UK: when is the weather going to be less ‘boring’?

Today has been mild all over the UK. Both maximum and minimum temperatures (Figure1) have been well above the average, with no values below 0 °C (except on the Highlands this afternoon).

Figure1. Maximum (left) and minimum (right) temperatures observed today. (source: Meteociel).

However, though the temperatures are pleasant, the weather is seeing overcast conditions mostly everywhere. In Figure2 we can see the satellite imagery of this afternoon. It is quite impressive: a deep low-pressure system (987 hPa) just north of Scotland and moving towards the Northern Sea is causing very strong winds (and frequent showers) in N. Scotland and N. Atlantic (gusts of 100 km/h), as well as a decrease in temperatures in this area (Figure1). Instead, the rest of the country, as well as Ireland, is seeing overcast conditions (with drizzle or light rain in some areas) with weak winds.

This is due to a high-pressure system positioned just south-west of the UK which is leading warm and humid air from mid-Atlantic (mostly Tropical maritime) towards the UK.

Figure2. Satellite imagery of today (12UTC). (source: Sat24).

The cold front, related to the low-pressure system (and which has caused showers today in Scotland) is moving southward this evening, causing a decrease in temperatures (especially from tomorrow evening when the skies will be clear mostly everywhere). Showers will be very rare, with dry conditions mostly everywhere.

However, temperatures won’t drop significantly, with values close or slightly below 0°C between Tuesday evening and Wednesday morning (especially in Scotland, N. England and Wales).

In addition, no rainfall is expected this week (until Friday) because of the semi-stationarity of the high-pressure system between Spain and the UK. Indeed, it will move northward from tomorrow, and the maximum pressure values would reach Ireland by Thursday, causing settled weather mostly everywhere.

In conclusion, this week will be still quite ‘boring’ with no interesting weather phenomenon on the country and also looking at the ensemble forecasts no significant change in temperatures or precipitation is expected for the next week.

Europe: 8th December or 8th November?

If we look at the minimum temperatures of this morning across Europe (Figure1), we can see how most of Central-Western Europe is observing minimum values well above 0°C (that this, almost 10 °C above the average in some areas between central Europe and S. Scandinavia).

Only in the Balkans, Russia and central-northern Scandinavia negative temperatures are observed, though with values still above the average (minimum temperatures below -10 °C are pretty normal in Russia and central Scandinavia at this time of the year, but these values are observed only between Lapland/ N. Sweden and N. Norway).

Very mild especially across the central-western Mediterranean region with values between 10-15 °C in central-southern Italy, eastern Spain and S. France. Colder, instead, in Greece with temperatures below or close to 0°C.

Figure1. Minimum temperatures observed this morning in Europe (Meteociel).

These temperatures are closer to the average of November than of December, and especially in W. Europe all the first week of December has been mild, with maximum values close to 20°C in the Mediterranean region. This was due to a high pressure system positioned on the western Mediterranean region, which has driven mild air from N. Africa/ mid-Atlantic towards W. Europe.

However, the weather condition (especially in Central Europe, Alpine region and S. Scandinavia) is going to change from this weekend due to an arctic maritime air mass which will move southwards on the eastern side of a high pressure ridge positioned between Spain (where mild conditions are expected) and the UK (Figure2).

Figure2. Synoptic condition on Sunday night 9/12/2018 (Met Office).

The arctic air is visible from the satellite imagery of this morning (see the scatter clouds on the N. Sea, Figure3) and is moving southward due to a deep low pressure system positioned on the N. Sea between the UK and Norway. The strong pressure gradient between central-northern Europe and the Mediterranean region is causing fohn (a dry and warm wind) in N. Italy, with bright skies and mild temperatures. Finally, the high-pressure system is still positioned west of Spain and Portugal, causing settled and mild weather in the western Mediterranean region.

Figure3. Satellite imagery of this morning (10.40 UTC) (Sat24).

The arctic air mass will cause a decrease in temperatures, and snow at low levels especially in Central Europe and Scandinavia. However, it won’t be a relevant episode, but simply a way back to the average temperatures values for December. So, in the next week, no cold waves are expected and temperatures will be mostly close to average (or slightly below), but it will feel ‘colder’ due to the drop in temperatures compared with the previous week.

Italy: warm week before possible cold spell

Today and the next ones are going to be mild, with both minimum and maximum temperatures above the average, after the short cold period occurred during the last week of November. As we can see from the satellite imagery of this afternoon (Figure1), showers have occurred in central-southern Italy, especially along the Appennines, instead in the north clear skies were mostly dominant, except for some fog along the Po valley during the night/early morning. On the west (towards Spain) a high pressure system is moving eastward, bringing very mild (Tropical) air in the Mediterranean region.

Figure1. Satellite imagery of this afternoon (Sat24).

The temperatures are already well above the average (especially in central-northern Italy and in the Alps), with maximum values above 10 °C mostly everywhere and close to 20 °C in Sardinia (Figure2). Temperatures (both minimum and maximum) will increase also tomorrow and this condition should last until the weekend (when colder air is expected from Central-Europe).  The anomalies are between 2/5 °C above the average. Only in Emilia Romagna and extreme S. Italy the maximum temperatures are closer to the normal values for December.

Figure2. Temperatures in Italy this afternoon (Meteociel).

The next days the weather conditions won’t change, with still mild air coming from the mid-Atlantic and N. Africa causing only few showers (especially on the Alps and Appennines) and high temperatures (for this month) with the 0 °C level above 3000 m on the western Alps both tomorrow and Friday, and no frost at low levels is expected. Moreover, in some areas (especially in Sardinia and Sicily) the maximum temperatures might reach 20 °C, especially tomorrow.

From the weekend, colder air coming from central Europe should reach the Alps, causing unsettled weather in the north (snow above 800-1000 m), and leading to a decrease in temperatures towards the average values. 

For next week a colder air mass might reach the Mediterranean region, decreasing the temperatures towards values below the average, but it is still too early to talk about it in a detailed way.