The snow and sub-zero temperatures of the US’s most northerly state should be the perfect setting for the teams taking part in the 43rd Iditarod Trail Sled Dog Race.

Unfortunately, temperatures well above freezing have resulted in very little snow on the ground.

To prevent a racing disaster, snow has been imported in trucks to cover 4th Avenue in downtown Anchorage for the starting spectacle.

The routes for this race, which alternate yearly, both start in Anchorage and end in Nome. Unfortunately, race conditions are poor. Ttemperatures have been above freezing, both night and day, since 3 March. To make matters worse, the last of the snow at the official meteorological site in Ted Stevens Airport melted on Sunday as rain fell.



So the decision was made to hold the official start, with a short run, in Anchorage on Saturday, followed by the race start in Fairbanks on Monday.

Fairbanks has experienced severe cold this winter with a temperature of -30C on February 11. Temperatures rose to -10C the following week and since February 17, temperatures have stayed above freezing. At the start of March it warmed up to 7C.

The reason for this change, and the lack of snow in Anchorage, is the development of a huge dome of warm air, known as an anticyclone, over California, Oregon, Washington and, more recently, British Columbia.

This anticyclone is diverting the train of winter storms, which originate close to Hawaii, known as the Pineapple Express. The Express is pushing warm air across Alaska, with rain falling rather than snow.

This warm air has even had an effect on the more northerly Fairbanks to Nome route. The course has had to be diverted around areas of open water which would be frozen in a typical year.

30cm of snow is on the ground and the wind is veering to a cold northerly direction.

Nome is 1,500km form Fairbanks and the dog teams will take at least eight days to reach the finishing line. In that time there could be further dramatic weather changes.