Thunderstorms occur whenever rain falls. But what about thundersnow? Perhaps a few people have heard the word “thundersnow” from TV meteorologists, yet they still do not know what it means. Rare as one might suggest, thundersnow occurs in a heavy snowstorm. It is similar to a general thunderstorm that is in a form of rain, thunder, and lightning, but thundersnow happens when the precipitation is in a form of plain snow.
The thundersnow occurs where there is a strong instability, along with plenty of moisture in the atmosphere, such as above a warm front. Thundersnow can happen whenever there is a heavy snowstorm across the world, but areas that are near large bodies of lakes, especially those that are prone to heavy “lake-effect” snow, may experience higher chances of thundersnow.
* Instability
Both elevated instability and dynamic lifting help create thundersnow. They reinforce each other, and the instability in the troposphere is a function of the tropospheric temperature profile as well the parcel of air’s temperature and dew point. The surface based CAPE (Convective Available Potential Energy) or (SB CAPE) is usually zero while elevating from another pressure level that produces a positive CAPE.
* Dynamic Lifting
A powerful dynamic lifting (UVV) then triggers instability by cooling the central layers of the troposphere. This effect can be responsible for making the elevated convection more possible. The dynamic lifting also causes the air to rise and continue rising from a pressure level that obviously ends in an elevated convection. As a result, thunder in the snowstorm is formed.
* Severe Thundersnow
In addition to the causes of thundersnow, there is even a term known as a “severe thundersnow.” Just like a severe thunderstorm with traditional rain, a severe thundersnow is defined when a thundersnow contains hailstones at least 3/4″ in diameter, or winds gusting at 50 knots or more. The hailstones can fall toward the ground if the elevated CAPE is high enough. However, a sounding profile that is below freezing can prevent the hailstones from growing larger, but in the meantime, they remain unmelted.
Thundersnow usually happens during a very large snow storm, when snow falls so quickly and heavily. So if you see a streak of lightning followed by a clap of thunder when it’s snowing hard outside, just think of it as one of the amazing events in weather. But be sure that you are indoors, because thundersnow’s lightning can be just as dangerous as thunderstorm’s lightning.
Sources
What Causes Thundersnow?
<http://www.theweatherprediction.com/habyhints/334; Questions & Answers About Winter Weather: FAQs
<http:www.nssl.noaa.gov/primer/winter/ww_faq.shtml>
