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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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Perhaps surprisingly for such a warm month, there was a
significant northerly component to the anomalous flow over the British Isles during January. However, the southerliness index is only very weakly correlated to temperature during the winter quarter ... much of the variance in mean temperature is explained by the magnitude of the westerliness index (with a smaller contribution from the cyclonicity index). It was, in fact, the most westerly January since 1983, and the 11th most westerly January in 133 years of records. The strength of the westerlies also resulted in a strongly orographically-modulated rainfall distribution (biggest percentages on west-facing upslopes and lowest percentages in the usual rain-shadow areas). Similarly, it was also a very sunny month in parts of SE Scotland and NE England, but a dull one in western Scotland. Mean pressure charts are now be available at: Charts: http://www.climate-uk.com/monpre/0701.htm The Monthly Review will shortly be uploaded to: http://www.climate-uk.com/monthly/0701.htm Graphs: http://www.climate-uk.com/graphs/0701.htm and http://www.climate-uk.com/graphs/200701.htm Not The Long Range Forecast will be found after 3 Feb at: http://www.climate-uk.com/page4.html The mean sea-level chart shows that the Icelandic Low was split, with on the one hand a pair of centres at 987mbar in the Barents and north Norwegian Seas, and on the other hand a centre of 994mbar near the southern tip of Greenland. (Such a split is very often a precursor of a lengthy blocking episode in the northeast Atlantic with a delay of 2-3 weeks). High pressure lay in a broad zone from Bermuda across the Azores, Iberia and the Mediterranean to the Levant; the main centre of 1029mbar was located just north of Madeira. The flow over the British Isles was due-westerly and more than twice as strong as the long-term mean. The sea-level pressure anomaly field showed below- normal pressure over northern and eastern Europe, the northern Atlantic, northeast Canada and adjacent parts of the Arctic, and above-normal pressure over southern Europe, Biscay and southern and central parts of the North Atlantic Ocean. The main anomaly centres we -19mbar over Novaya Zemlya and Finland -9mbar over the Labrador coast +9mbar over the Atlantic between Ireland and the Azores +8mbar in the central Mediterranean Over the British Isles pressure anomaly ranged from +5mbar at Scilly to -9mbar in Shetland. The anomalous flow was strongly WNW-ly, tending NW-ly in northern Scotland. CET (after Manley) 7.0°C (+2.8 degC wrt 1971-2000) making it the warmest since 1921 and the fifth warmest in the 349-year long record CET (after Hadley) 6.9 or 7.0°C (+2.7 or 2.8 degC) E&W Rain (provisional): 100.2mm (107% of 1971-2000 mean) the highest since 2004 E&W Sunshine (prov): 65.4 hr (118% of 1971-2000 mean) the highest since 2003 CScotT: 6.1°C (+2.4 degC) ScotRain: 145.5mm (128%) ScotSun: 45.0hr (103%) NIT: 6.8°C (+1.8 degC) NI Rain: 106.1mm (114%) NI Sun: 57.9hr (115%) Rainfall totals ranged from 591.6mm at Inveruglas (Dunbartonshire) to 31.3mm at Coningsby (Lincs). It was the equal-wettest January (alongside 2005) in the Renfrew/Abbotsinch/Bishopton record (just west of Glasgow) since 1928, while the 3-month total (Nov,Dec,Jan) in the southwest Highlands and the Clydeside area was almost 250% of the normal and far in excess of anything previously recorded for these months. Percentages ranged from 251 at Lake Vyrnwy (Montgomeryshire) to 42 at Glenlivet (Banffshire) [flagged as in need of checking; possibly too low] Sunshine totals ranged from 91.1h at Boulmer, Northumberland (KZ sensor) where it was the sunniest Jan since 1991, to 21.5h at Stornoway (KZ sensor). Percentages ranged from 172 at Church Fenton (near York) to 51 at Prestwick. One interesting additional statistic: at Lerwick the Januarys of both 2006 and 2005 were warmer. (c) Philip Eden |
#2
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In article ,
Philip Eden writes: snip The main anomaly centres we -19mbar over Novaya Zemlya and Finland -9mbar over the Labrador coast +9mbar over the Atlantic between Ireland and the Azores +8mbar in the central Mediterranean That -19mbar anomaly seems remarkably large. Does it represent any sort of a record? -- John Hall Weep not for little Leonie Abducted by a French Marquis! Though loss of honour was a wrench Just think how it's improved her French. Harry Graham (1874-1936) |
#3
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John Hall wrote:
In article , Philip Eden writes: snip The main anomaly centres we -19mbar over Novaya Zemlya and Finland -9mbar over the Labrador coast +9mbar over the Atlantic between Ireland and the Azores +8mbar in the central Mediterranean That -19mbar anomaly seems remarkably large. Does it represent any sort of a record? January and February 1963 both had anomalies of a little more than +30 over Iceland. -- Graham P Davis Bracknell, Berks., UK Send e-mails to "newsman" as mails to "newsboy" are ignored. |
#4
