Saturday, May 16, 2009

05/15/09 Central Illinois HP Supercell

HP supercell "wrapping-up" nearly producing a tornado east of Meredosia, IL

Yesterday, my target was Hannibal, MO playing a strong warm front throughout the afternoon in Illinois. I left home-base around 11:00AM and began heading southwest. At one point I considered heading into Missouri, but quickly changed my mind when I analyzed an outflow boundary in Illinois. On the way to my target I came across a beautiful shelf cloud in Macomb, IL shortly after noon. I stopped for a good 20-30 minutes to soak up the sight as most of the morning I was driving through elevated crapvection farther to the north typical of northern Illinois. This was a beautiful shelf cloud and I was worried that by stopping would possibly jeopardise making it to my target to reevaluate before the warm front began to fire by afternoon However, I indeed made it just in time for round two of the day. I reached my target around 3:00pm seeing all the signs of a warm front tornado outbreak possible for the evening in part thanks to an outflow boundary that was draped across the region from morning convection. The first storm (discrete) crosses the Mississippi River to my west and latches onto the boundary and quickly goes tor-warn (first tor-warn of the day) with good rotation on velocity scans. I did add one image as I first came upon it, but I wish I was able to get closer since there might have been a circulation rain-wrapped. I just couldn't tell since I wasn't close enough to it at that point. It had strong inflow, but boy did that not last long. It seemed to me that it was just too cold for tornadogenesis as it couldn't get warm surface-based parcels from it's south. Argh!... Nevertheless, this thing had good mid-level rotation all the way to Decatur, IL. The best it looked while I was chasing the HP supercell was west of the Illinois River and a little east of the river in two instances (west and east of Menedosia, IL I believe). After driving through several towns with tornado-sirens going off it was interesting to say the least how people "take-cover" these days. (It's by going outside to watch for the tornado). Granted us storm chasers are chasing tornadoes which is far more dangerous, but at least we have a meteorology background with Doppler radar to steer us clear of the tornado. The public does not and should take warnings seriously! Furthermore, I even saw one person mowing his grass for some odd reason as the tornado-sirens were sounding. Stupidity...to say the least. Anyhow, I watched many funnels and rotation for awhile with this supercell. I got cored at one point near Griggsville, IL and well the closest you ever want to be to a supercells rotation. I became the chased at this point. A circulation with rapid rotation maybe 100 yards away with a beautiful clear-slot right in front of me. At the same time the RFD wrapped in suspended ping-pong hailstones as I was taking some photos and I took one hit to my knuckle. Note: projectiles hurt...especially hail! Probably, the closest I've ever been to a circulation on a storm ever or that I ever want to be. Nevertheless, it was a good chase yesterday and Illinois does have a good road network, but the main problem yesterday was trying to avoid flooded roads so you could keep up. This was almost impossible and once when it seemed I couldn't catch back up I gave up on the supercell near Lincoln, IL. On another note, my rain gauge recorded 3.25" of rainfall yesterday. Now you know why the fields, creeks, and rivers are flooding around the area. It rained all day...heavily!

Beautiful shelf cloud outside Macomb, IL yesterday morning
After watching this for a good bit, the afternoon convection was a bonus on this day
New slogan: "Turn-around, don't get rolled-on"
Picturesque beauty along Illinois's flat terrain
Circulation and lowering from atop I-72
My close call: Yikes, rapid rotation to my north and notice clear-slot (left)
RFD wraps in suspended hail stones (right) into the circulation with rapid rotation near Griggsville, IL Click to enlarge...
My next play after punching through and now east of the Illinois River and Meredosia, IL
The wet RFD wraps-up producing this funnel cloud to my west-northwest (Oh..so close) Click to enlarge...
My rain gauge best illustrating the flooding problems due to one day of rainfall

A great day considering my target area was correct yet again and everything was in place for tornadoes in Illinois. Just another let down of a day in a sense that we didn't get a tornado, but damn close again. I do wonder if anytime soon the Great Plains will ever get into a favorable pattern for tornadoes with 0-6km shear greater than 30kts out there this spring-summer. I kind of feel sorry for everyone out there. Well not really...at least they've been able to enjoy nice convection though. Just think, take the shear in the last two systems we've had here in Missouri and Illinois out there and we'll all be in business. Anyhow, there will be a lack of opportunities to chase here in the next week so I'll use this time wisely to rest up for some plains chasing which will be later than I even imagined this year. Sooner or later the pattern has to change to southwest-flow, but how long is the question before it's too-late in the season...