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Patterns of hailstorms in Alberta
Author(s) -
Douglas R. H.,
Hitschfeld W.
Publication year - 1959
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49708536404
Subject(s) - storm , fell , meteorology , environmental science , altitude (triangle) , atmospheric sciences , climatology , radar , geology , geography , mathematics , geometry , paleontology , telecommunications , computer science
Between 14 June and 20 September 1957, nearly 3,200 surface reports of hail were collected in a 15,000 sq. mile area. Information included location, time and duration of hail and the largest size of hail encountered. Continuous radar records of the storm pattern were taken in a manner suitable for the preparation of constant‐altitude radar weather (CAPI) maps, to a range of 100 miles. At times, hail fell soon after a first echo (possibly within 10 min), sometimes no hail occurred for as long as an hour or two. Usually, the hail fell in short bursts (lasting up to 20 min and spread over a few miles) which would appear to be the products of single storm cells. But on several occasions (notably on 23 July) hail fell continuously for 11/2 hours and, without evidence of a multiplicity of cells, covered a strip 30 mi long. Sustained hail came from storms whose echo tops were steady close to 30 kft above surface. Hail associated with echoes of lesser height was not continuous and tended to fall in bursts which sometimes followed closely on the merger of previously separate storms. A study of 83 independent echoes showed that the probability of hail from a given storm was clearly related to maximum height of the storm, rising from zero for storms 10 kft or lower, to 100 per cent for storms 38 kft or more in height. A similar correlation holds between echo height of a hailstorm at any instant and hail arrival at the ground some minutes later.