2020 U.S. Hurricane Season Preview

Eric Uhlhorn, Ph.D.

Eric Uhlhorn, Ph.D. Principal Scientist

Primary Factors Influencing Hurricane Activity

Seasonal Forecasts

Secondary Factors Influencing Hurricane Activity

Tropical Cyclones, Climate Change, and COVID-19

AIR Hurricane Contest

2019 Avg.

Named 18 14 Storms

Hurricanes 6 7

Major 3 3 Hurricanes

U.S. Hurricane Landfalls 2 1–2

U.S. Major Hurricane 0 <1 Landfalls

2019 Avg.

Named 18 14 Storms

Hurricanes 6 7

Major 3 3 Hurricanes

U.S. Hurricane Landfalls 2 1–2

U.S. Major Hurricane 0 <1 Landfalls

©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 5 5 2019 Hurricane Season: Strongest Hurricane Dorian Hurricane Lorenzo August 24 – September 7 September 23 – October 2 Peak Intensity: 185 mph / 910 mb Peak Intensity: 160 mph / 925 mb

• Tied for most intense landfalling Atlantic hurricane • Easternmost Atlantic Cat-5 on record • Stalled over Bahamas for 27 hours at Cat-5 strength • Most destructive Azores storm on record and particularly moving only 25 miles in 24 hours (2nd in record) powerful extratropical storm for British Isles • Storm tide of 20-25 ft and ~3 ft of rainfall over Bahamas • Huge swells led to deaths along U.S. Eastern Seaboard • Extensive damage to Outer Banks and Nova Scotia

©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 6 6 2019 Hurricane Season: Wettest Hurricane Barry Tropical Storm Imelda July 11 – July 15 September 17 – September 19 Peak Rainfall: 23.58 in – Ragley, LA Peak Rainfall: 44.29 in – Fannett, TX

• Flooding along Atchafalaya River and Mississippi River • 5th wettest hurricane in contiguous U.S. which were already at record levels • Dumped rains of 30-44 in over 3 days between Houston • Surge was predicted to break New Orleans levees and Beaumont, TX • 16.59 in. of rain in Dierks, AR, is state record and 5th • 31 in of rain in Fannett, TX fell in just 12 hours U.S. state all-time TC rainfall record in span of 3 years

1. Warm Water

2. Vertical Instability

1. Warm Water

2. Vertical Instability

3. Elevated Moisture

1. Warm Water

2. Vertical Instability

3. Elevated Moisture

4. Added Vorticity

1. Warm Water

2. Vertical Instability

3. Elevated Moisture

4. Added Vorticity

5. Low Wind Shear

1. Warm Water

2. Vertical Instability

3. Elevated Moisture

4. Added Vorticity

5. Low Wind Shear

6. Off Equator

1. Phase of the El - Impacts vertical wind Niño – Southern shear and instability Oscillation (ENSO) over Atlantic 2. Tropical North - Provides energy for Atlantic Sea storms developing Surface over tropical North Temperatures (SST) Atlantic

Enhanced Convection & Lower Wind Shear

Atlantic Circulation Hurricane Enhances Activity Increases

SST Anomalies

NINO 4 1 0.5 0 JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN 1 El Niño NINO 3.4 0.5 0 -0.5 JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN NINO 3 0.5 0 -0.5 JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN La Niña 1 NINO 1+2

-1

JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN

ENSO Neutral to weak La Niña favored

Atlantic Multidecadal Oscillation

From Kaplan SST V2 per Enfield et al. (2001, GRL) Currently warmer than average trend in Atlantic SSTs

Atlantic Multidecadal Oscillation Cool Phase AMO

Warm Phase AMO

From Kaplan SST V2 per Enfield et al. (2001, GRL) Currently warmer than average trend in Atlantic SSTs Goldenberg et al. (Science, 2001)

July August September October

°C -3 -2 -1 -0.5 -0.25 0.25 0.5 1 2 3 NMME Models: ▪ NCEP CFSv2 ▪ CMC CanCM3 Abnormally warm Atlantic SSTs are favored all season ▪ CMC CanCM4 ▪ GFDL FLOR ▪ GFDL CM2.1 ▪ NCAR CCSM4 ▪ NASA GEOS5 ▪ NCAR CESM

• A trend toward the cool ENSO phase (La Niña) is under way

NINO 3.4 Atlantic Atlantic SSTs Wind Shear Hurricanes

• Atlantic sea surface temperature remains elevated relative to average

Atlantic Atlantic SSTs Hurricanes • Both are indicative of an ABOVE AVERAGE Atlantic Hurricane season

https://seasonalhurricanepredictions.bsc.es/

Named Storms Hurricanes Major Hurricanes LOW MEAN HIGH LOW MEAN HIGH LOW MEAN HIGH Forecast Average 13.6 16.9 19.9 6.5 8.5 10.4 2.9 4.0 5.5 30-Year Average 7 14 28 2 7 15 0 3 7

