An unusual summer in Europe

The first part of the summer has not seen significant heatwaves over much of the continent. If we think of the unusual heat that broke all-time-records in June 2019 in France, Germany and N Italy, this year the weather conditions are completely different.

We can see (Figure1) that all the Mediterranean region, W Europe and central/E Russia have experienced temperatures below or equal to the climatological average (1981-2010). The only areas that have seen significant positive anomalies are the E Balkans and Scandinavia (up to 5/8°C above the average).

Figure1. June 2020 temperature anomaly in Europe. (Source Copernicus)

The cooler temperatures in Southern Europe are caused by a very weak contribution of heat from N Africa, which expansion towards the Mediterranean has been blocked by several perturbations of the Jet Stream towards the mid-European latitudes. This has brought frequent rain and changeable weather conditions across W/S Europe. In addition, the Azores High (once a common characteristic of the central/Southern European summer that has been “replaced” by the N African High in the last two decades) has influenced the weather across most of the continent, limiting the increase in temperatures (as it brings tropical maritime air instead of continental from the Sahara).

Meanwhile, in Northern and E Europe, strong, persisting anticyclonic conditions have pushed very warm air up to the Arctic region causing record-breaking temperatures (34/35°C observed in Scandinavia).

Also July has not seen any significant hot event in central/W Europe so far, as many Europeans are experiencing a “cooler” summer compared with the most recent ones.

Looking into this weekend and next week, warmer conditions are expected over N Scandinavia and the UK, before cooler air from the N Atlantic should bring temperatures back to the average (or slightly below). Across Southern Europe, frequent thunderstorms and very warm temperatures are expected, but until mid-next week there is no risk of significant heatwaves.

It seems that for once we can enjoy a more liveable summer (until it lasts), though it is worth reminding that in many other regions of the N Hemisphere many records have been broken (record-high temperatures in Canada and Siberia to cite a few).

Blue skies over W/NW Europe chilly and rainy in the Mediterranean

In the last few days a strong High has set over the UK, moving E over the North Sea today. This High is causing dry and very warm temperatures across the British Isles, France, Spain and S Scandinavia.

On the other side of the continent, a Low over Ukraine is bringing unsettled and relatively cold weather across E Europe whilst another Low over the Gulf of Genoa is causing unsettled weather across the Central Mediterranean, with thunderstorms and strong winds observed in the last 24h over Northern Italy.

In Figure1 the current weather situation is shown.

Figure 1. Satellite image of this morning. Warm air and clear skies across W/NW Europe (yellow arrow) and colder air with showers/thunderstorms across E Europe/Central Mediterranean (blue arrow). (Source image Sat24)

Because of this synoptic situation, temperatures are above the climatological average across most of W/NW Europe (values already above 20°C this morning), whilst are below the average (temperatures below 20°C) over the E/SE areas (Figure 2).

Figure 2. Temperature observed today at 10UTC across Europe. (Souce Meteociel)

This situation is going to persist until mid-next week when the High will start to weaken and colder air from the Arctic seems to start pushing south towars the UK/Scandinavia.

Weather Europe: Cold in the north, hot and dusty in the south

Today’s weather conditions vary significantly across the continent. Indeed, looking at the minimum temperatures (Figure 1) we can see values below zero across Scandinavia, Belarus, W Ukraine and Tatra mountains, whilst the UK, N France, Germany and most of E Europe has seen temperatures between 0/+5°C. These values are well below the climatology (up to 10°C in some areas) and are due to the strong cold air flow which pushed south from the Arctic the previous weekend.

The cold air is moving E across Russia (see strong temperature gradient just E of Moscow) with snow occurring at low levels in some areas. On the southern part of the continent instead, very warm (sometimes hot) conditions are observed (see temperatures already above 20°C in Sardinia, Sicily and Tunisia). This is due to a significant hot air advection from the Sahara which will reach the peak between today and tomorrow across the central Mediterranean, before moving E over the Balkans during the weekend.

