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Sources: BBC, National Weather Services, Intellicast, Space Science and Engineering Center, the Met Office, Yahoo! Weather
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TODAY’S HEADLINES
TODAY’S EXTREMES
Hottest: Greenwood Senior High School, Western Australia, 35.4°C
Coldest: Rantakylan Koulu, Mikkeli, Finland, -5.5°C
Windiest: Pembroke School, Oamaru, New Zealand; Milford Haven School, Pembrokeshire, UK; Cardinal Gibbons High School, Raleigh, North Carolina, USA; all Force 6
TODAY’S REVIEW OF METLINK
OBSERVATIONS
Have you looked at today’s weathercams? If not, click here.
To view today’s observations in the database, click here.
To find out how your observations compare with the average for March, click here.
NB: It is early spring in the northern hemisphere, early autumn in the southern.
AUSTRALIA, NEW ZEALAND AND INDONESIA
Hazy, cloudy and calm at Jakarta at 7 am Local Time (00:00 GMT). Temperature 24.9°C, with 8 oktas of stratocumulus and altocumulus cloud. Maximum temperature 33°C, minimum 23°C. Calm and cloudy, too at Singapore (6 oktas). Temperature 32.0°C at 2.30 pm Local Time (06:30 GMT). Maximum temperature 33.0°C, minimum 25.0°C. No rain at either place.
"A beautiful clear sunny day" at Pembroke School, Oamaru, New Zealand, where at 10 am Local Time (21:00 GMT on 11 March) a wind of Force 6 was blowing from the north and the temperature was 16.0°C. Maximum temperature 16.0°C, minimum 13.0°C. A contrast at the Marine Discovery Centre, Woodbridge, Tasmania, where slight rain was falling from cumulonimbus clouds at 9.50 am Local Time (22:50 GMT on 11 March). Temperature then 15°C. Wind from the north-west 15 km/h.
"Typically autumn" at Millmerran, Queensland, where the day was "bright and clear" and a "warm gentle breeze" was blowing. Temperature 28°C at 12.15 pm Local Time (02:15 GMT) and the cloud amount 4 oktas (cumulus and stratocumulus). Wind from the east Force 1. Maximum temperature 29°C, minimum 15°C. "Calm and sunny" at Donald High School, Victoria, where at 4 pm Local Time the sky was cloudless and the temperature 28°C. Maximum temperature 33°C, minimum only 7°C. Cloudless, too, at Greenwood, Western Australia. Wind from the south-west 15 km/h at 2.30 pm (06:30 GMT). Temperature then 34.7°C. Maximum temperature 35.4°C, minimum 16.6°C.
AFRICA AND ASCENSION
Warm and cloudy on Ascension today. Seven oktas of cumulus cloud at 12.30 pm Local Time (12:30 GMT). Wind 15km/h from the north-east. Temperature 28°C. Maximum temperature 34°C. Warm and cloudy, too, at Greenside High School, Gauteng, South Africa. Six oktas of cumulus and cumulonimbus cloud at 2.30 pm Local Time (12:30 GMT) and, in the words of the students, "a chance of rain later on". Calm with a temperature of 26°C. Maximum temperature 29°C, minimum 15°C.
"We are definitely heading for autumn", said the students of Kgaswe Primary School, Botswana. Wind at 8 am Local Time 3 km/h from the west and the cloud amount 3 oktas of altocumulus. Temperature 23°C. Maximum temperature 34°C, minimum 20°C. Nothing autumnal about the weather at Micklefield School, Cape Town. "Warm with a cool breeze but getting hotter by the minute", the students wrote. Sky cloudless and the wind 9 km/h from the north-west at 10.30 am Local Time (08:30 GMT). Temperature 25°C. Maximum temperature also 25°C, minimum 20°C. "Cloudy warm and calm" at Penryn College, Mpumalanga. Temperature 24°C at 3 pm Local Time (13:00 GMT). Sky overcast with 8 oktas of stratocumulus cloud.
Still dry and the crops wilting at Banani International School, Lusaka, Zambia. Only one okta of cloud at 10 am Local Time (08:00 GMT). Temperature 29°C. Maximum temperature 33°C, minimum 16°C. Hot and sunny, too, at Marondera, Zimbabwe. Two oktas of cloud at 8 am Local Time (06:00 GMT) and the wind 9 km/h from the north-east. Temperature 22°C. Maximum temperature 26°C, minimum 19°C.
