April 13, 2002: Multiple Squall Lines, Gust fronts, and AP/BSs Author: Pam Heinselman, CIMMS/OU Last Updated: 17 April 2003

Forecast/Weather:

On 13 August 2002, multiple squall lines develop over northwestern Oklahoma and move southeastward through central Oklahoma in response to forcing ahead of a shortwave trough in the westerlies. The specific differential phase indicates that some of convective cells have high rainfall rates. As the convective lines move over KOUN, gust fronts are observed due to the lifting of biological scatterers (likely insects). The most dramatic example of insect lift by a gust front occurs between 7:31-11:24 UTC (Figs. 2,5,8,11,14). Anomalous propagation (ground clutter) occurs behind this gust front and within the precipitation northeast of KOUN (Figs. 3,6,9,12,15). A bright band signature is apparent in the polarimetric data from 13:04-17:17 UTC as the second precipitation system moves across OK (Figs. 16,18,20,22,24-northeast OK). AP is present around KOUN during most of the period. New cell development occurs in the vicinity of this AP during two periods (Figs. 17,19,21,23,25; e.g., 15:21-19:32 UTC and 20:39-23:55 UTC).

Radar Operations:

Start time: 05:34 8/13/02 UTC (19:34 8/12/03 local time)
Stop time: 23:55 8/13/02 UTC (18:55 8/13/03 local time)

Radar/Operational Status:

Hydrometeor Classification Algorithm: Cold season

Operational Delivery:

Not applicable.

Snapshots:

Figure 1: Radar reflectivity at 6:23 UTC 13 August 2002.	Figure 2: Radar reflectivity at 8:54 UTC 13 August 2002.	Figure 3: Radar reflectivity at 10:00 UTC 13 August 2002.
Figure 4: Differential reflectivity at 6:23 UTC 13 August 2002.	Figure 5: Differential reflectivity at 8:54 UTC 13 August 2002.	Figure 6: Differential reflectivity at 10:00 UTC 13 August 2002.

Figure 7: Correlation coefficient at 6:23 UTC 13 August 2002.

Figure 8: Correlation Coefficient at 8:54 UTC 13 August 2002.

Figure 9: Correlation Coefficient at 10:00 UTC 13 August 2002.

Figure 10: Specific Differential Phase at 6:23 UTC 13 August 2002.

Figure 11: Specific Differential Phase at 8:54 UTC 13 August 2002.

Figure 12: Specific Differential Phase at 10:00 UTC 13 August 2002.

Figure 13: Hydrometeor Classification Algorithm at 6:23 UTC 13 August 2002.

Figure 14: Hydrometeor Classification Algorithm at 8:54 UTC 13 August 2002.

Figure 15: Hydrometeor Classification Algorithm at 10:00 UTC 13 August 2002.

Figure 16: Radar reflectivity at 14:27 UTC 13 August 2002.	Figure 17: Radar reflectivity at 22:19 UTC 13 August 2002.
Figure 18: Differential reflectivity at 14:27 UTC 13 August 2002.	Figure 19: Differential reflectivity at 22:19 UTC 13 August 2002.
Figure 20: Correlation coefficient at 14:27 UTC 13 August 2002.	Figure 21: Correlation coefficient at 22:19 UTC 13 August 2002.
Figure 22: Specific differential phase at 14:27 UTC 13 August 2002.	Figure 23: Specific differential phase at 22:19 UTC 13 August 2002.
Figure 24: Hydrometeor classification algorithm at 14:27 UTC 13 August 2002.	Figure 25: Hydrometeor classification algorithm at 22:19 UTC 13 August 2002.