Figure1. Minimum temperatures observed in Europe 13/05/20 (Source: Meteociel)

This will be the first heatwave of the season for most of the central Mediterranean with risk of record-breaking temperatures in Sicily (expected 35/38°C). Meanwhile, between the cold and hot air masses, heavy rain and thunderstorms are occurring across the Alpine region, N Italy, S France and Spain (Figure2) due to a series of lows developing between the Balearics/Sardinia and S France.

Figure2. Europe sat image 13/05/20. Notice Saharan dust (yellow arrow) moving NE. The two lows (L), one south of France and one between Estonia and S Finland. Cold air advection (blue arrows) over central Europe. (Source of image Sat24).

Along the occluded front of this low, the strong S’ly flow is causing a dust advection across the Italian peninsula (Figure3), which will then move E over the Balkans into tomorrow.

Figure3. Dust load across Europe for today. (Source SKIRON).

In summary, it has been a interesting week, with very different weather patterns across the continent and possible record-breakings temperatures.

Europe upside down

Since yesterday Europe is seeing two very different weather conditions. Across the British Isles, Central Europe and Scandinavia sunny and mild conditions are occurring. Instead, moving south towards the Mediterranean region, rain and strong (sometimes disruptive) winds are observed.

This contrast is due to a broad High set over Scandinavia which is extending a ridge SE across central/E Europe where mild and sunny/dry weather occurs. Meanwhile, over the central Mediterranean (just off Sardinia) a low is trailing showers and thunderstorms across Italy, S France; finally, another weak low just S of Spain is causing rain and cool weather over the Iberian peninsula.

A nice picture of this situation can be seen from the satellite imagery of this afternoon (Figure 1).

Figure 1. Sat image 14UTC 21/04/20. In blue the two Lows and in yellow the High and its associated ridge. (Source image Sat24).

Also the temperatures reflect a significant difference between northern and southern Europe (Figure 2). Most of the Mediterranean region sees afternoon temps below 20°C, with some cities not reaching 15°C (i.e. central Spain, N Italy, Bulgaria, Serbia). Moving north instead, many areas see values betwen 17/22°C, with 20°C reached also in S Norway and Sweden. These values are between +5/+10°C above the climatology for this period. Finally, the areas of the continent showing the lowest values are Russia and Lapland, with temperatures just above 0°C (though nothing surprising as here spring has just started).

Figure 2. Temps oberved at 15UTC 21/04/20. (Source Meteociel )

The next few days will see a change, with the High expanding over most of the continent, with sunny and very warm conditions for many until the weekend.

Early Spring over Europe

Sat Imagery Europe 31/01/2020
Figure 1. Sat Imagery Europe 31/01/2020

Today’s satellite image (Figure 1) shows widespread clouds over the continent. This is caused by a Tropical Maritime air advection (TM) along the N flank of a High over Spain. All the moisture and warm air is pushed over the Mediterranean region and central Europe. Meanwhile, a deep low over the Atlantic brings unsettled and windy weather across the British Isles. On the E side of the continent cold air flows S from Siberia, though mitigated as it reaches E Europe/Russia.

The temperatures observed at 12UTC today (Figure 2) are significantly above the climatological average for this time of the year across most of the continent.

Temperature observed in Europe at 12UTC 31/01/2020
Figure 2. Temperature observed in Europe at 12UTC 31/01/2020

Indeed, temperatures between 10/15°C are observed over the UK, France, Germany, Italy and Iberian Peninsula (here with peaks of 20/22°C along the E coast). Also in the Balkans and Greece temperature are very mild (between 15/20°C in S Greece).

Only in Russia and Central/N Scandinavia wintry conditions are observed, with values below freezing. However, these temperatures are still ‘mild’ compared with the climatology (e.g. in Moscow 0°C, but it should be -9/-4°C).

The next few days will see a further increase in temperature over all W Europe, with risk of some record-breaking values in France/Spain/Italy (possible peaks above 20°C) in some areas. This is caused by a northward shift of the Jet Stream over W Europe combined with the strengthen of the High over Iberia. Only from next week, the Jet Stream will push S towards central Europe causing a drop in temperatures (but there is still some uncertainty about its effects on a local scale).

