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| Weekly Analysis – Cold and Wet to Mild and Windy By Matt Hugo - October 12, 2014 | |
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| Tweet Topic Started: 12 Oct 2014, 02:34 PM (20 Views) | |
| Audi-Tek | 12 Oct 2014, 02:34 PM Post #1 |
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Weekly Analysis – Cold and Wet to Mild and Windy By Matt Hugo - October 12, 2014 Weekly Analysis – Cold and Wet to Mild and Windy OVERVIEW: The forth coming week will be quite a typical October week in that distinctly changeable conditions are expected across the UK between Monday and Friday. October can provide the first cold weather of the season as winter approaches, but equally some late warmth can still be brought to the UK depending on the wind direction and both scenarios are expected this week. Due to the changeable conditions, confidence in the details is particularly low after mid-week but the usual mid-week update will take a closer look at the weather for the end of the week. ANALYSIS: As usual there are some specific features of interest evident on water vapour image and the primary feature is evident over Iberia at the moment, which will influence the weather across the UK during Monday. Other features of interest are discussed below; ![]() 1) This is a developing area of low pressure within the base of an upper trough over Iberia and the Bay of Biscay. This feature is heading northwards towards the UK will bring a wet start to the working week over most of England in particular and perhaps into Wales as well. The developing low will also be responsible for producing quite a cold and raw east or north-easterly wind over the top of the low pressure across parts of N England and Midlands during Monday. 2) This is a minor ridge of high pressure within the upper atmosphere ahead of an area of low pressure within the North Atlantic. Once Monday’s low has cleared away to the east during Tuesday this minor ridge of high pressure will build into the UK to bring a more settled spell of weather later on Tuesday and into Wednesday, but this is a transient feature and will soon be moved out of the way by more unsettled conditions. 3) I’ve highlighted region 3 because it is across the far west of the Atlantic that later today an upper trough will move out of E Canada and into the North Atlantic. This will be associated with an area of low pressure at the surface and this will then become a large and dominant feature of the weather within the North Atlantic. What this low pressure will do as well is introduce a much milder, if not quite warm south or south-westerly air mass to end the week, so after a cold start to the week, the week will end quite warm. MONDAY: Monday’s weather is dominated by low pressure moving across the south and east of England and this will bring a distinct north and west, south and east split in conditions across the UK. For most of Ireland and Scotland a mainly dry day is expected with bright or sunny spells after a chilly start with some rural frost, mist and fog. For England and Wales it will be cloudy with some rain, this will be heavy at times, especially so across parts of the Midlands and southern England in general with perhaps up to and over 20mm to 30mm falling in places. As I highlighted above the wind will also be a feature over the top of the low with a fresh or strong east or north-easterly wind across N England and the Midlands and this will create a cold and raw feel to the day here. This scenario is highlighted well by the 10KM model on the below images. ![]() TUESDAY and WEDNESDAY: Into Tuesday and Monday’s low pressure will continue to be a feature across some central and eastern areas of the country in particular. It will maintain rather cloudy conditions with some outbreaks of rain and showers at times, but through the day the weather will become increasingly dry and bright from the north and west. This is represented on the top image below with the low pressure beginning to pull away into the North Sea and note how Scotland and Ireland and more western areas of England and Wales are mainly dry by the end of Tuesday. With a lot of moisture present from the low pressure and lighter winds to end Tuesday then mist and fog could well be quite a widespread risk on Tuesday night and into Wednesday morning. Into Wednesday and a frontal system is forecast to move into more southern and western areas of the UK but the timing of this is subject to change and it may well be held at bay until later in the day. With the exception of some showers across Scotland many areas will be quite dry on Wednesday, especially away from the south-west, after a chilly and possibly foggy start. The scenario for during Wednesday afternoon is represented by the second chart below. ![]() ![]() THURSDAY and FRIDAY: The synoptic evolution for the end of the week becomes increasingly complex and there are a lot of uncertainties regarding the timing of frontal systems and, as a result, the details surrounding when areas will see spells of rain or showers. Overall what is forecast to happen is low pressure will become dominant to the west of the UK. This will introduce a much milder and potentially quite humid-feeling air mass from the south and south-west and this scenario has high confidence. Spells of rain and showers are possible at times, especially in the west and it may well become windy here too, but again the details are uncertain for now but will be reviewed mid-week. The 10KM model does highlight this evolution quite well and I’ve highlighted where the surface low pressure is and as can be seen there is a lot of fragmented areas of precipitation across the UK which produces the uncertainties as to which areas will see the most rainfall and when. Also note as well the developing south or south-westerly wind across the UK too which introduces the milder air mass to end the week. ![]() TEMPERATURES: Temperatures this week will generally start off near or slightly below average but then end up above average by the end of the week. As I highlighted earlier quite a cold and raw start to the week is expected across areas exposed to the east or north-easterly wind over the top of the high pressure, but temperatures will then slowly recover from mid-week. By the end of the week it will feel markedly different than compared with earlier in the week and overnight temperatures will be much higher as well. The change in temperatures through the week is highlighted well by the GFS model with temperatures on Monday ranging between just 8°C and 14°C with some chilly nights. However, note the difference by mid-afternoon on Friday. Temperatures across England and Wales may well be ranging between 14°C and 19°C and warmer too across Scotland and Ireland, so a very different ‘feel’ to the weather by the end of the week with some late warmth developing. ![]() SUMMARY: Changeable week ahead with some rain or showers at times, cold start to the week but becoming markedly milder, if not warmer to end the week. Risk of some heavy precipitation across parts of England and Wales during Monday then drier weather for a time Tuesday into Wednesday. However, despite uncertainties over the precipitation details for the end of the week further spells of rain and increasingly windy conditions are likely to develop. Source Info: eumetrain.org Source ................... http://www.ukweatherforecast.co.uk/weekly-analysis-cold-wet-mild-windy/#sthash.SiWOZvGl.dpuf |
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8:09 PM Jul 11