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How Thunderstorms Form
How Thunderstorms Form
Thunderstorms form from three main ingredients as well as one optional ingredient for the storm to become severe:
Lift: Front, Orographic LIft (Up a Mountain), Daytime Heating, etc.
Moisture: Gulf of Mexico, Atlantic, Pacific
Instability: the amount of energy in the atmosphere.
Wind Shear (Optional): change in wind speed and direction with height.
Severe Thunderstorms
Severe Thunderstorms
A severe thunderstorm, according to the NWS, is defined as three things (However, all three do not need to conincide at once; only one is needed):
58 mph wind gusts or greater OR
At least a 1/2-inch sized hailstone in diameter OR
A tornado
Severe Thunderstorm Watch
Severe Thunderstorm Watch
Think of a watch as to making a taco. All of the ingredients are there, but you don't exactly have a taco yet. Essentially, you are to BE PREPARED!
Severe Thunderstorm Warning
Severe Thunderstorm Warning
Think of a warning as all the ingredients coming together into a taco, and you are now ready to eat your taco. Essentially, you are to TAKE ACTION!
For further information, click on the image above to learn more about what the Storm Prediction Center does as well as their products.
Hazards Associated with Thunderstorms
Hazards Associated with Thunderstorms
Example of a shelf cloud, which is often a leading sign of a squall line and damaging straight-line winds are to come.
Radar showing a line of storms, or squall line. Fancy term is Quasi-Linear Convective System (QLCS).
Storm damages aftermath.
Damaging Straight-Line Winds
Damaging Straight-Line Winds
People underestimate straight-line winds as they are also capable of producing tornado strength damage to infrastructure. It is best to secure loose items and your home to ensure debris is not lofted in the air and produces further damage. It is best to GET TO SHELTER IMMEDIATELY and not out run or drive the storm. Sometimes, these straight-line wind storms can move at 70 mph, which is faster than your typical highway speed limit. This hazard is typical in your straight-line thunderstorms, or squall lines. When extreme winds reach the surface and bow out the storm, a stronger form of a squall line known as a derecho may form as long as the family of downburst winds produce:
a handful of wind gusts in excess of 75+ mph
a swath of 58 mph winds over the entire storm front for at least six hours
the wind damage path is at least 250 miles long
and no more than two or three hours between any successive wind reports.
These winds are caused by strong downdrafts in a thunderstorm, where rain-cooled air fall to the ground and move outwards as evaporative cooling may enhance the strength of the downdraft causing damaging wind gusts reaching the surface known as a downburst. These downbursts come with little warning time, so if you are caught in one, find the nearest shelter. If you're inside, STAY AWAY FROM WINDOWS.
Large Hail
Large Hail
Hail can come in all sizes from pea-sized all of the way up to softballs. As long as a thunderstorm has a very strong updraft, hailstones can continue being lofted up and down in the cloud growing larger and larger until gravity takes over and they fall to the surface. While small hail does not pose a great threat, it is the large hailstones that you need to watch out for. Take these necessary safety precautions if you are caught in a hailstorm:
GET INDOORS IMMEDIATELY. A sturdy building is the safest place. Avoid porches, carpots, tents, and trees. Even quarter-sized hail can injure someone; larger hail can be life threatening.
IF YOU"RE IN A VEHICLE. Pull over safely, ideally under a gas station or parking garage. Angle the car so hail hits the front (windshield is reinforced, side windows shatter more easily). Stay low in your seat and turn your back to windows if glass breaks.
PROTECT YOUR HEAD. If you're caught outside with no shelter:
Use a backpack, jacket, or your arms to shield your head.
Avoid open areas- run to the nearest solid structure.
Stay away from trees; they offer poor protection and can drop branches.
IF INDOORS. Stay away from windows! Large hail can break windows, especially with strong winds.
How to stay safe during a hailstorm whether you're inside or in your vehicle.
Examples of hailstones that have fallen from a thunderstorm.
Different sizes of hailstones as small as a penny to as large as a disk.
An example of the damage a large hailstone can cause on your windshield.
A snapshot of the EF-4 tornado that rampaged through the town of Mayfield, Kentucky on December 10, 2021.
Tornadoes
Tornadoes
Tornadoes are violently rotating columns of air that form when low-level winds are warped into an updraft of a thunderstorm that induce spin and change in wind speed (wind shear). They can be short-lived and weak in quick spin-ups from lines of storms to long-lived and catastrophic associated with supercells, rotating thunderstorms. Regardless of their duration and size, it is important to stay alert and aware.
Tornado Watch
Tornado Watch
Tornado Warning
Tornado Warning
Tornado Warning Categories
Tornado Warning Categories
Tornado warnings when issued by the NWS, are normally radar indicated rotation or have been reported by a trained weather spotter or local Emergency Manager. If there is a large, confirmed tornado heading towards a populated area, the NWS would upgrade the tornado warningn to a PDS (Particularly Dangerous Situation) Tornado Warning. However, in many rare cases, if there is a confirmed large, destructive tornado posing an immediate threat to life and property such as moving towards a major populated area, the NWS would upgrade the warning to a Tornado Emergency.