W Europe: winter in stand-by

This week is seeing very mild and settled conditions over most of the continent due to a strong high pressure set over central Europe.

If we look at the daily maximum temperatures (Figure1), we can see that mostly everywhere (except few areas in N Scandinavia and Russia) positive values are observed, with temperatures above 10 °C from the UK to the Balkans. Peaks above 15 °C are observed in France, Spain, Italy and SE Europe, with 20 °C reached in Spain.

This situation has not changed since last week.

maximum-temperatures-europe-20/02/2019
Figure1. Maximum temperatures observed today in Europe (source: Meteociel).

Looking at the satellite image (Figure2) the weather patterns over Europe are still the same of last week: clear sky (except some local fog) due to the strong high pressure over central-southern Europe, fronts moving quickly along the edge of the ridge between the UK and the N Atlantic and a low between Scandinavia and Russia causing snow in some places.

SATELLITE-IMAGERY-EUROPE-20/02/2019
Figure2. Satellite imagery of today. I have added the main weather features (rain over N parts of the UK and Ireland, High pressure over central-southern Europe, low-pressure system between Finland and Russia). (source: Sat24).

Unfortunately the synoptic condition won’t change later this week, with the ridge on W Europe moving north towards Scandinavia and pushing mild air from N Africa and the mid-Atlantic.

Only from the weekend, cold air from Russia will move SE towards the E Mediterranean leading to a drop in temperatures and snow at sea level between E Europe and the Balkans, but elsewhere it will be still mild and sunny.

It’s likely that February will end with dry and mild conditions in many areas, and it will be interesting to see the temperatures anomalies observed overall in this month over the continent.

Regardless of the ‘significance’ of the anomaly, February 2019 won’t certainly be remembered as a cold month in many areas.

A very mild Valentine’s day

This week a strong high pressure system has set over central western Europe, causing sunny days and mild temperatures. Today, maximum values are far above the average mostly everywhere in Europe, with temperatures reaching 20 °C in the Iberian peninsula (Figure1).

maximum-temperatures-Europe-valentine-day
Figure1. Maximum temperatures observed in Europe today (source:Meteociel).

Temperatures between 10/15 °C are observed in all the Mediterranean region, France, the UK and Germany. Moving eastward values are lower but still above the average of February. Only in Russia and north Scandinavia temperatures are below 0 °C.

The weather today (Figure2) has seen bright skies over all W Europe and central Mediterranean region, with only some local fog at the lowest levels (mainly in the morning). At the edges of the high-pressure ridge, clouds and band of rain are observed in the north Atlantic and E Mediterranean, instead over N Russia and Finland snowfall is occurring.

satellite-imagery-valentines-day-europe
Figure2. Satellite imagery of today. I have added the main weather features (rain, snow, high-pressure). (source: Sat24).

This weather condition won’t change during the next weekend, with still dry and mild conditions in central/southern Europe. Colder air will reach tomorrow the E Mediterranean, though without ‘freezing’ temperatures. From Sunday, colder and moister air from the N Atlantic will try to push the anticyclone eastward, causing unsettled and ‘colder’ weather over the UK, France and Spain. We will see next week if there is going to be a change in the weather patterns, though it seems likely that the high pressure will be still steady for the next few days.

January 2019 in Europe: cold and ‘mild’, but without extremes.

In this article I am going to analyse the temperatures observed in some cities in Europe during January 2019. A former analysis made two weeks ago had shown that the first two weeks of the year have been cold (and snowy) in Southern and Eastern Europe, with observed temperatures lower than in NW Europe.

Now that January has passed, we can see if the trend observed at the beginning of the month has occurred also throughout the last two weeks or if it has changed.

In Figure1 I have plotted the average daily temperatures observed in 17 cities in Europe.

average-temperature-January-2019-Europe
Figure1. Average daily temperatures January 2019 in some European cities. I have grouped them according to the region.

