Europe Summer Forecast 2021

Written by on May 31, 2021 in Rest of Europe with 0 Comments

Welcome to my 11th annual UK, Europe summer forecast. As always, when compiling this forecast for the upcoming June-August period there are multiple factors which I have taken into consideration. They include the past winter pattern, type of spring just observed as well as other factors including current ENSO state, global and regional sea surface temperature anomalies and even the current solar cycle.

Glimpse back at last year

For the UK and Ireland, last summer comprised of brief spells of warm, settled as well as cool and wet. The somewhat more unsettled with prolonged periods of cool and wet continued through the majority of July in which we observed our coolest July since 2012. The final few days of July saw hot conditions quickly develop over the UK from the south and this continued through the first 10 days of August. The front 7-10 days of August saw record warmth.

Here was last summer’s 500mb geopotential height anomaly.

The performance of my 2020 summer forecast was good when taking into account the whole June-August period with even a call for ‘coolest July since 2012’ materializing. Calling for a cool July is a fairly bold step given the warmer summers of the last 10 years. However, I was well underdone when it came to the end of July and first 10 days of August heat wave.

Global Temperature Update

While factoring in fluctuation, thanks in a large part to the La Nina and possibly the lag effect of the solar minimum, earth has cooled by over half a degree off a peak of nearly 0.8C in February 2020. We even saw the average dip slightly below average back in March.

February 2020

Credit: University of Alabama-Huntsville

March 2021

University of Alabama-Huntsville

As you can see from the above graphic representing temperature of the global lower atmosphere, we dropped off a peak in 2017 then re-climbed to nearly the same level in 2020. Since then, the temperature has yet again fallen and bottomed out a touch below normal.

The below graphic shows a rise from -0.01C back in March to 0.08C, likely in response to the ENSO returning to neutral.

May 2021

Credit: University of Alabama Huntsville

The next 6 months will be interesting to see how much warming we see.

One of the reason’s for the fall during the first 3 months of 2021 was thanks to a colder Northern Hemisphere winter 2020-21 than in 2019-20. Not difficult given how the previous winter was one of the warmest on record.

The AO/NAO was polar opposite from positive in 2019-20 to negative in 2020-21. The La Nina will have helped and arguably the potential response from the 2018 solar minimum.

Despite a warmer than normal March, the past spring and year-to-date 2021 has been very cool throughout Europe as well as other parts of the world.

Credit: Weatherbell.com

Summer 2021 will be most interesting to watch where the global temperature will go.

Despite strong warming across the North Pacific, there’s been moderate to strong cooling in the North Atlantic, especially towards Europe but overall earth’s oceans have cooled slightly over the last 12 months and with the help of La Nina, earth’s temperature has responded.

ENSO

After a 12 to 18 month La Nina which has cooled both ocean and atmosphere globally, we are now in an ENSO neutral state and should remain so through the summer months before we potentially return to a La Nina in autumn.

Current Global/Atlantic SST’s

Thanks to weeks of below average air temperatures, a large area of the North Atlantic as well as North Sea has cooled well below average.

Global SSTA

Credit: Tropical Tidbits

North Atlantic SSTA

Credit: Tropical Tidbits

Dry April, Wet May?

When it comes to forecasting upper atmospheric pressure anomaly, I always take spring rainfall distribution into account. Following a fairly wet 2nd half to the 2020-21 winter and March, soil moisture content was ok despite one of the driest April’s in the UK record. A very wet May followed and so ground moisture content stands average to above average.

Coming off a Solar Minimum

In 2019 the sun was at it’s weakest in 100 years with the most recent solar minimum occurring in December 2019.

There has been growing controversy in recent years regarding the link between solar cycles and climate in the short term. Following the previous solar minimum in 2008 we observed the coldest winter in 30 years and some very cool summers.

If we go by the most recent solar minimum in late 2019 and consider it’s cooling influences with increased northern blocking etc then winter 2020-21 should’ve been a tease to the bigger deal in 2021-22. If there is a cooling influence brought by solar minimums then this summer and possibly next should be somewhat cooler and the cold spring ‘may’ be a hint of what’s coming.

The Forecast 2021

So, a ‘modest’ cooling of the planet, a neutral ENSO, warm North Pacific, cool North Atlantic, modestly cold winter followed by unusually cold spring and possible lag effect of the solar minimum, what lies in store for the 2021 summer season?

The section shall mainly focus of the UK

1st half of June looking warm, dry!

We end May and begin June warm and dry. High pressure looks to dominate with a +AO/NAO setup.

Based on the current parameters, I believe the first 10 days of June will end up above average with both pressure and temperature over much of Western Europe.

The month of June starts well but I believe warm, sunny days may become skewered by lowering pressure from the Atlantic during the 2nd half of the month. While June could feature some warm to hot days with low 28-30C England, 30-36C France, 38-42C Spain, this is the kind of summer in which very cool days could also pay a visit.

June is likely to be the driest summer month for the UK!

Another cool, damp July?

Like last year, July could be quite disappointing with lower than normal pressure and above normal rainfall. More cloud and rain should make for below average temperatures through much of July and with Atlantic air crossing colder than normal waters, we could see unusually cool mid-summer days and possibly nights.

Warmth is expected to be limited with only a few brief days in which temperatures reach 26-29C. I wouldn’t be surprised if the UK’s witnesses it’s first July without reaching 30C since 2011.

August could be the coolest month of the summer but may feature warmest days!

August could be the coolest month of the season with a trough never far away. Heat will be brief but when it does come, it may provide the UK with it’s warmest days of the year at 30-32C.

SUMMER OVERALL SHOULD BE NEAR TO ABOVE AVERAGE FOR SCANDINAVIA, RUSSIA, BALTIC STATES, UKRAINE, ROMANIA, MOLDOVA, BULGARIA, ITALY, SPAIN ETC BUT AVERAGE TO BELOW AVERAGE FOR MUCH OF THE UK, IRELAND, FRANCE, BELIGIUM, NETHERLANDS, GERMANY, THE ALPINE COUNTRIES

By keeping up with tradition, here’s what the CFSv2 has for each month.

June 2021

500mb height anomaly

Credit: Tropical Tidbits

2-metre temperature anomaly

Credit: Tropical Tidbits

July 2021

500mb height anomaly

Credit: Tropical Tidbits

2-metre temperature anomaly

Credit: Tropical Tidbits

August 2021

500mb height anomaly

Credit: Tropical Tidbits

2-metre temperature anomaly

Credit: Tropical Tidbits

CFSv2 for June through August

2-metre temperature anomaly

Credit: Tropical Tidbits

FEATURED IMAGE CREDIT: Paul J McFarland

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