Evolution of a Supercell, Kansas

Welcome to Kansas USA.   On a day with not so perfect "textbook" conditions we head west from Hillsboro KS our Australian chase base in the USA,to hunt for expected afternoon storms from western Oklahoma to western Kansas. Overnight a broad area of storms developed and moved through Oklahoma and central Kansas - this type of overnight activity can dampen the day with surface cooling and a stable layer below 5000 feet...it will take strong heating to overcome the "CINH"...(convective inhibition) across Oklahoma and southwest Kansas.

Through the morning we drive toward Medicine Lodge, a small settlement and coffee stop. Looking southwest a large residual cirrus shield covers western Oklahoma and the southern fringe of central southwest Kansas - this will also affect surface heating. To the west of Medicine Lodge, southwest Kansas is clear but dew points are not high - mainly mid to high fifties.A check of the upper layers shows weak shear...today's storms if they get going will not move fast, that's good for chasing but usually not such a good thing for organised storms weak shear can allow precipitation to fall back onto the updraft core ...weakening the potential. This however is not always the case especially if the updraft core can keep itself away from its precipitation core by riding the outflow nose shifting its updraft core into its inflow quadrant. In the upper layers lapse rates are steep in the mid levels, a weak upper trough (shortwave) is progged to enter the equation across western Oklahoma and southwest Kansas through the late afternoon...

We head west from Medicine Lodge along Hwy160 towards Coldwater and eventually end up just east of Ashland. Earlier.a few storms got going near Woodward Oklahoma but have formed under a cirrus shield - they don't amount to much but just bubble away and eventually weaken...we term these early storms "sucker cells", often taking the interest of chasers who highball towards them only to be disappointed. As we approach Ashland a small multicell has developed to our southwest and undergoes the "splitting process"...a splitting cell is fascinating to watch, its left split twin moves north producing a reasonable rain shaft, meanwhile its right split looks weak but retains a rainfree base - the right split however has clear air to its southwest and an uninterrupted inflow potential, it's not all that warm but here in southwest Kansas we are elevated to near 2,500 feet - it's around 78F with a DP near 56. We park in a field with a great vista and watch.... this is part of the chasers oxymoronic habits.....driving around like mad monks then sitting in a field for hours doing nothing other than watching.....watching however is like fishing - sooner or later you get a good catch!.   Talking about sucker cells.... another risk is chasing radar, often another storm over 50 miles away looks better and off we go....only to look in our rear vision mirror at our former storm going off like Guy Fawkes Day.

By late afternoon our split right mover is cranking up - its rainfree base has broadened and has developed a fantastic circular anvil with a great backshear, still we can't see the updraft column which remains hidden in the anvil, thunder and lightning has also increased another good sign of intensification. The updraft core lowers a wall area and the mid levels start rotating...we have a Rota !....our storm has become a dominator - the former left split has just about died. Although shear is rather weak around 30knots at 500hpPa to 300hPa, the updraft core is managing to keep its main inflow away from the precipitation region - the cell has become an LP supercell, high based funnels appear and the storm drops golf ball hail. Over the next hour the storm increases in size to become a large LP type with a strong inflow, the mid levels are spinning like a top, however the low levels struggle to keep up and the lower parts of the wall become distorted into weird contorted lines.

We drop back to Coldwater to experience a sudden jump in intensity - within a few minutes the surface mesocyclone intensifies dragging precipitation into its circulation... this however is the death knell, the entire precipitation core collapses into the meso and produces a magnificent outflow gust, another interesting phenomena is the development of a horseshow vortex - a rare interloper.. Parts of nearby Coldwater are flash flooded intermixed with tennis ball hail. We follow the weakening storm east for awhile still sparking intense lightning ,then like magic rains out to leave just a large anvil with spectacular mammatus........home to Hillsboro and sleep off our adrenaline..........best regards Clyve Herbert.

Synoptic for May 8th...low pressure over southeast Colorado, triple point approaching the northern Texas Panhandle, a warm front lifts through northern Oklahoma,the triple point became a focus for convection later in the day as it approached southwest Kansas.

This is a great image....the cross shows the storm cell featured on this report, note the split off cell on the northwest quadrant, the rounded anvil shows well, a typical LP storm with a relatively large anvil compared to its small updraft column...

A later image of the Coldwater LP Supercell, note the channel of clear air to its southwest....

Radar image of the Coldwater LP, note the primary cell at this point is the left mover with higher reflectivity, however the Coldwater LP has already got a mid level rotation signature....the radar is not showing strong convection on the right mover primarily due to the deep condensate updraft...

A later radar image of the now stronger primary LP storm, this image shows the radar return at the point the storm collapses producing multiple outflow rotation near the surface, the former split left mover is still located to the northwest.

The early stages of the Coldwater supercell, with the multicell splitting - the poleward split is on the right of this southwest facing image, the soon to be Coldwater LP is on the left.

A feature of the strengthening of the right moving split is the appearance of the strong, rounded backsheared anvil now appearing, although the updraft base appears weak there is something big going on aloft...

Closer in to the wall area that appeared at a later stage, the powerful but small updraft at the rear comes into view.

Note the appearance of atmospheric pollution (the orange haze) appearing near the centre of convergence under the developing wall...

With strength of the storm increasing the wall area is very persistent and due to accelerated updraft drops the lifted condensation level...(LCL)

As the wall approached mid level rotation increases, the lower wall is distorted by an imbalance related to its surface inflow ...

A feature of the Coldwater supercell was multiple funnels - we observed about 8 separate funnels over the course of an hour, the funnels appeared elevated and protruding from the mid level meso area.

A rather fatter funnel appears just north of the wall area...

This image shows the distortion associated with the lower wall area.

The distortion of the wall appears connected to the faster mid level rotation twisting the lower wall into interesting shapes...

As the Coldwater supercell approaches maximum strength the wall becomes better defined with a bell shape and stronger low level inflow, the mid level rotation was now very pronounced...

The wall displays a developing inflow tail...

The northern edge of the wall becomes strongly defined with better collar development...

Striated inflow jets appear on the southern quadrant...note the appearance of a rare horseshow vortex above the tail...can you see it ?

A closer view of the horseshoe vortex above the inflow tail...these curiosities are a rare feature of the storm environs and appear associated with a stability factor near the stratified inflow tail...

This image shows the start of the very intense stage, the wall is splitting as a primary circulation finally becomes dominant....

The wall area distorts into what appears to be a splitting phase, rain wraps around the western quadrant...

The eastern quadrant features a split portion of the wall as outflow increases...

These images show the developing final stage of the Coldwater supercell, a split portion of the wall appears on the right with a primary surface rotation appearing on the left

Now we have what is a magnificent stage of the Coldwater supercell, the primary meso now wraps rain and hail into its western split...note the rain blowing near the surface into the circulation..

This is the maximum strength phase of the Coldwater supercell, the storm also transits to a classic phase...note the collar which has become very prominent as rotations gets well organised...

A view like this is why we chase...trying to understand the power of storms...the meso is at maximum strength and wraps the precipitation core into the circulation....unfortunately the storms strength will be its downfall...so to speak !

A great view of the mesocyclone, fractus spins under the wall cloud,spectacular collar.....rain wraps around the back into the circulation...

The supercell collapsed quickly producing strong outflow, the main inflow remains but rides a strong outflow boundary...

Later the Coldwater supercell is no longer a supercell with a feeble updraft starting to separate from the main cell....within 30 minutes all that was left was a large area of anvil ........note how the updraft is stretched by the outflow nose...