I noticed today that with the satellite out of rapid scan mode, the CI tool has not been nearly as effective. It does not give the type of lead times that we had seen in rapid scan mode. Here is an example:
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| 1945Z satellite imagery with the CI tool overlayed. |
In the above imagery, try to focus across the northern CWA (near the chimney region). As you can see, very low values of CI are being detected at 1945Z.
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| Satellite with CI tool overlayed at 20Z. |
I’ve circled the area of interest here. By this time, there’s one small area of 50-60% dBz. However, at this time, echoes were already beginning to show up on radar.
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| Satellite imagery with CI tool at 2015Z. |
The probabilites finally began to expand and increase in this scan. However, by now, the radar already had 30+ dBz echoes, which gave very little lead time to the probability of CI. Given this is a cold core convective case, perhaps the threshold of CI is lower? I noticed the other day 70% and above tended to result in CI, but perhaps in these type of environments the CI thresholds may be 50-60%. Either way, it appears that without rapid scan mode, this product’s utility and ability to increase lead time to convection is greatly diminished. Below is the radar slice at 2019Z which corresponds to the latest satellite/CI imagery seen above.
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| Radar image at 2019Z. |
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