Europe September 2023 Outlook (Summer ’23 Recap & Score!)

Written by on August 31, 2023 in Rest of Europe, United Kingdom & Ireland with 0 Comments

As meteorological summer draws to a close, so it ends on a cool, showery note. However change appears to be on the horizon as a new season dawns. That change comes courtesy of a strong northward progressing hurricane as well as the wakening up of the MJO.

It’s been quite a remarkable summer both in terms of weather and prediction.

FORECAST from 22nd May: Europe Summer 2023 Forecast

I clearly noted in the above forecast, for the UK and Ireland at least that summer 2023 would be in stark contrast to 2022.

UK’s hottest day and night on record was recorded last July…

Credit: BBC Weather

What happened in 2023?

For the UK and Ireland, a record warm, very dry June (sunniest since 1957) was followed by a slightly cooler, very wet July. Wettest on record for Northern Ireland and parts of NW England, sunniest on record for Iceland.

June according to the Met Office

Climate change impacts June temperature records

Credit: Met Office

Credit: Met Office

Credit: Met Office

Unusually persistent blocking & ‘lack of weather’ during March, April and May (triggered by sudden stratospheric warming in February) set the stage for an exceptional June of dry, warm conditions and unusual persistence in the Med-like conditions which resulted in OUR typical weather going south!

This high meant subpar rainfall across particularly Northern UK/Ireland since late winter right through spring and into early summer setting the stage for fire and exceptional ocean/land warming…

Atlantic ocean surface 4-6C above average

A so-called marine heat wave (category 4) surrounding and near to the UK and Ireland saw SST’s warm to between 4-6C above average for early June due to remarkably persistent blocking high pressure. This likely drove SST’s to rise to peak annual levels typically associated with late August/early September.

The cause? The unusually persistent and strong high covering this region of the Atlantic is likely in-part a contributor with strong incoming solar radiation reaching the ocean surface as well as lack of wind.

Credit: Climate Reannalyzer

Why the strong warming within the subtropical Atlantic if the ’cause of warming’ is a displaced Azores high 1,000 miles north?

The Azores high typically positioned within the latitudes of the Azores, Canaries and North Africa typically generates a strong easterly trade wind on it’s southern flank. The ‘lack of trades’ sweeping the ocean surface meant no upwelling of cool waters from beneath.

The combination of cold Canary current and trades typically regulate SST’s within this region of the Atlantic. The same could be said further south within the MDR which too warmed to typical peak late summer levels (September) exceptionally early this year.

Another aspect worth considering is the south displaced jet stream where the Azores high would typically be, When the weather is high pressure dominated over the UK, it’s often wet in Spain!

One could argue unusually far south depressions caused by the Azores high positioned well to the north caused warmer waters located in the western tropical/subtropical Atlantic to push east/northeastward into the typically cooler subtropical eastern Atlantic (similar mechanism which brings on an El Nino in the Pacific (westerly wind burst).

Another side effect of the exceptional ocean warmth could be a weakened Canary ocean current and lack of Saharan dust blowing westwards over the east Atlantic (both due to the above). Copious amounts of Saharan dust blowing off Africa out over the subtropical and tropical Atlantic is typical in early summer (this along with cool water is the reason for a lack of tropical cyclones in this region during June and July). Saharan dust has filtering effects on incoming sunshine and therefore lessens the strength of solar radiation penetrating the ocean surface. All these factors should be considered into WHY the Atlantic has warmed so dramatically. Why the incredible warming of our oceans in the first place? By products of sudden stratospheric warming… underwater volcanoes… Hunga Tonga, etc etc.

UK & Ireland highlights

Despite the June’s opening week being cooler than average due to position of the high, it quickly turned warm and largely stayed that way. Towards the 18th and with low pressure making an attack from the SW, the final 10 days or so turned wetter with an astonishing amount of thunderstorm days for Ireland, England and Wales esp.

Early into the month and Kinbrace, Sutherland fell to -2.6C making it the UK’s coldest June temperature since 2012. 10 days later, the earliest 30C since 2012 was recorded in !

On the 25th, an ‘initial overnight’ minimum of 20.1C was recorded at Achnagart, Highland making it the UK’s first ‘tropical night’. However temperature fell through the day and so the minimum didn’t stand.

Highest temperatures achieved during June 2023

ENGLAND/UK: 32.2C at Churtsey, Surrey & Coningsby, Lincolnshire

WALES: 30.8C at Porthmadog, Gwynedd

SCOTLAND: 30.7C at Threave, Dumfries & Galloway (new June record)

NORTHERN IRELAND: 28C at Armagh, Co Armagh

REP OF IRELAND: 28.8C at Oak Park, County Carlow

At one the UK’s most northerly outposts, Baltasound recorded a high of 23.2C. Just 0.1C shy of the Shetland record set in Lerwick back in 1958.

