Meteorological method to determine relative strength of thunderstorm cells
TheLemon technique is a method used by meteorologists using weather radar to determine the relative strength ofthunderstorm cells in a verticallysheared environment. It is named forLeslie R. Lemon, the co-creator of the current conceptual model of asupercell.[1] The Lemon technique is largely a continuation of work byKeith A. Browning, who first identified and named the supercell.[2][3][4]
The method focuses onupdrafts and usesweather radar to measure quantities such as height (echo tops), reflectivity (such as morphology and gradient), and location to show features and trends described by Lemon.[5][6] These features include:
Vertical cross-section through asupercell exhibiting a BWER.
Updraft tilt - Thetilted updraft (vertical orientation) of the main updraft is an indication of the strength of the updraft, with nearly vertical tilts indicating stronger updrafts.
Echo overhang - In intense thunderstorms, an area of very strong reflectivity atop the weak echo region and on the low-level inflow inside side of the storm.[7]
Weak echo region (WER) - An area of markedly lower reflectivity, resulting from an increase in updraft strength.[8]
Bounded weak echo region (BWER) - Another area of markedly lower reflectivity, now bounded by an area of high reflectivity. This is observed as a "hole" in reflectivity, and is caused by an updraft powerful enough to prevent ice and liquid from reaching the ground. This powerful updraft is often an indication of, or is facilitated by, amesocyclone. A mesocyclone is not strictly necessary for BWER development. Storm rotation can be reliably detected by theDoppler velocities of aweather radar.[9]
^Lemon, Leslie R. (April 1980).New Severe Thunderstorm Radar Identification Techniques and Warning Criteria. Kansas City, MO: Techniques Development Unit, National Severe Storms Forecast Center.
