February 20-22, 2003: Light Stratiform Event Author: Pam Heinselman, CIMMS/OU Contributors: Terry Schuur and Kevin Scharfenberg, CIMMS/OU Last Updated: 28 March 2003

Forecast/Weather:

On 20 February 2003, stratiform rain was falling near the Oklahoma/Texas border, and was expected to increase in coverage throughout the day. Indeed, the precipitation system moved northeastward into east-central Oklahoma between 20-23 UTC on 20 February. Very light, stratiform precipitation fell all day on 21 February 2003, and ended the next morning. The NSSL two-dimensional video distrometer recorded a little over 12 mm for this event.

Radar Operations:

Start time: 20:00 2/20/2003 UTC (14:00 2/20/2003 local time)
Stop time: 14:45 2/22/2003 UTC (08:45 2/22/2003 local time)

Radar/Software Status:

Hydrometeor Classification Algorithm: Cold season
Radar: Good. Algorithms were restarted in mid-afternoon (21 February).

Differential reflectivity seems about 1 to 1.5 dB too high: the rain is very light, yet low-level ZDRs are approximately 2dB.

Operational Delivery:

Data were shipped to the NWS for the entire event.

Snapshots:

Figure 1: Radar reflectivity (0.5 elevation) at 22:34 UTC on 21 February 2003.

Figure 2: Differential reflectivity (0.5 elevation) appears about 1 to 1.5 dB too high: the rain is very light, yet low-level ZDRs are approximately 2 dB.

Figure 3: The hydrometeor classification algorithm (0.5 elevation) classifies stratiform precipitation near the radar and snow at farther ranges at 22:34 UTC on 21 February 2003.