2020 U.S. Hurricane Season Preview Eric Uhlhorn, Ph.D. ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 1 1 Meet Dr. Uhlhorn Eric Uhlhorn, Ph.D. Principal Scientist ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 2 2 Agenda 2019 Hurricane Season Recap Primary Factors Influencing Hurricane Activity Seasonal Forecasts Secondary Factors Influencing Hurricane Activity Tropical Cyclones, Climate Change, and COVID-19 AIR Hurricane Contest ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 3 3 2019 Hurricane Season Recap 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 4 4 2019 Hurricane Season Recap 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 ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 7 7 Primary Factors Influencing Hurricane Activity ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 8 8 Primary Factors Influencing Hurricane Activity 6 Canonical Factors Involved in Tropical Cyclogenesis 1. Warm Water ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 9 9 Primary Factors Influencing Hurricane Activity 6 Canonical Factors Involved in Tropical Cyclogenesis 1. Warm Water 2. Vertical Instability ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 10 10 Primary Factors Influencing Hurricane Activity 6 Canonical Factors Involved in Tropical Cyclogenesis 1. Warm Water 2. Vertical Instability 3. Elevated Moisture ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 11 11 Primary Factors Influencing Hurricane Activity 6 Canonical Factors Involved in Tropical Cyclogenesis 1. Warm Water 2. Vertical Instability 3. Elevated Moisture 4. Added Vorticity ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 12 12 Primary Factors Influencing Hurricane Activity 6 Canonical Factors Involved in Tropical Cyclogenesis 1. Warm Water 2. Vertical Instability 3. Elevated Moisture 4. Added Vorticity 5. Low Wind Shear ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 13 13 Primary Factors Influencing Hurricane Activity 6 Canonical Factors Involved in Tropical Cyclogenesis 1. Warm Water 2. Vertical Instability 3. Elevated Moisture 4. Added Vorticity 5. Low Wind Shear 6. Off Equator ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 14 14 Factors Influencing Seasonal Hurricane Activity 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 ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 15 15 Factors Influencing Seasonal Hurricane Activity: ENSO ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 16 16 Factors Influencing Seasonal Hurricane Activity: ENSO Enhanced Convection & Lower Wind Shear Atlantic Circulation Hurricane Enhances Activity Increases ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 17 17 Factors Influencing Seasonal Hurricane Activity: ENSO 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 0 -1 JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 18 18 Factors Influencing Seasonal Hurricane Activity: ENSO ENSO Neutral to weak La Niña favored ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 19 19 Factors Influencing Seasonal Hurricane Activity: SST Atlantic Multidecadal Oscillation From Kaplan SST V2 per Enfield et al. (2001, GRL) Currently warmer than average trend in Atlantic SSTs ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 20 20 Factors Influencing Seasonal Hurricane Activity: SST 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) ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 21 21 Factors Influencing Seasonal Hurricane Activity: SST 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 ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 22 22 The Bottom Line • 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 ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 23 23 Seasonal Forecasts ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 24 24 Seasonal Forecasts https://seasonalhurricanepredictions.bsc.es/ ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 25 25 Seasonal Forecasts: Storms Forecast Number of Named Storms Forecast Number of Hurricanes Forecast Number of Major Hurricanes 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 26 26 Seasonal Forecasts: Storms ©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 ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 32 32 Secondary Factors Influencing Hurricane Activity ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 33 33 Factors Influencing Seasonal Hurricane Activity 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 ©2020 AIR Worldwide CONFIDENTIAL: For Webinar Attendees Only 34 34 Factors Influencing Seasonal Hurricane Activity: SAL Cools Surface Dries Mid-Levels Saharan Dust Stabilizes Air Column Saharan dust appears across the tropical North Atlantic Ocean in this image captured by