Monthly retrospective for September 2015

September saw temperature anomalies range from just above average in far northern parts (Lerwick was 0.8C above average) and well below average in parts of the south Midlands (Hereford & Benson were 1.7C below average). One of the warmest places by day was Hurn with a mean maximum temperature of 18.8C. The coldest was Shap Fell with a mean minimum of 5.4C. However, most of the UK was only just below average in fact. Pressure was about 2mb above average over most northern parts and near average in the south.

September was a notably wet month in places at first in the south east & east but became much drier by the end. However, parts of the east still saw above average, Wattisham saw about 125% of its normal amount of rain but elsewhere it was generally rather dry. Much of Western Scotland & NW England and N Wales & N Ireland saw just 30-35% of its average rainfall.

Generally, it was rather sunnier than average right across the UK as a whole away from the far northern Isles where amounts where about 70% with most parts seeing about 100-115% of average sunshine hours. Valley though saw more like 140%. By the end of September sea temperature anomalies were still about a degree above average around most UK coasts but slightly below average around south western coasts. Soil temperatures were near average but soil moisture was generally near average for most parts of the southern UK and slightly above in some eastern & SE'ern parts but generally somewhat below average in the north.

 

Now looking at September in more detail.

On the 1st, as low pressure moved into the North Sea a cold front moved south during the late evening of the 31st August introducing a cool NW airstream to most areas. Around midnight on the 1st showers developed over the south of the Mersey and tracked SE into Cheshire just to the east of Chester, while at the same time further showers started to develop in Liverpool Bay and moved SE down the Mersey and parts of the Wirral. Over the next few hours these increased in intensity and the whole shower train gradually transferred slightly further west. The highest rainfall totals were in an area down the higher ground on the western side of the Wirral with up to 50mm in places. Several funnel clouds were observed near Shoreham (W Sussex) in the evening.

The 2nd saw a northerly to NW'ly flow develop with low pressure in the North Sea bringing a lot of showery rain in places in the north west & north east. In North Wales, just after midnight on the 2nd a shower train redeveloped as more showers developed south of the Mersey and over the next few hours further heavy ones developed again in Liverpool Bay area. These again ran SE over the Wirral but this time parts of NE Wales were also affected together with many parts of Cheshire and eventually Shropshire as far as Whitchurch. Highest totals were over the higher parts of the Wirral with around 50mm+. In fact by 1600 on the 2nd Heswall (Wirral) unofficially reported 92mm since the 0900 on the 1st. Officially, Hawarden in North Wales saw 40mm in the 24 hours to 21Z. A funnel cloud was reported too in the late afternoon at Birmingham & also Valley (Anglesey). The Rivers Fender at Bidston and Birket at Moreton burst their banks and water flooded across the bypass and near the M53. Torrential rain rendered several properties in Tern Way, Moreton, uninhabitable.

On the 6th as high pressure ridged in from the west it was a chilly night inland across some parts of the UK, with local ground frosts in prone areas; Shap (Cumbria) fell to 0.7C and Benson (Oxon ) to -2C on the grass. Parts of East Scotland were very warm & sunny by day thereafter, Leuchars saw 21C reached with 12.6 hours of sunshine.

On the 7th, under high pressure a warm day in parts of the Highlands, Braemar reached 22.2C, likewise on the 10th under quite a warm E-SEly wind as high pressure relaxed away eastwards it was sunny & warm in parts of the south, Chivenor (Devon) and Coton in the Elms (Derbyshire) saw 22.9C reached. On the 11th although quite dry in Britain and locally reasonably warm as fronts slowly pushed in from the far west against the high pressure to the east of the UK, it was very wet in the extreme west, more esp in western Ireland where Newport (Co Mayo) saw 83mm in the 24 hours to 21Z. The 12th was warm in eastern parts, Writtle (Essex) reached 23.0C. However it was wet in parts of N Ireland, Ballypatrick Forest saw 33mm in the 24 hours to 21Z.

By the 14th low pressure was slow moving across the southern UK and it was a wet and disturbed day for many. Milford Haven in SW Wales saw 55mm of rain in the 24 hours to 21Z. Thundery showers developed widely in the afternoon across the Midlands and conditions were conducive for tornado formation, at least five were reported: at Duston (Northants), Tewkesbury (Worcs), Sleaford (Lincs), Old Dalby (Leics) and Leamington Spa (Warwickshire) with localised damage to houses and gardens. It became windy along western & southern coasts too, the Needles (Isle of Wght) gusted to 61kt (70mph) in the early afternoon, Pembrey Sands to 60mph in SW Wales. Meanwhile Highland Scotland saw a pleasantly sunny day ater a cold night, Altnaharra (Highlands) fell to -0-4C.

The 15th was wet in places as low pressure moved away east only slowly, Loftus (Northumberland) saw 52mm in the 24 hours to 21Z. A funnel cloud was seen in Yeovilton in the late afternoon. More rain moved into the SW by the late evening as another deep low moved up from Biscay towards the English Channel. On the 16th as a deep low ran NE across the south east it was rather wet in many parts of the south and east, 38mm at Portland (Dorset) in the 24 hours to 21Z, some parts saw torrential rain in a short period, 19mm fell at Weirwood reservoir, Forest Gate, East Sussex. A chilly start though in parts of N Ireland, -1.0C at Katesbridge (Co Down). The 18th saw a weak tornado quite widely photographed about 1130 near Steyning, W Sussex along with a funnel cloud spotted later near Gravesend (Kent).

On the 22nd as fronts moved through there was some heavy rain overnight in the south in places with about 30mm nr Bishops Watham (Hants), showers later streaming into Cardigam Bay gave 29mm in the 24 hours to 21Z at Syyddfftynnon in Ceredigion but likely nearer 40mm in places. At Cambridge a funnel cloud, possibly a tornado was spotted in the early evening.

The 24th was very wet in parts of northern & western Scotland, Cluanie Inn (Highlands) saw 39mm in the 24 hours to 21Z.

A quiet end to the month. Under high pressure on the 27th it was a chilly night in central parts, South Newington (Oxon) fell to -0.5C with -3C on the grass at Pershore (Worcs). However bright sunshine by day made it warm in Aberdeenshire by the afternoon, Fyvie Castle reaching 20.8C. Again on the 28th under high pressure it was a warm day in parts of the west after a chilly start, 11 hours of sun at Aberborth and Porthmadog (both on the west Wales coast) reached 20.8C with a possible foehn effect. On the 29th high pressure still dominated the UK giving a quite warm & sunny day for many after a chilly start. In fact it was the warmest day of the month as Aboyne (Highlands) recorded 23.2C, possibly enhanced by a foehn effect in a SE wind.

The 30th was another day dominated by high pressure across the UK, remarkably Braemar (Highlands) saw both the lowest temperature of -1.3C and the highest temperature, 24.0C in the UK this September and a range of 25.3C. The 30th saw a cold night, Tulloch (Highlands) reported a low of -0.7C with -4C on the grass.

 

David Wiseman disclaimer – Issued as a non commercial ‘Not for profit’ forecast. The user assumes the entire risk related to its use of this data. I am providing this data "as is" and disclaim any and all warranties, whether express or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose. In no event will I, David Wiseman, or any related contactors be liable to you or to any third party for any direct, indirect, incidental, consequential, special or exemplary damages or lost profit resulting from any use or misuse of this data . Climate stats have been compiled with the partial use and help of UKMO news page data , with thanks. Other news data was compiled from many sources including UKww reports, news papers & some BBC local news reports.