We will discuss a different topic each day. Today we discuss the most common theme as of late, Severe Thunderstorms.
Throughout each day, Thunderstorms are occurring. Although most are small, all are dangerous. Lightning, flash floods, hail,
straight-line winds, and tornadoes all come from thunderstorms.
Only a handful of thunderstorms are severe in Arkansas and across the United States. A thunderstorm is considered severe when it produces winds of at
least 58 mph, hail at least 1 inch in diameter or the size of a
quarter and/or a tornado.
Hail forms in the upper layer of thunderstorms where air is below freezing. Updrafts, which are the caused by rapidly ascending air generally warm, moist air, rushes upward it causes raindrops to go upward and rain turns to ice. Quite often, hailstones fall through the cloud,
collect water, and updrafts will force them aloft. These stones tend to
refreeze and get larger, causing baseball, softball sizes etc. When you hear us mention these sizes, this is what is occurring inside the storm at any given time.
When updrafts are taken over by rain and hail, air from aloft can descend in a hurry. This is what we call a downdraft. When downdrafts hit the ground, they can spread out in multiple directions, sometimes causing damage. Damage from this type of wind, called straight line wind gusts is most common in severe thunderstorms, especially severe lines. These types of gusts are common all year around and not necessarily just in spring or fall. These can happen in the middle of the summer to and are the number 1 cause of damage in the state.
Occasionally, thunderstorms can spawn tornadoes. Sometimes, they can spawn them with little or no warning, an is quite common along thunderstorm lines, that tornadoes are so short lived they can go undetected by radar. Most tornadoes are produced in the spring and fall during the afternoon and evening, however, Arkansas tends to see more overnight tornadoes, especially in the eastern parts of the state. The last few years, we have seen more tornadoes at night than in the afternoon. Tornadoes are possible all year long though the aforementioned seasons are most common.
Arkansas averages 33 Tornadoes in each year. Last year we only saw 25 tornadoes.
The other hazards with thunderstorms are lighting and flash floods but these are not considered severe and we will discuss these during the week.
Whenever thunder is heard, there is lightning nearby. Lightning is deadly, especially during peak times of outdoor activity. Lighting can strike up to 50 miles from a parent storm.
Flash floods are another thunderstorm hazard. People driving into flash floods result in the most deaths during severe weather events. The key thing here is turn around don’t drown.
Across the country, the top three deadliest thunderstorm hazards
in the last 30 years were flash floods, tornadoes and
Below are some severe weather safety rules passed on by the NWS and are taught in nearly every Skywarn training class, and you will hear on each warning issued by the NWS.
Know the difference between a watch and a warning. The National
Weather Service issues watches when conditions are favorable for
the development of severe weather. Warnings are reserved for cases
where severe weather is imminent or occurring.
If a Severe Thunderstorm Warning or Tornado Warning is issued
for your area, do not hesitate to find a place of safety. If a
safe room is not available, the next best location is the lowest
floor of a permanent structure in an interior room away from
windows. Put as many walls between you and the outdoors as you
Make sure that you have a source to receive the latest
information, such as NOAA Weather Radio All Hazards, commercial
radio, TV stations or cable TV. Other sources of warning
information can include telephone notification services to
which people subscribe, pagers and cell phones.
Remember that we will always post watches and warnings as they come in as well but we are human and do miss some. That is why it is good to have a secondary source. All photos slides are from the NWS posts, with our own write ups as well as excerpts from the NWS. This week is used to build you a better understanding of severe weather and to help you prepare just in case. One more way for AWW to keep you ahead of the storm.
TUESDAYS TOPIC: LIGHTINING