MetLink Report 4 Feb 1999
(Day 9)

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School Weather News 1999

Weather analysis - 4 Feb 1999
From: education@royal-met-soc.org.uk
Subject: MetLinkInternational Week 2 Thursday
Date: Thu, 4 Feb 1999 21:31:07 -0000

Dear MetLink friends

The High pressure won! The subtropical anticyclone over the South Atlantic re-established itself today, with a central pressure of 1021 mb very close to Tristan da Cunha . Indeed, there was high pressure all the way from Tristan da Cunha to southern Africa today. To the south, there were several depressions over the South Atlantic between the parallels of 40 and 60 degrees S, and there was a depression not far south of Harare, too, giving quite a lot of thunder-type clouds (cumulonimbus) over eastern parts of southern Africa. Otherwise, however, the impression one gains from today's satellite images (e.g. the METEOSAT infra-red DTOT images) is that the majority of the cloud over southern Africa was high cloud. There did not appear to be as much cumulonimbus activity as of late. The METEOSAT ETOT images, which show us where the atmosphere is moist (whitest = most water vapour), also suggest a reduction in cumulonimbus activity over southern Africa today.

The ITCZ lies in a line across the Atlantic two to five degrees north of the equator, which is where the textbooks lead you to expect it at this time of year. It does not appear to be very active, however. As the ETOT images show, there are rather few cumulonimbus systems embedded in it. As on previous days, there is medium-level cloud and cirrus cloud across central and eastern North Africa from the ITCZ to the Middle East, which I suspect is associated with subtropical jet stream activity over the Middle East.
The weather over Malta appears to be settling down again, with temperatures rising, though they are still below normal. At Tarragona, it seems to have been a nice day with plenty of sunshine, as one would expect with an anticyclone not very far to the west.

Winter seems to have loosened its grip a little in Scandinavia today. The temperature reported by Christer and his team at Varnamo i n Sweden was a very respectable +5.5 deg C today, and the temperature reported from Vora in Finland was as high as -1.9 deg C! Only at Eno was the temperature still quite low (-10 deg C). By 1200 GMT, however, only in the farthest north of Finland and at places in nearby parts of Russia were temperatures below -10 deg C to be found. Fronts brought quite a lot of snow to southern Finland and northern parts of Sweden, these fronts associated with a depression crossing central Norway and central Sweden. Ahead of the fronts, as the observations from Eno, Vora and Varnamo show, there were east to south-east winds. To the south, as the observations from Oslo show, there were westerly winds and much higher temperatures than in Finland (+8.9 deg C at Oslo).

Around the depression which has been crossing central Norway and Sweden, there are strong winds. Notice the reported wind speed of 48 km/h at Larne and 47 km/h at Edinburgh. Even in southern England, it has been noticeably breezy, but it has been nowhere near as windy in the south of the British Isles as in central and northern Scotland and over the waters of the northern North Sea and north-east Atlantic. To see just how strong the winds have been over the sea, you are recommended to visit Marine buoys - Atlantic gales or go live to one of the Web sites:

http://www.nws.fsu.edu/buoy/uk.html

but visit it soon, as the data, which are updated every hour, cover the most recent period of 24 hours.
The cold front which is moving south across the British Isles has not moved as fast as forecast but is still expected to reach France by tomorrow, leaving the United Kingdom in a run of cool north-westerly winds (well ... cool for us!). In accordance with Buys Ballot's Law, which states that, in the northern hemisphere, low pressure is on your left if you stand with your back to the wind, we can expect pressure to be high tomorrow to the west and south-west of Ireland (1044 mb near 50 deg N 20 deg W is forecast for 1200 GMT tomorrow). The cold front to which I refer shows up well on the 1517 GMT satellite images from Dundee, particularly so on the NOAA Europe Ch4 (infra red). At this time, the front was lying from the Wash across North Wales and central Ireland. From there, it runs as a continuous feature south-westwards over the North Atlantic almost to the West Indies (as the DTOT Meteosat Image image shows).

On the Dundee images, notice the cells of cumulonimbus (shower) activity over the ocean north, north-west and north-east of Scotland. Notice also on the NOAA Europe Ch1 (visual) image the parallel bands in the stratocumulus cloud over southern England at right angles to the westerly wind. These are wave clouds, caused by the air passing over hills -- the hills of southern Wales, in particular. You have to look quite carefully at the NOAA Europe Ch1 (visual) image to see these undulations and you need to have the contrast setting of your VDU well set to see them, but I can assure you they are there.

