The tree on the line just before the London Road Viaduct. Picture from @GarnetBerliner on Twitter (Image: The Argus)
The railway line between Lewes and Brighton is blocked due to a fallen tree.
Southern Rail made the announcement just before 5pm.
It is a small tree partly on the track just before the London Road viaduct.
A spokesman for Southern Rail said: "Network Rail are on site and confirm that it will take approximately 30 minutes to switch the power off and remove the tree.
"The line towards Brighton will be blocked at this time."
The Met Office issued a yellow weather warning for thunderstorms which is in effect between 4am this morning and 2am tomorrow.
There was a heavy spell of wind and showers just before 5pm.
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