We can see that E Europe and N Europe have observed the lowest average temperatures (Moscow is the coldest: -7 °C). Moving westward and southward temperatures rise, with positive values mostly everywhere (except in the Balkans: Bucharest -1 °C). The warmest cities have been Lisbon, Athens and Instanbul.

Regarding the anomalies of the average temperatures compared with the long-term average (1981-2010), in Figure2 I have plotted the results, in order to determine where it has been colder than the average and where it hasn’t.

daily-average-temperature-anomaly-Europe-January-2019
Figure2. Daily temperature anomaly observed in January 2019 in some European cities. In blue negative anomaly and red positive; and the bigger is the circle, the more significant is the anomaly (in terms of absolute values).

We can see how the most significant anomalies (in absolute values) have been observed in Scandinavia (colder temperatures) and E Mediterranean (warmer temperatures). Warmer than the average also in Germany, Iceland and Ireland (though the anomalies are mostly between +0.2/+1 °C). In southern Europe little negative anomalies are observed.

This ‘picture’ is different than what seen two weeks ago, when significant negative anomalies were observed in SE Europe and ‘warm’ conditions were observed in the north (especially in Iceland, UK and Germany).

This change in the weather conditions was due to a different type of air masses moved towards the continent. After the new year’s eve, cold air from Russia moved towards the Balkans and the Mediterranean region on the southern part of a strong high-pressure system positioned between central Europe and the N Atlantic. Instead, after the second week of the month, the cold air was flowing from Greenland and the Arctic (thus from the N Atlantic) causing a decrease in temperatures in Iceland, the UK and central Europe, and causing warmer air to flow from N Africa towards the Balkans and E Europe.

In conclusion, January has been ‘mild’ in some places (i.e. in central/western Europe, Iceland and SE Europe) and cold (compared with the average) in Scandinavia and Mediterranean region, though in both cases, the anomalies have’t been too significant.

Europe: first week of ‘spring’

During the last two weeks wintry conditions have occurred in numerous countries, both in W Europe and E Europe. Very cold temperatures were observed in Scandinavia and Russia and snow has fallen in many areas between central Europe, the UK and the Mediterranean region.

However, these weather conditions are changing, with milder air coming from mid-Atlantic and N Africa. Indeed, already today higher temperatures are observed (Figure1) with values above 10 °C in many areas in S Europe (especially S Spain, Italy and E Mediterranean region) and above 0 °C mostly everywhere, except in the Alpine region, Scandinavia and N Russia.

Europe max temperatures 4/02/2019
Figure1. Maximum temperatures observed today in Europe. (Source: Meteociel)

The satellite imagery (Figure2) shows the main features of the weather conditions over the continent.

A high-pressure is setting on W and Central Europe, with bright conditions in Spain, S France and central/N Italy and fog/low clouds between Germany and Poland. Between France, the UK and the N Sea a (weak) low pressure system is causing showers across England and Benelux.

Moving eastward, warm air from N Africa is causing settled and mild conditions in the E Mediterranean and convection is occurring between S Italy and Greece. This is due to a (weak) low-pressure system positioned close to Sicily which is leading to a temperature contrast between the (relatively) cold air from central Europe and the mild air from N Africa. Thus, convective cells are forming on the sea, causing numerous thunderstorms in the area.

Finally, in E Europe and Scandinavia cold temperatures are still observed, with snowfall between Finland and Russia.

satellite imagery Europe 4/02/2019
Figure2. Satellite imagery of this afternoon. I have highlighted the Tropical air (yellow) and the convection (red) in the Mediterranean region; the snow
(blue) at the ground in central Europe and Alpine region, and the low-pressure system (black) in the N Sea. (Source Sat24).

