What is a severe thunderstorm?
A severe thunderstorm is any storm that contains one or more of the following:
Hail of 1"(quarter size) or larger
Winds of 58mph(50kts) or greater
While severe thunderstorms can occur any time of the year, the most common
time for occurrence is during the months of March, April and May.
What is the difference between a watch and a warning?
PDS WATCH - Conditions are favorable for development of intense severe weather during the watch time.
|Two main kinds: Tornado and Severe Thunderstorm|
|Can be issued for a long period of time(6 hours or longer)|
|Covers many counties|
|Usually is issued before severe weather occurs and exceptionally intense and well organized wind storms are possible.|
|Remain weather aware of rapidly changing conditions|
Straight line damaging winds are common across Mississippi any time of the year. Damaging winds (sometimes referred to as straight line winds) can do just as much, if not more, damage than a tornado. These storms can knock down trees and cause damage to structures. While these winds can occur any time of year, damaging wind reports tend to increase during the spring months and peak during the summer months in Mississippi. In mid June 2012, a large complex of thunderstorms moved across the state from the northwest. This complex of storms brought widespread tree and power line damage with 60 to 70 mph wind gusts. Some pockets of significant wind damage occurred in the Mississippi Delta where winds likely gusted around 80 mph.
Another example of damaging winds was in mid October 2012, when supercell thunderstorms moved through with 11 confirmed tornadoes across the region. One supercell thunderstorm in Greenville, MS did not produce a tornado but produced downburst winds up to 80-90mph. Extensive damage occurred on the south side of Greenville where many trees and powerlines were downed.
Hail is formed when water droplets are drawn into an area of strong upward moving air, known as an updraft, of a storm. Once the water droplets are transported above the freezing level, they combine with tiny airborne particles, such as dirt, salt, etc., and freeze on contact, forming tiny ice particles. These ice particles are light enough that they remain suspended in the cloud, where they undergo processes that allow them to combine with other supercooled water droplets and grow into hailstones. Once the hailstones are heavy enough to overcome the upward force of the updraft, they fall out of the cloud.
Hail can occur throughout the year as long as temperatures aloft are cold enough to support freezing of the hailstone, and won't melt the hail as it falls. The spring months tend to be the time of year that the largest number of severe hail reports occur. In addition, the highest number of large hail
(2 inches or larger) reports also occurs during the spring months.
Large hail can cause significant damage to crops and property. On March 18, 2013, hail to the size of ping pong balls, tennis balls and even softballs fell across several locations in central Mississippi. The largest of the hailstones fell across portions of the Jackson metro area during rush hour. This caused significant damage to thousands of cars and many buildings. Around 550 million dollars in damage was caused by this destructive hailstorm. The softball size hailstone that fell in Clinton, MS was the third largest hailstone to fall in March in Mississippi since 1950 and the seventh largest to fall in the state for any month of the year.
Taken in Clinton, MS on March 28, 2013. Credit: Stephanie Wallace Mumbower
The largest hailstone to fall in Mississippi history was 5 inches in diameter, or CD/DVD size. This fell in Lafayette County on April 10, 1962.