Kirkwall also topped 23.2C, falling just shy of the Orkney record 23.9C set back in 1940.

On the 13th, Oak Park, Co Carlow reached 28.8C, the earliest such reading for Ireland since 6th June, 1950.

Courtesy of the Met Office

Highest Maximum 32.2°C on 10th at Chertsey, Abbey Mead P Sta (Surrey, 12mAMSL)
also on 25th at Coningsby (Lincolnshire, 6mAMSL)
Lowest Maximum 10.2°C on 1st at Fair Isle (Shetland, 57mAMSL)
Highest Minimum 19.4°C on 25th at Crosby (Merseyside, 9mAMSL)
Lowest Minimum -2.6°C on 2nd at Kinbrace, Hatchery (Sutherland, 103mAMSL)
Lowest Grass
Minimum -4.9°C on 2nd at Aboyne No 2 (Aberdeenshire, 140mAMSL)
Most Rainfall 70.4mm on 18th at Wiley Sike No 2 (Cumbria, 230mAMSL)
Most Sunshine 16.9hr on 15th at Orkney: Loch Of Hundland (Orkney, 28mAMSL)
Highest Gust 47Kt 54mph on 24th at South Uist Range (Western Isles, 4mAMSL)
Highest Gust
(mountain*) 66Kt 76mph on 25th at Cairngorm Summit (Inverness-shire, 1237mAMSL)

Europe highlights

With strong high pressure over the UK and Ireland, so Atlantic disturbances were forced south causing unusual, exceptional conditions over the Canary Islands and particularly the Portuguese island of Madeira.

The final 10 days of the month saw the gradual breakdown of the northward displaced Azores high and so it returned to it’s more typical position bringing record heat further south.

July according to the Met Office

Possibly helped by the so-called category 4 marine heatwave surrounding and west of the UK/Ireland AND developing El Nino (highlighted in forecast), the upper pattern flipped on it’s head for July. Both temperature and precipitation was dramatically different throughout July compared to the 2nd half of May and first 18 days of June.

Credit: Met Office

Credit: Met Office

Courtesy of the Met Office

Highest Maximum 30.2°C on 7th at Chertsey, Abbey Mead P Sta (Surrey, 12mAMSL)
Lowest Maximum 11.0°C on 19th at Fair Isle (Shetland, 57mAMSL) and Lerwick (Shetland,
82mAMSL)
Highest Minimum 19.7°C on 8th at Kenley Airfield (Greater London, 170mAMSL)
Lowest Minimum 1.2°C on 26th at Loch Glascarnoch (Ross & Cromarty, 269mAMSL)
Lowest Grass
Minimum -1.8°C on 22nd at Port Henderson (Ross & Cromarty, 18mAMSL)
Most Rainfall 110.9mm on 22nd at White Barrow (Devon, 445mAMSL)
Most Sunshine 16.1hr on 8th at Lerwick (Shetland, 82mAMSL)
Highest Gust 69Kt 79mph on 15th at Wight: Needles Old Battery (Isle Of Wight, 80mAMSL)
Highest Gust
(mountain*) 79Kt 91mph on 1st at Cairngorm Summit (Inverness-shire, 1237mAMSL)

REP OF IRELAND: 24.1C at Malin Head, Co Donegal

UK & Ireland & Europe highlights

July 2023 opened rather similar to how July 2015 ended with a record-breaking wind storm for the Netherlands.

An unusually strong, rapid deepening Atlantic system swept through the English channel bringing a months-worth of rain to East Anglia before really winding up over the southern North Sea.

Storm Poly

With a likely ‘sting jet’ present, particularly strong winds aloft transferred down to the surface generating quite widespread damaging gusts including in the cities of Amsterdam and Rotterdam (70+mph gusts). It was a remarkable 92 mph gust on the coast which likely set a new Dutch wind speed record for any month during summer. The previous record was July 2015.

A brief heat spike swept up through the UK between 6-8th July.

Due to strong south to southeast winds crossing the Grampian mountains, Lossiemouth along the Moray coast observed a high of 28.5C.

Beyond the brief early month heat surge, there was a straight 4-week period between 8/9th of July through mid-August where nowhere in the UK could muster a maximum at or above 26C. Pretty rare and particularly so for recent times.

The heat rather than being focused across northern Europe in June was focused further south in July.

ALBANIA: 44.0 at Kucova NEW ALL TIME NATIONAL RECORD

In the Netherlands, Eindhoven recorded 34.6 °C setting a new record for July 8th. On July 13th, northern Norway’s Slettnes lighthouse reached a record 28.8 °C surpassing the previous record set 80 years ago.