The weather conditions for this week will see an increase in the strenght of the high-pressure in central/southern Europe with settled conditions and relatively mild temperatures (though fog/low clouds are possible in the valleys limiting the increase in temperatures). In fact, from Tuesday possible peaks of 20 °C are expected in S Spain, Portugal, S Turkey and Cyprus. Temperatures between 10/15 °C are expected in S France, Italy and the Balkans and close to 10 °C in the UK and Central Europe. In addition, during the night temperatures will be close or slightly below 0 °C especially in the valleys (and in case of clear sky),causing a strong temperature gradient between day and night.

Only in E Europe and Scandinavia it will be still cold, though with values above the average.

On Thursday, colder air from N Atlantic should cause a slight decrease in temperatures (with frequent showers) in Central Europe, though with no snow or ‘freezing’ conditions. However, only from next week (so in 7 days) a more significant change in the weather conditions should be observed, though it is still too early to talk about its possible effects.

First day of the week: low temperatures in central and northern Europe.

During the weekend and today temperatures have dropped in central Europe and northern Europe, with ‘freezing’ conditions in some areas.

The minimum temperatures observed this morning (Figure1) are well below 0 °C mostly everywhere in central and northern Europe, with values between -5/-10 °C especially in Germany, Alpine region and Czech republic; in some areas (central Germany and in the Alps) values between -10/-15 °C are observed.

Moving north towards Scandinavia, temperatures are well below -20 °C, with peaks of -30/-35 °C especially between Sweden and Finland.

Cold conditions are also occurring in Russia and E Europe, instead moving towards the Mediterranean region and the Atlantic coast temperatures tend to increase, with values above 0 °C mostly everywhere. The warmest conditions are observed in S Greece, Cyprus and S Spain, with minimum temperatures between 10/15 °C in some areas.

Europe minimum temperatures 21/01/2019
Figure1. Minimum temperatures observed today in Europe. (Source: Meteociel)

The afternoon has seen still very cold temperatures in central/northern Europe, with numerous cities observing maximum temperatures below 0 °C (Figure2), instead moving southward and westward temperatures have been milder, with values above 10 °C especially in Portugal, S Spain and E Mediterranean.

Europe maximum temperatures 21/01/2019
Figure2. Maximum temperatures observed today (source: Meteociel).

The low temperatures observed in central Europe are due to the combination of the cold air, moved southward last week, with a high-pressure system (Figure3) settled on central Europe since this past weekend. Thus, the cold air is ‘trapped’ at surface causing temperature inversion (temperatures in the free atmosphere around 1500 m a.s.l are ‘warmer’ than at surface) and fog/low clouds.

Looking on the Atlantic, a low pressure system is moving towards the UK, leading Polar maritime air to move south-eastward (notice the scattered clouds).

Scandinavia and Russia are reached by very cold air coming from Siberia, which is moving southward towards central Russia (see the cold front, band of clouds, from Sweden to central Russia).

Finally, in the Mediterranean region settled conditions occur on the Iberian peninsula (positioned on the warmer side of the anticylone); in Italy a weak low-pressure system is causing overcast conditions and rainfall especially along the peninsula and finally, in the E Mediterranean, showers are occurring mainly in Turkey.

Satellite imagery of Europe 21/01/2019

Figure3. Satellite image of today. I have coloured in blue the Polar maritime air, in purple the Polar continental and in yellow the high pressure. Notice the fog/low clouds in central Europe. (source: Sat24).

The next days will see colder air towards the UK and W Europe, with showers and snow at low levels especially between tomorrow and Thursday, with the high-pressure moving eastward towards Russia.

The cold air will move towards the central Mediterranean region, causing the development of a deep low pressure system between Spain and Italy which will bring rain, strong winds and snow (at low-medium levels) along the Italian peninsula and in N Spain; some snow should fall also in the Po valley and Alpine region.

Later in the week, the low pressure system will move towards Greece and the Balkans causing unsettled weather.

In Central and N Europe instead, the weather will be nice (but still cold), with some snow showers especially mainly between central Sweden and Finland.

In conclusion, it will be a very interesting week, because of the presence of different air masses on the continent and possibility of snow at low levels in numerous areas.