Why last night’s rain didn’t stop: NCM explains ‘main wave’ behind UAE storm

A slow-moving 'main wave' within a broader weather system kept rain pouring over the UAE for up to nine hours overnight, triggering flooding and near-constant lightning – a sharp shift from the shorter rain bursts seen earlier this week.

The prolonged downpour that swept across the UAE late Thursday into Friday was caused by a slower, more dominant weather wave, according to the National Centre of Meteorology (NCM).

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Dr Ahmad Habib said earlier rainfall episodes during the week were driven by shorter, fast-moving disturbances, typically lasting between six and ten hours or less.

“Those were smaller waves within a larger system, moving quickly across the country,” he explained. “But what we saw overnight was the main wave, and it behaved differently.”

The system moved into Abu Dhabi around midnight and persisted until early morning, resulting in nearly nine hours of continuous rainfall in some areas.

Why it lasted longer

According to Dr Habib, the main wave slowed down as it reached the UAE, particularly as it transitioned from land into areas influenced by surrounding water bodies.

“This type of transition changes the dynamics of the system,” he said. “Moisture increases, instability increases, and the movement becomes slower – so rainfall lasts longer.”

The system also pulled in large amounts of moisture from the Arabian Sea and Red Sea, fuelling cloud development across the country.

Lightning ‘one after another’

Residents reported near-constant lightning throughout the night – something Dr Habib said was expected given the type of clouds involved.

“All the clouds were convective, meaning they were electrically active,” he said. “As long as these clouds persist, lightning continues, which is why people saw it happening continuously.”

Flooding linked to duration, not just intensity

While rainfall totals were significant – with some areas recording up to 77.5mm - the flooding seen in parts of the country was largely due to how long the rain lasted, rather than extreme hourly intensity.

“When rainfall continues for long hours, even moderate rates can lead to water accumulation,” he explained.

Worst over, but caution remains

Dr Habib confirmed that the most intense phase has now passed, though scattered rain may continue.

“There may still be some rainfall, but not at the same intensity,” he said, urging residents to remain cautious around standing water.

“Water pools remain the main risk after the rain ends.”