July 20, 2003 Storm Chase |  Northeast NE Tornadic Supercells

Original Target:  Vermillion, SD

The first Cbs popped NW of KSUX...soft and elevated...later became orphan anvils. I caught a glimpse of some crisp TCu to my WSW near Norfolk and went after them since nothing else looked better.
A full blown Cb was already in progress not more than 30min after the previous shot! The "Fist of God" (or mushroom cloud) upstream of the initial Cb.  A time lapse would have been beautiful, but I chose to keep driving given its explosive development.  Check out the backshearing just minutes later!
Anvil canopy south of Wayne, NE. Rotating wall cloud to the NW...not far from Stanton, NE.  I observed two separate funnels before this shot which were picked up immediately by the local spotters...compliments to them for their work which got the warning out in time.
Another shot.  I'm on the edge of the FFD, but found it hard to keep driving knowing this would likely produce at any moment. "I went down to the Crossroads....but took a left!"  I considered continuing west here, but instead went south to avoid a repeat of last month's close encounter.
Rather strong rotation here with a tail cloud becoming more evident.  The RFD is just beginning its work. Debris cloud!  The diagonal streaks are hailstones catching back up with me.  I was not going to start driving as this tornado developed.
Condensation fills in and removes all doubt.  My view was deteriorating rapidly due to the dense FFD. Dissipating fast.  I shot south only to encounter scattered 3" stones that cracked my windshield and left several souvenirs.  I looked back but didn't see any sign of the tornado.  A minute or so later I looked again and saw a much larger vortex unfolding!  The official NWS survey has these tornadoes listed as two separate events.
I didn't get any stills or video of it during its most impressive phase, but I did catch everything thereafter.  Wide shot showing meso, distant precip core on the right underneath the vault and signs of RFD advancement.  A new wall cloud is developing along the stormscale triple point (top foreground). A closer look.  Early on, the debris cloud was very firm and compact with NE soil.  The tornado moved very slowly...generally to the S and later SE. I'm roughly 8 miles SE of Stanton. Steve Peterson and company in the foreground.
Roping out as I see the precip core racing south down the HWY.  I don't recall seeing rotation with the new wall cloud. Heading west and getting in the preferred viewing quadrant for the Stanton supercell.  To my west there lies a behemoth of a left split supercell.  I could see the base of the right split early on, but was more concerned about the supercell just to my north at this point.
So much for the meso from the Stanton supercell.  That dense precip cascade in the previous image was moving ENE and surprised me at this time with golfball sized hail. Here is the right mover's meso looking SE.  Wow!  I aborted this after a hailshaft wrapped it up...but not before producing a wall cloud.  There may have very well been a tornado in this guy afterwards that no one saw.  A new supercell caught my attention to the SW after all of this.
I love chases that involve decisions made solely on visual observations!  I may have just gotten lucky, but this new supercell would soon have a very persistent funnel behind a significant rainfoot.  This is the view to the SW heading south on HWY 81.  The slope of this rainfoot will coincide perfectly with what's about to develop! A better view of the funnel.  No debris was seen while on top of the hills at this time.  Shortly after this, an Arby's truck came by and picked up the cow....mmmm.    :)
I'm still mobile trying to find a good spot to pull over.  Debris was visible at this point. Very picturesque.  It would have been nice to be west of this seeing that there is backlighting underway.  Note the slope of the vortex is identical to the slope of the rainfoot/cold pool from 3 images previous. 
Wider view with a new meso developing to its south. Roping out.
Still roping out...what a slacker! Successive tail-end Charlies.  Following the performance of the first supercell, I went SW for the next cell in line (in Howard Cty) all the while watching the last one.  What was likely happening was updraft seeding and/or undercutting. Radar verifies pretty well with this.
The next supercell to the SW viewed from near Archer, NE. North of Grand Island looking south.  RFD winds were picking up dust left and right closer to the updraft.  This cell seemed to lose its features fast as a western cell's precip core invaded the updraft.  The supercell later regenerated before sunset.
At the motel in Grand Island observing the supercell back at full strength. Simply gorgeous.  Eerily, I was given the exact same motel room from one month ago while chasing in this area! Another view.
Beautiful mammatus at sunset. I got out of the city to document the vivid lightning display at night, but I started taking stills too late.  The video captured the show, though when I started the stills this renegade LP cell developed in the supercell's wake and blocked the lightning.  A nice beaver's tail nonetheless!
All photos copyright © Matt Ziebell
 
Notes and conclusions:
  • 13Z  |  sfc pressure rises and winds revealing cold pool mesohigh
  • 13Z  |  sfc theta-e and streamlines w/mesolow and moist axis readily evident
  • 20Z  |  1hr RUC 0-1km EHI forecast (max of 6!) - image courtesy Earl Barker
  • 21Z  |  9hr RUC 500mb height and speed forecast - speed max w/increasing diffluence over the MO River
  • 2143Z  |  sfc frontal analysis - southernmost cold front is actually a non-classical dryline while the convergence axis in E NE was placed via radar imagery (likely leftover from the remnant cold pool) - note strong moisture convergence around Norfolk
  • 2202Z  |  visible satellite w/overlays
  • Formation of the initial supercell was attributed to a bulge in the sfc boundary immediately ahead of the gusty NW winds with some possible enhancement from the cold pool signature to the SE.  The mesolow had waved out by the time of convective initiation, through minor pressure falls may have also assisted.  Crude hodograph constructions showed linear paths above the boundary layer which supported left splits throughout the event.
  • Significant theta-e pooling ahead of boundary (bullseye of 382 K near Norfolk!),  MLCAPEs of 5600+J/kg (SBCAPEs >6000),  0-3km CAPEs ranged from 240-300 J/kg while 0-1km SRHs averaged around 65 m²/s²

Back to Chase Logs