Severe Weather Discussion for February 27, 2011.
– Severe thunderstorms are possible across central and eastern Oklahoma Sunday afternoon/evening.
18z GFS/NAM continue to advertise an upper system moving eastward towards the region on Sunday. Very strong mid/upper level winds will overspread a somewhat unstable and capped boundary layer during the day. Model disagreement is high and oddly so at D4 regarding the placement of the upper system. The 12z ECMWF is slower than the prior two models and must be considered. Given that the upper system is not in the upper air network, variability is likely to continue the next several model runs.
There is enough agreement to point towards a medium-end event and hence the likelihood of a moderate risk on Sunday. The most likely area, going with the faster GFS/ECMWF will be east of HWY 177. However, a shift west has to be considered and we may end up looking at HWY 81 and east by Sunday. GFS/NAM BUFKIT data shows marginal instability across the threat area but this may not end up being the actual occurrence.
Either way, there is enough confidence on the setup and impacts to Oklahomna to initiate discussions for Sunday. SPC Day 4 hit the main points well and a few notes in the afternoon AFDOUN also provide some guidance. I’d expect SPC to go with a moderate risk on the morning Day 3.
Risk area for any part of OK/TX (valid: 02/25 Day 3):
Level 1 – Normalby