Severe Wind-Driven Hail Events: Dependence on

Convective Morphology and Larger-Scale Environment

Nicholas CarlettaMentors: William Gallus, Michael

Fowle, and Daniel Miller

Hypothesis What is Wind-Driven Hail? Methodology Morphologies in Wind-Driven Hail Cases Comparisons of Environmental Parameters Conclusions

Outline

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.

Hypothesis

An event where severe hail greater than 1 inch in diameter occurs simultaneously with severe wind in excess of 50 knots/ 58 mph

What is Wind-Driven Hail?

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

Credit for pictures: Michael Fowle

From Otho, Iowa near Fort Dodge during 8/9/09 event

Damage from Eldora, IA

Credit for picture: Karl Jungbluth

Credit for picture: Karl Jungbluth

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

Picture from William Gallus

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

Methodology continued

Results: Comparing Years

Wind-driven Hail from 2002

Wind-driven Hail from 2007

TS23%

NS7%

IC19%CC

16%

PS4%

NL8%

BE8%

BL15%

TS13%

NS7%

IC19%

CC39%

NL14%

BE1%

BL4%

LS1%

Category CAPE Average (J/kg)

0-3 km SRH Average(m2/s2)

CAPE Standard Deviation (J/kg)

0-3 km SRH Standard Deviation (m2/s2)

2002 2678 124 1491 1102007 2823 127 1500 123Wind-only 2631 192 1259 127Hail-only 3066 116 1690 127Known 2515 225 1458 186

Comparing CAPE and SRH between the 2007 and 2002 Seasons

Comparing Parameters between MorphologiesMorphology CAPE Average

(J/kg)0-3 km SRH Average (m2/s2)

CAPE Standard Deviation (J/kg)

0-3 km SRH Standard Deviation (m2/s2)

BE 2442 195 1428 117BL 3175 154 1434 175CC 2630 130 1660 100IC 3137 99 1118 122LS 774 378 0 0NL 3040 94 1540 84NS 2222 117 1371 98PS 2021 66 530 84TS 2657 124 1617 113

Comparing Parameters between Morphologies continued

BE BL CC IC LS NL NS PS TS0

5

10

15

20

25

30

35

cat 1 cat 2

cat 3

Comparing Based on Hail Size and Wind SpeedCategory CAPE

Average (J/kg)

0-3 km SRH Average (m2/s2)

CAPE Standard Deviation (J/kg)

0-3 km Standard Deviation (m2/s2)

1 2609 121 1254 1192 3188 141 1585 1143 3486 118 1279 77

Comparing Supercell Events to Non-Supercell Events

Supercell? CAPE Average (J/kg)

0-3 km SRH Average (m2/s2)

CAPE Standard Deviation (J/kg)

0-3 km SRH Standard Deviation (m2/s2)

Yes 3140 146 1387 97No 2548 109 1585 147

• 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

Morphology 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

Parameters Conclusions

Expand to additional seasons More environmental parameters

Possible Future Work

William Gallus Michael Fowle Daniel Miller Karl Jungbluth

Acknowledgements

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. Forecasting 22, 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.

References

Questions?