A Severe Thunderstorm Warning was issued on a storm in Marshall County, IA with a much more robust storm further south in Marion/Mahaska Counties. After checking up on the southern storm, I did a quick check-in on the Z/V fields at 0.5 degrees for the northern storm. At the time, the storm didn’t look immediately capable of tornadic production, but earlier LSRs with low thresholds prompted the Severe/Tor possible. At 0.5 degrees, Velocity showed a bit of increased shear but nothing too substantial with a Delta-V of approx 30kts, and NROT of approx 15kts. The TDA picked up on this, but what intrigued me was the MDA did as well which had been very stingy at picking up mesocyclones which caught my eye. The readout suggested a meso signature was being detected within several bottom layers, which prompted me to look at all tilts, and voila! Above the 0.5 degree scan a decent-looking mesocyclone was much more prevalent. This mesocyclone indicated the storm was much more organized than originally expected and lead to the issuance of a tornado warning while anticipating further strengthening of the circulation. Eventually, the Tornado Warning was verified by an LSR report at 2122Z.

-#ProtectAndDissipate