Weather Alert: Heavy rain and snow in the southeast

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By Cyrille DUCHESNE, meteorologist

The full weather forecast live by phone at
3201*

From Thursday, November 14 at 12:00 to Friday, November 15 at 6:00.
Situation
Within a vast low pressure system on Western Europe, a secondary depression is brewing on the Gulf of Lion this Thursday and heads to the French Riviera and the Italian Riviera in the night from Thursday to Friday. It brings an episode of bad weather on the southeastern regions with heavy rain storms in the PACA and Corsica regions and snow at very low altitude from the Massif Central to the Alps.

Observation
This morning at 9amthe moderately rainy axis stretches from the Pyrenees to the Grand-Est with stormy cells that develop at the front in the Gulf of Lions and progressively win towards the lower Rhone valley. It snows from 800 meters above sea level on the central massif. During the last hour, he fell a fortnight of millimeters in Camargues, as in Aigues Mortes (30).

This morning at 7am, the rains are locally strong, but they move quickly. In the last few hours, the cold front rises from 1 to 7 mm, and the Pyrenees-Atlantiques region is locally 10 to 15 mm. As a result of blockage, the rains were stronger but they gradually lessen over the next few hours.
The snowfall is gently set up from 800 m on the Massif Central, especially on the Tarn, Aveyron and Lozere.
Evolution
This morning, degradation is gradually taking place in the south-east with rains on the Languedoc and snow from 500 meters on the reliefs of the Massif Central. The first thunderstorms occur at the end of the morning on the lower Rhone valley with high intensities of rain. The first snowfalls occur from 600 to 700 meters on the southern part of the Alps.

This afternoon, heavy stormy rains are set up on Provence and quickly win the Côte d'Azur and the Nice hinterland with rainfall intensity of 10 to 20 mm per hour on average. The wind is strong for 2 or 3 hours east of the Var and the Côte d'Azur with gusts of 80 to 90 km / h. In the Southern Alps, the snow becomes stronger and becomes abundant with a snow-fall limit of 400-500 meters. The snow falls in a moderate but durable way on the east of the Massif Central from 400 meters. By isothermal phenomenon at the end of the day, the snow can mingle with the rain until the Rhône valley. The mountains of Lyon bleach from 400 meters.

Tonight, heavy thunderstorms persist in the east of the Var and the Côte d'Azur with snow from 600 meters above sea level. The first stormy rains approach the western part of Corsica with strong gusts of wind. From the east of Auvergne and from Lyon to the Southern Alps, snowfalls are long-lasting and sometimes abundant. The snow-water limit is only 300 meters above sea level and the snow layer reaches 10 to 15 cm at an altitude of 600 meters.

In the night of Thursday to FridayCorsica will be swept by a passage of heavy rain storms. The precipitation will evacuate Provence and the Côte d'Azur. The snow will continue to fall between the eastern Massif Central and the Alps with snowfall likely to reach some valley bottoms.
At the end of the night, the weather situation will improve with a weakening of the snowfall which will be gradually evacuated by the northeast.

Here are the main features to remember from this episode of bad weather:

– High rainfall intensity in thunderstorms in the PACA and Corsica regions with significant runoff, a risk of mudslide and flooding in low points.
– rainfall totals of 60 to 80 mm over eastern Var and the Alpes-Maritimes with locally more than 100 mm, equivalent to 3 weeks of precipitation.
– a strong gale in the late afternoon on the east of the Var and the Alpes-Maritimes with gusts of up to 90 km / h and a strong swell that will break on the coast (waves from 3 to 4 meters) .
– a very low rain-snow limit (400 to 600 m depending on the massifs) with isothermal, possible snow to the plain at the end of the day and night from Thursday to Friday in average Rhone Valley and Lyon.
– lasting snowfall on the eastern Massif Central, the Southern Alps to Isere. We expect 10 to 15 cm to 600 m on the east of the Massif Central and snow heights more consistent on the Southern Alps with up to 60 cm to 1000 m altitude.
– a wet and sticky snow that could cause problems of circulation on the plateaus at low altitude and damage to electrical networks and vegetation.

List of departments concerned

  • 01 – Ain Snow – Important Risk

  • 04 – Alpes de Haute Provence Precipitation – Important Risk

    Snow – Important Risk

  • 05 – High mountains

    Snow – Important Risk

  • 06 – Alpes-Maritimes

    Precipitation – Orange Alert

    Thunderstorms – Orange Alert

    Wind – Important Risk

  • 07 – Ardeche

    Precipitation – Important Risk

    Snow – Orange Alert

  • 13 – Bouches-du-Rhône

    Precipitation – Orange Alert

    Thunderstorms – Orange Alert

  • 2A – Corse-du-Sud

    Precipitation – Important Risk

    Thunderstorms – Important Risk

  • 2B – Upper Corsica

    Precipitation – Important Risk

    Thunderstorms – Important Risk

  • 26 – Drôme

    Precipitation – Orange Alert

    Snow – Orange Alert

  • 38 – Isere

    Snow – Orange Alert

  • 42 – Loire

    Snow – Orange Alert

  • 43 – Haute-Loire

    Snow – Important Risk

  • 48 – Lozere

    Snow – Important Risk

  • 69 – Rhône

    Snow – Orange Alert

  • 83 – Var

    Precipitation – Orange Alert

    Thunderstorms – Orange Alert

  • 84 – Vaucluse

    Precipitation – Orange Alert



Source link
https://actualite.lachainemeteo.com/alerte-meteo/4748-fortes-pluies-et-neige-au-sud-est

Dmca

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