While the Mediterranean baked, the UK was soaked and struggled temperature-wise with some (many) days stuck at between 12-15C for highs.

One weekend after the next saw low pressure spread a band of rain across Ireland and UK followed by heavy showers and thunderstorms.

One particular system saw a central pressure fall to 984mb over Northern Ireland, possibly the deepest July low to affect the UK and Ireland since 1988 according to Syran Bruan.

Unseasonably strong winds gusting 40-60 mph affected southern England and Wales which thunderstorms and downpours causing floods affected northern UK.

 

A particularly deep low on the 15th produced a wind gust of 80 mph along England’s south coast. Meanwhile on the 22nd thanks to a series of fronts, one rain gauge on Dartmoor reported 110.9mm of rain within a 24-hour period.

August according to the Met Office

Credit: Met Office

Credit: Met Office

August, like July was a largely low pressure dominated month, often hosting an unusually strong jet stream and unusually deep lows. Not one but TWO named storms paid a visit to UK and Irish shores during August. Hence a duller than average month for most.

Credit: Met Office

After a cool first half, a slightly warmer second half tipped the overall balance to slightly warmer and wetter than average for August.

However, it was still dominated by average to below average heights, trapped either side by higher pressure over Greenland and the Mediterranean.

UK & Ireland & Europe highlights

Courtesy of the Met Office

Highest Maximum 28.4°C on 10th at Wellesbourne (Warwickshire, 47mAMSL)
Lowest Maximum 12.3°C on 8th at Lerwick (Shetland, 82mAMSL) and Baltasound No 2 (Shetland,
15mAMSL)
Highest Minimum 18.9°C on 11th at Thornes Park (West Yorkshire, 35mAMSL)
Lowest Minimum 1.4°C on 6th at Altnaharra No 2 (Sutherland, 81mAMSL)
Lowest Grass
Minimum -2.2°C on 31st at Port Henderson (Ross & Cromarty, 18mAMSL)
Most Rainfall 83.0mm on 18th at Trassey Slievenaman (Down, 220mAMSL)
Most Sunshine 14.7hr on 1st at Stornoway Airport (Western Isles, 15mAMSL)
Highest Gust 68Kt 78mph on 5th at Berry Head (Devon, 58mAMSL)
Highest Gust
(mountain*) 85Kt 98mph on 18th at Cairngorm Summit (Inverness-shire, 1237mAMSL)

REP OF IRELAND: 26.6C at Shannon Airport, Co

Europe

Summer 2023 Stats according to the Met Office

Credit: Met Office

Credit: Met Office

Credit: Met Office

Credit: Met Office

Credit: Met Office

MET OFFICE: Mixed conditions bring warm and wet summer for the UK

Southern Europe, as expected, was very warm with multiple heat waves and record temperatures.

DETAILS ON EUROPE TEMPERATURE RECORDS TO COME…

Most -NAO summer since 2009

July and August produced some of the UK and Ireland’s deepest summer lows since the 1980s, likely aided by one of the most -NAO summer’s since 2009.

Geopotential height anomaly for the period 1 June – 27 August, 2023

2m temp anomaly for the 1 June – 27 August, 2023 period.

The quite dramatic flip in heights and weather late June onward was of NO surprise or coincidence. In fact it was very well predicted.

My reason for believing a dramatic flip was ‘likely’ was down to one key development… EL NINO and even the February SSW leading to enhanced and unusually persistent mid to high latitude blocking! The late winter SSW appears to have produced a hangover which lingered throughout summer 2023.

El Nino along with anomalously warm Atlantic and other global drivers are the likely cause of the dramatic flip in extremes and that was highlighted in my forecast. Late June saw that anticipated flip from high to low pressure across the UK, Ireland and Scandinavia while the opposite took place across Southern Europe… As a resulted, heat waves across southern Europe was expected.

All in all, a highly accurate summer forecast and arguably the best in 13 years!

Summer 2023 maximum compared to summers all the way back to 2000.

Credit: Sryan Bruen

MY STATION STATS

Credit: Mark Vogan

JUNE

MAX Temp: 27.5C MIN Temp: 2.5C WETTEST DAY: 16.99 mm PEAK GUST: 31.3 kph WET DAYS: 12

DAYS ABOVE 20C: 15 MAX PRESS: 1032mb MIN PRESS: 996mb TOTAL RAIN: 66.17mm AVG Temp: 15.3C

JULY

MAX Temp: 27.6C MIN Temp: 5.2C WETTEST DAY: 14.81 mm PEAK GUST: 38.5 kph WET DAYS: 22

