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Have you ever heard of a Quasi-Linear Convective System? They are common in Northeast Ohio

Quasi-Linear Convective System is a strong squall line. But these lines of thunderstorms are not always straight. Sometimes there are 'kinks' within the line, and this is where tornadoes can spin up.

By: Katie McGraw

Posted at 6:30 AM, Apr 24, 2023

and last updated 2023-04-25 09:56:14-04

CLEVELAND — Simply put, a quasi-linear Convective System (QLCS) is a strong squall line. But these "lines" of thunderstorms are not always perfectly straight. Sometimes there are 'kinks' or 'notches' within the line and this is where tornadoes can quickly spin up. This is not rare for our region; most tornadoes we see in Northeast Ohio are from QLCS.

It is less likely for our region to see supercells. For example, this is exactly what happened across our region back on Oct. 21, 2021.

They form just any thunderstorm which includes sufficient moisture, lift and instability. These squall lines can happen at any time of the year but through different processes. Typically, these lines start off as an individual storm and merge into one line or a family' of storms. That can happen very quickly though!

The line also moves quickly, often racing across the area at 40 - 60 mph. QCLS can result in damaging straight-line winds, heavy rain, hail and tornadoes. These tornadoes, however, tend to be weaker and shorter-lived on average than those associated with supercell thunderstorms. Severe squall lines and bow echoes are quite common in Northeast Ohio. Some bow echoes can become derechos as well.

RADAR CHARACTERISTICS:

During a bow echo's early stages, a strong downburst may descend within or on the rear flank of the convective echo. This will result in a bulging look to the line.
Bow echoes look like an archer's bow and typically contain strong straight-line winds. Usually, a strong low-level reflectivity gradient is present on the leading edge of intense convection indicating strong convergence and a vertical updraft.
Subtle weak echo regions may be present on the leading edge of the reflectivity gradient marking the location of significant storm-relative inflow and the updraft zone.
Rear inflow notches/weak echo channels frequently are noted behind the leading intense convection.
Within an overall serial-type squall line, there may be several bowing echo segments embedded.
The leading convective line remains intense if the low-level cold pool beneath the convection balances the ambient vertical wind shear so that the outflow boundary and intense updrafts remain on the leading edge of the convective line. An outflow boundary propagating ahead of the line may initiate new cells downwind but will eventually diminish updrafts and the intensity within the main line.
There may or may not be a relatively large "stratiform" precipitation area (albeit still some thunder and lightning) behind the leading convective line depending on the amount of storm-relative elevated front-to-rear flow. Squall lines that exhibit significant stratiform rainfall behind the entire length of the line are referred to as symmetric, while those with significant trailing rainfall only with the northern portion of the line are referred to as asymmetric. Serial-type "cool season" squall lines usually are associated with more training stratiform precipitation than progressive "warm season" events.