Following up Tuesday's post on the use of simulated imagery, the low cloud deck turned out to be quite important for the storm evolution. Above is the observed GOES-East visible image from 1845UTC. The stratus deck had burned off between 15-18 UTC, and a cumulus cloud/no-cloud boundary was clearly evident in the visible image across southern Indiana and central Illinois. This boundary presumably resulted from the differential heating resulting from the morning clouds. Also note the storm which had formed on the boundary in eastern Illinois, and the multiple storms in southeast Missouri. These progressed to the east-northeast and subsequently grew upscale into a bowing MCS. The severe reports are below.
The blue dots represent severe wind reports. It's interesting that the northern boundary of the wind reports across central Illinois and Indiana corresponds quite well with the cumulus cloud boundary noted above. Most of the high-res models, including the NSSL WRF (for which we looked at the simulated imagery yesterday) had a bowing MCS further north. It turned out that the low clouds limited the instability further north, and the severe weather was confined to the south where more heating had occurred. This was a nice example of how the simulated imagery might be used to diagnose the model's treatment of morning clouds.
The blue dots represent severe wind reports. It's interesting that the northern boundary of the wind reports across central Illinois and Indiana corresponds quite well with the cumulus cloud boundary noted above. Most of the high-res models, including the NSSL WRF (for which we looked at the simulated imagery yesterday) had a bowing MCS further north. It turned out that the low clouds limited the instability further north, and the severe weather was confined to the south where more heating had occurred. This was a nice example of how the simulated imagery might be used to diagnose the model's treatment of morning clouds.
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