"Looks like rain", the students of Highbury Preparatory School in Kwa-Zulu Natal thought at 7 am Local Time (05:00 GMT). Sky almost overcast (7 oktas of cumulus and altocumulus) and the wind from the south-west, 9 km/h. Temperature 18°C. Maximum temperature 24°C, minimum 18°C. The forecast proved correct. Light rain falling at 1 pm Local Time, from 8 oktas of cumulus-type cloud. Temperature then 20°C. Wind from the south, 9 km/h. Overcast with light drizzle early in the day at Port Elizabeth but this cleared to give what the students said was a "lovely day". Cloud amount 3 oktas (cumulus and altocumulus) at 1.30 pm Local Time (11:30 GMT). Wind 15km/h from the south. Temperature 24°C. Maximum temperature 26°C, minimum 18°C.
EUROPE
Slight rain falling at Constanta, Romania, at 3 pm Local Time (13:00 GMT). Sky completely overcast with stratocumulus and altostratus cloud. Wind from the south, 24 km/h. "The wind blows and it is very cold", the students wrote. Temperature 6.4°C. maximum temperature 7.1°C, minimum 5.4°C. Unpleasant weather in Latvia, too. Heavy rain falling at Aizpute at 11.30 am Local Time. Sky completely overcast with nimbostratus cloud. Temperature only 3.2°C. Maximum temperature 4.1°C, minimum 2.5°C. Wind from the south-west, 15 km/h.
Slight snow falling at Mikkeli, Finland. Temperature just above freezing, which the students considered "mild"! Temperature at 12 noon Local Time (10:00 GMT) 1.4°C. Calm with 8 oktas of altostratus cloud. Maximum temperature 1.6°C, minimum —5.5°C. "Depth of snow 70 cm", the students reported. For pictures of the snow at Mikkeli, visit the MetLink Gallery. Better weather at Vasa, Finland, today. Only 4 oktas of cloud (cirrus and stratus) at 4.30 pm Local Time (14:30 GMT). Temperature 2.8°C. Maximum temperature 5.3°C, minimum 2.4°C.
Raining at Bor School, Sweden, at 8 am Local Time (07:00 GMT) from 8 oktas of nimbostratus cloud. Temperature 4.6°C. Maximum temperature 6.8°C, minimum 0.0°C. "Mild for the time of year" in Oslo, where the temperature at 12.20 pm Local Time (11:20 GMT) was 9.2°C. Cloudy, though, with 8 oktas of cumulus and altostratus. Maximum temperature 15.5°C, minimum -1.3°C.
Cloudy and wet today in Tarragona, Spain. Completely overcast at 12 noon Local Time (11:00 GMT) but not actually raining at the time. Wind from the south-west, Force 1. Temperature 14.9°C. Maximum temperature 14.9°C, minimum 12.9°C. "A miserable and dark day" but comparatively mild in Madrid, with slight drizzle falling from 8 oktas of cumulonimbus cloud at 9 am Local Time (08:00 GMT). Wind from the east, 15 km/h. Temperature 12°C. maximum temperature 16°C, minimum 12°C. The weather improved during the day. At 3.25 pm Local Time, the cloud amount was only 2 oktas and the students said the weather was "lovely".
Sky almost cloudless in Milan at 11 am Local Time (10:00 GMT). Wind from the north-east 15 km/h. Temperature 16°C. Quite a pleasant day today in Strasbourg, where there was no wind and the temperature reached 20°C. Warm, too, in Luxembourg, where the maximum temperature was 21°C. Quite a lot of cloud, with 6 oktas, but the clouds were at medium and high levels and fairly thin. Temperature 18.0°C at 11.45 am Local Time (10:45 GMT). Also warm for the time of year in Denmark, the maximum temperature at Aalborg being 18°C. Only 2 oktas of cloud (stratocumulus) at 12.06 pm Local Time (11:06 GMT) and the wind a light southerly (9 km/h). Temperature then 10°C.
Cold with snow showers at Farr High School on the north coast of Scotland. Temperature only +1°C at 9 am today. Maximum temperature 4.7°C, minimum +0.6°C. Wind 15 km/h from the north-west. "Cold and showery" at Paible School, North Uist, north-west Scotland, but considerably warmer than at Farr. Temperature 6°C at 9.30 am. Maximum temperature 11.5°C, minimum +1.5°C. A cold morning, too, at Stirling, where the temperature was only 3.6°C at 8.25 am. Maximum temperature 3.6°C, minimum 1.2°C. "Bright and clear becoming cloudy" in Dublin, where, at 10 am, the temperature was 6°C and the cloud amount only 3 oktas (altocumulus, cirrus and cirrocumulus).
