Weather Wednesday – Hail

On this April Fools Day, we’ll be discussing hail. Hail is widespread throughout the world, but doesn’t often have the top of mind awareness of other storm-related topics…unless, that is, you’re growing crops or insuring buildings or vehicles. According to the National Weather Service’s hail page, the average loss from hail each year is about a billion dollars. However, in 2001 there was one storm event that eventually stretched from Kansas City to Illinois that caused $2-billion damage on a single day.

Hail is not normally considered a major threat to human life. The last reported fatality in the United States was in 2000 when a Texas man died after being struck by a softball sized hail stone. Two children reportedly perished in Russia in 2014. Livestock losses are reported from time to time.

The National Weather Service rates hail from less than a quarter inch or pea sized to over 4 inches or softball sized. The preferred references are actual measurements or approximations based on fixed sizes such as a quarter or a regulation sized softball. “Grapefruit sized” is a far less precise term. One of the reasons for using common objects as references is it allows storm spotters and others to report the size without venturing out into a storm with its associated risks to take actual measurements.

vivian_hailThe largest hail stone reported in the U.S was over 8 inches in diameter with a circumference of over 18 inches.

corn_field_hail_6-24-14
Phil Katz-MSU Extension

Crop loss from hail is a significant risk to producers. Depending on where crops are in the growth cycle and the extent of the damage, growers are often cautioned to have a little patience to determine if the crops can bounce back. Many state extension services can provide more information.

 

hail carDamage to vehicles is usually pretty obvious in terms of dents and broken glass. There are some DIY fixes for smaller dents including letting the vehicle sit in the hot sun so the metal expands a bit. The best advice though is to contact your insurance carrier and/or a competent body shop. A worst case scenario is when a new car dealer’s lot or other parking lot is hit. Damage can easily escalate into six figures or more. Several years ago here in the Champaign-Urbana area, dozens and dozens of cars parked at the local airport were badly damaged.

thHail can also damage roofs constructed of various materials. Again, working with your insurance carrier to arrange for an inspection by a qualified roofer is always a good idea. Some damage may be hard for the untrained eye to see and ladder work is often best left to professionals anyway.

Siding on homes also can be easily damaged. Steel or aluminum siding can be dented and still maintain its structural and weatherproof integrity.Bad_Siding_Hail_Damage Hail can absolutely shred vinyl siding and immediate action to cover exposed underlayment or insulation is necessary to avoid more widespread water damage.

 

 

howhail
NOAA Graphic

One question that is often asked is, does the presence of hail, especially large hail, tell us anything about the structure of a thunderstorm? Since hail is formed when water droplets freeze as they are lifted above the 32-degree line by updrafts, it stands to reason that the presence of ever larger hail stones in a storm reflects the strength of that updraft so it can be an indicator of both the strength and height of a thunderstorm cell. Hail is easily seen on radar because of its dense mass. Many videos shot by storm chasers show large hail as part of some tornadic thunderstorms.

Weather Wednesday – Lightning

This is Severe Weather Preparedness Week in several states. Others may have just observed the week and still others may be doing so soon. Over the next several posts, we’ll cover several topics related to severe weather in greater depth.

NOAA
NOAA

As outdoor baseball and soccer practice, along other activities such as golf, gardening, boating will be on the upswing in coming weeks, we’ll start our coverage with lightning. Of course, the threat of being struck by lightning has been known for centuries. The History Channel recounts a particularly devastating lightning strike that killed 300 people.

The National Weather Service has a very good lightning resource page including actions you should take to protect yourself and others.

As our understanding of how lightning works, the different kinds of lightning and other aspects of the science involved improves, best practices have been refined and much more attention is being given to protecting participants and fans at outdoor sporting events.

NOAA
NOAA

The National Collegiate Athletic Association (NCAA) has developed some guidelines for when to clear the practice field and when to ask fans to leave a stadium. Some institutions have modified these to be even more conservative based on estimates of how long it would take to empty a stadium of fans and where the closest safer shelter is. During the 2014 football season lightning delays and even suspensions were fairly common.

Many states require the installation of lightning alarms at recreational facilities and sports venues. Participants and fans should follow the local guidelines when those alarms are triggered. However, as always, alarms are never a substitute for personal responsibility. There are a variety of smartphone apps that link to databases of recent lightning strikes. They can be a good tool, but be aware that there may be a delay in the process of detecting the strikes, assembling the data and posting in the app. So it is best to assume that the data may be a few minutes old and act accordingly.

As mentioned in the content in the links above, a good rule of thumb is that a 30-second lag between sighting the lightning bolt and hearing the thunder means the bolt was roughly six miles away. And at six miles, you should be headed to a safer place immediately.

Additional resources from eXtension.org are good reads.

Family Preparedness Friday

When Thunder Roars, Go Indoors!

Did you see pictures from last night’s thunderstorm in the Northeast? If not check out this awesome video footage of the lightning over New York City from CNN.com.

Here is a still frame of the video:

Lightning over New York City. Stillframe from a video on CNN.com.

Lightning is fascinating to watch but also extremely dangerous. In the United States, there are about 25 million lightning flashes every year. Each of those 25 million flashes is a potential killer. You need to understand that there is little you can do to reduce your risk while outside. The only completely safe option is to get inside of a safe building or vehicle.

When you hear thunder – no matter how far away it may sound – you are already in danger of becoming a victim of lightning.

What can you do to prepare you family? Here are some tips to teach everyone in your household.

Run to a safe building or vehicle when you first hear thunder, see lightning or observe dark threatening clouds developing overhead. Stay inside until 30 minutes after you hear the last clap of thunder. Do not shelter under trees. You are not safe anywhere outside.

Plan Ahead! Check your local weather forecast or  NOAA Weather Radio (NWR) before heading outdoors.  Stay updated throughout the day. Make a plan for where your family will go if you hear thunder. Find a safe building nearby.

What is a safe building or safe vehicle? A safe building is one that is fully enclosed with a roof, walls and floor, and has plumbing or wiring. examples include a home, school, church, hotel, office building or shopping center. Once inside, stay away from showers, sinks, bath tubs, and electronic equipment such as stoves, radios, corded telephones and computers. Unsafe buildings include car ports, open garages, covered patios, picnic shelters, beach pavilions, golf shelters, tents of any kinds, baseball dugouts, sheds and greenhouses.

A safe vehicle is any fully enclosed metal-topped vehicle such as a hard-topped car, minivan, bus, truck, etc. While inside a safe vehicle, do not use electronic devices such as radio communications during a thunderstorm. If you drive into a thunderstorm, slow down and use extra caution. If possible, pull off the road into a safe area. Do not leave the vehicle during
a thunderstorm. Unsafe vehicles include golf carts, convertibles, motorcycles, or any open cab vehicle.

Here are some other tips to remember:

  • If camping, hiking, etc., far from a safe vehicle or building, avoid open fields, the top of a hill or a ridge top.
  • Stay away from tall, isolated trees or other tall objects. If you are in a forest, stay near a lower stand of trees.
  • If you are camping in an open area, set up camp in a valley, ravine or other low area. Remember, a tent offers NO protection from lighting.
  • Stay away from water, wet items (such as ropes) and metal objects (such as fences and poles). Water and metal are excellent conductors of electricity. The current from a lightning flash will easily travel for long distances.

Remember to be safe this weekend. And when thunder roars, go indoors!