From Glossary of Meteorology
(Also called free foehn.) The presence of south foehnlike conditions at higher elevations of the Alps while the lower elevations and the plains or "foreland" to the north are under a cold air mass.
Under these conditions, the mountains are often warmer than the lowlands. The warming is attributed to subsiding air in a synoptic anticyclone above the cold surface air. Although the winds in the warm air are apt to have a southerly component, the high foehn does not necessarily have strong, gusty foehn winds. However, this situation often precedes the foehn at the surface.