On June 26, 2020, ICLR conducted a special webinar on the June 13, 2020 Southern Alberta storm. On the evening of Saturday, June 13, 2020, large swaths of southern Alberta, including portions of Calgary, where hit with high winds, torrential rain and tennis ball-sized hail. ICLR estimates that the hailstorm could very well be the costliest hail event in Canadian insurance history, surpassing the $580 million in insured damage caused by the August 7, 2014 hailstorm in Airdrie, Alberta. In this session, presenters discussed the meteorology of the event (what happened, when, why and how); the damage, as experienced by insurance adjusters responding to storm claims, and the impacts of hail on structures, including a look at building material performance, damage thresholds and damage mitigation. Presentations include: The anatomy of a billion dollar hailstorm Dr. Julian Brimelow, Physical Sciences Specialist, Applied Environmental Prediction Science, Prairie & Northern Region, Environment and Climate Change Canada. Boots on the ground: The adjusters’ view Glenn Smith, Head of Global Catastrophe Logistics, CRU Group. Calgary Hailstorm: Exposing our vulnerability to hail & where do we go from here? Dr. Ian Giammanco, Lead Research Meteorologist and Senior Director for Product Design, Insurance Institute for Business and Home Safety (IBHS).

1. THE ANATOMY OF A
BILLION DOLLAR
HAILSTORM
By
Julian Brimelow and Sudesh Boodoo
26 June 2020
Julian.Brimelow@Canada.ca
Candeena Langen

2. OVERVIEW
• Background on Canada’s “Hail Alley”.
• Information on hailstorms in this area.
• How rare was this event?
• Impacts of the 2020 hailstorm.
• Antecedent atmospheric conditions.
• Atmospheric profiles.
• Overview of reflectivity and Doppler products.
• Introduction of PARCA.
• Comparison with GPM overpass.
• Brooks/Duchess hailstorm.
• Summary.
Tyler Clowes

3. HAIL ALLEY
• Region between Edmonton and High River
known for damaging hailstorms.
• Most active region for hail is between Red
Deer and Calgary.
• High incidence of thunderstorms and
atmospheric conditions favoring hailstorms.
• Storms typically develop over the foothills
and intensify as they move eastwards.
• Area has a relatively high population density
and also extensive agriculture.
• Short but intense severe storm season from
mid June through late August.
• Former study area of the Alberta Hail Project.
Kochtubajda & Burrows (in prep.)
Lightning Days (1999-2018)

4. HAIL ALLEY: TYPICAL SEVERE
HAILSTORM CONDITIONS
• Conditions preceding hailstorm formation
in this region are well documented.
• Warming during morning and afternoon.
• Upslope flow in low levels, drawing
moisture against foothills.
• Approaching upper-air trough with strong
mid- and upper-level SW’ly to W’ly flow.
• Result: steep lapse rates, instability,
vertical wind shear, convergence along
orography to trigger storms.
• Storms typically intensify as they move
off the foothills into deeper moisture.

5. CALGARY: GROWTH AND
HAILSTORMS
• Area is no stranger to damaging hailstorms. Previous storms:
• 28 July 1981 ($150 million)
• 7 September 1991 ($342 million)
• 12 July 2010 ($400 million)
• Similar to other hail-prone areas (e.g., Denver), Calgary has
experienced rapid growth in recent decades (since 1996 1.4 to 3.7%).
• Population for Red Deer, Airdrie, Calgary and Okotoks is ~1.5 million.
• Rapid urban growth and marked urban sprawl.
Monthly housing
starts in Calgary
since 1948

6. CONTEXT
Pentad data for days with
> 5 cm hail in the vicinity
of Calgary for 1978-2019
Hail days over the AHP
between 1957 and 1973
(Wojtiw 1975)