Finally, a word of warning. I quoted Buys Ballot's Law in terms of your back to the wind. When temperatures are low -- certainly as low as they have been in Finland lately -- it can be very unpleasant or even dangerous to face the wind.

I attach for your information a product of the UK's Meteorological Office. It's a forecast for inshore waters issued to BBC Radio 4 for broadcasting to the public and I thought you'd be interested to see it. It is available from the following UK Met.Office Web page:

http://www.met-office.gov.uk/sec3/sec3.html

Wind strengths are given as Beaufort Force values.

And one more thing: Buys Ballot (1817-1890) was a celebrated Dutch meteorologist. He formulated his famous Law in 1857, at which time he was the Director of the Royal Netherlands Meteorological Institute.

Best regards Malcolm



Winds in Edinburgh, Scotland 4 Feb 1999

From: George Meldrum of James Gillespie's HS, Edinburgh, Scotland
Subject: Winds in Edinburgh, Edinburgh
Date: Thu, 4 Feb 1999 21:31:07 -0000

Met Link Friends - Edinburgh ( Scotland) Update 4 Feb 1999

We have been jealously noting the significant weather events which you have been recording while we have been sitting for the most part under a huge high pressure system. However, the weather in Scotland is at last responding and giving us something interesting to report. The wind has been building over the last two days and gusts of 50 mph were recorded here in the city early this morning. In more exposed places this figure would be considerably higher. Radio reports tell us of ferries to the northern isles being cancelled or disrupted, several roads in the Highlands are blocked by fallen trees and the large bridges over the sea estuaries such as the Forth and Tay are either closed or the traffic is restricted. The synoptic forecast suggests that a cold front is going to sweep over the country today introducing much colder weather and in the high winds, blizzard conditions are expected. Severe weather warnings have been issued for the north of Scotland.



INSHORE FORECAST 3 Feb 1999>>>>>

To Radio 4 From the National Meteorological Centre, Bracknell.

Here now is the weather forecast for the inshore waters of Great Britain and Northern Ireland.
Until 1800 hours today Thursday 4 February 1999.

Pressure is high to the southwest of Britain, with a complex area of low pressure dominating waters to the north of the country. A strong west or northwest airflow will dominate United Kingdom coastal waters.

From Berwick-upon-Tweed to Spurn Head.
Wind:southwest veering west 6 or 7, occasionally gale 8, and perhaps severe gale 9 until mid-afternoon.
occasional rain followed by scattered showers.
Visibility:moderate or good.

From Spurn Head to Harwich.
Wind:westerly 5 or 6 perhaps 7 at times later.
patchy rain dying out.
Visibility:moderate or good.

From Harwich to Lizard Peninsula.
Wind:west or southwest 4 or 5 occasionally 6 later.
patchy rain.
Visibility:moderate or good.

From Lizard Peninsula to St. Davids Head.
Wind:westerly 5 or 6.
patchy rain or drizzle becoming mainly fair.
Visibility:moderate or good.

From St. Davids Head to Mull of Kintyre including from Carlingford Lough to Belfast Lough
Wind:southwesterly veering westerly, 6 or 7, increasing gale 8 at times, especially in north.
occasional rain followed by showers.
Visibility:moderate or good.

From Mull of Kintyre to Ardnamurchan Point including from Belfast Lough to Lough Foyle.
Wind:southwest veering west 6 to gale 8, perhaps severe gale 9 at times later. rain then squally showers.
Visibility:moderate or good.

From Ardnamurchan Point to Fraserburgh including the waters around Orkney and Shetland.
Wind:southwesterly veering westerly, 7 to severe gale 9, increasing storm 10 for a time in north.
drizzle then squally wintry showers.
Visibility:moderate or poor becoming mainly good.

and finally from Fraserburgh to Berwick-upon-Tweed.
Wind: southwest veering west 7, occasionally gale 8 or severe gale 9.
occasional rain followed by scattered showers.
Visibility: moderate or good.

(c) Crown copyright 1999.

DTOT Meteosat Image 4 Feb 1999

ETOT Meteosat Image 4 Feb 1999




N Atlantic synoptic chart 4 Feb 1999





S Atlantic synoptic chart 4 Feb 1999




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