette may not be finished yet but just a low chance and staying well out at sea.


So, a game of atmospheric push and shove for the UK in coming days. High pressure surging in from the southwest but a deep low pressure away to the north. Then further developments and deepenings in the north Thursday and Friday which will bring gales and windy weather to more of the UK and rain to parts. High pressure lurks close to southern Britain through the weekend. The ECM model is keener to see an active frontal band from a low pressure to the NW sweep right across the UK early next week with a low pressure circling around behind. The GFS waits a bit and with high pressure for Monday allows a pull of warm air from the south whilst low pressure sits west of Ireland.

Tags: UK Weather  

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