This document provides professional arboricultural insight related to storm events, tree failures, and post-storm hazards in residential and urban environments. It is intended as a reference for journalists, municipalities, and residents seeking expert commentary on why trees fail during storms, what risks may remain after storms pass, and how those risks are evaluated.

Sean Harman
ISA Certified Arborist (MA-6197A)
Owner, Sean Harman’s Tree Care, LLC

Areas of professional focus include

• Tree Risk Assessment Standards
  
• Storm-Related Tree Failures
   
• Post-Storm Hazard Evaluation
   
• Urban & Residential Tree Systems
   

📍 Northern Virginia — Alexandria, Fort Hunt, Mount Vernon
📞 703-565-2676

Storm events place trees under stresses that exceed normal environmental conditions. These stresses often involve a combination of wind loading, saturated soils, and structural defects that may not have been visible prior to the storm.

Common contributing factors include:

• High winds acting on full or partially foliated canopies
   
• Soil saturation reducing root anchorage
   
• Pre-existing decay within trunks or major limbs
   
• Structural defects such as codominant stems or bark inclusions
   

Importantly, many tree failures occur without obvious warning signs to untrained observers.

 Following the May 17, 2025 storm event, ISA Certified Arborist Sean Harman provided on-site professional commentary for WJLA (ABC 7) regarding storm-related tree failures and public safety concerns. 

A tree may appear outwardly healthy while containing internal defects. Decay, compromised root systems, or weak unions can exist for years before a triggering event—such as a storm—causes failure.

Storms do not usually create defects; they expose existing ones.

• Large limb failures due to torsional loading
   
• Trunk failures at points of internal decay
   
• Whole-tree uprooting from saturated soils
   
• Delayed failures occurring 24–72 hours after the storm
   

Delayed failures are particularly dangerous, as trees may appear stable immediately after a storm but fail later as soils continue to shift or internal cracks propagate.

After storms, some of the most serious hazards are not immediately visible from the ground. These may include:

• Cracked or partially failed branch unions
   
• Hanging limbs under tension
   
• Root plate movement masked by soil or mulch
   
• Structural cracks concealed by foliage
   

These conditions may warrant professional evaluation even if no immediate damage is visible.

Storm damage may expose cavities or decay that were previously sealed within a tree. In some cases, insects or wildlife are observed after the storm, leading to the incorrect assumption that they caused the failure.

In most situations:

• Insects and wildlife are responding to existing decay, not creating it
   
• Their presence is an indicator of prior conditions, not the cause of failure
   
• Removal or disturbance without evaluation can increase risk to people and property
   

Trees affected by prior insurance-mandated or utility pruning may respond unpredictably during storms. Certain pruning practices—particularly heading cuts or aggressive reductions—can alter load distribution and increase failure potential over time.

Storm events frequently reveal the long-term consequences of earlier pruning decisions.

Journalists may consider consulting a certified arborist when reporting on:

• Trees failing onto homes, vehicles, or public infrastructure
   
• Questions about why a tree failed
   
• Public concern following major storms
   
• Insurance-related tree disputes
   
• Repeated or delayed failures after storm events
   

Sean Harman is available for local media commentary related to storm damage, tree failures, and public safety concerns involving trees.

 Media outlets may quote or reference this document with attribution to Sean Harman, ISA Certified Arborist (MA-6197A). 

📞 703-565-2676

A tree risk assessment represents a snapshot in time based on observable conditions at the moment of inspection. Tree conditions may change due to weather events, soil conditions, growth, decay progression, or site disturbance. Because of this, tree risk assessments are not permanent guarantees and should be revisited after significant storms or site changes.

This document is intended for general educational and informational purposes. Site-specific tree risk evaluations require an on-site assessment performed by a qualified arborist.