Thursday, April 18, 2013

17 April 2013 - Southwest Oklahoma - Supercell

I got off of a mid shift at 8am on the morning of April 17th anticipating a decent shot at seeing a good supercell later in the afternoon.  A frontal boundary was rapidly retreating northward toward central Oklahoma, with rich low-level moisture located to its south over southern Oklahoma into Texas.  The big negative for this day was weak surface cyclogenesis and a cold airmass that was stubbornly locked over the southern high plains.   After a few hours of sleep, I woke up for a quick data check, and then hit the road by 2 pm.  After passing Lawton, OK, I headed south toward the Red River, and then went west on highway 70.  One ongoing storm was already displaying supercellular characteristics west of Lawton.  However, it was moving into a warm sector characterized by stratocumulus and high convective inhibition.  Another cell  approaching Frederick, OK was emanating off of steep low-level lapse rates, stronger boundary layer heating/destabilization, and higher MLCAPE values.  Thus, this became my target storm.  I sat in Frederick for 30 minutes waiting for the developing supercell to approach...and then decided to get aggressive and drove west on highway 5 toward the updraft base. 

Updraft rotation was strengthening rapidly at this time (~520 pm), and inflow winds at the surface were screaming out of the east.  However, shortly after I reached the low hanging updraft base, a cold RFD surged outwards, and the base took on a cold looking appearance.  Nevertheless, I followed this messy HP storm east along highway 5, with a northward jog up highway 36 back to I-44.  Just south of Lawton, I headed east on highway 7, and then went a few miles north and waited for the storm as it moved northeast.  During my drive east of Lawton, other chasers reported power flashes over Lawton, which may have been caused by a brief tornado.  The storm was a full fledged HP supercell as it crossed I-44, and I gave up the chase shortly after 715 pm.  I took I-44 northeast for my drive back to Norman, and encountered heavy rain, quarter size hail, and strong winds.  Although there were not many drivers on the turnpike, the few that I did come across were acting very stupidly.  Every overpass I drove under was filled with cars trying to avoid the hail, with cars parked off the side of the road, cars parked in the slow lane of the turnpike, and cars parked on the shoulder adjacent to the median of the turnpike.  Some Oklahomans never fail to disappoint when it comes to bone headed stupidity...I mean seriously, parking on the shoulder is fine, but out on the active roadway with cars approaching in near zero visibility???













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