NWP guidance has been trending toward an increasing, albeit somewhat limited, threat of severe weather across the Southeast and Mid-Atlantic on Monday afternoon in the emerging warm sector ahead of an advancing cold front. The latest SPC Day 2 outlook highlights the region in a Marginal threat and notes that the low-level moisture return may lead to a maximum of 500-1000 J/kg of MLCAPE within the warm sector. A very strong shear environment with 0-6km bulk shear values ranging around 50 kts will lead to the conditional threat of damaging winds and possibly a tornado.
Collaborators at NC State are now making available SREF forecasts of the SHERB parameters including forecasts of the ensemble mean and the probability of the SHERB greater than 1. Forecasts from the 15Z/16 SREF run are indicating rather high confidence in large SHERB values Monday afternoon in eastern NC. Forecasts of the SHERB from the SREF are available online at http://storms.meas.ncsu.edu/users/mdparker/sref/. Forecasts from other NWP models along with real-time SPC mesoanlysis are available from http://www.meas.ncsu.edu/mdparker/sherb/index.html#realtime. You can learn more about the SHERB and High Shear Low CAPE convection (HSLC) via the NC State one-stop page for HSLC and SHERB information at http://www.meas.ncsu.edu/mdparker/sherb/index.html.
Here are some examples of the 27-hr SREF forecast of the SHERBS3 ensemble mean and the probability of the SHERBS3 greater than 1 valid at 18Z/17.
Here are some examples of the 27-hr SREF forecast of the SHERBSE3 ensemble mean and the probability of the SHERBE greater than 1 valid at 18Z/17.