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Weathercam "image of the day"London, UK
Student maps & analysis for 21 March, 2000 |
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Over France, Germany, the Alps and southern England, high pressure dominated today, but pressure was lower than yesterday. At 0000 UTC today, an extensive ridge of high pressure covered Ireland, Wales, England and the Low Countries, with the pressure 1027-1028 mb over most of this area. By 0600 UTC, the ridge had declined a little and pressure was highest (1026 mb) over north-west Germany. By 1200 UTC, it had declined still further, with the pressure highest (1024 mb) in the far north of Germany.
The UK Met.Office's 0000 UTC chart shows that pressure was still low (967 mb) off northern Norway. An occlusion wrapped right round the Low, heading first westwards then north-westwards from near the Lofoten Islands, passing round the northern and eastern flanks of the Low before heading south-westwards across north-west Russia to Estonia. The cold front extended from there across southern Scandinavia and northern Scotland to the Grand Banks of Newfoundland. There were waves on this cold front, one of which brought cloud and a little rain and drizzle to Scotland, northern parts of the North Sea and southern parts of the Baltic. Radar images show that the rain was patchy over Scotland and Northern Ireland. They also show that the band of rain moved slowly southwards across Scotland and Northern Ireland.
Pressure was again low today over Portugal and Spain. At 0000 UTC, a Low of 1009 mb was situated off Portugal. By 0600 UTC, it had deepened a little to 1007 mb. By 1200 UTC, its central pressure was 1008 mb. Pressure was high near Malta (1021 mb).
There was much cloud and rain in Spain and Portugal and fog over the Low Countries, Lithuania and Latvia. There was light rain and drizzle over parts of Poland, and there was snow over Romania and northern parts of Ukraine. Snow showers again occurred over central and northern parts of Norway. Skies remained clear of all but contrails over southern England, France, Germany, the Alps, the northern half of Italy and western parts of the Mediterranean. Satellite images show that cumulus and cumulonimbus activity was widespread over the seas to the west of Norway and north of Scotland. This activity shows as a speckled appearance to the cloud patterns; and close inspection of the images shows that cellular patterns of cumulus and cumulonimbus clouds developed. This is normal in areas of convective cloud.
The winds over Scotland and Scandinavia were from a westerly point. Over Spain, they were from an easterly point. Elsewhere, they tended to be rather light and variable.
Like yesterday, very few CloudWatch participants reported precipitation. Both stations in Spain reported nimbostratus cloud and rain. So, too, did the schools in Scotland, while the school in Krakow reported slight drizzle (from stratus cloud). At The Eagle's Nest, where there was snow yesterday, skies were clear today and most of yesterday's snow melted. Contrails were seen but did not persist, indicating that the upper troposphere was not very moist. For upper-air soundings at stations across Europe, click here.
Contrails persisted today over southern England, as the reports from several CloudWatch participants show. Much of the thin cirrus observed over the Reading area was aircraft generated and a sundog (mock sun) was seen in this cirrus near Reading between 1645 and 1705 UTC. Sundogs (also called 'parhelia') form when sunlight is refracted by hexagonal plate-like ice crystals. Many of the contrails over the Reading area today spread laterally. Some of the contrails developed pendulous features, suggesting convection taking place in the contrails. During the day, when the sun was fairly high in the sky, the fine structure of the cirrus was not easy to see, especially as the weather was a little hazy. Late in the day, however, when the sun was low in the sky, it could be seen that some of the cirrus was, in fact, cirrocumulus.
Satellite images from Dundee show that wave clouds again occurred over southern Norway and central Sweden.. These clouds are clearly evident on the satellite images (see, particularly, the 1312 UTC and 1452 UTC Channel 1 and Channel 4 images). They show up as parallel bands of cloud at right angles to the wind, which blew from the west. At one of the Stockholm schools (Lännbo Friskola), altocumulus lenticularis (wave) clouds were reported.
Contrails were also observed at Bonn (Germany), Bozen (northern Italy), Hautlieu (Jersey), Turin (Italy), Inverness (Scotland) and Clarens (Switzerland). They were observed, too, at Strasbourg, where the observer reported that the contrails were elongated and saucer-like. Upper-air soundings show that the upper troposphere was moist in all of the places where persistent contrails occurred.
Lastly today, like yesterday, we mention Holywell, North Wales, where the nearby power station generated some cumulus clouds this morning.
Austria | Belgium | Czech Republic | Denmark | Finland | France | Germany | Hungary
Italy | Jersey | Latvia | Lithuania | Netherlands | Norway | Poland | Portugal | Russia
Spain | Sweden | Switzerland | United Kingdom
For the UK Met.Office's weather coverage of Europe, click here.