Over most parts of the British Isles today wind speeds have been low and wind directions rather variable. At some places, indeed, the wind was calm. Even in Cornwall, which has been quite a windy place during MetLink 2002, there was little or no wind today. Cloud amounts were quite high in many places, including Cornwall, but there were exceptions. At Coed Cae Junior School in South Wales, today was "a pleasant day with sunny spells and a cool breeze"; and at Edgbaston High School (Birmingham) the cloud amount at 10.30 am was only 4 oktas (of cirrus and cumulus). Temperatures have topped 10°C today at most places in England and Wales after a cool start. The students at Pitsford Hall Weather Station near Northampton recorded a minimum temperature of —0.8°C, and the temperature fell to —1.0°C last night at Queen’s Park Community Technology College in Lancashire.
NORTH AND SOUTH AMERICA
At Buenos Aires in Argentina, there was an "intense cloud covering" of cumulonimbus (5 oktas) at 9.30 am Local Time (12:30 GMT). The temperature was then 22.1°C, the same as the maximum temperature. The minimum temperature was 21.9°C. The temperature variation during the day was remarkably small.
At Punta Arenas in southern Chile, the day was cloudy, with "moderate wind in the afternoon". The temperature was 6.0°C at 6 pm Local Time (22:00 GMT) and the cloud amount was 8 oktas (altostratus). Maximum temperature 11.5°C, minimum 2.9°C.
The weather was "very cloudy" at 1.50 pm Local Time (16:50 GMT) at Raleigh, North Carolina, USA, and heavy to moderate showers were expected. The temperature was 10°C and the sky was completely overcast, with stratus and stratocumulus cloud. Maximum temperature 11°C, minimum 10°C. Another place where the day’s temperature range was very small. The weather at Aurora in Illinois was a complete contrast. "A beautiful day with blue skies and lots of sun", the students said. "A great day to enjoy the nature". Cool, though, with a temperature of 3°C at 10 am Local Time (16:00 GMT).
Unusually warm for the time of year at Reseda, California, where the maximum temperature was 29.5°C. Temperature 20.9°C at 10.36 am Local Time (18:36 GMT). Just 3 oktas of cirrus cloud. Minimum temperature only 2.7°C. Warm and sunny, too, at Pasadena, where the maximum temperature was 25°C and the cloud amount at 2.50 pm Local Time (22:50 GMT) was only 1 okta (of cirrus). Another place that was sunny and pleasant today was Moses Lake in Washington State, where the cloud amount was only 3 oktas at 11 am Local Time (19:00 GMT) and the temperature was 10.6°C. Maximum temperature 15°C. Sunny with a cool wind at Victoria in Texas. Temperature 16°C at 9.10 am Local Time (15:10 GMT). Maximum temperature 23°C. Wind north-easterly, 33 km/h.
INTRODUCTION TO SATELLITE IMAGES
On the so-called ‘visible’ images from satellites, what you see is more or less what you would see with your own eyes if you were in the satellite and looking in black and white.
On the so-called ‘infra-red’ images, the whitest areas are the coldest and the blackest the hottest. Thus, high clouds (e.g. the tops of cumulonimbus anvils and the sheets of cirrus clouds ahead of warm fronts) show as white areas. Medium-level clouds and very cold land areas show as grey.
On the so-called ‘water vapour’ images, the whitest areas are the most humid, the blackest areas the driest. The water vapour indicated by these images tends to be in the upper half of the troposphere, not lower down.
For information on how to obtain satellite images of the highest quality, see the Notes section below.
AUSTRALIA, NEW ZEALAND AND INDONESIA
For a chart showing isobars and fronts over New Zealand at 06:00 GMT, click here. For a chart showing isobars and fronts over Australia at 06:00 GMT, click here. These charts show that an area of high pressure (1026 mb) was centred to the east of New Zealand, giving a flow from the north-east over both the North Island and the South Island. The chart for Australia shows that pressure was low over central Queensland (1010 mb) and over the south-west of Western Australia (1012 mb). An anticyclone (1028 mb) was centred over the Great Australian Bight and a weak area of high pressure (1014 mb) was situated over the Gulf of Carpentaria. Cold fronts lay to the south of the Bight and between Tasmania and New Zealand’s South Island.
