Subject: MetLinkInternational Week 2 Tuesday
Date: Tue, 2 Feb 1999 23:07:02 -0000
Dear MetLink participants
I wasn't sure where to start today, so I've decided to travel from south to north!
Let's begin with Tristan da Cunha. Did high pressure win the battle I mentioned in yesterday's review, or did low pressure? Well .... a bit of both! There's been high pressure today to the north-west (1017 mb) and south-east (1021 mb) of Tristan da Cunha, with the island itself between the two in a trough of low pressure. This trough extends from a deep primary depression (967 mb) centred just to the east of South Georgia and a secondary depression (987 mb) on its cold front. The satellite images have shown that there has been a lot of cloud over the South Atlantic near Tristan da Cunha today. Will the high pressure win tomorrow? We wait to see.
The Meteosat Image shows a lot of cirrus over southern Africa again today, but my impression is that there has not been as much convective activity as yesterday. There do not appear to have been as many cumulonimbus systems as yesterday. Those of you who live in Zambia/Zimbabwe/Madagascar: has this been so?
The weather has still not settled down in Malta. There have been showers again today and cool north-easterly winds. At least the depression which gave the unsettled weather of the past few days has weakened considerably and may well have disappeared by tomorrow, to leave a cool but fairly dry northerly wind over Malta.
The high pressure which has been over southern Britain these past few days is gradually drifting southwards, but maintaining its pressure value, with 1045 mb over the Bay of Biscay forecast for tomorrow. There should be fine weather at Bilbao and Tarragona tomorrow, with light easterly winds at Bilbao and light north-easterly winds at Tarragona. You seem to have had a very nice day today, Tarragona, judging by your weather report.
It was much nicer in Reading today than yesterday, with light, variable winds and a lot of sunshine. Much of the cloud we had today was high cloud, some of it from persistent aircraft condensation trails. It appears from the weather reports in our data base that other places in southern Britain had a nice day today. What weather will we have later in the week? A cold front which was over Scotland today is moving southwards. According to the weather chart for 1800 GMT, it was then situated a little to the south of Edinburgh and about to enter Northern Ireland from the north. The forecasters say it will reach the English Channel by the end of the week.
Over Scandinavia at 1800 GMT today, there was a cold front lying north- south from about Oslo to the Lofoten Islands and a warm front lying north-south from the southern Baltic through the Gulf of Bothnia to Hammerfest. To the east of the warm front, over the whole of Finland and over northern Sweden, there was very cold air, with temperatures at 1200 GMT below -25 deg C in northern Finland and about -10 deg C in southern Finland. There was also a little light snow on the front. Between the warm front and cold front, temperatures at 1200 GMT were between -4 and +5 deg C, and over western parts of southern Norway they were +7 or 8 deg C. There was quite a lot of fog over Denmark and Germany today (warm air passing over cold air and cold ground) and snow over many parts of central and eastern Europe and western parts of central Asia. The apparent battle between warm and cold air over Finland and Sweden continues. What will happen tomorrow?
The Intertropical Convergence Zone has again been quite well marked over the Atlantic Ocean, and situated a few degrees north of the equator, exactly as the textbooks say. It is still far from continuous, but more interesting today is the apparent continuity of the ITCZ with extensive areas of medium-level and cirrus cloud over central and eastern North Africa. I suspect the latter clouds are associated with a jet stream (a ribbon of fast-moving air - typically 50 m/s or more - in the upper troposphere). I suspect, to be more specific, that the clouds lie on the southern side of the entrance region of the part of the subtropical jet stream which blows fastest over the Middle East. Have any of you any information about the winds at 11-12 km altitude over Egypt, Israel and Jordan in the past few days? That's the height the subtropical jet stream is found.
That's all for today.
Best regards Malcolm
