The Morning Brew: 10 tornado and severe weather terms to know
It's Friday. Here's a primer on the language of the Great Plains in spring:
10. Dry line
While out covering the storm-plagued Festival of the Arts in April, I met an exhibitor from South Carolina who had to scratch his head as people kept talking about the dry line.
Here's a vintage interview with News 9's weather icon Gary England. I have it on file from an anniversary story of the terrible May the state experienced in 2013. Now you, too, understand how "dry line" is casually dropped into sentences.
"On May 31 (2013), the dry line was just west of Oklahoma City, hot and humid, all the parameters to create tornadoes and rotating thunderstorms. It looked pretty likely we were going to have severe thunderstorms and tornadoes in Oklahoma, and the metro was a good target area."
And here's what a dry line is:
A boundary separating moist and dry air masses, and an important factor in severe weather frequency in the Great Plains ... it separates moist air from the Gulf of Mexico (to the east) and dry desert air from the southwestern states (to the west) ... Severe and sometimes tornadic thunderstorms often develop along a dry line or in the moist air just to the east of it, especially when it begins moving eastward.-National Oceanic and Atmospheric Administration
Vintage Gary England:
"A supercell is a thunderstorm that has rotation."
Vintage Gary England:
"The entire thunderstorm is the mesocyclone."
A storm-scale region of rotation, typically around 2-6 miles in diameter and often found in the right rear flank of a supercell (or often on the eastern, or front, flank of an HP storm). The circulation of a mesocyclone covers an area much larger than the tornado that may develop within it. Properly used, mesocyclone is a radar term; it is defined as a rotation signature appearing on Doppler radar that meets specific criteria for magnitude, vertical depth, and duration. It will appear as a yellow solid circle on the Doppler velocity products. Therefore, a mesocyclone should not be considered a visually-observable phenomenon (although visual evidence of rotation, such as curved inflow bands, may imply the presence of a mesocyclone).” — National Weather Service
“A small-scale current of rising air. If the air is sufficiently moist, then the moisture condenses to become a cumulus cloud or an individual tower of a towering cumulus or Cb.” — National Weather Service
6. Wall cloud
Vintage Gary England interview:
"Within a matter of minutes, a wall cloud formed. For it to be dangerous it must be rotating."
“A localized, persistent, often abrupt lowering from a rain-free base. Wall clouds can range from a fraction of a mile up to nearly five miles in diameter, and normally are found on the south or southwest (inflow) side of the thunderstorm. When seen from within several miles, many wall clouds exhibit rapid upward motion and cyclonic rotation.
However, not all wall clouds rotate. Rotating wall clouds usually develop before strong or violent tornadoes, by anywhere from a few minutes up to nearly an hour. Wall clouds should be monitored visually for signs of persistent, sustained rotation and/or rapid vertical motion.
‘Wall cloud’ also is used occasionally in tropical meteorology to describe the inner cloud wall surrounding the eye of a tropical cyclone, but the proper term for this feature is eyewall.” — National Weather Service
5. Scud clouds
“Small, ragged, low cloud fragments that are unattached to a larger cloud base and often seen with and behind cold fronts and thunderstorm gust fronts. Such clouds generally are associated with cool moist air, such as thunderstorm outflow.” — National Weather Service
4. Hail core
“The core refers to the heaviest precipitation. The most violent rain and hail in a supercell tend to be on the outer edge of the updraft on the downdraft side of the storm. Extreme turbulence on the edge of the updraft can contribute to significant hail growth. As hail falls into above freezing air it sheds its moisture as rain.” — TheWeatherPrediction.com
3. Hook echo
“A radar reflectivity pattern characterized by a hook-shaped extension of a thunderstorm echo, usually in the right-rear part of the storm (relative to its direction of motion). A hook often is associated with a mesocyclone, and indicates favorable conditions for tornado development.” — National Weather Service
“A tornado in which two or more condensation funnels or debris clouds are present at the same time, often rotating about a common center or about each other. Multiple-vortex tornadoes can be especially damaging.” — National Weather Service
Rain-wrapped tornadoes are twisters cloaked by a wall of rain and thunderstorms. This makes visibility of the tornado almost impossible and, because of that, are considered to be some of the most dangerous kinds of tornadoes.
Juliana Keeping is on the enterprise reporting team for The Oklahoman and NewsOK.com. Keeping joined the staff of The Oklahoman in 2012. Prior to that time, she worked in the Chicago media at the SouthtownStar, winning a Peter Lisagor Award... Read more ›
Richard Hall is an award-winning newsroom developer, editor and blogger for NewsOK. He was born in Austin, Texas, spent his childhood in southern California and has lived in Norman since 1999. He graduated from the University of Oklahoma in 2008. Read more ›