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uk.sci.weather (UK Weather) (uk.sci.weather) For the discussion of daily weather events, chiefly affecting the UK and adjacent parts of Europe, both past and predicted. The discussion is open to all, but contributions on a practical scientific level are encouraged. |
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#1
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![]() "nguk." wrote in message ... I don't know how to word this correctly but here goes How does a cold pool come about and what sort of temps can be expected if one arrives here this month? This is an excellent question: It is quite straightforward really. That is assuming my description is correct. A cold pool forming from a high pressure system is created soon after an intensification of the high pressure to the east or north east of the UK. This would cause the high to pull a wedge of cold air from NW Russia in our direction. This cold pool would accumulate over the UK until the high pressure weakened sufficiently to allow warmer west or sw winds to remove it. In rare occasions the cold pool would sit until it was reinvigorated by a resurgence of the high or even a shift in the high pressure to an even more advantageous position. In most cases though the cold pool will sit until the air warms in its lower altitudes giving a few good night frosts until such time as the high declines and then the cold pool is replaced by milder air. The sort of temperatures I would expect in a cold pool over S and Eastern England in mid November would be daytime maximums of 5C or 6C and nightime temps of -2C to -3C. I hope my answer is OK. Regards, Gavin. -- ************************************************** ************************** ************************************************** * Gavin Staples. website updated regularly www.gavinstaples.com Currently writing book titled: Contemporary Societies East and West. The introduction of this is on my homepage. "I can calculate the motions of the heavenly bodies, but not the madness of the people" ~ Sir Isaac Newton, in (1720), referring to the South Sea Bubble share crisis in which he lost £20,000 at 1720 prices. All outgoing emails are checked for viruses by Norton Internet Securities 2003. ************************************************** ************************** ************************************************** ** |
#2
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![]() Regards, Gavin. -- ************************************************** ************************** ************************************************** * Gavin Staples. website updated regularly www.gavinstaples.com Thankyou for your time in writing that it was most helpful! |
#3
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"Gavin Staples" wrote in message
... This would cause the high to pull a wedge of cold air from NW Russia in our direction. An excellent explaination. ![]() I sometimes use the phrase "cold pool" in my analysis to indicate such a pool moving across the UK. In fact (at the time of writing) the 12z GFS run shows this in action: http://129.13.102.67/wz/pics/Rtavn001.gif Have a look near the Balkans - there's currently a pool of colder air over there, which would have come about before the Scandinavian and Siberian Highs linked. It then tracks westwards over France... http://129.13.102.67/wz/pics/Rtavn121.gif http://129.13.102.67/wz/pics/Rtavn361.gif By T+36, a new ridge NE of Scandinavia allows another cold plunge of air to head southwards. http://129.13.102.67/wz/pics/Rtavn601.gif Sunday sees the first cold pool finally make it across the Channel, as it's pushed NW'wards around the high. Meanwhile low pressure moves southwards over NW Russia as a ridge topples southwards and by T+72 the greens start moving towards eastern Europe, heralding another cold pool. http://129.13.102.67/wz/pics/Rtavn721.gif By now, the first cold pool moves over Scotland, cooling further as it moves back northwards again. There are also signs of yet another ridge between Scandinavia and Greenland - if the high remained in situ, you'd see cold pools circling it, like the teeth of a cog rotating. Finally, by T+96 our cold pool merges with the cooler air north of Iceland, while the cold NE'ly flow over NW Russia gets cut off, with a cold pool heading over the Black Sea: http://129.13.102.67/wz/pics/Rtavn961.gif Of course, this is pretty tame stuff - that cold pool will reduce temperatures by a few degrees, but for a wintry cold pool, you can't really beat January 1987: http://217.160.130.220/wz/pics/archi...0119870106.gif http://217.160.130.220/wz/pics/archi...0119870108.gif http://217.160.130.220/wz/pics/archi...0119870110.gif http://217.160.130.220/wz/pics/archi...0119870112.gif http://217.160.130.220/wz/pics/archi...0119870114.gif http://217.160.130.220/wz/pics/archi...0119870115.gif High pressure moving over the UK then merging with a high originally to the east of Svalbard, with an intense cold pool pushed towards and eventually over the UK, warming considerably as it did so - but not by enough to stop it being an exceptionally cold spell of course. |
#4
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The point about a cold pool, whatever its origin, is that the air is cold
over a considerable depth. The effect of this is to enhance any convection that may occur. In summer, possibly thunderstorms, in winter maybe snow showers. In winter low surface temperatures can occur (in a High) with no trace of a cold pool anywhere near, due to a strong surface inversion, even by day. Tudor Hughes, Warlingham, Surrey. |
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