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| Weekly Analysis – Often Wet and Windy By Matt Hugo - October 19, 2014 | |
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| Tweet Topic Started: 19 Oct 2014, 01:01 PM (58 Views) | |
| Audi-Tek | 19 Oct 2014, 01:01 PM Post #1 |
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Weekly Analysis – Often Wet and Windy By Matt Hugo - October 19, 2014 10:57![]() OVERVIEW: The coming week will provide quite ‘typical’ October weather really with some drier and brighter intervals but equally there will be some spells of wet and windy weather too. Of primary significance this week will be an area of low pressure that will cross the UK that will originate from the remnants of hurricane Gonzalo. This will bring a spell of wet and windy weather late in the day on Monday and overnight into Tuesday. Further spells of wet and windy weather are expected across the northern half of the UK through the latter half of the week, but there are uncertainties over Thursday and Friday’s weather at the moment. ANALYSIS: Through the coming week the weather will progress towards what is known as a more ‘mobile/zonal pattern’. This is essentially when the jet stream has a track that is more directly west to east across the North Atlantic rather than meandering from north to south or south to north as it has done of late. Some primary features of interest that relate to this development can be seen on recent water vapour imagery. ![]() 1) This is an upper trough that is expected to disrupt and become a closed area of low pressure over the Azores in the coming few days. This was responsible for the very mild conditions during Friday and Saturday, but clearly it is declining away to the south-west of the UK. This process of it disrupting allows for the flow to the north of it to become more zonal and have a west to east orientation. 2) The more zonal and mobile pattern is in evidence here across the far North Atlantic. Note how the green lines (500mb geopotential heights) stretch from just to the west of the UK all the way back towards Canada and this is the more mobile and zonal pattern. Clearly this regime allows areas of low pressure to develop and then track towards the UK. MONDAY and TUESDAY: The early part of the week will be dominated by the remnants of hurricane Gonzalo being ‘picked up’ by the jet stream and being allowed to develop into a significant low pressure system as it crosses the UK. Before that Monday provides a bright and breezy day with a simple mixture of sunshine and showers. The showers may merge to give longer spells of rain across the northern half of the UK for a time, but in-between it will be drier and brighter. For many central and southern areas of England it is likely to be predominantly dry, especially across SE England. This scenario is highlighted well by the 10KM model and of which is also picking up the area of low pressure, containing the remnants of Gonzalo, to the west of the UK. ![]() The approaching low pressure will bring an increasingly wet and windy overnight period on Monday night, initially to Scotland and Ireland but extending to many other areas into the early hours of Tuesday. For more specific details on this development then see the analysis produced yesterday at the following link – http://www.ukweatherforecast.co.uk/remnants-gonzalo-analysis-outlook/ - An update to this is expected to be issued on Monday morning. For many areas on Tuesday morning it will be wet and very windy with gales, locally severe gales in places, especially across the northern half of the UK and around coasts and hills. This development of initial wet and windy conditions spreading into more northern and western areas and then progressing eastwards by Tuesday morning is highlighted well by the 10Km model. As the low pressure then quickly clears to the east throughout the remainder of Tuesday the day is then dominated by a chilly NW’ly wind which will simply bring a mixture of sunshine and blustery showers. The showers also perhaps turning to sleet and snow across the hills and mountains of Scotland, especially above 1500ft or so. ![]() WEDNESDAY: By the time we get to mid-week the more mobile/zonal pattern will be well established across the North Atlantic and this will signal another low pressure and frontal systems approaching from the west. Wednesday, as a result, is likely to start predominantly dry but outbreaks of rain, drizzle and showers are likely to develop across N Ireland, Scotland and N England through the day along with a gusty westerly wind. With high pressure situated just to the south of the UK then many central and southern areas of England and Wales are set fair on Wednesday with some bright or sunny spells. This evolution is highlighted well by the forecasted jet stream pattern by mid-week and note the general flat and west to east track of the jet stream across the North Atlantic and into the UK, before it then dives down into Central Europe. The 10KM model picks up on the precipitation across more northern areas as well for the middle of Wednesday and I’ve highlighted where the high pressure is likely to be mid-week and that is just to the south and south-west of England. ![]() THURSDAY and FRIDAY: There is some uncertainties surrounding the end of the week at the moment as it would seem that a possible frontal wave will develop somewhere across central areas of the UK. Overall though the general trend for more northern and western areas of the UK to be at risk of showers and longer spells of rain continues, whilst for more southern areas further dry weather is likely. Depending on where the possible frontal wave develops then more prolonged spells of rain are likely, some of which could be heavy as well. For now, a north and south split in conditions is preferred and using the 10KM model to highlight that (left image). Also note the accumulated precipitation totals from present day to the latter stages of Thursday (right image) with some southern and south-eastern areas of England experiencing very little rainfall compared with further north and west and this places emphasis on Ireland, Scotland, N England and Wales seeing most of the rainfall through this coming week. ![]() TEMPERATURES: Temperatures this week will, overall, be near to average but there will be quite significant variations taking place at times through the week. One significant variation will occur behind the eastward moving low pressure on Tuesday. As this clears it will introduce a chilly NW’ly air mass and, as a result, Tuesday is expected to be the coldest day of the week. However, as the westerly flow returns on Wednesday then temperatures will rise slightly from the middle of the week onwards. Temperatures, as a result, are expected to range between 10°C and 14°C across Scotland, Ireland and N England through the week and between 12°C and 16°C across central and southern areas of England and Wales. Clearly any persistent rain and windy weather will make things ‘feel’ cooler as well. Overall there’s no risk of frost this week, Tuesday night may well be the coldest night of the week but increasing cloud and wind from Wednesday onwards will signal quite mild nights. Chief Forecaster: MH Source Info: eumetrain.org | mag.ncep.noaa.gov Source ............... http://www.ukweatherforecast.co.uk/weekly-analysis-often-wet-windy-2/#sthash.ZEwNwlkl.dpuf |
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8:08 PM Jul 11