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In article ,
Graham P Davis writes: John Hall wrote: That -19mbar anomaly seems remarkably large. Does it represent any sort of a record? January and February 1963 both had anomalies of a little more than +30 over Iceland. Phew, that's impressive! Thanks, Graham. -- John Hall Weep not for little Leonie Abducted by a French Marquis! Though loss of honour was a wrench Just think how it's improved her French. Harry Graham (1874-1936) |
#5
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![]() "Graham P Davis" wrote : John Hall wrote: Philip Eden writes: snip The main anomaly centres we -19mbar over Novaya Zemlya and Finland -9mbar over the Labrador coast +9mbar over the Atlantic between Ireland and the Azores +8mbar in the central Mediterranean That -19mbar anomaly seems remarkably large. Does it represent any sort of a record? January and February 1963 both had anomalies of a little more than +30 over Iceland. Well, Jan '63 did, but not February. There was a -30mbar anomaly south of Iceland in February 1990. In January 1983 the anomalies ranged from -24mbar SE of Iceland to +18mbar in Biscay. Philip |
#6
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"Philip Eden" philipATweatherHYPHENukDOTcom wrote:
"Graham P Davis" wrote : John Hall wrote: Philip Eden writes: snip The main anomaly centres we -19mbar over Novaya Zemlya and Finland -9mbar over the Labrador coast +9mbar over the Atlantic between Ireland and the Azores +8mbar in the central Mediterranean That -19mbar anomaly seems remarkably large. Does it represent any sort of a record? January and February 1963 both had anomalies of a little more than +30 over Iceland. Well, Jan '63 did, but not February. There was a -30mbar anomaly south of Iceland in February 1990. In January 1983 the anomalies ranged from -24mbar SE of Iceland to +18mbar in Biscay. My memory must be playing tricks again. I was sure the charts I'd seen had similar anomalies for both months. It's only about 35 years since I last saw them so I can't think why I got it wrong. Mind you, I've been quoting this "fact" for the past 34 years so perhaps it was short-term memory-loss that was to blame. -- Graham P Davis Bracknell, Berks., UK Send e-mails to "newsman" as mails to "newsboy" are ignored. |
#7
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On Feb 1, 3:38 pm, "Philip Eden" philipATweatherHYPHENukDOTcom
wrote: Perhaps surprisingly for such a warm month, there was a significant northerly component to the anomalous flow over the British Isles during January. However, the southerliness index is only very weakly correlated to temperature during the winter quarter ... much of the variance in mean temperature is explained by the magnitude of the westerliness index (with a smaller contribution from the cyclonicity index). It was, in fact, the most westerly January since 1983, and the 11th most westerly January in 133 years of records. The strength of the westerlies also resulted in a strongly orographically-modulated rainfall distribution (biggest percentages on west-facing upslopes and lowest percentages in the usual rain-shadow areas). Similarly, it was also a very sunny month in parts of SE Scotland and NE England, but a dull one in western Scotland. Mean pressure charts are now be available at: Charts: http://www.climate-uk.com/monpre/0701.htm The Monthly Review will shortly be uploaded to:http://www.climate-uk.com/monthly/0701.htm Graphs: http://www.climate-uk.com/graphs/0701.htm and http://www.climate-uk.com/graphs/200701.htm Not The Long Range Forecast will be found after 3 Feb at: http://www.climate-uk.com/page4.html The mean sea-level chart shows that the Icelandic Low was split, with on the one hand a pair of centres at 987mbar in the Barents and north Norwegian Seas, and on the other hand a centre of 994mbar near the southern tip of Greenland. (Such a split is very often a precursor of a lengthy blocking episode in the northeast Atlantic with a delay of 2-3 weeks). High pressure lay in a broad zone from Bermuda across the Azores, Iberia and the Mediterranean to the Levant; the main centre of 1029mbar was located just north of Madeira. The flow over the British Isles was due-westerly and more than twice as strong as the long-term mean. The sea-level pressure anomaly field showed below- normal pressure over northern and eastern Europe, the northern Atlantic, northeast Canada and adjacent parts of the Arctic, and above-normal pressure over southern Europe, Biscay and southern and central parts of the North Atlantic Ocean. The main anomaly centres we -19mbar over Novaya Zemlya and Finland -9mbar over the Labrador coast +9mbar over the Atlantic between Ireland and the Azores +8mbar in the central Mediterranean Over the British Isles pressure anomaly ranged from +5mbar at Scilly to -9mbar in Shetland. The anomalous flow was strongly WNW-ly, tending NW-ly in northern Scotland. CET (after Manley) 7.0°C (+2.8 degC wrt 1971-2000) making it the warmest since 1921 and the fifth warmest in the 349-year long record CET (after Hadley) 6.9 or 7.0°C (+2.7 or 2.8 degC) E&W Rain (provisional): 100.2mm (107% of 1971-2000 mean) the highest since 2004 E&W Sunshine (prov): 