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Weekend Analysis – Cooler with Rain and Showers By Matt Hugo - October 31, 2014
Topic Started: 31 Oct 2014, 10:57 PM (60 Views)
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Weekend Analysis – Cooler with Rain and Showers
By Matt Hugo - October 31, 2014 15:10




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Weekend Analysis – Cooler with Rain and Showers



OVERVIEW: October is clearly ending on a particularly warm spell of weather (22C has been recorded at Cranfield, Bedfordshire for example this Friday afternoon) but as you would imagine at this time of year the warmth won’t last and the overal progression this coming weekend is towards something far more typical for early November as rain and showers develop and temperatures fall to nearer average values, especially across the north and west.

ANALYSIS: We’ll start by taking a look at the broader synoptic features that are dominating the weather at the moment and how these will progress over the weekend. As usual water vapour can provide a lot of information and the recent water vapour image with 500mb heights is overlaid below.

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1) The warmth to end October is due to the combination of an area of low pressure to the NW of the UK (area 2) and a ridge of high pressure to the south and south-east, which is region 1. This combination is allowing for a very mild, if not warm and moist SW’ly air mass to develop across many areas through Friday producing the particularly high temperatures. However, this ridge of high pressure is set to decline into the near continent this weekend and this process will allow for much cooler, if not colder weather to develop.

2) This is a region of low pressure at the surface and within the upper atmosphere (an upper vortex) and it is expected to remain quite slow moving to the north-west of the UK throughout the weekend. An active weather front associated with this low pressure is currently across Ireland and is bringing outbreaks of rain. As the upper ridge declines this area of low pressure will then become the dominant feature of the weather and the weather front associated with the low pressure will then have the opportunity to move across all areas of the country overnight tonight and into Saturday and introduce a much cooler air mass.

SATURDAY and SUNDAY: This change to more unsettled and cooler conditions will take place overnight and many western areas of the UK will become fresher into the early hours of Saturday whilst the quite warm and humid conditions will persist across the eastern half of the UK in what will be an exceptionally mild night across England and Wales tonight for the time of year. The 10KM model highlights the situation well and the cold front by Saturday morning is expected to be situated from Newcastle down through the Midlands and down towards the Isle of Wight. Once again ahead of this it will be a mainly dry start to Saturday and it will continue to feel quite warm, behind this feature it will be cooler and fresher with a scattering of showers across Scotland, Ireland, N England and Wales.

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During Saturday afternoon and into the overnight period a developing area of low pressure is expected to take place to the west of the UK and this will re-introduce a risk of more organised spells of rain and showers later on Saturday. The low pressure develops within the base of the vortex that is situated to the north-west of the UK throughout the weekend. This developing feature then is expected to quickly move into many western areas by Saturday evening bringing a spell of wet and windy weather. The feature in question can be seen on latest satellite imagery and I’ve highlighted where the low pressure is expected to develop from on the images below and it is currently within the Central North Atlantic.

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Ahead of this feature some drier and brighter weather is expected across England and Wales for a time, but clearly a particularly wet and quite windy Saturday evening and overnight period is then to be expected as active frontal system sweep eastwards across many areas but it will take until Sunday for the fronts to clear SE England as a potential frontal wave may develop and this will delay the process. The approaching rainfall is highlighted well by the 10KM model for 2100GMT on Saturday with many western areas of the UK quite wet and windy, but still dry in the east and then note the rainfall is still expected across parts of S and SE England well into Sunday morning, as highlighted by the image on the right for 1100GMT on Sunday.

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SUMMARY: The unusual warmth of today (31st Oct) is expected to be replaced by much cooler and fresher conditions this weekend as weather fronts move across the UK and introduce a much cooler and fresher W or SW’ly air mass off the N Atlantic across all areas. One spell of wet weather is expected overnight in Saturday but with very little rain reaching SE England into Saturday morning and across SE England it will remain quite warm still for most of Saturday. However, it will then turn quite wet and windy from the west later on Saturday and overnight into Sunday as a more significant spell of wet and windy weather affects many areas and reinforces the change to cooler conditions as well by the end of the weekend.

TEMPERATURES: Temperatures across SE England still reaching 17C to 19C on Saturday, but elsewhere it will be a much cooler and fresher day with temperatures back down to nearer average values and feeling markedly cooler than compared with Friday. Many other areas of the UK seeing temperatures ranging between 10C and 14C. Into Sunday and maximum temperatures across Scotland, Ireland, N England and Wales will be between 9C and 13C and across other areas of England temperatures are likely to range between 11C and 16C. It won’t be until later in the day on Sunday that the much cooler and fresher conditions will reach SE England.



Chief Forecaster: MH

Source Info: eumetrain.org | mag.ncep.noaa.gov



Link .......... http://www.ukweatherforecast.co.uk/weekend-analysis-cooler-rain-showers/#sthash.egB1PFIx.dpuf



Source ............... Posted Image
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