Carmarthenshire bore the brunt of Storm Callum as parts of mid and west Wales were hit by the worst flooding for the last 30 years.
"As well as coastal flooding very heavy rain is likely to occur in southern and southeastern parts of the country during Callum and from a second weather system during Saturday. Some roads and bridges may close".
Officers are "dealing with" the landslide and the road will be closed for some time, the force said, adding the family of the dead person is being supported by specialist officers.
There are more than 20 flood warnings for Wales and three in Dorset and Hereford. "We have already seen this impact on the roads and we could see more flooding as the rain flows down from the mountains".
In the West Midlands people are being warned to check before they travel due to disruption on the railways.
Several flights have been cancelled out of Dublin and Belfast due to the storm. "That's quite a substantial amount of rain to come and could bring flooding".
"The rain will continue to push northwards through Saturday night, though it will linger in the far north and northern isles".
Thousands of homes were left without power, and the storm lead to school and business closures and one fatality.
Dyfed-Powys Police confirmed Corey was the victim of the landslide which happened at 5pm on Saturday evening.
About 100 sheep washed away in flood waters in Carmarthenshire.
Secretary of State for Wales Alun Cairns has spoken of his sadness at the loss of life during Storm Callum.
A search was launched yesterday afternoon after reports that a man had fallen into the swollen waters of the River Taff in Cardiff.
"Once again members of our police, fire and rescue and voluntary services have done an excellent job to try to keep people safe and communities connected during some of the worst weather conditions we have seen in decades".
The temperature at Weybourne (Norfolk) is now 25.7 °C, making today the warmest October day in 7 years.
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