Tuesday, June 23, 2009

June 22, 2009 chase: southern ND

Our initial target was west of Fargo, ND. All the ingredients were there for supercells, but the 850 mb winds were on the weak side; this told us that tornadoes were a lot less likely.

We got to Fargo and storms were going on a couple of hours west, and there was also a line of agitated cumuli around Jamestown. The towers were trying to go up near JMS, but it seems they were struggling with the shear. They leaned over in a big way. So we decided to target some of the storms to our west, all while keeping an eye behind us in case storms should go up there in the better moisture.

Well, the towers near JMS never did anything, but the storms west did. There was a north to south scattered line of discrete supercells going on, and it was just a matter of picking the right one. The one we initially targeted got choked off by one attacking it from the southwest, but there was one farther south along the line that was moving well to the right of the motion of the others. (Baron Mobile ThreatNet, while not very high resolution, helped us tremendously in this regard.) We got to a good vantage position on it and observed a good hard set of towers going up on it, with some ragged organization at the updraft base.

The storm was clearly having troubles keeping the outflow from cutting off the inflow, but for a while it seemed to strike that delicate balance where the rain-moistened air was being re-ingested into the storm and causing more structural beauty. It was looking like an almost small HP supercell at this point; we were not surprised at this point to hear a tornado warning for the storm. This was the most organized it got.

Soon after, the outflow won. It showed us a nice outflow tail attached to the storm.

And soon after that, it was gone.

All in all, a great day with beautiful structure.


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