A cold drop is a term used in Spain and France that has commonly come to refer to any high impact rainfall event occurring in the autumn along the Spanish Mediterranean coast or across France. In Europe, cold drops belong to the characteristics of the

Mediterranean climate A Mediterranean climate ( ), also called a dry summer climate, described by Köppen and Trewartha as ''Cs'', is a temperate climate type that occurs in the lower mid-latitudes (normally 30 to 44 north and south latitude). Such climates typic ...

. The Spanish-language name of was directly adapted from the term introduced by German

meteorologists A meteorologist is a scientist who studies and works in the field of meteorology aiming to understand or predict Earth's atmosphere of Earth, atmospheric phenomena including the weather. Those who study meteorological phenomena are meteorologists ...

, and became very popular in 1980s Spain as a blanket term to refer to any high-impact rainfall event. In the Spanish Levante, these events are typically caused by the interaction of upper-level low pressure systems strangled and ultimately detached from the zonal (eastward) circulation displaying stationary or retrograde (westward) circulation with humid warmer air masses that form over an overheated

Mediterranean Sea The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...

in the

Autumn Autumn, also known as fall (especially in US & Canada), is one of the four temperate seasons on Earth. Outside the tropics, autumn marks the transition from summer to winter, in September (Northern Hemisphere) or March ( Southern Hemisphe ...

. The Spanish equivalent of cut-off low is DANA (''Depresión Aislada en Niveles Altos'').National Geographic Spanish edition article about DANA)
/ref> Such recurring synoptic configurations are not necessarily associated to cold drop events.

Occurrence

Spain

If a sudden cut off in the jet stream takes place (particularly on the

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

), a pocket of cold air detaches from the main

jet stream Jet streams are fast flowing, narrow thermal wind, air currents in the Earth's Atmosphere of Earth, atmosphere. The main jet streams are located near the altitude of the tropopause and are westerly winds, flowing west to east around the gl ...

, moving southward over the

Pyrenees The Pyrenees are a mountain range straddling the border of France and Spain. They extend nearly from their union with the Cantabrian Mountains to Cap de Creus on the Mediterranean coast, reaching a maximum elevation of at the peak of Aneto. ...

into the warm air over

Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...

, causing its most dramatic effects in the southeast of Spain, particularly along the Spanish

Mediterranean The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern ...

coast, especially in the

Valencian Community The Valencian Community is an Autonomous communities of Spain, autonomous community of Spain. It is the fourth most populous Spanish Autonomous communities of Spain, autonomous community after Andalusia, Catalonia and the Community of Madrid wit ...

. The torrential rain caused by a cold drop can result in devastation caused by torrents and flash floods. This phenomenon is associated with extremely violent downpours and storms, but not always accompanied by significant rainfall. For this, high atmospheric instability in the lower air layers needs to combine with a significant amount of moisture.

Disasters

The great Valencia flood on 14 October 1957 was the result of a three-day-long cold drop and caused the deaths of at least 81 people. The Vallès floods on 25 September 1962 in the

province of Barcelona Barcelona (; ) is a province of eastern Spain, in the center of the autonomous community of Catalonia. The province is bordered by the provinces of Tarragona, Lleida, and Girona, and by the Mediterranean Sea. Its area is .Llobregat and Besòs rivers. The official death toll was 617. On the night of 29-30 October 2024, a DANA event caused considerable loss of life and extensive damage, especially in the

and the provinces of

Albacete Albacete ( , , ) is a city and municipality in the Spanish autonomous community of Castilla–La Mancha, and capital of the province of Albacete. Lying in the south-east of the Iberian Peninsula, the area around the city is known as Los Llan ...

Almería Almería (, , ) is a city and municipalities in Spain, municipality of Spain, located in Andalusia. It is the capital of the province of Almería, province of the same name. It lies in southeastern Iberian Peninsula, Iberia on the Mediterranean S ...

, and

Málaga Málaga (; ) is a Municipalities in Spain, municipality of Spain, capital of the Province of Málaga, in the Autonomous communities of Spain, autonomous community of Andalusia. With a population of 591,637 in 2024, it is the second-most populo ...

Other areas

Cut-off lows are apparent near the

Sierra Nevada de Santa Marta The Sierra Nevada de Santa Marta (English: ''Snow-Covered Mountain Range of Saint Martha'') is an isolated mountain range in northern Colombia, separate from the Andes range that runs through the north of the country. Reaching an elevation of ...

in the Colombian Caribbean, with peaks surpassing 5 km in altitude in close proximity to a warm sea. They can also occur elsewhere in the southern hemisphere, such as in

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

Namibia Namibia, officially the Republic of Namibia, is a country on the west coast of Southern Africa. Its borders include the Atlantic Ocean to the west, Angola and Zambia to the north, Botswana to the east and South Africa to the south; in the no ...

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

and southern

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

. In the northern hemisphere, besides

Southern Europe Southern Europe is also known as Mediterranean Europe, as its geography is marked by the Mediterranean Sea. Definitions of southern Europe include some or all of these countries and regions: Albania, Andorra, Bosnia and Herzegovina, Bulgaria, C ...

and

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

, they can occur in

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

and

Siberia Siberia ( ; , ) is an extensive geographical region comprising all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has formed a part of the sovereign territory of Russia and its predecessor states ...

North Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the contine ...

Northeastern United States The Northeastern United States (also referred to as the Northeast, the East Coast, or the American Northeast) is List of regions of the United States, census regions United States Census Bureau. Located on the East Coast of the United States, ...

and the northeast Atlantic.

Notes

References