©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 27 27 Seasonal Forecasts: ACE Forecast ACE Storm Accumulated Cyclone Energy (ACE): • Storm Intensity 푻 ퟐ • Storm Duration 푨푪푬푺푻푶푹푴 = ෍ 푽풎풂풙 ퟏ Season ACE: Computed over each storm and depends on the frequency of occurrence of storms

푵 ACE 푨푪푬 = ෍ 푨푪푬 푺푬푨푺푶푵 푺푻푶푹푴 LOW MEAN HIGH ퟏ Forecast Average 104.2 149.0 192.3 30-Year Average 32 119.6 245.3

©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 28 28 2020 Atlantic Basin Storm Names Arthur Hanna Omar Bertha Isaias Paulette Cristobal Josephine Rene Dolly Kyle Sally Edouard Laura Teddy Fay Marco Vicky Gonzalo Nana Wilfred

©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 29 29 2020 Atlantic Basin Storm Names Arthur Hanna Omar Bertha Isaias Paulette Cristobal Josephine 17# Rene Dolly Kyle Sally Edouard Laura Teddy 6th Year in a Row Fay FirstMarco Named Storm Before Start Vickyof Season Gonzalo Nana Wilfred

©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 30 30 2020 Atlantic Basin Storm Names Arthur Hanna Omar BerthaArthur Bertha Isaias Paulette Cristobal Josephine 17# Rene Dolly Kyle Sally Edouard Laura Teddy 6th Time6th Year in Entire in a RowRecord Fay First2+Marco Named Named Storms Storm BeforeBefore StartStart ofVickyof SeasonSeason Gonzalo Nana Wilfred

©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 31 31 2020 Atlantic Basin Storm Names Arthur Hanna Omar BerthaArthur Bertha Isaias Paulette Cristobal Josephine 17# Rene Dolly Kyle Sally Edouard Laura Teddy 6Earliestth Time6th Year 3inrd EntireNamed in a RowRecord Storm Fay First2+Marco Named Namedin Atlantic Storms Storm Hurricane BeforeBefore StartStart History ofVickyof SeasonSeason Gonzalo Nana Wilfred

1. Saharan Air Layer - Impacts SST, shear, (SAL) moisture, and instability 2. Madden-Julian - Impacts instability and Oscillation (MJO) moisture 3. Atlantic Meridional - Impacts SST, shear, Mode (AMM) and instability 4. North Atlantic - Impacts steering Oscillation (NAO) currents

Cools Surface

Dries Mid-Levels Saharan Dust Stabilizes Air Column

Saharan dust appears across the tropical North Atlantic Ocean in this image captured by the GOES East satellite on June 27, 2018 ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 35 35 Factors Influencing Seasonal Hurricane Activity: MJO

Moves eastward through the tropics for 40-60 days Enhances & suppresses instability

Moving eastward with time

More active Less active

MJO becoming less active in Atlantic through mid-June

• Atmosphere & ocean evolve in tandem to increase (AMM+) or decrease (AMM-) hurricane activity

Kossin & Vimont (GRL, 2007) Chiang & Vimont (J. Climate, 2004)

• Atmosphere & ocean evolve in tandem to increase (AMM+) or decrease (AMM-) hurricane activity

• Can increase or decrease effects of ENSO

Change in Accum. Cyclone Energy

Patricola et al. (J. Climate, 2014) Chiang & Vimont (J. Climate, 2004)

NAO Positive Phase

Modified from UCAR

Elsner (2003)

NAO Negative Phase

Modified from UCAR

Elsner (2003)

Forecast for NAO to trend negative = More likely western Atlantic tracks

Murakami et al. (PNAS, 2020) • Trends in tropical cyclone frequency since 1980 cannot be explained entirely by natural variability

• High-resolution global climate models show this pattern is due to human activity

• Overall decrease in tropics is due to greenhouse gases while difference between basins is driven by aerosols

©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 47 47 Tropical Cyclones & Climate Change Kossin et al. (PNAS, 2020) • Built a record of tropical cyclone intensity for 1979-2017 using satellite data • Statistically significant trends across the globe and in individual basins • Major hurricane exceedance probability across the globe increases by 8% per decade • The odds of an Atlantic hurricane developing into a Category 3 storm or greater has increased by 42% every decade since 1979

Business & Out-of- Special Needs State Support

Long Distance Unemployment Evacuees Post-Event Hospitalizations

For the latest COVID-19 information, explore our COVID-19 Projection Tool: Business & Out-of- Special Needs https://www.air-worldwide.com/models/Life/ State Support verisk-covid-19-dashboard

Long Distance Unemployment Evacuees Post-Event Hospitalizations

Web-based analytics platform

Complete transparency into AIR’s10,000- year catalog of simulated U.S. hurricanes

Hosted entirely on the cloud

Flexible data queries and data analysis

Easily export event sets to Touchstone® and TouchstoneRe™

Academic and scientific institutions predict an above- average 2020 U.S. Atlantic hurricane season

Several primary and secondary climate factors impact hurricane frequency and severity—their cycles can range from days to years

AIR has a complementary set of solutions to help the (re)insurance community manage risk across policy lifecycles

0 Named Storms Hurricanes Major Hurricanes Landfalls

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Image credit: NOAA/RAMMB