Chase Log: June 07th, 2009

Click on any of the SPC products below (Convective Outlooks, Watches, or MCDs) to see the SPC's "Severe Thunderstorm Events" page pertaining to this event.

     
MAP

Total Distance: 540 miles
Target Area:
Chase Area: Forest City to NE of Cameron, MO
Maximum SPC Risk category: Moderate

Another good shear, high instability chase day that ultimately resulted in an extremely intense, yet largely non-tornadic, supercell that moved across far northwestern Missouri. We collected data on the intensifying, non-tornadic (at least at the time of scanning) supercell scanned the west . The supercell took a right turn that eventually brought the mesocyclone over the deployment location. Eward advancing precip at south end of hook echo noted ~1-2 km to our south. We waited as long as possible in an attempt to catch tornadogenesis, but that never came. We experienced hail of approximately baseball size in Forest City, and hail larger than baseballs in Oregon. I vividly remember at least two hailstones on the lawns of two houses in Oregon that are certainly the largest hailstones I have ever seen; I would not be surprised if these stones were larger than 4.25" in diameter. A storm chaser (per a report on Stormtrack) measured a 5.25" diameter hailstone in Oregon, and there are several accounts by other chasers in and around Oregon of hail well beyond baseball size. Unfortunately, being on the very north side of the meso, I was not concentrating much on collecting hail, as we were trying to make a hasty exit from under the storm. The only thing I can say with relative certainty is that the stones were at least as large as 3.5" in diameter, though I expect that a few stones were as large as, or exceeded, 6" in diameter. We did take some scans as were driving under the north side of the meso, with the hook echo to our immediate south. This should be a very good polarimetric case of a largely non-tornadic, significant supercell that produced gargantuan hail.

We moved eastward to get back out ahead of the supercell to deploy again. We didn't find a terribly good deployment spot, with a tall gas station sign to our N, and a set of trees to our W. However, it was the best we could find in the area. Apparently, at least one or two tornadoes were reported to our WNW, though the first (near Amity) likely occurred before we began data collection. We noted several low-level, rain-wrapped meso occlussions with the storm was it moved to our NW through NE (e.g. Image 3), and it should have been in a dual-Doppler lobe with at least one other Xband radar. Extremely large hail (4.0") was reported to our NE during our deployment, and there were several other reports of >2" hail throughout the deployment time. New convection developed after we undeployed, and a large tornado was reported to have caused damage ~10 km S through E of our deployment location approximately 45 minutes after we left the location (approximately 90 minutes after we ended data collection). We repositioned the truck slightly to the east (~100-150 feet) so we could scan to the ENE - NE without significant beam blockage issues.

06-07-2009 Chase Pictures

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