April 26
Black Hawk County Iowa
A rather odd set up with a low pulling out from the Omaha, Nebraska area towards southwestern Minnesota.  For a few
days I had been eyeing northern Iowa and southeast Minnesota for the potential of a tornado or two as a warm front
pushed it's way north along with some decent moisture.  I knew the day was getting off to a bad start as soon as western
Iowa began to light up just after sunrise.  After keeping tabs on conditions, it became apparent the player was going to be
the warm sector of the system as a line from the morning convection formed but smaller discreet cells forrmed out in front
in a highly sheared low level environment.    The hardest part of the chase today was trying to get in front of the line into
the clean air as we headed towards Waterloo, IA and the narrow belt of instability and rich moisture.  The line was
dumping extremely heavy rain and we saw no less than 6 vehicles which had hydroplaned off  highway 20 as we
approached Waterloo.  Cullen pointed out a cell which formed near Tama, IA and looked promising so we continued east
on 20 for an intercept.  Some of the WORST underpass clogging by cars I have seen in years was encountered as the cell
went tornado warned as it entered Back Hawk county as we neared Waterloo.  This slowed us down considerably as I
wanted to get east to have a clear view just in case the cell produced over the city.  Just like 2008, this cell had a wet RFD
which we had to navigate and get into the clean air.
As we popped out of the wet RFD in Raymond, IA, we got a short look at what I thought
was a small meso and wallcloud.  
Tadd Paris' pictures show the meso was enormous and
almost on the ground.  This was just the wallcloud looking north-northwest.
Moving east to Independence, IA looking west over the airport.  There was actually a
really nice roll cloud for a bit until the linear updraft ingested it morphing it into a beautiful
shelf.  Interesting as the southeast backing surface winds would veer quickly to the
southwest with a half mile or so of the shelf then out of the west as the shelf passed
over.  You can see what is left of the roll cloud on the right and the shelf taking shape on
the left.
The shelf really starts to take shape as it surges to the east along highway 20
Cullen hanging out in the car while waiting to see if I get soaked by staying out too long.  Kind of a
funny moment when I was yelling at him to unlock the doors as I was trying to get in as I could see
the precip coming down the road.  Um...Dad?  The window is open.  You can unlock it yourself.  
Grrrr...
Heading back south to highway 20 to head east.  Looked like the
Country Inn and Suites was going to get eaten by the shelf.
The shelf at its most mature stage.  The area straight south would periodically have a
lot of rising motion into the flattened updraft area.  I kept waiting for a sheriffnado
report but none came in thankfully.  Or better yet, I was hopeful I might finally score a
leading edge suction vortex but I was in the wrong CWA for that to happen today.
Loosing strength and starting to break up east of Winthrop, IA
Shooting a little time lapse near dark.  The
instability was pretty much spent at this point so
there was very little lightning unfortunately.
Nothing special. Just a cool kink in the shelf as the line overtakes us as we call it a day
on the first real chase of 2009.  I was happy to see our gear and setup is pretty much
bullet proof and it looks like we won't be wasting a bunch of time and money trying to
tweak stuff this year.  Just a matter of getting in the car and going which will put a lot
more of the fun back into why I started doing this in the first place.
2009 Images
Here is a short time lapse
showing the shelf just after dark