A broad area of low pressure has remained west of the British Isles during the past week. South-westerly winds associated with this system have transported air from north-western Africa to western and central Europe.
The result of this advection has been anomalously warm temperatures across large parts of Europe – in particular across France and Spain, where temperatures soared to over 10C above normal. Maximum temperatures widely exceeded 30C in parts of Spain on Thursday, with 35.2C measured at Morón de la Frontera, south-east of Seville.
Parts of the western US received an early taste of winter this week. A potent cold front tracked southwards across the northern Rocky Mountains and surrounding regions on 22 October, bringing the warm conditions of mid-October to an abrupt end as temperatures plummeted and snow levels fell to valley floors.
Northern Utah was particularly affected, with maximum temperatures in Salt Lake City decreasing from 25C on 21 October to 7C two days later. Adventurous skiers got to experience some early-season action in the mountains east of the Salt Lake Valley, with 26 inches of snow falling at the Alta resort in the Wasatch Front.
Valleys in the region were not spared from significant snowfall. Despite persistent drought and overuse of the watershed leaving the Great Salt Lake at record low levels, anomalously warm water temperatures combined with the cold atmosphere to generate active bands of lake effect snow. One such band brought up to seven inches of snow to the valley floor in an area from Stansbury Park to Tooele, west of Salt Lake City.
Meanwhile, a tropical depression known as 26W developed west of the Yap Islands in the western Pacific on 26 October, tracking towards the west-north-west. Intensification was initially slow due to an inhospitable upper troposphere. However, conditions began to improve on 27 October. The storm, named Nalgae by the Japanese Meteorological Agency, is expected to intensify before making landfall on 29 October in the Philippines, east of Manila. Maximum sustained winds of 85mph are currently expected at landfall. The system will continue into the South China Sea next week.