On Sunday, May 5, 2019 severe weather was forecast to occur from southern Nebraska, down through Kansas, Oklahoma and Texas. A cold front descended through Nebraska and triggered storms east of Grand Island and over Lincoln. A supercell over Lincoln produced a probable EF-2 multi vortex tornado which caused damage throughout the area.
Closer to home storms also initiated south of Dawson County along the Nebraska and Kansas state line. The storm pictured had a severe thunderstorm warning due to the two inch hail it produced. The cell moved east at 36 knots. Ping pong ball sized hail was reported along with 60 mile per hour winds.
The photos show the powerful flanking line which was feeding this cell for a period, before smaller individual updrafts began to form as the main cell weakened. These cells were short lived and could not produce the same damage the parent cell did.
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The supercell thunderstorm at the its most powerful. The main updraft to the left leans down shear as winds aloft influence it. An overshooting top edges above the main anvil thanks to powerful internal winds. An inflow tail supplies the storm with warm moist air and as a result the storm continues to build.
A severe warned thunderstorm churns over Harlan and Franklin County on Sunday, May 5, 2019. The billowing clouds in the center represent the updraft as it climbs into the sky.
A closer look at the thunderstorms updraft, the billowing structure to the clouds is due to the rapid rise of air thanks to the instability in the air.
As the updraft begins to penetrate the stable layer of air aloft and form an overshooting top, more updrafts start to form in the flanking line to the right. This storm is being fed by a tail of inflow which is several miles long.
As the old updraft begins to weaken, a new updraft has formed along the flanking line. The flanking line is formed by the downdraft, warm moist air is forced upwards, creating new updrafts to feed the storm.
The new updraft goes off like a bomb in the unstable atmosphere. Instability exists when warmer air enters into cooler air aloft. Warm air is less dense than cold air and will rise with great speed given the right conditions.
The flanking line erupts with several new individual cells. The storm mode began to transition from supporting a single discrete cell to a line of storms. These subsequent cells were not as strong as the initial storm.
At least four new individual cells have now formed along the flanking line of the original storm. Instead of one large tail of inflow feeding one storm, these smaller cells have their own inflow tails. As a result these storms will rob each other of moisture needed to keep cycling and will fade quickly.
One of the last strong updrafts rises upward. This would updraft would not reach the height its parent updraft had earlier in the evening. Storm mode often shifts from discrete, individual cells, to lines of storms.