Verisk Severe Thunderstorm Model for the United States

Enhancements to the Verisk Severe Thunderstorm Model for the United States

Scope

Updates to the hazard and vulnerability modules to incorporate new data, research, and innovations; framework enhancements; and adjustments to interpretation of observational data.

General model updates

Hazard

  • The updated hazard model represents present-day climate conditions.
    • Trends in hail frequency and intensity
    • Incorporates latest data (2018-2023)
  • All subperils
    • New observational data through 2023
  • Hail
    • Improved physical representation of hail events, including hail frequency and improvements to hail swath placement in areas of sharp elevation transitions.

Vulnerability

  • All subperils
    • New support for solar farms (Touchstone)
    • Updated building damage functions, including
      • Unknown year built, based on updated age distributions
      • Unknown primary features, based on the updated Industry Exposure Database
    • Updated infrastructure damage functions
  • Hail
    • Enhancements to roof aging based on recent research, including roof covering-specific aging and deterioration impacts
    • Updates to the hail performance of hurricane wind-rated roof covering feature, resulting in smoother hail loss cost across states
    • Updated building damage functions across all supported risk types
  • Wind and tornado
    • Yearly adjustments that account for roof aging and deterioration
    • 10-year roof aging bins updated, current as of 2025
    • Updated manufactured homes damage functions for commercial risks
    • Updated large industrial facilities damage functions (Touchstone)
Catalogs and event sets
  • Stochastic catalog(s)
    • Redefined catalogs (Baseline, Expanded Events)
      • The Baseline catalog includes significant loss events defined using both country-wide and state-specific loss criteria. The Baseline catalog is the smaller of the two catalogs.
      • The Expanded Events catalog includes all events from the Baseline catalog and additional events that do not exceed the Baseline loss thresholds but do meet the meteorological criteria defined for this model. This catalog is the larger of the two catalogs.
    • New catalogs (events regenerated)
      • Touchstone
        • 10,000-year Baseline
        • 10,000-year Expanded Events
        • 50,000-year Baseline
        • 50,000-year Expanded Events
        • 100,000-year Baseline
        • 100,000-year Expanded Events
      • Touchstone Re
        • 10,000-year Baseline
      • All event IDs are new.

Touchstone-specific updates

  • New catalogs
    • 10,000-year Baseline
    • 10,000-year Expanded Events
    • 50,000-year Baseline
    • 50,000-year Expanded Events
    • 100,000-year Baseline
    • 100,000-year Expanded Events
  • Support for solar farms across all sub-perils, including
    • New construction and occupancy classes
      Construction Classes Occupancy Classes
      • 500 - Solar Rooftop Unknown Anchorage
      • 501 - Solar Rooftop Anchored
      • 502 - Solar Rooftop Ballasted
      • 510 - Solar Ground Mounted Unknown
      • 511 - Solar Ground Mounted Single Axis
      • 512 - Solar Ground Mounted Dual Axis
      • 513 - Solar Ground Mounted Fixed Tilt
      • 514 - Battery Energy Storage System (BESS) Unknown
      • 3001 - Residential Solar Energy Risk
      • 3011 - Commercial Solar Energy Risk
      • 3020 - Utility Solar unknown
      • 3021 - Utility Solar Small Energy Risk
      • 3022 - Utility Solar Medium Energy Risk
      • 3023 - Utility Solar Large Energy Risk
    • Over 70 damage functions (coverages A and D combined) for all U.S. severe thunderstorm subperils (hail, straight-line wind, and tornado) for solar con/occ classes
    • Solar support does not include height and age characteristics.
  • Updated large industrial facility damage functions
  • Updated marine damage functions
  • Updated Secondary Risk Characteristics
    • All perils: Updated impacts for aging and deterioration for both building and roof
    • Hail: Updates to
      • Roof covering
      • Roof year built

Touchstone Re-specific updates

  • New catalog
    • 10,000-year Baseline
    • Industry losses are included for baseline events in the Touchstone Re ILF. The additional events in the Expanded catalog will produce company losses in Touchstone Re if a CLF or CLA from detailed loss analysis in Touchstone produces loss for them.