Cold windchill spells in the south Balkans: A study of the synoptic situations

Using hourly data of temperature and wind speed for Thessaloniki over the period October 1959 to April 1978, values of windchill in excess of 1000 Kcal m−2 h−1 were ed. Windchill days and windchill spells are defined and 67 of the latter noted, all occurring in winter between November and March. Within these spells, windchill episodes were identified from an hour by hour analysis of the data and 22 discontinuous episodes were excluded from further consideration. The surface and 500‐hPa charts for the remaining 45 episodes were used to note the main synoptic features over Europe and the Mediterranean. None of the standard synoptic classifications were found to be suitable for this purpose but a basic patterns did emerge. We identified six surface and seven 500‐hPa patterns and these are discussed in association with the windchill episodes.