May 1, 2003: Hail, Biological Scatterer, and AP Signatures Author: Pam Heinselman, CIMMS/OU Last Updated: 7 May 2003

Forecast/Weather:

On 1 May 2003, isolated cells initially developed northwest and north of KOUN (00-2 UTC). By 2:08 UTC, a short line of convective cells had formed north of KOUN. Several of the cells have polarimetric hail signatures, indicated by high reflectivity and low differential reflectivity values (see Figs. 1,2). Biological scatterers are observed by KOUN during two data collection periods: 2:08-4:29 UTC and 7:51-11:20 UTC. AP occurs west and southwest of KOUN between 10:01-12:19 UTC. Examples of the biological scatterers and AP are shown in the second set of Figs. 1-9.

Radar Operations:

Start time: 00:04 5/01/03 UTC (19:04 4/30/03 local time)
Stop time: 04:29 5/01/03 UTC (24:29 4/30/03 local time)

Start time: 07:51 5/01/03 UTC (02:04 5/01/03 local time)
Stop time: 16:14 5/01/03 UTC (11:14 5/01/03 local time)

Radar/Operational Status:

Hydrometeor Classification Algorithm: Warm season

Operational Delivery:

TBD.

Snapshots:

These storms are north of KOUN, observed at the 0.5 deg elevation with the closest storm at a height of 11,000 ft AGL and the farthest storm at 17,000 ft AGL. The colocation of high reflectivity and low differential reflectivity indicate hail.

Figure 1: Reflectivity at 3:17 UTC 1 May 2003.

Figure 2: Differential reflectivity at 3:17 UTC 1 May 2002.

This second set of figures show examples of biological scatterers and a combination of biological scatterers and anomalous propagation.

Figure 1: Reflectivity at 8:57 UTC 1 May 2003.

Figure 2: Reflectivity at 10:01 UTC 1 May 2003.

Figure 3: Reflectivity at 11:07 UTC 1 May 2003.

Figure 4: Differential reflectivity at 8:57 UTC 1 May 2003.

Figure 5: Differential reflectivity at 10:01 UTC 1 May 2003.

Figure 6: Differential reflectivity at 11:07 UTC 1 May 2003.

Figure 7: Correlation coefficient at 8:57 UTC 1 May 2003.

Figure 8: Correlation coefficient at 10:01 UTC 1 May 2003.

Figure 9: Correlation coefficient at 11:07 UTC 1 May 2003.