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Monday, October 2, 2017

Positive cloud-to-ground lightning show on September 4; St. Louis storms on Setpember 9

By DAN ROBINSON

Editor/Photographer

The recent long-term low-shear conditions that favor tropical cyclones in the Gulf and Caribbean are usually able to maintain so well because the jet stream is staying so far to the north so consistently. This results in active hurricane periods usually correlating to lackluster Midwest storm patterns. Consequently, this year's September was one of the quietest I've experienced in many years, with only one camera-worthy event to shoot the entire month: a somewhat unusual display of positive-only cloud to ground lightning east of St. Louis on the 4th. These were atypical in that the positive bolts were associated with the primary thunderstorm cores, instead of back in the trailing stratiform region where they are more commonly seen. The visual identifying characteristic of positive cloud-to-ground lightning leaders is their minimal to no branching, very apparent here. Each bolt was interconnected to a in-cloud discharge above. These types of storms that produce fascinating oddities are one part of what keeps storm chasing interesting for me.

These were all shot a half-mile from my apartment in New Baden, Illinois with a Canon 50mm F1.8 lens.

Looking west down Haselhorst Road:

Looking north over town, this positive leader managed to branch one time. One branch became the main channel of the discharge, the other terminating before ground contact. I can't recall seeing a single-branching +CG before, with the sole branch itself not branching again:

Another looking north. The loop in the middle is a result of perspective, where a portion of the channel is coming straight toward the camera:

Two more distant bolts to the north-northeast. This first one shows how the "looping" illusion happens as in the previous image - imagine you are looking at this bolt straight-on from 90 degrees to the right of the picture. That little section that goes back up toward the cloud would appear as a loop crossing over the channel as it continues back toward the ground: