High pressure dominates the south for the rest of September, unsettled at times towards the NW. Perhaps an unsettled start to early October, but temperatures still above average in the south.
General synopsis for next 14 days.
Mean upper troughing and surface low pressure will persist to the N and NW of the UK throughout this week and next week, bringing a threat of cloudier conditions with some rain to northwestern areas at times. Upper ridging and high pressure will spread east across southern Britain and the near continent, bring mostly fine and settled conditions with above average temperatures here. Troughing to the NW may eventually spread SE towards the UK next week, bringing rain to western areas later next week.
Short Term (until the end of this week)
Upper level troughing and surface low pressure will dominate across Greenland, Iceland and Norwegian Sea areas for the rest of this week. Weather fronts from these low pressure systems to the NW of the UK will pass over the UK over the next few days, bringing cloud and rain at times today and tomorrow for many areas. A cold front will slip south across central areas today, bringing cloud and rain which will turn locally heavy, this front and its rain reaching southern areas tonight, before clearing SE England by 12z Wednesday. An occluded front follows from the northwest, bringing rain southeast across northern Britain later today and overnight, before clearing southeast into the North Sea Wednesday morning.
A ridge of high pressure then builds in from the SW for the rest of Wednesday, confining any rainfall to northern Britain Wednesday onwards to the end of the week. A deepening depression moving NE close to Iceland on Thursday, will draw Tropical maritime warm air advection in from the Atlantic, bringing a warmer and more humid end to the week for many. This warmer air moving in behind a warm front crossing the UK on Thursday, which will bring low cloud, light rain or drizzle and hill fog across northern areas, these conditions perhaps spreading further south Thursday night. A weak cold front moving southeast on Friday should clear the low cloud and drizzle from most areas by the afternoon to brighter clearer conditions.
Longer Term (this weekend through to the first weekend of October)
Upper ridging and surface high pressure are indicated to become more prominent across southern Britain over the weekend, so expectations are for predominantly dry weather with above normal temperatures across England and Wales, particularly by Sunday – with temperatures of 23-24C possible across S England with any sunshine. Lower pressure towards NW Britain and glancing Atlantic weather fronts across the far north suggests cloudier conditions with outbreaks of rain at times for W Scotland and N Ireland over the weekend.
Into next week, model indications are that there will be a mean upper ridge and surface high over the near continent for much of the week, with mean upper trough extending south across the far north Atlantic from Greenland, with a conveyor of low pressure systems passing across Iceland. Therefore, England and Wales, along with eastern Scotland are likely to stay mostly dry and fine early on in the week, with temperatures above normal for the time of year. Cloud and rain could affect the northwest at times early in the week, with a risk of more persistent and heavy rain moving in across northern and western areas from mid-week, as high pressure retreats southeast, central, southern and eastern areas perhaps remaining dry and warm all week though.
Both GFS and ECMWF weather models, for now, indicate the mean trough to the NW eventually translating south and east across the UK for the first weekend of October, bringing unsettled conditions to all areas, but temperatures still above average across the south. So perhaps an unsettled start to early October, but still warm in the south.
