Storm Gloria lashes Spain, Morocco with strong winds, thundersnow and flooding

Gravity waves ripple through a veil of dust in this Nasa satellite image of the Alboran Sea. Photo / Nasa Worldview

A potent storm is battering Spain and Morocco, bringing powerful winds, pounding waves and plentiful precipitation as it swirls through the western Mediterranean.

More harsh weather is in the offing as the storm stalls today and tomorrow, eventually drifting westward by Friday as it reemerges into the eastern Atlantic. The unusual system will finally diminish by the weekend.

However, it has already proved deadly and has caused damage and disruption across the Iberian Peninsula.

The system, named "Gloria" by the State Meteorological Agency of Spain, has triggered rare red alerts for "extreme risk" of heavy snowfall in the higher elevations of eastern Spain, while wave heights top 7.5m just offshore in the Balearic Sea.

Meteorologists are forecasting that snowfall totals for this storm will top 50.8cm in locations above 1370m in elevation. Thundersnow was even detected over southeastern Spain todeay. An additional amount is possible in some locations, on top of what has already fallen.

Orange wind warnings were in effect for much of eastern Spain. At one point, nine provinces were placed under red warnings for powerful winds.

Strong gales forced the closing of Alicante Airport yesterday, reportedly disrupting more than 200 flights and closing schools and public services.

Farther north, vehicles were submerged by sea waters in Denia, where strong onshore winds piled up water along the coast. That same combination of wind-driven waves and storm surge smashed the windows of a restaurant on Triana Street in nearby Javea. Waves also threatened railroad tracks in Maresme, north of Barcelona.

It is Spain's east coast that has been hit hardest by the storm, which is hitting unusually far south for this time of year. The low-pressure area has remained virtually locked in place for more than 48 hours.

Satellite imagery reveals a strip of bubbling thunderstorms on the system's eastern flank, developing in the comparatively warmer, more humid air ahead of a punch of cold air beneath the storm's core. Those same thunderstorms have been helping to focus the jet stream's fury over the Balearic Isles, including Mallorca, and Valencia.

The strong southerly winds have even been picking up copious amounts of dust from Algeria, shuttling it northward and bringing a coffee-coloured haze over southeastern Spain. Dust could even make it to southern France by tomorrow, and snow is forecast to fall in the Pyrenees-Orientales, in extreme-southeastern France.

Ripples are visible in the cloud of dust moving north from Africa. Much like ripples atop the water's surface in a fish tank, small undulations can form between layers of air that have different densities. In this case, dust is acting as a tracer to make these waves visible.

Unlike most storms that affect Western Europe, which tend to move in from the west off the North Atlantic, this storm developed late last week over northern Africa as a disturbance over the Atlantic raced southeast, entangled within a dip in the jet stream. That same jet stream plunged southward from Norway and Sweden, all the way down to the Sahara Desert. This anomalous dip, or "trough," in the upper-level winds allowed a chilly air mass to move far to the south.

This proved to be the perfect recipe for a gnarly storm that is in no hurry to leave.

Snow is even in the forecast for parts of Morocco as the system retreats westward. The High Atlas mountains have already seen several cm of snow.

The influence of another weather system well to its north are heightening the impacts of this storm. A sprawling ridge of high pressure has reached record values over Britain this week. The weight of the atmosphere as measured in London was 1049.6 millibars - the highest air pressure reading recorded in three centuries of observation. Typical sea-level air pressure tends to be around 1013 millibars.

The ridge, or area of sinking air, has created a significant air-pressure contrast between the storm over Spain and areas to the north. This contrast is helping to cause the strong winds, as air seeks to equalise the difference in air pressure.