65.4 hr (118% of 1971-2000 mean) the highest since 2003 CScotT: 6.1°C (+2.4 degC) ScotRain: 145.5mm (128%) ScotSun: 45.0hr (103%) NIT: 6.8°C (+1.8 degC) NI Rain: 106.1mm (114%) NI Sun: 57.9hr (115%) Rainfall totals ranged from 591.6mm at Inveruglas (Dunbartonshire) to 31.3mm at Coningsby (Lincs). It was the equal-wettest January (alongside 2005) in the Renfrew/Abbotsinch/Bishopton record (just west of Glasgow) since 1928, while the 3-month total (Nov,Dec,Jan) in the southwest Highlands and the Clydeside area was almost 250% of the normal and far in excess of anything previously recorded for these months. Percentages ranged from 251 at Lake Vyrnwy (Montgomeryshire) to 42 at Glenlivet (Banffshire) [flagged as in need of checking; possibly too low] Sunshine totals ranged from 91.1h at Boulmer, Northumberland (KZ sensor) where it was the sunniest Jan since 1991, to 21.5h at Stornoway (KZ sensor). Percentages ranged from 172 at Church Fenton (near York) to 51 at Prestwick. One interesting additional statistic: at Lerwick the Januarys of both 2006 and 2005 were warmer. (c) Philip Eden Isn't the mean flow anomaly a little misleading, at least to someone unversed in these matters? The monthly flow was mainly SW'ly but with a week of northerlies, to put it rather simply, and there was very little in between. It's true that the mean flow is as stated and it is quite in order to make correlations with temperature and rainfall but it doesn't quite give the flavour of the month, if you'll excuse the phrase. Tudor Hughes, Warlingham, Surrey. |
#8
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![]() "Graham P Davis" wrote : "Philip Eden" philipATweatherHYPHENukDOTcom wrote: "Graham P Davis" wrote : John Hall wrote: Philip Eden writes: snip The main anomaly centres we -19mbar over Novaya Zemlya and Finland -9mbar over the Labrador coast +9mbar over the Atlantic between Ireland and the Azores +8mbar in the central Mediterranean That -19mbar anomaly seems remarkably large. Does it represent any sort of a record? January and February 1963 both had anomalies of a little more than +30 over Iceland. Well, Jan '63 did, but not February. There was a -30mbar anomaly south of Iceland in February 1990. In January 1983 the anomalies ranged from -24mbar SE of Iceland to +18mbar in Biscay. My memory must be playing tricks again. I was sure the charts I'd seen had similar anomalies for both months. It's only about 35 years since I last saw them so I can't think why I got it wrong. Mind you, I've been quoting this "fact" for the past 34 years so perhaps it was short-term memory-loss that was to blame. I'll draw up the charts and post them when I have some spare time (short supply these days) ... I'm sure there'd be quite a wide interest in them. Feb 1963 was actually quite synoptically diverse ... highest pressure near Iceland during the opening days, then the Baltic or northern Scandinavia, briefly the Azores (shock, horror), but over central Europe during the last week. Philip |
#9
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![]() "Tudor Hughes" wrote; Isn't the mean flow anomaly a little misleading, at least to someone unversed in these matters? The monthly flow was mainly SW'ly but with a week of northerlies, to put it rather simply, and there was very little in between. It's true that the mean flow is as stated and it is quite in order to make correlations with temperature and rainfall but it doesn't quite give the flavour of the month, if you'll excuse the phrase. Weeeeeeell ..... you get the flavour of the month in the Monthly Review at http://www.climate-uk.com/monthly/0701.htm which starts off: "The very unsettled southwesterly type which set in just before the New Year lasted without interruption until the 20th. This was followed by a brief northerly outbreak, but rising pressure led to the establishment of an anticyclone close to southwestern Britain from the 26th onwards." So it was all there if you had wanted to follow the links. The beauty of the monthly synoptic overview is that it's a pretty-much objective assessment. The description of January as having a northwesterly anomalous flow is entirely consistent - of course - with the sequence of events that we had. I accept your point, though, about the "unversed". OK, so these overviews are constricted by that human invention, the *month*, but I do occasional post links to a chart of running W-ly, S-ly and Cy indices to show where (or, rather, when) the peaks, troughs, and turning-points are. And I try to answer people's questions. If there's anything else you'd like, feel free to ask ... I can only say no. Philip |
#10
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In case anyone missed by Wind Graphs for January here they are again.
Wind Direction Days (Exeter @ 18:00 BST) http://s2.excoboard.com/forums/16030...331/370815.jpg Wind Speed Totals mph (Exeter @ 19:00 BST) http://s2.excoboard.com/forums/16030...331/370817.jpg It shows that the wind came predominantly from a Westerly Direction. Also, it is worth noting that the wind did not come from any direction from NE through to SE on any day at 18:00 GMT. |
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