A supercell moves east along I-74 on this evening near Alpha, IL
On June 22nd, I work up early on this day and took a peak at the radar on my iPhone. On this morning, a derecho that originated in South Dakota the previous evening was working its way through Iowa and moving into northwest Illinois. I got out the door fairly early on this day and headed north on IL Rt. 78 with a target near Prophetstown, IL on this day in hopes of viewing severe thunderstorms during the morning and possibly tornadic supercells in the evening as well. The evening potential would be re-examined throughout the day due to convective outflow impeding the warm front's advancement northward. By mid-morning, I arrived just south of Morrison, IL and found a spot off IL Rt. 78 to pull over and watch the shelf cloud from this dissipating derecho push southeast toward my location. Upon arrival this line of severe thunderstorms began to weaken surprisingly enough, but still provided quite a photogenic shelf cloud however. I would follow this shelf cloud south and east along IL Rt. 78. I was able to keep up with this shelf cloud all the way to Annawan, IL. At this point, it was time to re-evaluate the afternoon severe weather potential that appeared to put northern Illinois or Wisconsin in the cross-hairs the previous night. Convective debris and a southward advancing outflow boundary complicated the forecast which didn't allow much in the way of destabilization however. I actually found myself pushing farther and farther southwest most of the day heading into west-central Illinois where this outflow boundary would set up during the evening hours hoping for a thunderstorm to develop and latch onto the boundary. This area featured 3,000J/kg of CAPE, 0-6km shear at 50kts, a supercell composite of 20, and a very moist boundary-layer yet again with dew points near 75°F. I would spend most of the afternoon near Lynn Center, IL along I-74 once again waiting for storms to develop. By 6:30pm, storms were getting more organized along the cold front in Iowa and slowly pushing southeast which would take them very close to this outflow boundary from the morning's convection. I would head northwest near Preemption, IL where a tornado warning was issued as a severe thunderstorm became a supercell fairly quickly. This storm was very HP (high-precipitation) which did not bode well in hopes of viewing this storm's rotation even a few miles away at this point. This supercell had a very nice velocity couplet indicating a possible tornado which would later be reported north of Reynolds, IL. Since I was not able to see this tornado from my location due to it being obscured by rain I headed back south for better positioning choosing not to mess with a rain-wrapped tornado. I would keep up with this supercell however as it traversed southeast toward Windsor, IL and Alpha, IL. This was quite a HP supercell along I-74 where I stopped to take a few structure shots from a good few miles away near sunset. I would travel back to Peoria, IL during the late-evening after a full day of chasing across Illinois. I've added photos from the morning chase and afternoon supercell below:
First view of the shelf cloud from a dissipating derecho!
The shelf cloud approaching north of Prophetstown, IL
Knee-high cornfields meant getting a clear view of the shelf clouds more difficult!
"A shelf cloud moving across the corn belt"
One of my best shots of the shelf cloud farther southeast along IL Rt. 78!
A steel grain silo providing a nice photo-op with the shelf cloud moving overhead!
A wide-angle shot of the shelf cloud north of Annawan, IL
A closer-view looking north...
Whale's mouth moving overhead!
HP (high-precipitation) supercell near Alpha, IL
Not the greatest lighting on this late-evening as this was an incredibly "dark" supercell!
Supercell along I-74 moving east toward Galva, IL near sunset!
A decent storm structure on the backside of this supercell!
One more shot before I head back home...
That wraps up this chase day. It was a long day chasing storm's in the morning and in the evening, but I was quite happy viewing another supercell so close to home. I also ended up storm chasing on June 28th as well and will update with that post in the near future.
