Yellow weather warning issued for heavy rain for parts of Lancashire this weekend
As much as 40-60 mm of rain is expected in 24 hours, with the possibility of as much as 100 mm over higher ground.
Residents have been warned to expect difficult driving conditions, the possibility of power cuts to homes and business and a chance of flooding.
A Met Office spokesman said: "Rain is expected to arrive across parts of the UK during Friday and become heavy and persistent, this is especially true for high ground exposed to the strong southwesterly wind.
"There remains some uncertainty to the locations likely to see the highest rainfall totals.
"This rain is expected to continue falling in similar areas for around 24 hours.
"As such during this period 40-60 mm of rain is likely, with perhaps as much as 100 mm over higher ground."
What to expect
• There is a small chance that homes and businesses could be flooded, causing damage to some buildings
• There is a small chance of fast flowing or deep floodwater causing danger to life
• Where flooding occurs, there is a slight chance of delays or cancellations to train and bus services
• Spray and flooding could lead to difficult driving conditions and some road closures
• There is a small chance that some communities become cut off by flooded roads
• There is a slight chance of power cuts and loss of other services to some homes and businesses