KOUN Snow Band Event: February 6, 2003

February 6, 2003: Snow Bands in Central Oklahoma

Contributors: Terry Schuur and Kevin Scharfenberg, CIMMS/OU

Last Updated: 1 April 2003

Forecast/Weather:

On 6 February 2003, snow fell across central Oklahoma, with 2" snow reported in Oklahoma City. A cloud of ice crystals (henceforth, snow band) was observed initially over northwest OK, following the snowfall event (beginning at 17:58 UTC). This feature moves southeastward toward Oklahoma City (Fig. 1). At the same time, a chaff "cloud" released from an Air Force base in eastern New Mexico moved across southern Oklahoma (Figs. 1-3). Even though the snow band and chaff looked very similar from reflectivity, the polarimetric data indicated the chaff was a non-meteorological echo (Figs. 2-3).

Radar Operations:

Radar/Software Status:

Operational Delivery:

No comments.

Snapshots:

Reflectivity

Figure 1: The snow band in northern Oklahoma and chaff in southern Oklahoma look similar in the radar reflectivity data (0.5 elevation) at a)1826 UTC, b) 2024 UTC, and c) 2228 UTC.

Figure 2: The ZDR data (0.5 elevation) indicate a variety of habits within the snow band (greater horizontal orientation on its northern periphery) in northern Oklahoma and a mix of particle sizes within the chaff in southern Oklahoma (0.5 elevation) at a)1826 UTC, b) 2024 UTC, and c) 2228 UTC.

Reflectivity

Figure 3: The RhoHV data (0.5 elevation) indicate that the echo in southern OK is non-meteorological, owing to its extremely low corresponding values of RhoHV at a)1826 UTC, b) 2024 UTC, and c) 2228 UTC.

Figure 4. Hydrometeor classification shows limited ability to discriminate between the snow band and the chaff (although classified as birds and insects) at a)1826 UTC, b) 2024 UTC, and c) 2228 UTC.