Microburst

This image is made from radial velocity data collected in Colorado. Like all single Doppler systems, we are only able to measure the radial (towards or away) component of the target's motion.

The color table in this example image has had the near 0 mps values blacked out. The microburst pattern is indicated by the region of inbound motion (blues and greens) that is associated with an area of outbound velocities (pinks and yellows) located at more distant ranges. This is the depiction of a flow pattern that's more or less diverging outwards from a single source region near the ground. The white range rings are only at 10 km intervals, so the phenomenon is not large.

The maximum velocity differences in this example image are only separated by approx 6 - 7 km. The formal microburst definition requires that the max velocity differences be within ~4 km of each other. Thus, this example is edging into the "macroburst" category. Airplanes attempting to take off or land in such diverging wind patterns can suffer serious performance losses.

If the diverging motions are due to birds, then it's normally a false alarm in terms of an aircraft performance hazard. Terminal Doppler Weather Radar systems that the FAA uses to detect low level wind shear hazards near airports incorporates some logic to reduce false alarms due to birds.

Pat Kennedy
CSU-CHILL Radar