There could be a “danger to life” from heavy rain and flooding across much of Wales until Tuesday, with up to a month’s worth falling within 24 hours, forecasters have warned.
An amber warning that “heavy rain is likely to bring some disruption and probable flooding”, issued by the Met Office, has been extended in most of South Wales until 11.59pm on Monday.
The warning states “fast flowing or deep floodwater is possible, which could cause a danger to life” in the majority of South Wales.
Yellow rain warnings, meaning disruption is possible, have also been issued in parts of England and Wales from the early hours of Monday to 3am on Tuesday, and for most of Monday in southwest Scotland.
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Forecasters predict 120mm (4.7in) of rain could fall in the highest ground of the area covered by the amber warning, while 20mm (0.8in) to 40mm (1.6in is expected widely and up to 80mm (3.1in) is likely in hilly parts.
The amount of rain projected to fall on Monday has caused landslides in Wales in the past, according to the British Geological Survey.
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Monday could be “a significant event for many”, and its impact will likely be greater because the ground is already saturated, the Met Office said.
Around 240mm (9.4in) has already fallen in Wales this month, almost 100mm more than its November average of 162mm (6.4in), according to one of its meteorologists.
England and Wales together have had 143% of the normal rainfall, he added.
Senior operational Met Office meteorologist Marco Petagna said: “All areas have seen above normal rainfall, Scotland and Northern Ireland are less of an issue for tomorrow [Monday], away from southwest Scotland.”
He said parts of England and Wales “have seen already well-above normal rainfall and another several inches to come”.
Monday could be a “significant event for many” with flooding and landslides possible, he warned.
“Strong south to southwesterly winds will also accompany the heavy rain, with gales possible around coasts and over high ground.”
Homes and businesses could be flooded, and there may also be transport cancellations and power cuts.
Some communities could be cut off by flooded roads, officials said.
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Natural Resources Wales (NRW) has listed 34 alerts in southern parts of Wales, warning people to be prepared for possible flooding.
Richard Preece, NRW’s duty tactical manager, said: “With some rivers already swollen and the ground saturated, we expect to see a number of flood alerts and warnings issued.”
The Environment Agency has posted three alerts that say flooding is expected and 42 warning that it is possible.
