A succession of extreme weather events have happened in the Mediterranean basin since the beginning of October.
Generally, when Arctic air flows in the Mediterranean during fall, when the sea temperature is still warm, which is especially true this year with an average water temperature above 20°C, the coast can be impacted by severe episodes of quasi tropical storms.
Storm Adrian which swept the south of Europe on Monday October 29 caused very strong winds, particularly in Corsica, and exceptional snowfall on the Massif Central with a cold intensity rarely equaled by late October.
This situation is the result of very cold air of polar origin extending to the Mediterranean which encountered hot air from Tunisia to Italy. It was this violent conflict that caused strong instabilities. Thanks to a persistent high pressure field in Europe, this particular configuration has allowed these low pressures to form intense and slow-moving storms.
Peaking at 980hPa between Var and western Sardinia in the early afternoon of Monday, Adrian produced very rainy and windy thunderstorms between Var, Alpes-Maritimes and Corsica in the morning. In addition to locally important downpours (sometimes 80/100 mm in 3h near Cap Corse), hailstorms and violent gusts have been recorded (locally 100/130 km/h during thunderstorms). Maximum gusts of wind reached records with a peak at 189 km/h at Cape Pertusato. A tornado was officially reported in Tanneron at the limit between the Var and the Alpes-Maritimes. Strong waves have also caused a lot of damage and some floods have been observed locally on the most vulnerable parts of Corsica and the French Riviera.
<- Adrian took a form almost cyclonic arriving on Corsica developing an "eye" quite clearly defined (source: sat24)
Important snowfall were particularly significant in other parts of the country for this time of year. These snowfalls were first brought by the shock between the warm stream coming from the south and cold air at the level of the Massif Central, producing severe cold weather. With an average temperature of 6°C, this is the coldest ever observed in October in France. It was colder than in the heart of winter in most of our regions, except in the southeast.
If Corsica and eastern side of the french Riviera were the most severely affected areas, the storm did not stop at the border. In Liguria, damage are even more spectacular. The region of Genoa, where the wind broke records up to 180 km/h, was the most impacted. Wind gusts exceeded 115 km/h in some areas ripping trees, destroying several boats, damaging coastal infrastructures and suspending train traffic. Residents of the old port of San Remo had to be evacuated at night due to the threats of storm surges. At least nine people lost their lives as a result of Adrian hitting Northwest Italy.
Ana was the first storm to be officially named by the national meteorological services of France (Météo-France), Spain (Aemet) and Portugal (IPMA) for the 2017/2018 season. It formed on 10 December as an area of low pressure that underwent explosive cyclogenesis to the northwest of Iberia passing through the Bay of Biscay into France on the morning of December 11. It then took a northeasterly direction to affect the Netherlands, Germany, Austria, Scandinavia and eventually Russia. Its highest gusts reached 249 km/h in the Austrian Alps and its minimal pressure reached 957 hPa on the morning of December 11.
Storm Bruno (alias Edilbert) originated from a strong depression on the east coast of Canada and was off the coast of Newfoundland on December 25. The next day she was south-west of Ireland making her way to the French coast. Bruno passed on France on December 27th causing high air mass instability on the Atlantic coast and triggering explosive cyclogenesis. South west was the region most affected by these thunderstorms in the departments of Gironde, Landes, Pyrénées-Atlantiques, Charente-Maritime and Vendée. During the day of December 27, the axis of strong winds and storms moved towards the western Mediterranean. On December 28, weather maps showed that Bruno had traveled to the Scandinavian countries and that a reformation named Felix had occurred in the Gulf of Genoa from the unstable air mass passing over the Mediterranean. Storm Bruno has caused a severe wind advisory for southern Corsica and the Pyrenean region. The gusts of wind were notable in the Basque Country and the Gulf of Lion where they exceeded 140 km/h several times. This storm also produced a particularly violent blizzard on the Alps and the Jura mountains.
On December 29, storm Carmen, also named Ingmar by the Free University of Berlin, was expected in France which she approached from the northwest (Brittany) between December 31 and January 2. The following day, 19 departments were put on orange alert by Météo France. On January 1st, gusts blowing at over 130 km/h and waves of five meters impacted the south west of France. Strong gusts were recorded in the north west of the country: 129 km/h in Camaret, 109 km/h at Pointe du Raz and 91 km/h at Ouessant (Finistère). The orange alert was lifted in the early evening for the 19 departments concerned, except for parts of Gironde which remained under flood alert, and Corsica until tuesday morning January 2.
Storm Eleanor (also named Burglind by the Free University of Berlin) was named so by the Irish Meteorological Service (Met Éireann) on January 1st. The service issued a severe weather alert the next day for winds of 110 to 130 km/h. The British service (Met Office) issued its own alerts for the 2nd and 3rd of January for Northern Ireland and Scotland. As Eleanor approached, heavy rains swept Ireland and winds of 84 knots (156 km/h) were recorded at Knock Airport in northwestern Republic. The worst wind damage, however, was in Northern Ireland in the British Isles: winds of 90 miles per hour (145 km/h) were recorded at Orlock Head and 100 miles per hour (161 km/h) at one station of Great Dun Fell. While heading to the north east, the storm showed signs of formation of an occlusion jet stream in its southwestern region, a zone of extremely violent winds, but it did not develop completely. However, thunderstorms started to develop in this area producing hail in England and Wales. On January 3rd in France (north), part of the roof of the steeple of the church of Saint Rictrude (Marchiennes) was blown away and found in a neighboring public square. On January 7, officials report six dead and two missing in France.
