A developing area of low pressure is expected to track north across the UK through the weekend. The heaviest rainfall is currently expected to develop on the western flank of the low, with the western side of the Border region most at risk from widespread 20 to 40 mm of rain, and locally perhaps exceeding 50 mm in 12 hours.
This is a complex situation, and the warning may well be updated again as the situation develops.
The rain will be persistent and sometimes heavy, especially across western areas at first (Cumbria), and later over northern areas (into Dumfries & Galloway).
There remains some uncertainty in how far how far the rain will push into Scotland during the afternoon and evening but there is the possibility that the warning area will be revised again.
Strong winds will present an additional hazard later in the day and into Sunday, becoming particularly gusty along areas adjoining the northern part of the Irish Sea
The public are advised to be aware of the risk of disruption to travel and outdoor activities due to localised surface water flooding.
Rain will continue for a time into Sunday. Additionally strong winds will affect many areas for a time and are likely to gust 40-50 mph over some coasts and hills.
Conditions should improve for central and eastern areas as the persistent rain moves away but further scattered thundery downpours may occur where sunny spells develop.