After analyzing the 18z RUC model output (see below), our excitement about today's potential has sky-rocketed. It's currently around 1 pm CDT, and we are driving towards a target in north-central/northeast SD. As can be seen below, the RUC is forecasting a low-level jet from 21-00Z of 35 knots extending westward all the way to the cold front in the Dakotas! This is dramatically different than the WRF forecast, which was still favorable for tornadoes! The RUC also forecasts EXTREME instability with CAPEs exceeding 5000 J/kg. If the storm mode is cellular and convective inhibition is eroded sufficiently, large tornadoes are likely with these parameters today in eastern SD.

Conditions appear to be coming together for a mini tornado outbreak in eastern South Dakota tomorrow (Saturday) afternoon and evening. Substantial instability, an unseasonably strong low-level jet, insane moisture, and a potent mid-level jet streak will set the stage for explosive supercell development after 4 pm in central to eastern SD. The presence of any outflow boundaries from overnight storms will also enhance the threat for tornadoes. I left Norman at 6 pm this evening for a target in eastern South Dakota, once again without Joel (who is very close to having his profile removed from this site due to lack of stormchasing passion). For those interested, the WRF forecast 0-1 and 0-3 km helicity, CAPE, CIN, and 500 mb wind for tomorrow afternoon/evening are displayed below. The 0-1 km helicity values of 150-200 are sufficient for large tornadoes, especially with the presence of outflow boundaries. Tomorrow could be the apocalypse.

Stay tuned to the StormWatch player (upper right) for videotaped updates on our progress throughout the chase.