UK issued yellow wind and rain warning as low-pressure system may become first named storm

The Met Office has issued a yellow warning for wind and heavy rain for parts of England and Wales as an area of low pressure develops beneath a powerful 160 mph Atlantic jet stream, raising the possibility it could strengthen into the season's first named storm.

The warning is in force from 20:00 BST on Sunday until 18:00 BST on Monday and covers large parts of the south and west of England and much of Wales. Forecasters said Sunday will begin relatively bright but that heavy outbreaks of rain will spread across the region and winds will increase, with gales developing in coastal and upland areas.

The Met Office said gusts of 50-60 mph are likely around coasts and hills, which could bring down some tree branches and cause localised disruption. There is a chance that gusts could reach 70-80 mph in exposed locations, with the greater winds increasing the risk of fallen trees, transport delays and power outages. Widely 10-30 mm of rain is expected, with some western hills receiving around 70 mm, raising the prospect of surface water flooding and difficult driving conditions.

Forecasters noted an additional hazard this autumn: an early "false autumn" has led to premature leaf fall in some areas, increasing the likelihood that drains could be blocked by leaves and exacerbating flood risk on urban streets.

Whether the developing low-pressure system will be named Storm Amy depends on how much it intensifies over the coming days, the Met Office said. Officials cautioned that the exact track and strength of the system will determine the areas most affected and whether gusts reach the higher end of current projections. Residents and authorities were urged to monitor updates and heed any local travel or safety advice.

There will be continued showers and some thunderstorms across the UK in the days before the low-pressure system arrives, with sunny spells between downpours. Showers are expected to merge into longer spells of rain in parts of west Scotland on Saturday, ahead of the weekend's more widespread wet and windy weather.

The change to more unsettled conditions comes after a period of notable weather contrasts this year. The UK experienced its hottest summer on record but for many regions that summer was unusually dry. In recent weeks a series of low-pressure systems has already brought widespread rain and showers, and some areas in the north and west have recorded more rainfall than average for September even before the month is half over.

Meteorologists said the autumn transition typically brings a more active jet stream, which can steer stronger Atlantic systems towards the UK. That pattern is in place for the coming days, with the intense upper-level jet stream contributing to the potential for a stronger and more wind-driven storm.

Local authorities and transport operators said they were monitoring the forecast and preparing for possible disruption. Motorists were reminded to drive to conditions, allow extra time for journeys and be aware of the potential for spray and surface water during heavy rain. People are advised to secure loose garden items and check for local warnings.

The Met Office and national weather services will issue updates as models converge on the system's intensity and track. Members of the public can follow the latest official forecasts and warnings to stay informed about developments over the coming days.