Mesoscale Convective Vortex in Mississippi
Observant blog readers may have noticed medium-scale rotation in the group of thunderstorms moving through northeast Mississippi this morning. If I may be so brave as to borrow some terminology from My Buddy Scott [JessePedia], I believe what we're seeing is a Mesoscale Convective Vortex or "Neddy-Eddy". Take a look at the end of this AccuWeather.com RadarPlus loop:
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Overnight, the storms moving through northern Mississippi formed a Mesoscale Convective System, which we have discussed before on this blog. MCS are fairly common this time of year but it's more rare to see them start to spin as this one has.
If you look at the Radar/Sat combo loop, you can see how the storms came together overnight to form the MCS:
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And finally here's a look at the Enhanced Infrared satellite, which I think is the easiest way to identify a MCS - look for a large area of bright colors.
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A quick look at the surface pressure map this morning (be it the RUC Model Analysis or your classic "weather map") and the RUC 11Z 500mb chart shows that this rotation is not associated with any synoptic (large-scale) weather system such as a surface or upper-level low, so the only explanation left, I believe is the good old Neddy Eddy. There is a trough or lobe of low pressure at 500 mb but I'd be surprised if that is causing the circulation that we see.
Scott's Blog [JessePedia] says that Neddy-Eddys were so named after Edward "Ned" Johnston, a NWS meteorologist who first identified such a feature in GOES imagery.
As the NWS technical paper on the MCV that Scott describe says, MCV's can spark new convection so we'll need to keep an eye on this one as it moves northeastward over Tennessee today.
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