April 21, 2004

Today would bring round 2 of severe weather to Oklahoma. The cool front which moved through the area last night would lift back northward and stall around I-40, and the dryline would mix back eastward towards I-35 by mid-afternoon. This would put the Oklahoma City metro area under the gun, which meant I probably wouldn't have to go far to see anything today. I would have to work until 5pm today, so I packed by camera, maps, and change of clothes in my car as I was sure I would be on the road right after work.

I spent much of the afternoon looking off to the west and northwest as towering cumulus began to build in that direction. Skies became quite dark to the west by 4pm, and with a severe thunderstorm warning issued for Grady County I was becoming anxious to leave. Fortunately my relief showed up early today so I was allowed to leave at 4:30pm. I went outside to a see a little high based supercell going up just to my north, but my main concern was the precip core of the warned cell just to my west. I hastily changed clothes in the car while listening to the radio and looking at maps to plan my strategy. I finally got on the road at 4:50. I looked off to my west northwest to see a bell shaped, high based updraft tower. An interesting funnel shaped lowering was hanging from the base about 60% of the way to the ground, and although it persisted for several minutes it never rotated. I went west on Main to NW 48th Street, then north to Tecumseh Rd to follow this storm. This storm was being heavily seeded with rain from another cell just to my south, so the base became very ragged and disorganized, and before long the updraft totally dissipated. I was hearing reports that the cell just to my south was going outflow dominant as well, so I decided to head back to I-35 then head south to look for new activity.

Once I got to I-35, I could clearly see that the storms east of Norman were mushy looking and that cells were building further and further south - just like yesterday. So I headed down I-35, marveling at the nice pileus clouds that were developing atop many of the towers. The goal was to get the tail end cell, but again it was going to be difficult to see where exactly that would happen as the trail of developing Cb's was seemingly endless. But once I got south of the Arbuckles, it became clear I was coming close to end of this broken line. South of Ardmore, my tail end cell was coming into view. As I approached Marietta, I could see the RFD punching down, with lots of scud forming along its leading edge. This signalled to me this was RFD was likely cold, which would cut down the tornadic potential. The base of this storm was rather high as well. Still, I headed east on Hwy 32 out of Marietta and watched as the lower levels of this cloud took on a sheared, laminar appearance. The updraft was very similar in appearance to the updraft I saw southeast of Norman on March 17, 2004 - a pinkish orange cauliflower against a deep blue sky. Thin inflow bands were feeding the storm from the south. I ended up pulling off a dirt road east of Marietta to get video of the updraft as it churned away, also taking in a nice view of the sun setting in the totally cloudless sky to the west, and also noticing some towers which tried to go up well off to my south-southwest (probably in the DFW area). I got about 6 minutes of video before turning around and heading back.

For the second day in a row, many hail producing storms developed over Oklahoma, but few if any of the storms produced long lived tornadoes. Massive accumulations of hail occured in Oklahoma City, where roads were covered with hail in places. A fairly long lived tornado occurred along the front in far northwestern Oklahoma, although it was seen by few chasers as the majority of chasers targeted the Oklahoma City area. So why the storms that formed on the dryline in central and southern Oklahoma end up being non-tornadic? In addition to too many storms developing, moisture again was a big problem. Dewpoints across central and southern Oklahoma dropped from the low 60s to mid to upper 50s just before storms intiated early in the afternoon as drier air mixed down from aloft. The lack of moisture caused the storms to have high bases, but more importantly it aided in evaporation and sublimation of precipitation, which in turn caused a lot of cold downdrafts which choked off the storm's inflow. But even with the lack of tornadoes, the great storm structure I saw today made the trip worthwile.

Video captures

Total Mileage: 262 miles
Total Driving Time: 5 hours, 15 minutes

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