Sunday 10 June 2012

2012 Chase Day 4 - Hutchinson (KS) supercell

Sun 10 Jun

Today we drove from Okarche (OK) to Newton (KS), leaving at midday and arriving at ~3pm. We had our sights set on somewhere just north of Wichita (KS) for some supercellular storms to develop, based on various model output. After grabbing a bite to eat, we sat in position hoping the approaching cold front would be enough to break the cap and allow thunderstorms to develop.

By late afternoon, storms had already fired in the far north of Kansas, and we began to feel slightly nervous that we might've been too far west given the eastward-moving cold front. So we drove west to Florence, and parked up at a gas station to re-asses the situation.

It became apparent that there was more significant cumulus growth right on the back edge of the cumulus field, and that we were probably positioned too far east, so naturally we drove north to Marion, then west again, parking up at Hillsboro. By now we could see some low-topped anvils in the distance, and radar returns suggested some deeper convection was starting to form way to our west.

We chased north then west again, and found a hill at Roxbury where we had a really good view of the western sky.
Our chase vehicle, parked at Roxbury
The first couple of anvils really struggled and began to shear off, and the cloud bases disintegrated very quickly, later confirmed by the drop in radar activity. One anvil debris went overhead with some mammatus on it's southern edge.
Waiting patiently we were finally rewarded with some new shooting towers to our southwest over Hutchinson, forming a new anvil at a much higher level than the previous one, indicating the cap was broken.
New anvil began to form at a significantly higher level than the previous anvil
It was at this point that the Weather Radio raised the alarm that a severe thunderstorm warning had been issued for large hail and gusty winds.
This was the beginning of a supercell which despite the frontal progression eastwards, became very slow moving, and over time began to head southeastwards, against the main northeastwards flow.
We chased southwards to Canton, where we stopped to take some photos of this storm in it's mature stage - some signs of lowering along the wall cloud, but I remain to be convinced that a funnel was forming.
Flanking line allowing new towers to form, with the back-sheared anvil also visible
As the sun set, a new anvil with overshooting top was visible to the north
Nice crisp edge to the supercell's anvil to the west, with some low-level fractus clouds in the foreground
At this stage the storm wasn't producing a huge amount of lightning, but appeared to be back building on the radar, so we headed southwards again as darkness began to fall to Park City, then westwards towards Maize. As the sun set, lightning became very frequent, but largely inter-cloud with quite a few anvil crawlers - very little in the way of CGs (cloud-to-ground).
Plenty of IC and CC lightning, and anvil crawlers

We pulled over to take some lightning shots in the dark, but sadly after a short while the storm ceased to produce anymore lightning. It was also apparent that the base had really become high-based, and over the next 30mins the storm vanished on radar - surprising given the additional forcing of the cold front (it wasn't purely generated by surface temperatures). Reports from the SPC suggest hail up to 1.75inches (4.44cm) in diameter fell in parts of the storm.

Nevertheless, it was a cracking day with being able to pinpoint the only supercell for miles 24hours in advance. It also makes it the fourth day of lightning in a row.


Radar for the storm, including the Severe Thunderstorm Warning box
Visible satellite image of the supercell/anvil over S-C Kansas

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