As the visible and infra-red satellite images for 03:00 GMT show, skies were clear and day-time surface temperatures high over much of Australia. An extensive area of high cloud can be seen over eastern parts of Western Australia, and small cumulus clouds were widespread over eastern Queensland. The aforementioned cold fronts can be seen clearly on the satellite images. The images show that the South Island of New Zealand was almost wholly free of cloud today.
These satellite images show that the Intertropical Convergence Zone (ITCZ) was again today, like yesterday, weak between Australia and south-east Asia. Cloud amounts were small over Singapore and Indonesia. The images also show that tropical cumulus and cumulonimbus activity was very extensive over the Pacific to the north-east of Australia.
INDIA
The INDOEX geostationary satellite is nearly 36,000 km above the Indian Ocean. Today’s 08:00 GMT visible, infra-red and water vapour images from this satellite show an extensive area of cloud over north-western parts of the Indian sub-continent. For a detailed infra-red view of the cloud, click here. For a detailed water vapour view, click here. The infra-red image shows that the clouds are in the upper troposphere (because the clouds are white and therefore cold). It also shows parallel strips of cloud in the southern half of the cloud band. The water vapour image shows that a broad strip of moist air appears to link these clouds to an area of cumulonimbus activity near the equator south-west of the Maldives (in an area extending, roughly, from 5°S to 5°N and 60° to 65°E).
Today’s 00:00 GMT chart of winds at 300 mb (approximately 9 km height) shows that winds over the Arabian Sea are south-westerly and quite strong (120-130 km/h). A jet stream lies over eastern Asia. In this, wind speeds exceed 230 km/h (in the areas shown in yellow and purple on the 300 mb chart). The jet is a feature of the subtropics in the winter half of the year, especially over Florida, the Middle East and eastern Asia. It is called the subtropical jet stream and it is strongest at a height of about 12 km.
To the right of a jet stream’s acceleration region (right looking in the direction of the wind in the northern hemisphere, left in the southern), ascent of air occurs in the upper troposphere. This is probably the reason why the cloud has formed over north-west India. The right-hand side of the jet stream’s entrance region lies here. The reason for the parallel strips of cloud may well be that rolls of cloud have formed perpendicular to the wind direction because of wind shear, i.e. a rapid increase of wind speed with height. Put rather simply, the top of the cloud moves faster than the bottom, so rolls of cloud tend to form.
AFRICA
Today’s chart of isobars and fronts over Africa and adjacent oceans at 06:00 GMT shows that Tropical Cyclone Hary, which was close to eastern Madagascar yesterday, is now moving away south-eastwards and weakening. It also shows several depressions over the Southern Ocean between 40°S and 70°S, with the cold front of one of them extending almost to Port Elizabeth. Pressure was high over the South Atlantic (1021 mb). A shallow depression brought cloud and precipitation to southern and eastern parts of South Africa but a ridge of high pressure brought clear skies and fine weather to most parts of Zimbabwe, Zambia and Botswana.
The 08:00 GMT visible, infra-red and water vapour images from the INDOEX satellite show Tropical Cyclone Hary to the south-east of Madagascar and illustrate how useful satellite imagery is for tracking these devastating weather systems. The 12:00 GMT visible and infra-red images from METEOSAT, the geostationary satellite 36,000 km above 0° lat 0° long, show that the ITCZ was more active over the Atlantic Ocean today than it was yesterday, its axis lying a little to the north of the equator. Cumulonimbus activity over central and southern Africa was also a little greater today than yesterday. Clusters of cumulonimbus clouds with extensive anvils can be seen clearly on both the visible and infra-red images. Skies were clear over most parts of North Africa and the surface temperatures were high (as the blackness of the infra-red image shows). An extensive area of thin high cloud can be seen over Morocco. The reason for this cloud’s formation is not obvious. A possible factor is orographic influence from the Atlas Mountains. The apparent continuity of the cloud mass with the frontal cloud over France and eastern Spain is also suggestive. Winds in the upper troposphere were very strong over Morocco today (more than 200 km/h), so a jet stream influence is another possibility. Without a thorough research investigation, however, the real reason for the cloud’s existence has to remain unknown.