In the voice of the cicada,
How soon it will die.
Reading weather maps
The isobars of a weather map are lines that connect areas of equal atmospheric pressure. The pressure is usually noted on every other isobar so you can see the pattern of pressure distribution. The point with the highest pressure is called a High. It is usually marked with a capital letter “H”. This high pressure center is surrounded by concentric circles of isobars, the isobars closest to the center of the High will have a higher number, than the ones further out. The area with the lowest pressure on the map is called a “low”, this is designated by a capital “L”.
The atmospheric pressure will attempt to reach an equilibrium, so air will flow from a high pressure area toward a low pressure area. The horizontal flow of air is called wind. The wind blows from High to Low, but not directly. Because of the earth’s rotation (Corriolis force) the wind will blow more parallel to the isobars. The wind blows clockwise around a High in the northern hemisphere. The Wind blows counterclockwise around a Low in the northern hemisphere. In the southern hemisphere the wind rotational direction is reversed. A lot of lines close together means strong winds. Areas with widely spaced isobars will have little or no wind.
On a weather map, you will notice some lines that have semi-circles or triangles on either side, or both. These indicate the boundaries for various types of fronts:
1. Cold front: Rainfall can be torrential and wind speeds can be high. Represented on a weather map as a (blue) line with triangles bordering one side. The direction that the triangles point is the direction in which the cold front is moving.
2. Warm front: Often brings a gradual increase in rainfall as the front approaches, followed by prompt clearing and warming after the front passes. If the warm air mass is unstable, the weather might be characterized by prolonged thunderstorms. Represented on a weather map by (red) lines with semi-circles on one side. The side that the semi-circles are on represent the direction in which the warm front is heading.
3. Occluded front: Formed when a cold front overtakes a warm front. Associated with a variety of weather events (possibly thunderstorms) depending on whether it is a warm or cold occlusion. The passing of an occluded front usually brings drier air (lowered dew point). Represented on a weather map by a line with semi-circles and triangles both on the same side. Whichever side they’re on is the direction the occluded front is going in.
4. Stationary front: Indicates a non-moving boundary between two different air masses. Long continuous rainy periods that linger for extended periods of time in one area and move in waves. Represented on a weather map by a line with semi-circles bordering one side and triangles along the opposite side, indicating that the front is not moving in any direction.
These mark the boundary between warmer air on one side and colder air on the other. If you are close to a front and you know the front is moving towards you, you can expect a change in weather (e.g. cloud formation, precipitation, thunderstorms, and wind) when the front boundary passes over you. Their path can be distorted by mountains and large bodies of water.
- Global Forecast System – NCEP/NOAA.
- European Centre for Medium-Range Weather Forecasts.
- Navy Operational Global Atmospheric Prediction System.
- The Meteorological Office.
- Weather Online.
Nearly each year usually in the fall period, when the Mediterranean Sea is still warm, a depression system comes to develop the characteristics of a tropical storm, with cloud patterns wrapped around an eye, intense thunderstorm activity, strong winds at sea level surface and a higher groundlevel temperature within the clouds than outside. This type of storm might possibly intensify into a tropical storm, also called a “Mediterranean hurricane” or medicane.
Xandra is the second tropical-like mediterranean storm after Qendresa who hit hard the island of Lampedusa on november 7. It is the first time in ten years that two systems occur within a month of each other. With a minimum pressure of 992 hPa, Xandra on her course across the Mediterranean Sea has been delivering heavy rainfall to Portugal and most of Spain, affected parts of Morocco, triggered flash floods in south east France before finally hitting the italian coast near from the area of Rome.
As for the waves, forecasts never stopped changing during the two weeks before. After a couple days of wonky east swell, rain and strong winds, a clean four to six foot south swell finally hit on december 01 mid afternoon. It was not Indo perfection on this tricky shorebreak but glad I was free for the short two hours window before the backwash finally ruined it.
However it looks like the models are turning on again, showing bright colors we’ve never seen before. More is yet to come?
Dirk, Petra, Ruth, Qumaira, Stéphanie, Tini, Ulla, continuous flow of deep lows over the North Atlantic these days has finally set up a week of swell in the med. You can also score great waves here, like anywhere else, tracking the swell where it goes. There’s usually a lot of driving involved and a bit of luck as well. Nothing worthwhile ever comes easy.
Normally, we do trips to tropical places, this one was a surf trip at home: long road ahead, heat, sun and pumping waves, all this in the midst of the indian med winter.
Hard to be excited about the last days of swell while many people are affected by the aftermath of “cyclone Cleopatra” which has severely hit the island of Sardinia last week. High water temperatures in the Mediterranean sea have created the conditions for a low pressure system to take up enough energy and organize itself into an extratropical storm. This combined with a slow moving center produced extreme rainfall over a localized area. The equivalent of six months of rain affected Sardinia in less than twenty four hours causing massive flooding, significant damage and the death of 16 people. Italy declared a state of emergency after what turns out to be one of the largest natural disasters over there.
However, this kind of storm is not unusual, even in the Mediterranean. Dramatic weather conditions happen each year especially in the fall/winter season. Meanwhile, a clean swell also pulsed a bit with fun uncrowded waves to enjoy somewhere.