Articles / 2007-04-30 Long Narrow Thunderstorm Line

2007-04-30 --- Long Narrow Thunderstorm Line
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These thunderstorms were notable only due to their appearance, by which I mean both their development and their characteristics as seen by radar or satellite. We only received 0.33" rain, there was brief small hail (pea size), and occasional lightning.

An extremely thin --- only one thundercell wide for the first couple of hours --- and eventually quite long line of thunderstorms developed virtually out of clear air in less than two hours.

As time passed, the nearly stationary line of thunderstorms filled in and expanded slowly before finally kicking off to the north and east. Though the line was stationary, the individual cells raced along that line.


A beautiful, virtually cloud-free morning over northeastern Indiana, with a prominent line of clouds from southern Wisconsin, across Lake Michigan and through southern Michigan, then across northern Ohio.


Only fifteen minutes later, a pencil thin line of clouds (almost like a jet contrail) begins to develop within a broader area of scattered clouds, nearly parallel to that prominent line of clouds.


Another fifteen minutes later, that pencil thin line grows in length and the lower clouds expand and fill in a bit.


By 11:15, an area of thunderstorms over southern Wisconsin has moved into the picture. The original prominent line of clouds is beginning to dissipate, virtually gone over Lake Michigan and western Michigan.


An hour later, the big area of thunderstorms has reached the western shore of Lake Michigan, and that pencil thin line of clouds across northeastern Indiana has rapidly grown into a line of thunderstorms; still, it has not noticeably moved. Also, there is now an even thinner line of clouds just north of the line of thunderstorms; this is an outflow boundary. That it is nearly parallel to the line of thunderstorms indicates that those thunderstorms are all about the same age and intensity.


Finally, only fifteen minutes later, the thunderstorms are growing quickly within that virtually stationary line of clouds across northeastern Indiana, and rain begins to fall on my weather station. That outflow boundary has moved slightly further away from (to the north) the line of thunderstorms.

Here is the radar view of the development of that line of thunderstorms.

Radar Loop

The thunderstorms grow in intensity, and expand to nearly reach me at work (I-69 and Illinois Road). However, just as the fringe of precipitation reaches me, the line begins to move off to the north and east.

Precipitation fell on the About My Weather Station between 1230 and 1255 and then again (as another cell moves down the line) between 1320 and 1340. My wife reported small hail during one of those episodes. We received only a total of 0.33" in the big black bucket. Though the temperature dipped by 8° as the first rain hit, the winds dropped to nearly a dead calm, remaining virtually calm for four or five hours.

The line of storms broadened and weakened as it moved north and east toward Flint--Detroit--Toledo by around 1800.

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