The National Building Research Organisation has warned that landslides could be triggered in areas left unstable by Cyclone Ditwah, as a disturbance over the Bay of Bengal strengthens towards Sri Lanka.

NBRO geologist Wasantha Senadeera told a media briefing on Wednesday that warnings had been issued for 12 divisions, the Daily Mirror reported. He said residents in those areas should be vigilant.

Where the warnings apply

Senadeera said sand erosion could also occur, and that residents might see water flowing mixed with sand — a sign slope material is moving.

The significance of the warning is the ground condition rather than the rainfall. Slopes destabilised during Cyclone Ditwah can fail under rain that would not otherwise be enough to move them, which is why divisions on this list may slip before the heaviest falls arrive.

The forecast, and a change from yesterday

Merril Mendis, Director of Forecasting at the Department of Meteorology, said the Bay of Bengal disturbance is expected to deepen into a depression that will affect Sri Lanka.

“The Depression is expected to travel parallel to the Eastern coast of Sri Lanka and this could trigger effect Sri Lanka. Heavy rains can be expected in the Western, North Central, Central and Sabaragamuwa provinces after November 13,” he said.

That differs from the department’s position a day earlier in two respects, and no filing reconciles them. This desk reported on Wednesday that forecasters expected the system to bring heavy rain to the east coast from around 15 November. Mendis places the heavy rain on the other side of the island — Western, North Central, Central and Sabaragamuwa — and brings the date forward to after 13 November. The track itself is unchanged: both accounts have the system moving parallel to the east coast.

Readers should treat the province list and the date as the department’s current statement rather than a settled forecast. This system’s described geography and timing have now shifted more than once.

Mendis added that Sri Lanka will generally see wet weather until January, followed by a dry spell from January to April which he attributed to El Niño.

Eleven drownings in a fortnight

The Disaster Management Centre disclosed that 11 people have drowned in Sri Lanka in the past fortnight after bathing in high-risk areas.

The public has been asked to heed warnings from the Department of Meteorology, the NBRO and the DMC, to avoid excursions, and to stay out of rivers.

Not reported

The filing does not give warning levels — whether these are amber or red alerts — or say how long the warnings remain valid. It gives no rainfall thresholds for the divisions listed, no count of households at risk and no evacuation advice. It does not state when Cyclone Ditwah struck or which of the listed divisions were damaged then. Nothing explains the shift in the forecast province list, and the depression is not named or given an expected date of formation.