Lemon technique

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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.^[1] The Lemon technique is largely a continuation of work by Keith A. Browning, who first identified and named the supercell.^[2][3][4]

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.^[5][6] These features include:

• 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.^[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, 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.^[9]

[edit] References

[edit] See also

• Convective storm detection

[edit] 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)