May 17, 2002: Line of Convective Cells Associated with a Cold Front and Flying Biological Scatterers Author: Pam Heinselman, CIMMS/OU Last Updated: 22 April 2003

Forecast/Weather:

On 17 May 2002, a cold front moves through Oklahoma between 00-12 UTC, producing a line of convective cells. These cells produce heavy rainfall. Polarimetric signatures indicate flying creatures south of KOUN between 2:48-4:19 UTC.

Radar Operations:

Start time: 01:09 5/17/02 UTC (20:09 5/17/02 local time)
Stop time: 06:13 5/17/02 UTC (01:13 5/17/02 local time)

Radar/Operational Status:

Hydrometeor Classification Algorithm: Cold season

Operational Delivery:

Not applicable.

Snapshots:

The initial development of the convective line is shown in Figs. 1-4. Polarimetric signatures also suggest the presence of biological scatterers (likely insects) around KOUN, an isolated convective cell just west of KOUN, and possibly a group of flying creatures south of KOUN (area of low reflectivity, high ZDR, and zero KDP (cf. Figs. 1,2,3). Later, the convective line is in its mature stage, with trailing stratiform precipitation behind it (Figs. 5-7). The specific differential phase product suggests these cells produce heavy rainfall (Fig. 7). Figure 8 shows that by 12 UTC, a cold front has passed through most of Oklahoma.

Figure 1: Reflectivity at 3:13 UTC 17 May 2002.	Figure 2: Differential reflectivity at 3:13 UTC 17 May 2002.
Figure 3: Specific differential phase at 3:13 UTC 17 May 2002.	Figure 4: Correlation coefficient at 3:13 UTC 17 May 2002.

Figure 5: Reflectivity at 5:57 UTC 17 May 2002.	Figure 6: Differential reflectivity at 5:57 UTC 17 May 2002.
Figure 7: Specific differential phase at 5:57 UTC 17 May 2002.	Figure 8: Surface map at 12:00 UTC 17 May 2002.