May 25, 2002: Precipitation bands associated with a Cold Front, and AP NW of KOUN Author: Pam Heinselman, CIMMS/OU Last Updated: 22 May 2003

Forecast/Weather:

On 25 May 2002, a cold front at the surface progresses from northwestern Oklahoma through central Oklahoma between 00-12 UTC (see Figs. 1,2). Several bands of precipitation develop in association with this front.

Radar Operations:

Start time: 00:43 5/25/02 UTC (19:43 5/24/02 local time)
Stop time: 17:55 5/25/02 UTC (12:55 5/25/02 local time)

Radar/Operational Status:

Radar: Radar data occasionally is missing data along several radials. PRF has apparently changed, resulting in a decreased maximum range. Hydrometeor Classification Algorithm: Cold season

Operational Delivery:

Not applicable.

Snapshots:

Several bands of precipitation with embedded convective cells move across Oklahoma on 25 May 2002. The first band is shown in Figs. 1-3, as it moves across central Oklahoma. Notice that several of the cells have high KDP values, indicating high rain rates (Fig. 3). Anomalous propagation occurs behind the band, to the northwest of KOUN (Figs. 1,2). Following the passage of the cold front, the character of the precipitation bands becomes predominately stratiform, with small droplets and low rain rates (Figs. 4-6). Near the end of data collection, an interesting "cone" of weak reflectivity is seen east of KOUN (Fig. 8), containing low ZDRs and KDPs, that is likely second trip echo from a distant storm.

Figure 1: Reflectivity at 2:13 UTC 25 May 2002.

Figure 2: Correlation coefficient at 2:13 UTC 25 May 2002.

Figure 3: Specific differential phase at 2:13 UTC 25 May 2002.

Figure 4: Reflectivity at 11:53 UTC 25 May 2002.

Figure 5: Differential reflectivity at 11:53 UTC 25 May 2002.

Figure 6: Specific differential phase at 11:53 UTC 25 May 2002.

Figure 7: Reflectivity at 15:55 UTC 25 May 2002.

Figure 8: Differential reflectivity at 15:55 UTC 25 May 2002.

Figure 9: Specific differential phase at 15:55 UTC 25 May 2002.