The distribution of snow in Israel

Abstract

The area researched is characterized by changes in the weather according to fluctuations in the world pressure belts throughout the year. The temperature climate in this region is typified in winter by changes in the pressure system from cyclonic to anti-cyclonic conditions in spells of about 5 days. When Israel is under the influence of a low pressure system, and the 500 mb surfaces are approximately 250 m lower than average, the temperatures along the vertical cross-sections are 6° – 8° C lower than average on rainy days, then snow may be expected in various sections of the country. This paper investigated the 35 years period from 1938/9 to 1971/2, concentrating on two mountain stations — Jerusalem in the centre of the country and Mt. Kena'an in the north —because of the high snow incidence and its greater regularity than other stations. The conclusions are as follows: The maximum number of days of snow (between 2/3 and 3/4 of the annual total) is noted at all stations during January and February, although there are also years in which there was snow but not during those months. Regional devision of the snowy days indicates that the number increases with altitude, and decreases from north to south. Snowfall in regions which have lower incidence is less stable and given to greater fluctuations. There was no indication of periodity of the number of days of snow per season, nor did it appear that a very snowy year followed a dry one. Investigation of the lenght of the snowy and the number of days of snowfall does not indicate any connection between them, and there may well be a long season with few days of snow, or a short one with relatively many snowy days. Comparison between the shorter period of readings — from 1938/9 till 1971/2 — and the longer one — from 1860/1 till 1971/2 (111 years) — at the Jerusalem station shows the same trends, which reinforce the conclusions presented above.