Climatological Aspects of Eastern United States Back-Door Cold Frontal Passages

Abstract

Results of a study on back-door cold fronts for the months April through October of 1964?71 are presented. Results include information on frequency, associated air-mass duration, precipitation, temperature and dew-point temperature changes, sky cover, and rate of frontal movement. Composite 850- and 500-mb height contours are also constructed. Our findings include: (1) for the sample period, southward penetration of back-door cold fronts is a maximum in June as is frontal frequency, (2) orography plays a prominent role in funneling shallow cold air pools southward east of the Appalachians, (3) more than half of all frontal passages are associated with trace amounts or less of precipitation, (4) heaviest precipitation tends to occur in conjunction with the advancing cold fronts at the more southern and western locations and with the returning warm fronts at northern and eastern locations, (5) temperature changes following frontal passage decrease from north to south and from the coast inland (dew-point temperature changes follow a similar pattern but not so clearly), and (6) cloudiness increases following frontal passage, especially at southern and inland locations. The composite study reveals a short-wave trough at both the 850- and 500-mb level just east of Hudson Bay preceding the initial movement of back-door cold fronts southward. This short wave intensifies east-southeastward toward the Canadian Maritime Provinces while anticyclogenesis takes place upstream.