Some Behavior Patterns of New England Hailstorms
- Helmut Weickmann
Published Online: 18 MAR 2013
Copyright 1960 by the American Geophysical Union.
Physics of Precipitation: Proceedings of the Cloud Physics Conference, Woods Hole, Massachusetts, June 3-5, 1959
How to Cite
Donaldson, R. J., Chmela, A. C. and Shackford, C. R. (1960) Some Behavior Patterns of New England Hailstorms, in Physics of Precipitation: Proceedings of the Cloud Physics Conference, Woods Hole, Massachusetts, June 3-5, 1959 (ed H. Weickmann), American Geophysical Union, Washington D. C.. doi: 10.1029/GM005p0354
- Published Online: 18 MAR 2013
- Published Print: 1 JAN 1960
Book Series Editors:
- Waldo E. Smith
Print ISBN: 9780875900056
Online ISBN: 9781118668931
- Cumulative frequency distribution;
- Echo top temperatures;
- New England hailstorms;
- Radar echo;
Radar measurements of New England thunderstorms have been combined with reports furnished by cooperative observers during three years. Echo tops in storms releasing hail of less than ¾-inch diameter were higher, colder, and penetrated the tropopause more often than tops of rain thunderstorms. The differences are even more striking for storms with large hail (¾-inch or larger) compared with the other two categories. Extreme tropopause penetrations of 10,000 to 15,000 ft occurred on five days, of which all but one were tornado days.
A study was made of the histories of 20 hailstorms. Ten of them dropped hail for long periods of time (hail repeaters), the others for less than 20 min and at only one or two locations. All cases of severe damaging winds and tornadoes occurred with the hail repeaters. Within a wide scatter, both echo tops and maximum intensities in the hail repeaters attained higher peaks and remained high for longer periods of time than in the single hail producers. Hail locations in all storms exhibited a slight tendency to appear in the right, rear quadrant of the storm, with the larger hail sizes located to the right of the smaller hail, facing downstream.
Echo areas of various intensities as a function of height were measured in two hailstorms, one just getting under way and the other a well-developed producer of several tornadoes. Computations are made of hail-mass concentration versus height at various times in the two storms, assuming the radar echo is scattered from 1-cin ice spheres. Mean 1-cm hail concentrations in the tornado storm, averaged over the total echo area at the height of the most intense echo, varied from 0.3 to 1.3 g/m3, but the maximum concentrations in the echo core ranged from 9 to 170 g/m3, subject to a possible over-estimate by a factor of 5 due to an unresolved radar calibration error. During two observations of echo tops penetrating the tropopause, the echo volume above the tropo-pause increased rapidly with time, suggesting a progressive modification of the lower stratosphere above the storm.
Hailstone information furnished by cooperative observers is summarized. Median values are: maximum diameter, 7 mm; max/min size ratio in a hailfall, 2; number concentration, 0.1/m3; hailfall duration, 3–4 minutes; hailfall started four minutes after heavy rain began. About 75% of hail shapes were divided between spheres and oblates.