A solid chase day with a beautifully structured supercell unexpectedly forming just ahead of a crashing cold front north of Anadarko, Oklahoma. A weak, positively-tilted shortwave rapidly moved through the central Plains with a strong westerly component at 500 mb. Dewpoints from 58-61F overspread much of central and southwestern Oklahoma ahead of the sweeping cold front approaching from the due north. Multiple other supercells would occur this day along the front, including the Sand Springs tornado and a weak spinup out of another HP supercell in Moore. The Anadarko supercell would end up being the be the most classic of the storms that day, with most chasers ending up in a logjam at the junction of US-62 and US-81.
This would promise to be the first major chase day on the Plains for 2015. The Storm Prediction Center slapped a moderate risk across northeastern Oklahoma into southwest Missouri, with a broad 5% tornado swath along the I-44 corridor through Lawton. A brisk cold front was progged to rapidly move through northern and central Oklahoma by later that evening with forcing being exceptionally strong along the southward sag of the front just west of the OKC metro, hinting at the possibility of a linear mode from the getgo.
A lead impulse ahead of the main trough swung through central Oklahoma around 19Z, exacerbating worries about a premature initiation and persistent cloud cover across the area. It shot off a few small cells and led to some strange mammatus under a stratus deck in Norman before firing off the strongest supercell of the day northeast of OKC that would eventually follow I-44 into Sand Springs and produce an EF3 stovepipe.
My chase partner and I left Norman shortly after the lead impulse swung through around 19:45Z with an initial target of Minco, OK. We cut through Chickhasha and swung just north of Pocasset to watch the struggling Cu field off to our northwest. After sitting for half an hour, the first signs of life stirred in the Cu field to our west around 21:30Z. By 22Z, full blow intitiation was underway and we were hauling it west towards a pretty beefy cell southwest of Gracemont and northwest of Anadarko. We ended up taking a brutal dirt road detour towards Gracemont on Dutton Road before finally emerging in some rolling terrain north of Gracemont and stopping on E1250 Rd to watch a beautiful storm take shape.
We were forced to move after about 15 minutes of watching the storm and a brief chat with a nice farmer who's home was about a 1/4 mile down the road from where we were sitting. The linear mess to our north was encroaching rapidly and the storm was continuing to be pushed southeast by the front.
We passed the OU radar trucks on the way down US-281/OK-8 before stopping about 100 yards north of the Gold River Casino to watch the supercell wind it's way south, with a few gustnadoes dancing around under it's gust front.
Miles Driven: 132 miles
Largest Hail: Ping pong (1.5")
Highest Winds: 45 mph (estimated)