After the Storm...

(... but before the cleanup starts)

It was a dark and stormy night. A flash of lightning, a deep, rolling peel of thunder. Then a loud, ear splitting crash...

No, this is not a murder mystery, nor Snoopy's latest novel. This is what happened the night of June 1, when a cold front moved through the region, bringing powerful thunderstorms, high winds, and a few tornadoes. The storm woke many from a sound sleep, sent some scurrying for the basements, and turned out the lights in many homes. Damage was wide-spread throughout southeastern Pennsylvania, Delaware and New Jersey.

Lightning destroyed some trees, but most of the damage was from the fierce winds that accompanied the storm. Strong winds gusted to over 80 miles per hour. Microbursts (see below) damaged trees in areas of a half acre to as much as 25 acres, in scattered locations. And tornadoes, rated F-0 to F-2*, were investigated by the National Weather Service in several counties.

If you are reading this article, you are probably well aware of the consequences of storms like this, and the scramble to get things cleaned up. There are regular customers to keep happy, new customers to deal with, and lots of work to get done in a hurry! But in the confusion that follows, don't overlook some of the details. Before you start up the chainsaw, before you make a single cut -- make sure that any damage is documented. It only takes a few minutes to get what you need. Those minutes can be worth a lot in the long run.

Any tree damaged in a storm, or by vandalism, tresspass or accidents, may be insured or may be eligible for a casualty loss tax deduction. Don't assume it isn't covered in some way. Document the details right at the beginning, and you won't have to worry about it later.

What are the details? Start at the beginning, with the species of tree. Then measure the trunk at 4.5 feet above the ground level. Take either the diameter or the circumference -- just indicate which you used. Check the tree for its condition -- look for signs of decay, especially if it was visible before the damage occurred. Look for insect or disease damage. You don't have to be an expert at this, just record if there is some type of damage from a pest, and describe that damage.

Next, write down details of where the tree was located. This includes where on a property it stood, how far from structures, etc. A simple site sketch will help. If the tree damaged other things when it fell, make note of the type and extent of damage. Include other landscape plants and hardscape features that were damaged or destroyed, especially if they will be removed with the tree. If vehicles were involved, indicate where they travelled, and where they came to rest. Also list the names of anyone who worked on the cleanup: this may be critical to a later investigation.

Finally, take some photographs of the tree and the damage. Again, this is very important when buildings or other items are damaged by the tree or if there was an injury, and when the tree must be promptly removed from the site. In cases where the tree failed due to a defect, make notes describing the defect, where it was located, and any other details you can find. Photographs of the broken or defective parts can be very helpful when the situation must be reconstructed. In cases of personal injury, it is best if you can also collect the defective parts of the failed tree. Be sure you tag and label them with the date and details of the sample, and store them in a safe location.

This may sound like a lot of work, but it really isn't. A field form can be set up to quickly record this information and to serve as a reminder of the details you need to collect. A few minutes should be sufficient to gather what you need. Document with plenty of photographs, too. A simple camera will do, preferrably with color film (slides or prints are best, but digital cameras can also be used). You can even suggest that the tree owner collect the information, and take the pictures. The important thing is to have the information available when it is needed, after the cleanup has been finished.

By now you are wondering why go to all this trouble. As a consulting arborist, I have been called on many cases long after the trees have been cut up and hauled away, and asked to reconstruct the "scene of the crime." When there is just a bare patch of soil and a 10-year old picture of the bottom part of the tree, it is difficult, if not impossible, to determine why a tree failed, or what it may have been worth. Sometimes it isn't even known who removed the tree. You may be called on to perform or help with the investigation. This kind of record keeping can make the process much easier.

By documenting the case before the tree is removed, you may be saving your customer a lot of headaches, and a lot of trouble. You may be saving them a lot of money, too. The time it takes to investigate a tree damage case can actually decrease as more information is available, and the results are more accurate and defensible. So take a few minutes to make some notes, take some pictures, and properly document the damaged tree. The time you spend will be well worth it to your client. Make this a routine part of your service for your customers, and they will be glad they hired you as their arborist.

Fujita Scale

The Fujita Scale is used to rate tornado wind speed and strength.


Wind can be a highly destructive force of Nature. Wind is more than just a gust of air molecules floating by. It comes in many shapes and sizes -- hurricanes, tornadoes, gust fronts, and lots of other forms. One common, but not well known form is called a microburst.

Microbursts are a form of wind shear, caused by convective currents of air within a thunderstorm. A microburst is an intense, highly localized, downward atmospheric flow with velocities of 2,000 to 5,000 feet per minute that emanate below a convective cloud base. Microbursts can occur anywhere convective weather conditions like thunderstorms, rain showers, and virga (rain columns that evaporate before reaching the earth) occur.

Microbursts often form in storm cells, as columns of air cool due to evaporation and melting of precipitation particles. As the air cools, it becomes more dense and sinks rapidly. Downdrafts of air in the cell are intensified by heavy rain pulling the air downward, further cooling the surrounding air. In severe cases, microbursts form as a narrow column of fast-moving air, often only a few hundred to 3000 feet across. When this downdraft hits the ground, it forms a vortex ring or "donut-shaped" ring of rolling air, which can extend as much as one to two miles across. The wind intensifies for about 5 minutes after the microburst hits the ground, and usually dissipates within 10 to 20 minutes. The wind speed near the center of the microburst is usually about 40 to 45 miles per hour, but microbursts have been measured over 100 mph, and one was reported with winds near 200 mph.

The microburst may hit the ground in a vertical direction, or it may strike at an angle, usually moving in the direction the storm cell is moving and pushed by the surface winds below the cell. A vertical strike can cause a "starburst" pattern of damage, with the wind pattern appearing to splash outward from the center. In an oblique strike, the wind will flow in one general direction, and broken trees will fall in the same general direction. This is unlike tornado damage, which has overlapping patterns of swirls, and damage may occur in different directions on opposite sides of the wind path.

Read more on Microbursts: Microburst Handbook.

Reprinted from the Arboricultural Consultant, newsletter of the American Society of Consulting Arborists
© Copyright 1998, Russell E. Carlson

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This page was last updated on June 11, 2003.