DAYS ABOVE 20C: 8 MAX PRESS: 1017 mb MIN PRESS: 987mb TOTAL RAIN: 112.61 mm AVG Temp: 14.0C

AUGUST

MAX Temp: 23.9C MIN Temp: 4.8C WETTEST DAY: 20.29 mm PEAK GUST: 36.7 kph WET DAYS: 17

DAYS ABOVE 20C: 10 MAX PRESS: 1024 mb MIN PRESS: 994 mb TOTAL RAIN: 73.87 mm AVG Temp: 14.6C

TOTAL RAINFALL: 252.65 mm

THE FINAL SCORE

The below score takes into account what was said and what happened including how accurate the forecasted temperatures for both the UK and Ireland as well as across Europe’s regions…

June predicted maximums

UK maximum: 28-30C (Scottish borders, Greater London)

ACTUAL: 32.2C

July predicted maximums

UK maximum: 31-33C (Greater London, Kent, E Anglia)

ACTUAL: 30.2C

August predicted maximums

UK maximum 29-31C (Greater London, Cambridgeshire)

ACTUAL: 28.2c

These numbers are based on a call made back in late May for each individual month. While exact figures aren’t particularly important, it is the overall upper atmospheric state which is more important and has been pretty accurate for June, July and August. More often that not, the deeper one goes into a particular season, the harder it is to call. 2023 has been highly accurate pretty much throughout, a rare forecast in my opinion and possibly to never be repeated again.

JUNE SCORE: 8.5 OUT OF 10

JULY SCORE: 8.5 OUT OF 10

AUGUST SCORE: 7.5 OUT OF 10

OVERALL: 8 OUT OF 10

Do you agree with the above score?

Can September break the 9-week low pressure dominated rut?

Even after a poor summer, historically, September often heralds the return of ‘better weather’ with higher pressure during particularly the first half.

High pressure is one thing but it’s position is another and factoring in a weakening sun and lengthening nights, temperatures are on a natural decline. However, September, at times, can bring either a continuation or return of summer. For this year, it’s the latter.

2016 was not only the UK’s 2nd warmest September on record (behind 2006) but produced a quite remarkable UK annual maximum of 34.4C! Notably the UK’s warmest September day in over 100 years!

Pleasantly warm days and increasingly cool, foggy nights often becomes the theme beneath anticyclonic conditions. However, I still believe low pressure is never far away and could frequently attempt to nibble away at high pressure especially towards mid-month and beyond.

With the northward transport of tropical air towards Greenland courtesy of Hurricane Franklin, this shall fuel a deep low off S Greenland but in turn forces height rises in the NE Atlantic and eventually over UK and Ireland for the month’s first weekend.

Credit: Tropical Tidbits

It would appear heights remain high through much of week 1 and towards mid-month. Note the trough displaced south. This should present a cool, wet spell for Iberia, possibly France with threat of thundery showers drifting north possibly affecting UK and Ireland Sept 10-13th.

There’s a chance at seeing the first real surge of summer since early July next week according to GFS and ECMWF models…

Credit: wxcharts.com

Credit: wxcharts.com

With strong high pressure over central Europe and low pressure edging towards UK/Ireland, there’s a chance we could see some of the hottest air since June lift north aboard stiff SSE winds which could send the thermometer into the 30-32C range for several days between 4-8th with even mid to high 20s as far north as Moray.

Week 2 according the latest run of the CFSv2 indicates strong ridging across northern Europe including UK, this supports the ‘best conditions’ with warm days, cool nights across the north and likely more unsettled weather across southern UK and near continent including Iberia and France.

Credit: Tropical Tidbits

While I believe the first half of September is largely high pressure dominated across the north with ‘lower’ heights further south, a lot hinges on both MJO and tropics for the 2nd half of the month.

Here’s week 3 off the CFSv2.

Credit: Tropical Tidbits

Note it takes the core of the high west, suggesting somewhat of a cooler, northwesterly flow but off a warm Atlantic, not necessarily a cold one.

Even week 4 sees high pressure dominate.

Credit: Tropical Tidbits

With high pressure, more often than not comes drier than average conditions and I believe we have our first drier than average month since June.

The CFSv2 agrees week 1 through 4.

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

A warmer than average month as a whole looks likely with low pressure to the south could often threaten to push north and therefore the southern UK and Ireland may see a slightly wetter month, depending upon distribution, frequency and intensity of any rainfall.

There’s also a chance a lower pressure dominated pattern may well return during the final week to 10 days of the month.

Anticipated UK/Ireland maximum temperatures: 30-32C England, 27-29C Wales, 26-28C Scotland, N Ireland & Ireland.

OVERALL: SLIGHTLY WARMER & DRIER THAN AVERAGE FOR BOTH UK & IRELAND

A big thank you to Richard Traut and Sryan Bruen for their contribution to this article.

FEATURED IMAGE CREDIT: Sryan Bruen

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