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Severe Wind-Driven Hail Events: Dependence on Convective Morphology and Larger-Scale Environment. Nicholas Carletta Mentors: William Gallus, Michael Fowle , and Daniel Miller. Outline. Hypothesis What is Wind-Driven Hail? Methodology Morphologies in Wind-Driven Hail Cases
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Severe Wind-Driven Hail Events: Dependence on Convective Morphology and Larger-Scale Environment Nicholas Carletta Mentors: William Gallus, Michael Fowle, and Daniel Miller
Outline • Hypothesis • What is Wind-Driven Hail? • Methodology • Morphologies in Wind-Driven Hail Cases • Comparisons of Environmental Parameters • Conclusions
Hypothesis • Wind-driven hail events occurred most frequently with certain storm morphology and these storms had high values of CAPE and SRH, as expected of a high end severe event like wind-driven hail.
What is Wind-Driven Hail? • An event where severe hail greater than 1 inch in diameter occurs simultaneously with severe wind in excess of 50 knots/ 58 mph Credit for picture: Karl Jungbluth
Examples Severe wind damage Severe wind-driven hail damage Credit for pictures: Michael Fowle
Eldora 8/9/09 Event • 103 mph wind and 3 inch hail reported • Crop Damage $175 million+ Picture and information from Karl Jungbluth NWS-Des Moines
From Otho, Iowa near Fort Dodge during 8/9/09 event Credit for pictures: Michael Fowle
Damage from Eldora, IA Credit for picture: Karl Jungbluth
Methodology • Severe wind reports and hail reports >1 inch that occur within 5 miles of each other no more than 30 minutes apart obtained from the National Climatic Data Center’s Storm Data • 69 cases in 2002 and 69 cases in 2007 • Morphologies assigned from Duda and Gallus (2010) and Gallus et al (2008) data
Methodology continued • Supercell data from Gallus and Duda (2010) • Categories from strength of event • 30 Wind-only, 30 hail-only, and 14 known base cases to compare • Archived 00 hour RUC data analyzed with GEMPAK for CAPE and SRH
Results: Comparing Years Wind-driven Hail from 2002 Wind-driven Hail from 2007
Morphology Conclusions • The NS, TS, IC, and CC morphologies over the two years were the most frequent • The CC, IC, and NL morphologies were the most frequent morphologies higher categories
Parameters Conclusions • 0-3 km SRH was significantly smaller for the wind-driven hail events than in the wind-only and known events • Higher CAPE is present in supercells during wind-driven hail events • Events with larger hail and higher winds had higher CAPE values than events with smaller hail and lower wind speeds
Possible Future Work • Expand to additional seasons • More environmental parameters
Acknowledgements • William Gallus • Michael Fowle • Daniel Miller • Karl Jungbluth
References Das, P., 1962: Influence of the wind shear on the growth of hail. J. Atmos. Sci., 19, 407–414. Donavon, R. A. and K. A. Jungbluth (2007). "Evaluation of a Technique for Radar Identification of Large Hail across the Upper Midwest and Central Plains of the United States." Wea. Forecasting22, 244-254. Duda, J. D. and W. A. Gallus (2010). "Spring and Summer Midwestern Severe Weather Reports in Supercells Compared to Other Morphologies." Wea. Forecasting 25, 190-206. Gallus, W. A., Jr., E. V. Johnson, and N. Snook, 2008: Spring and summer severe weather reports over the Midwest as a function of convective mode: A preliminary study. Wea. Forecasting, 23, 101-113. Lemon, and S. Parker, 1996: The Lahoma deep convergence zone: its characteristics, and role in storm dynamics and severity. Preprints, 18th Conf. on Severe Local Storms, Boston, Amer. Meteor. Soc., 70-75. Morgan Jr., G. M. and N. G. Towery, 1976: On the role of strong winds in damage to crops by hail and its estimation with a simple instrument. J. Appl. Meteor., 15, 891–898. Nelson, S. P., 1983: The influence of storm flow structure on hail growth. J. Atmos. Sci., 40, 1965–1983. Rasmussen, E. N., and D. O. Blanchard, 1998: A baseline climatology of sounding-derived supercell and tornado forecast parameters. Wea. Forecasting, 13, 1148-1164.