A mesocyclone typically will develop at the midlevels of a tomadic storm and build down to lower levels as the storm matures. It may be possible to monitor development of storm rotation or a mesocyclone in the velocity field. The time lapse capability with continuous update may be useful in monitoring this development. In the velocity field, the feature will appear as two velocity peaks of opposite signs, separated azimuthally. Interrogation of different elevation scans of the Mean Radial Velocity product (at 2000 ft intervals between 15,000 and 19,000 ft) can aid in determining the height continuity of a mesocyclone. The Quarter Screen mode can be useful for this purpose. If correctly oriented through the storm, storm rotation (cyclonic or anticyclonic) or a well-developed mesocyclone may be evident in the Mean Radial Velocity Cross Section product. The cross section should be generated perpendicular to the mean flow. If a mesocyclone is not evident in the Mean Radial Velocity product or the Severe Weather Analysis Mean Radial Velocity product, the Storm Relative Mean Radial Velocity Map or Region products may display this feature (part C of the FMH-11).

 Removing the storm motion may aid in the detection of a mesocyclone, but the mesocyclone circulation pattern will exist in the velocity field even if the storm motion is not removed.

In the presence of a strong rotational signature, the Combined Moment product can be very useful in determining the existence of a mesocyclone. In such a case, rotational phenomena should be clearly evident due to the relative position of the arrows in a given area. In addition, high reflectivity core and high spectrum width values may be evident in the area.

In a tornadic supercell, doppler data have indicated that a separation of the mesocyclone core from the bounded weak echo region occurs prior to or during the collapse of the bounded weak echo region. With the development of severe weather possible at this stage, the separation of the mesocyclone core from the bounded weak echo region may be monitored by displaying an appropriate Reflectivity product on one graphic screen and a Storm Relative Mean Radial Velocity Map product on the other. A time lapse of the Mean Radial Velocity or Storm Relative Mean Radial Velocity Map product, magnified on the storm under investigation, may prove very useful in determining the separation of the mesocyclone core from the bounded weak echo region. If a mesocyclone is evident in the Mean Radial Velocity product, this separation may be monitored using the time lapse capability with continuous update for the Mean Radial Velocity and Reflectivity products.

The mesocyclone algorithm provides the position of the feature reflected onto the lowest elevation angle in which the feature was detected. This is due to the fact that mesocyclones are often tilted and are, therefore, displaced at higher elevations. Mesocyclones may not always be identified by the algorithm for high reflectivity core storms, for storms that produce downbursts, or for weak tornadoes produced as a result of convergence boundaries. Since there is no tracking algorithm for mesocyclone features, time continuity must be established. In addition, the Storm Relative Mean Radial Velocity Map and Region products display the maximum velocity sampled over four 0.13 nmi range bins. The peak velocity values, and thus the peak shear associated with a mesocyclone feature, are more likely to be displayed on these products than on the Mean Radial Velocity product, which simply displays every fourth 0.13 nmi range bin at the same resolution. Depending upon selection of storm motion removal, the existence of a mesocyclone may be more evident in the Storm Relative Mean Radial Velocity Map and Region products than in the Mean Radial Velocity product.

Due to beam broadening and an average mesocyclone size of 2.7 nmi, the range of detection is generally limited to about 124 nmi. Mesocyclones formed in vertical wind shear may not be detected beyond 38 nmi due to the small size vorticity maximum found at low levels, and initial formation in a precipitation-free environment.

Multiple mesocyclone cores can form within a storm complex, but not in the same cell.

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