A plume of volcanic ash snaked its way through southern France, Switzerland, Italy and Germany Sunday, shutting down airports and disrupting flights across Europe.
Trans-Atlantic connections were also being diverted around a larger patch of cloud stretching from southern Greenland to the coast of Portugal, adding several hours to flights between Europe and North America and causing congestion as airlines tried to squeeze their planes through remaining routes.
Weather forecasts said the ash cloud hovering over the continent will gradually dissipate as it spreads to southern parts of Germany, the Czech Republic and Austria by Sunday night. With volcanic eruptions weakening, the plume in the mid-Atlantic was also slowly clearing.
"We're expecting rain to thin the cloud, leaving only a small band left by Monday morning," said Daniel Gerstgrasser, meteorologist with Switzerland's national weather agency. No further ash drifts are expected to reach the continent in the coming 24 hours, he said.
The ash, stretching from the surface up to 20,000 feet (6,000 meters), forced the closure of airports throughout much of northern Italy until 2 p.m. (1200 GMT) Sunday. As the cloud moved northward, German authorities halted takeoffs and landings at Munich airport at 3 p.m. (1300GMT) but said high-level overflights remained possible.
Air traffic control spokeswoman Kristina Kelek said Stuttgart airport would be closed until 4 p.m. (1400GMT), but it appeared that the volcanic ash was heading eastward and likely would be largely out of German airspace by midnight (2200GMT).
The closure of German airports forced Swiss airlines to cancel 16 flights, mainly to Germany but also to Budapest and Amsterdam, said spokesman Jean-Claude Donzel.
In Austria, authorities said several airports would close starting in the afternoon, with Vienna shutting at midnight. Austro Control spokesman Markus Pohanka said the flight bans were expected to stay in effect until Monday 5 a.m (0300 GMT).
Separately, a finger of the main ash cloud centered over the mid-Atlantic at altitudes of up to 35,000 feet (10,500 meters) was touching on parts of Portugal and Spain, affecting airports at Porto, La Coruna, Vigo, and Santiago.
Portuguese airports canceled 223 flights, including 119 at Porto and 71 at Lisbon. Faro airport in the south was operating normally.
The Irish Aviation Authority described the main cloud as 2,100 miles long and 1,400 miles wide (3,400 kilometers by 2,200 kilometers). It ordered Ireland's five westernmost airports to close Sunday afternoon. However Ireland's three biggest airports in Dublin, Shannon and Cork were expected to stay open because the cloud is remaining off Ireland's Atlantic coast.
Irish airline Aer Lingus apologized to its customers for a string of flight cancellations since Tuesday, when the ash threat returned to Irish air space after a two-week break. Its trans-Atlantic services to Boston and New York were operating Sunday subject to delays.
"When the plume impacts on our air space, our first focus is to plot a different flight path to avoid canceling flights. However this is often unavoidable. When airports are closed for business, or flight paths are not available, we must unfortunately cancel flights," Aer Lingus chief executive Christoph Mueller said in a statement on the airline's Web site.
The disruptions to air traffic appeared minor compared with the five-day closure of European airspace last month, which forced the cancellation of over 100,000 flights, stranded passengers around the world and caused airlines direct losses of more than euro1 billion.
Eurocontrol, the Brussels-based agency that coordinates air traffic control centers throughout the continent, said trans-Atlantic flights will continue to be diverted northward over Greenland to avoid the cloud stretching from Iceland to the Azores Islands.
It warned airlines to plan on taking on more fuel for the longer flight around the oceanic no-fly zone.
"Flights are required to make significant rerouting to avoid the area of ash cloud coverage," a midday advisory said. "This is leading to some delays. However significant numbers of cancellations have not occurred."
Eurocontrol said there would be approximately 24,500 flights within the European area, about 500 below average for a Sunday at this time of year. It said the ash cloud was expected to dissipate and that most of the closed airports were likely to reopen later Sunday.
Geneva airport is one of the main hubs for budget carrier easyJet. The airline warned passengers Sunday to expect further disruption to flights operating to and from Switzerland, southern and central France, northern Italy and northern Portugal.
Donzel, the spokesman for Swiss airlines, said the carrier expects to incur extra fuel costs for trans-Atlantic flights and canceled connections, but wasn't planning to pass those on to passengers at this stage.
Meteorologists say that until Eyjafjallajokul (pronounced ay-yah-FYAH-lah-yer-kuhl), the volcano in southern Iceland, stops erupting, the future course of Europe's ash crisis will depend heavily on the prevailing winds. The eruption of the glacier-capped volcano has shown no signs of stopping since it began belching ash April 13. It last erupted from 1821 to 1823.
Jordans reported from Geneva. Associated Press Writers Frances D'Emilio in Rome, Geir Moulson in Berlin, Veronika Oleksyn in Vienna and Shawn Pogatchnik in Dublin, Ireland, contributed to this report.
Irish Aviation Authority map of ash-cloud movement, http://tinyurl.com/25yzuwo