EUROPE
Today’s 06:00 GMT chart of isobars and fronts over Europe shows that pressure was low (983 mb) to the west of Iberia, with fronts from this depression bringing cloud and precipitation to Spain and to the eastern Atlantic south-west of Ireland. Pressure was again low (as it was yesterday) over Greece (1010 mb), with cloud associated with this depression lying over Greece, Bulgaria, Romania and western Turkey. The areas of cloud and precipitation associated with these depressions can be seen on the 12:00 GMT visible and infra-red satellite images and the 06:00 GMT chart of significant weather. A ridge of high pressure extended from eastern Europe across the western Mediterranean to North Africa, bringing clear skies over the Alps and most of Italy. A complex area of low pressure extended north-westwards from the northern North Sea to the east coast of Greenland, with distinct centres of low pressure centred over the northern North Sea (988 mb), Iceland (1004 mb) and Jan Mayen (1001 mb). The fronts associated with this area of low pressure tended to be weak, as the satellite images suggest. An active warm front brought rain to Latvia.
A col lay over the British Isles, giving light variable winds over most parts of Ireland, Wales and England. For satellite views of clouds over the British Isles at 13:37 GMT today, see the visible and infra-red images from Dundee University. These show the swirl of the cloud bands around the low centred between Shetland and Norway, a few cumulonimbus clouds over northern Scotland and sheets of cloud over many parts of southern Ireland, the northern half of Wales, much of northern England and most of southern England. Lough Neagh in Northern Ireland can be seen clearly on the visible image.
The 06:00 GMT chart of significant weather over Europe and the 06:00 GMT chart of observations over Scandinavia show that inland temperatures were very low (below —20°C) over northern parts of Norway, Sweden and Finland this morning.
NORTH AND SOUTH AMERICA
For a chart showing isobars and fronts over North America at 09:00 GMT today, click here. For another plot of isobars and fronts over North America at 09:00 GMT today, one that shows concurrent satellite-derived distributions of cloud and precipitation, click here. These charts show that pressure was high to the east, south and west of the USA and comparatively low (996 mb) between the Great Lakes and British Columbia. A trough of low pressure brought cloud and precipitation to eastern parts of the USA, as the infra-red satellite image for 09:00 GMT shows. As the weather forecast chart shows, showers of rain and/or snow were expected today over many parts of eastern and western North America.
The infra-red satellite image of North and South America at 09:00 GMT shows that cloud amounts were large today over the northern half of South America, with many cumulonimbus clouds bringing downpours of rain. A large area of cumulonimbus activity lay, too, over Paraguay, whilst an area of cloud associated with a depression centred off southern Chile covered the southern tip of South America.
For Today’s Review of MetLink Observations, click here.
For Today’s Analysis, click here.
NOTES
You can obtain satellite images of the highest quality from the Dundee Satellite Receiving Station, Dundee University, Scotland. First, though, you must complete an on-line registration form. Registration is free and the images are free. Do not hesitate to register. The staff at Dundee welcome new users and you gain access to images of very high quality. You go first to http://www.sat.dundee.ac.uk/ and click on the button labelled "Register for free images". All you do then is fill in the form, press the button labelled "Create account", remember the user name and password you chose and start using the site.
From the satellite station’s home page, i.e. http://www.sat.dundee.ac.uk/, you click on "Home for registered users" and then choose the images you require. I suggest you begin with "Geostationary satellite images — view the whole earth". On this page, which provides links to the latest images from geostationary satellites, you select whichever image you require. If you want an image from a previous day, choose "Archive".
Images from the following satellites are available: METEOSAT (which covers Europe and Africa), Japanese GMS (which covers the western part of the Pacific, Australia and Indonesia), US GOES-EAST (which covers North and South America), US GOES-WEST (which covers the eastern Pacific) and IODC (which covers central Asia, southern Asia and the Indian Ocean).
From all of these satellites, images can be obtained in Visible and Infra-Red formats. From METEOSAT and IODC, images showing distributions of water vapour can be obtained. From METEOSAT, colour-enhanced images of Europe can be obtained.
If you wish to view images from polar-orbiting satellites covering western Europe and the eastern Atlantic from Greenland and northern Scandinavia to western Asia and North Africa, go from "Home for registered users" to AVHRR Images — latest images or, for archived images, AVHRR Images- Archive.
To return to Today’s Analysis, click here.