Enhanced Fujita Scale
This is the scale used to rate tornadoes on a range from EF-1 to EF-5 with the associated wind speeds. Keep in mind, this scale is used primarily with damage indicators and not solely on wind speed.
Tornado Safety
Tornado Safety
TAKE SHELTER IMMEDIATELY! Go to a basement, storm shelter, or if not applicable, move to an interior room with no windows. Have as many walls between you as much as possible.
IF IN A MOBILE HOME, go to a sturdier shelter. Worst case scenario, go outside and lay in a ditch.
IF IN A VEHICLE, DO NOT go under an overpass. Winds accelerate under an overpass, and you are backing up traffic that way. DO leave the car and go to a sturdier shelter.
Tornado Sirens
Remember, tornado sires are only to warn those who are outside. They are not meant to be heard inside and should not be used as the ONLY source of warning. It is important to have multiple ways to receive warnings through your NOAA Weather Radio, local TV meteorologist on the news, or social media.
The Enhanced Fujita Scale.
Lightning
Lightning
Lightning is not a criterion for severe thunderstorms, but about 300 people are struck every year in the United States:
WHEN THUNDER ROARS GO INDOORS! Seek shelter immediately. Remember, if you see blue skies, DO NOT stay outside. Lightning can strike away from a parent storm up to 25 miles away no matter if it's rain or shine.
GET TO A SAFE PLACE. Get to the nearest sturdy shelter with fully enclosed walls, plumbing and wiring. A hard-topped metal vehicle with closed windows is also safe. Stay inside until 30 minutes after the last rumble of thunder. DO NOT seek shelter in sheds, picnic shelters, tents, covered porches, or under a tree!
KEEP AWAY FROM ELECTRICAL EQUIPMENT AND PLUMBING. Lightning is a current and will travel through wiring and plumbing.
DON'T GET CAUGHT OUTSIDE. Avoid open areas as lightning tends to strike the tallest objects. Do not become the tallest object. Avoid trees. metal fences, and utility poles. Stay away from any metal conductor.
IF SOMEONE IS STRUCK. Call for help! Give first aid. Use an automatic external defibrillator if one is available. Don't become the victim!
Types of lightning and how they form.
Flash Flooding
Flash Flooding
When water rises rapidly in a short-period of time, it is known as a flash flood. Flash floods are particularly dangerous and life threatening and can sweep you off your feet instantly. These are usually caused by prolonged heavy rainfall, saturated soils or very dry soils not used to excess water, and excess runoff. Flash floods could lead to river flooding as all excess runoff goes into the creeks, streams, and rivers.
Flood Watch
Flood Watch
Issued at least 72 hours in advance if the ingredients are there such as heavy rainfall, saturated soils, prolonged rainfall, etc.
Flood Warning
Flood Warning
Typically lasts longer than a flash flood and can last several days.
Flash Flood Warning
Flash Flood Warning
In rare cases, may be upgraded to a Flash Flood Emergency if it threats all life and property.
Flood Safety
Flood Safety
TURN AROUND AND DON'T DROWN! Most flood related deaths are in vehicles. Six inches of water can sweep you off your feet. 12 Inches of water can sweep off a small vehicle. A foot of water can sweep off a large SUV. Make sure to stay informed and GET TO HIGHER GROUND IMMEDIATELY!
For further information, click on the image above to learn more about what the Weather Prediction Center does as well as their products.
Before A Thunderstorm
Before A Thunderstorm
BE WEATHER AWARE. Check the latest forecast on the daily and listen to your local NOAA Weather Radio to stay informed on updated watches and warnings. Be prepared!
SIGN UP FOR NOTIFICATIONS. Make sure you don't have wireless emergency alerts off. Sign up for any community alerts.
CREATE A PLAN. Gather with your family and come up with an emergency plan such as picking a safe room and keeping in contact.
PRACTICE THE PLAN. Conduct a drill or exercise on the regular.
SECURE YOUR HOME. Trim your trees. Put away or secure loose items. Close all windows and doors.
CHECK ON NEIGHBORS. Take any CPR trainings and conduct any drills with the disabled and elderly.
During A Thunderstorm
During A Thunderstorm
BE WEATHER READY. Continue monitoring your local news forecast and NOAA weather radio to stay up to date on the latest information and alerts.
AT YOUR HOUSE. Go to the safeest part of your home whether it be the basement, storm shelter, or interior room away from windows. Don't forget your pets!
AT SCHOOL OR WORK. Do not go into large rooms like gymnasiums, cafeterias, or auditoriums. Stay away from windows.
OUTSIDE. Seek shelter to a nearby shelter or ditch.
IN A VEHICLE. A hard-topped vehicle is safer than outside, but drive to the closest shelter for a safer option.
After A Thunderstorm
After A Thunderstorm
STAY INFORMED. Keep your local NOAA Weather Radio with you at your shelter to stay up to date on the latest updates.
CONTACT. Get in touch with your loved ones to tell them you are okay. Keep in mind cell towers and powerlines may be down.
THE AFTERMATH. Access the storm damage and contact any local authorities and insurance agencies for coverage.
HELP YOUR NEIGHBOR. If someone is injured, make sure to call 911! If trained, use first aid kits to help until first responders arrive at the scene.
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