Update on 3/6-7 Storm
First off I will mention that a renegade flurry or sprinkle is possible today as some light precipitation will be generated by an upper level trough to our west that will move across the area today and tonight. I have been watching this system closely all week to see if the models would try and pop something from this but they have not. I do think we will probably see mostly light rain east of the mountains if anything as the boundary layer warms up through the morning if any snow did fall it would be light and not accumulate.
Now to the bigger storm. The trends have continued to point to any important snowfall with this event likely being form NC northward. The synoptic situation is that a trough moving into the northern plains will split and a piece will cut off and drop through the Ohio Valley to the Carolinas. It looks like a lead part of this will be rain as it moves through Tuesday and Tuesday night. However, as the cut off low moves into the Carolinas it will slow take on a neutral tilt and eventually a negative tilt it appears. This will allow an area of low pressure to form and rapidly strengthen off the SC/NC coast Wednesday morning. As this happen it appears a deformation band could set up over central/eastern NC/Va Wednesday and into Wednesday night. If this occurs it will result in a period of moderate to heavy snow with the period being longer and more intense the further north and NE you are.
Taken literally the 00z ECMWF had a 18-24 inch bullseye in central Va, and 12-18 inch area across most of central Va, a thin 8-12 inch area surrounding that into the northern piedmont of NC, a 4-8 inch area surrounding that including RDU, the Triad and RIC, and lesser amounts into central NC. The 6z GFS was not as intense, but you can see it in my attached photo. It is showing a 8-12 inch snow in N-C Virginia with several inches for many and accumulating snow as far south as the NC/SC border.
The bottom line on this is that the models have come into better agreement on the overall scenario, even the 00z Canadian is on board now with the general ideas. The main thing is that the 500mb cut off is forecast to go neutral and then negative resulting in a rapidly strengthening coastal low near the NC coastline Wednesday morning. With the upper level energy diving in this should result in a deformation band setting up and an area of snow as the atmosphere rapidly cools. I do think this has potential to produce some accumulating snow, but in these scenarios where we don’t have a cold enough air mass preceding the storm and are counting on a coastal to form and take over and change us over, rarely, overproduce. So while for the Carolinas, I do think this has potential, as of this moment, I have doubts on it being a blockbuster by any stretch. Further north that could be different.
I will update on the model output today via twitter @RaleighWx and make a post this evening if one is needed and certainly again tomorrow.