Field Methods – Day 4 Recap

Posted by: Kate Wilson

After yesterday’s incredibly photogenic super cell thunderstorms, expectations were high. The parameters for today were also more favorable than the previous day. One surface low sat over eastern South Dakota, another over central Kansas. Warm, moist air was being drawn into the western Mississippi River valley, allowing surface dewpoints to reach upwards of 70 degrees. Instability was high, with CAPE values estimated to hit 500 J/kg by the afternoon across the western Mississippi River valley, alluding to a promising afternoon. With sufficient wind sheer and this high instability, a target could then be deliberated. Many students, including myself, considered Iowa as a potential target. However, this presented the issue of travel and distance, and it was decided that Kansas would be a wiser decision as it was closer in proximity and put us in better position for tomorrow.

Early in the afternoon, cells began to fire in the Coffeyville, KS area. It wasn’t long until we were in pursuit of one that had been severe thunderstorm warned within 20 minutes of initiation. We watched this cell develop and mature for several hours, which produced many wall clouds and funnels.  As we were observing these features, a strong rear flank downdraft (RFD) moved through.  It was this warm RFD to the east of our location that allowed an area of circulation to tighten enough to produce a tornado.  This was indicated on radar as a defined hook, and in a later scan showed a debris ball.  This debris ball was evidence of a tornado capable of extensive damage.  Later we discovered that these were this images of the large, damaging multi-vortex tornado that all but demolished the town of Joplin, Missouri. We abandoned this cell 10 miles from Joplin because there was no way to intercept it without going through a precipitation core containing large hail around 1.75 inches in diameter.  We were disappointed to learn that a tornado was so close but out of our reach.  However, the group was later relieved to have been out of the path of such a powerful tornado.

It wasn’t long until we had another complex of supercell thunderstorms in our sight. This lead us into Grove, Oklahoma, where we got trapped trying to avoid swaths of hail that kept forming on the tail-end of the cell. This caused us to take a detour across Cherokee Lake, where we saw twin waterspouts. On the other side of the lake we just came from, a stovepipe tornado was reported. Also, up the road a rain-wrapped cone was reported. Within one cell, four separate areas of rotation were determined, resulting in some tricky navigation for Dr. Durkee. By nightfall, the storm was still indicating areas of rotation and we pulled over to observe these features with frequent lightning illuminating the landscape. When this storm failed to produce a visible tornado, we decided to call it a day, but not after battling flash flooding and hail to reach our destination of Bartlesville, OK. Tomorrow appears even more promising, and the chase continues.

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