A benefit of the CSPP Geosphere site is that long animations can be constructed that don’t include every image. The animation above (link) shows hourly true-color (daytime) and Night Time microphysics RGB (nighttime) from 1801 UTC on 18 May 2022 to 2001 UTC on 20 May 2022. This is achieved after clicking on the date in the upper right corner of the image by adjusting the ‘stride’ to — in this case — every 12th image, and increasing the number of frames viewed. The animation above shows a Mesoscale Convective System (MCS) generating over the High Plains late in the day on 18 May and developing into a Mesoscale Convective Vortex (MCV) that persists through late in the day on 20 May 2022 over the mid-Atlantic States. It is unusual for MCVs to persist through the night.

For a MCV to persist, certain environmental conditions must be present. In particular, atmospheric wind shear should be small, and moisture and instability should be greater than normal. In this way, convection can be continually generated to help sustain the cyclonic vortex. The stepped animation below shows 6-h HRRR forecasts (from this website) of Most Unstable Convective Available Potential Energy (CAPE), Total Precipitable Water, and 0-6 km shear, valid at 1800 UTC on 19 May (when the MCV was over central Missouri) and 0600 UTC on 20 May 2022 (when the MCV was over Ohio). The region near the MCV center has small values of shear, and large values of moisture and instability.

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