Lemon technique

The Lemon technique is a method used by weather radar operators to determine the relative strength of thunderstorm cells in a vertically sheared environment. It is named for Leslie R. Lemon, the co-creator of the current conceptual model of a supercell. The Lemon technique is largely a continuation of work by Keith A. Browning, who first identified and named the supercell.

The method focuses on updrafts and uses weather radar to measure quantities such as height (echo tops), reflectivity, and location and to show features and trends described by Lemon. These features include:

Vertical cross-section through a supercell exhibiting a BWER.

• Updraft tilt - The tilt (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 the weak echo region and on the low-level inflow inside side of the storm.

• Weak echo region (WER) - An area of markedly lower reflectivity, resulting from an increase in updraft strength.

• 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, a mesocyclone. It should be noted, however, that a mesocyclone is not strictly necessary for BWER development. Storm rotation can be reliably detected by the Doppler velocities of a weather radar.

See also

• Convective storm detection

External links

• Paul Sirvatka and Les Lemon The Lemon Technique – College of DuPage Meteorology (PDF)
• The Lemon Technique (LT) to determine updraft strength (University of Illinois)