Wed PM 2/27/13: Quick update on the 12Z GFS and 12Z Euro: still big differences between the two models as the Euro continues with a real mid-week Mid-Atlantic threat while the GFS continues to suppress and minimize it. Both models begin with a low near the South Carolina coast by early Wednesday morning. From here, the 12Z GFS moves it due east without any impact to the Mid-Atlantic and the storm stays relatively weak. However, the 12Z Euro slowly intensifies the storm as it moves slowly to the northeast for awhile and it is still precipitating as late as Thursday PM near I-95 and points east of there to the coast. The Euro forecasts a pressure drop to 984 mb by later Thursday with the low in a position by then well east of the NC/VA border. The big differences in the models can be seen at 500 mb. While both models have two upper-level waves (one northern and one southern) near the east coast by next mid week, the Euro waves are stronger and showing a negative tilt with some phasing together whereas the GFS waves are weaker with a positive tilt and no phasing. Stay tuned on this on - it is a good battle between these models. Keep in mind the overall pattern is somewhat favorable for an east coast storm with a negative NAO and positive PNA and both may be undergoing a transition at about that time which historically has often resulted in a storm (ie during a transtion period). Euro surface forecast map (top) is for next Thursday morning as is the 500 mb forecast map (bottom). Detailed morning video discussion on this threat at thesiweather.com.