7. • Impact energy of hail scales with D4.
• European research found that hail
damage increases significantly when
its diameter exceeds 3 to 4 cm.
• For diameters beyond 5 cm, even more
serious impacts to vehicles and houses.
• The amount of hail is also critical. Hail has
a density of ~900 kg m-3, so its weight can
inflict damage.
• Consequently, damage potential is a
function of the size and amount of hail, N*D4.
• Did the storm produce copious amounts of
small hail or small amounts of large hail?
• Winds are also a major factor.
• For a 5-cm stone, impact energy falling in 50
km h-1 winds is increased by 25% compared
to calm and 50% for 70 km h-1 winds.
COMMENTS ON HAIL DAMAGE
Púčik et al., 2019: MWR

8. SUMMARY OF 13 JUNE 2020 STORM
• The storm developed over south-central Calgary
near 0025Z June 14, and rapidly intensified in the
next 15-20 minutes to a severe storm.
• Most of the city and Airdrie to the north were
spared the worst of the hail and rain.
• The northeastern portion of Calgary bore the
brunt of the damage.
• Copious amounts of golf ball & larger hail,
coupled with high winds, caused devastating
damage to homes, vehicles & other assets.
• The hail was accompanied by torrential rain
that led to widespread urban flooding.
• As the storm moved northeastwards from
Calgary, it left a long hail swath that destroyed
young crops and flooded fields.
• Farther to the southeast, supercell storms
produced very large hail and an EF-0 tornado.
• These storms also caused extensive damage
to crops and localized flooding.
Beth Allen

9. THE HAIL

10. THE HAILSTORM WxKenYYC
7:44 am5:31 pm6:37 pm6:58 pmMelanie Brown

11. IMPACTS FROM HAIL
Tom RossSaif Kaisar
Stevieiss

12. IMPACTS FROM HAIL
Autumn Barnes

13. IMPACTS FROM RAIN
• Stations at Calgary Int’l
reported 60 mm.
• Daily record for June is
79 mm in 1932.
• NE of Calgary, two sites
measured 35 mm.
Spencer

14. THE BIG PICTURE:
ANTECEDENT CONDITIONS

15. CONTINUED

16. PROFILES AND HODOGRAPHS:
CALGARY
• MLCAPE = 1360 to 2240 J kg-1
• 0-6 BWD = 45-50 knots
• SRH3 = 110 to145 m2 s-2
• SR flow0-3 = 40-50 degrees at ~20 kt
• SCP = 2 to 7
• SHIP = 1.2 to 1.8
• Hodograph shape is intriguing

17. PROFILES AND HODOGRAPHS:
BROOKS/DUCHESS
• MLCAPE = 1528 to 1971 J kg-1
• 0-6 BWD = 45 to 55 knots
• SRH3 = 140 to 240 m2 s-2
• SR flow0-3 = 55 to 60 degrees
at ~20 kt
• SCP = 5.0 to 8.5
• SHIP ~ 2 Kyle Brittain

18. MAXIMUM MESH MAP

19. STORM EVOLUTION: CALGARY

20. CROSS-SECTIONS

21. PARCA

22. GPM DATA

23. BROOKS/DUCHESS STORM

24. BROOKS/DUCHESS CONTINUED

25. SUMMARY
• The storm developed over south-central Calgary near 0025Z, and rapidly
intensified in the next 15-20 minutes to a severe storm.
• The northeastern portion of Calgary bore the brunt of the damage.
• Copious amounts of golf ball and larger hail, coupled with strong winds caused
devastating damage to homes, vehicles & other assets.
• The hail was accompanied by torrential rain that led to widespread urban
flooding.
• Farther to the southeast, two long-lived supercell storms produced giant hail
and an EF-0 tornado.
• Still very early in the process of understanding why this storm developed over
Calgary and why is produced so much large hail.
• Initial indications are that it is rare to have such a severe hailstorm this early.
• Some aspects of antecedent conditions at odds with conceptual model for
severe hailstorms in this area. Hybrid multicell-supercell storm?
• Scale and nature of hail damage raises questions about building codes for
houses in hail-prone areas and mitigating risk.

26. THANKS
• Dan Kulak (ECCC)
• Randy Chase (GPM data)
• Pivotal Weather and College du Page
Thank You – Merci Beaucoup