Rain with 0 degrees in the Channel: why no snow?

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Ce Saturday January 4, 2025throughout the day, the mercury struggled to reach the positive side. Early in the morning, thanks to clear skies, it even dropped to -5.9°C in Équilly, near Granville, or -4.1°C in Bricquebec (Manche).

Then the clouds piled up above the Channel, as a storm approached. perturbation going up through the Atlantic. This one, full of precipitationreturned to Normandy still kneaded by the cold. While the temperature flirted with 0 degrees at the end of the day, rains were invited without them passing through a solid state. How can we explain the absence of snowwhen the conditions seemed to be met?

Redux at altitude

If in the lower layers of the atmosphere, the air barely regained a few degrees, at altitude, the air quickly softened. Indeed, while it was 0 degrees in Cherbourg around 6 p.m. under a light rain, the disturbance drained with it much milder air towards 1,500 meters of altitude, transforming the solid precipitation falling from the clouds into rain .

This meteorological characteristic is common in winter, during significant mild spells. And she gives him slippery phenomena on the roadsmuch more treacherous than the snow, the freezing rain.

This is how around thirty departments in the north of France found themselves, this Saturday, on orange alert for this phenomenon. At the edge of the persistent cold air, the episode was very short-lived in the Cotentin, requiring no particular vigilance.

This Sunday, the warm weather is widespread. Gentleness has taken over all levels of the atmosphere. Between Saturday and Sunday, the thermal amplitude is even strikingof the order of 10 to 12°C.

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