Future hail characteristics using HAILCAST and well-behaved dynamically downscaled regional climate models By Julian Brimelow, William Burrows and John Hanesiak Meteorologist Operational Internship Program (MOIP) 16-17 November 2010 Neil M. Taylor Hydrometeorology and Arctic Lab, Environment Canada
Hailstorms are dangerous and costly Page 2 October-7-15
Objectives 1) Are hail and severe hail environments likely to occur more or less frequently in the future? If so, where and when? 2) Will there be a shift in potential hail days to higher latitudes, or a shift in the time of year with greatest hail potential? Page 3 October-7-15
Background Until now, research on the response of severe thunderstorms to AGW focussed on CAPE-SHR6 phase space Greater the CAPE and/or SHR6 => greater potential for severe thunderstorms CCCCCCCCCC[SSSSSSSS] γγ > ββ γγ = 11. 6666; ββ 2222, 000000 γγ = 11; ββ 1111, 000000 Page 4 October-7-15
Rationale While insightful, this approach has its limitations: Does not always discriminate between severe and non-severe environments No way of knowing type of severe weather associated with exceedances No differentiation between marginal and significant exceedances How do these changes translate into changes in hail frequency and size? What about changes at high latitudes? Diffenbaugh et al. (2013, PNAS) Page 5 October-7-15
HAILCAST TS > TC Observed or modelled profile Page 6 October-7-15 Sublimation
pppppppp EEEEEEEEEEEEEEEEEEEE CCCCCCCCCC = ii,jj vvvvvv ii,jj Page 7 October-7-15 Identified 3 well-behaved AOGCM-RCM pairings HadCM3-MM5; HadCM3-HRM3 and CCSM3-MM5 1971-2000 and 2041-2070 SRES A2 ~50 km grid; ~5000 points Profiles @ 18, 21, 00 and 03 UTC 1 March to 30 September ~ 1 billion profiles Identified largest hailstone for each day from HAILCAST Aggregated exceedances (e.g., D > 2 cm) by month, season and year for each of 14 ecozones
pppppppp EEEEEEEEEEEEEEEEEEEE CCCCCCCCCC = ii,jj vvvvvv ii,jj Page 8 October-7-15 Identified 3 well-behaved AOGCM-RCM pairings HadCM3-MM5; HadCM3-HRM3 and CCSM3-MM5 1971-2000 and 2041-2070 SRES A2 ~50 km grid; ~5000 points Profiles @ 18, 21, 00 and 03 UTC 1 March to 30 September ~ 1 billion profiles Identified largest hailstone for each day from HAILCAST Aggregated exceedances (e.g., D > 2 cm) by month, season and year for each of 14 ecozones
pppppppp EEEEEEEEEEEEEEEEEEEE CCCCCCCCCC = ii,jj vvvvvv ii,jj Page 9 October-7-15 Identified 3 well-behaved AOGCM-RCM pairings HadCM3-MM5; HadCM3-HRM3 and CCSM3-MM5 1971-2000 and 2041-2070 SRES A2 ~50 km grid; ~5000 points Profiles @ 18, 21, 00 and 03 UTC 1 March to 30 September ~ 1 billion profiles Identified largest hailstone for each day from HAILCAST Aggregated exceedances (e.g., D > 2 cm) by month, season and year for each of 14 ecozones
Performance What do we mean by well-behaved? AOGCM-RCM pairing must capture current climate over N. America (see Elguindi and Grundstein, 2013) AOGCM-RCM pairing must capture spatiotemporal variability of hail over study area (comparison with hail climatologies) Page 10 October-7-15
Results Mann-Whitney U test 95% confidence level Increase 2/3 Increase 3/3 Decrease 2/3 Decrease 3/3 27% 26% 23% Future-Present ANNUAL Percent change 4.0 of days with D 4 cm Future-Present MAM Percent change 4.0 of days with D 4 cm Future-Present JJA Percent change 4.0 of days with D 4 cm >50% 21% 75% 66% 22% -6% Page 11 October-7-15
Future-Present ANNUAL Percent change of accumulated EK Damage potential 32% Accumulated Kinetic Energy Increase 2/3 Increase 3/3 Decrease 2/3 Decrease 3/3 29% 29% Future-Present MAM Percent change of accumulated EK Future-Present JJA Percent change of accumulated EK 83% 27% 30% 67% 87% 25% Page 12 October-7-15
D max * Future-Present ANNUAL D max * Maximum hail diameter Future-Present MAM D max Future-Present JJA D max Page 13 October-7-15
Summary First study to explicitly model response of hail to warming Presents a significant advance over previous methods Running HAILCAST using dynamic downscaling seems feasible Marked inter model spatio-temporal variability in present and future time frames Response of hail to warming varies by region and by season Dramatic decrease in hail potential over east and southeast Fewer hail days expected in the future over most areas, but increase in the portion of severe hail days and median hail diameter => greater hail damage potential Increase in hail damage potential over most areas in MAM, and over higher latitudes and mountains Page 14 October-7-15 in JJA
Acknowledgements The following individuals and groups were a huge help in bringing this project to fruition: CCRN Seth McGinnis from NCAR for extracting sending the data Al Pankratz for writing some of the code Scott Kehler for writing some of the code Neil Taylor for insightful and helpful discussions Jennifer Bruneau My supervisors at EC for their support Page 15 October-7-15
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