Identification

Title

Colorado plowable hailstorms: Synoptic weather, radar, and lightning characteristics

Abstract

Synoptic weather, S-band dual-polarization radar, and total lightning observations are analyzed from four thunderstorms that produced "plowable" hail accumulations of 15-60 cm in localized areas of the Colorado Front Range. Results indicate that moist, relatively slow (5-15 m s⁻¹) southwesterly-to-westerly flow at 500 hPa and postfrontal low-level upslope flow, with 2-m dewpoint temperatures of 11°-19°C at 1200 LST, were present on each plowable hail day. This pattern resulted in column-integrated precipitable water values that were 132%-184% of the monthly means and freezing-level heights that were 100-700 m higher than average. Radar data indicate that between one and three maxima in reflectivity Z (68-75 dBZ) and 50-dBZ echo-top height (11-15 km MSL) occurred over the lifetime of each hailstorm. These maxima, which imply an enhancement in updraft strength, resulted in increased graupel and hail production and accumulating hail at the surface within 30 min of the highest echo tops. The hail core had Z ~ 70 dBZ, differential reflectivity ZDR from 0 to -4 dB, and correlation coefficient ρHV of 0.80-0.95. Time-height plots reveal that these minima in ZDR and ρHV gradually descended to the surface after originating at heights of 6-10 km MSL ~15-60 min prior to accumulating hailfall. Hail accumulations estimated from the radar data pinpoint the times and locations of plowable hail, with depths greater than 5 cm collocated with the plowable hail reports. Three of the four hail events were accompanied by lightning flash rates near the maximum observed thus far within the thunderstorm.

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document

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http://n2t.net/ark:/85065/d7x3502b

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Dataset language

eng

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geoscientificInformation

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title

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publication

effective date

2016-01-01T00:00:00Z

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publication

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2016-04-01T00:00:00Z

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Copyright 2016 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be "fair use" under Section 107 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Law (17 USC, as revised by P.L. 94-553) does not require the Society's permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statements, requires written permission or license from the AMS. Additional details are provided in the AMS Copyright Policies, available from the AMS at 617-227-2425 or amspubs@ametsoc.org. Permission to place a copy of this work on this server has been provided by the AMS. The AMS does not guarantee that the copy provided here is an accurate copy of the published work.

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OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

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pointOfContact

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