northwest of Grinnell, IA
A few weeks ago I chased in central Iowa as a cold front plowed into a region with extreme instability in place. I targeted Grinnell, IA as it appeared this area would provide an opportunity at a discrete supercell before the cold front "lined-out". This area was characterized by 3,000J/kg + of CAPE, 0-6km shear nearing 35kts, and a moist boundary-layer with dew points above 70°F. It was quite nasty in the pre-convective environment before storms erupted along the cold front as surface temperatures soared into the lower 90's. My target ended up being pretty accurate as the first severe thunderstorm that would later become a supercell developed near Marshalltown, IA. I headed north on U.S. 63 to chase this developing supercell as a tornado ended up being reported by local law enforcement. I ended up finding myself quickly disappointed as I approached this supercell however in its lack of structure. New severe thunderstorms quickly formed along the cold front which led to complex storm mergers which in turn made chasing visually rather difficult. Nevertheless, I continued chasing but gave up on this storm as it neared the south side of Waterloo, IA. I decided to drive back west ending up on the east side of Des Moines, IA as new severe thunderstorms were forming. My hope here was maybe a chance at a "tail-end charlie" supercell that could tap the extreme instability to the south of the boundary. I ended up setting up shop again near my target of Grinnell, IA and watched some high-base convection "try" to gain some rotation. Near sunset one storm on the tail-end of the cold front did show some brief rotation at times with a pronounced lowing for a period as well. I took some time-lapse video of this severe thunderstorm trying to tap some horizontal vorticity upright into the vertical, but like I said it struggled to concentrate rotation for a long period of time. Anyhow, this severe thunderstorm did manage to provide some decent contrast near sunset providing some photography opportunities. I've posted photos and some time-lapse video below:
Picturesque high-base convection
in central Iowa
in central Iowa
One of my favorite shots from the evening...
This storm weakens for a brief period here...
I'm about to get overtaken...
On the backside of the storm now as this storm
tries to gain some rotation...
tries to gain some rotation...
Wall cloud/lowered base forms...
Wall cloud takes on a "flying saucer" appearance...
Convection struggling to form as the boundary-layer
to the south remains capped...
I've added a YouTube time-lapse (above)
to the south remains capped...
I've added a YouTube time-lapse (above)
That will wrap up this chase account. It has been awhile since I last posted as I've been extremely busy as of late thanks to Mother Nature. I actually just completed my "chasecation" over the past week. During that period I ended up chasing in CO, MO, NE, IA, and IL. I had some tough days, but also some good days which wraps up chasing for myself in the near term. Some time off I could use as I'm pretty sure over the last two months I have chased the most storms I've ever chased in about 4 years of storm chasing. You'll still find me chasing in the local-area (IA/IL) over the next couple of months due to the closer proximity. Anyhow, stay tuned for more posts that I'm working on as I begin catching up over the next week or so...
