The day unfolded pretty much as expected on Saturday as much cooler air blasted into the region. The story of the day was not the cold, however, as winds gusted to between 40 and 50 mph for much of the day. In fact, the peak wind gust reported at BWI was 55 mph and the National Christmas Tree was toppled around 11 a.m. as winds gusted to 50 mph! The good news is that winds will gradually weaken through the morning with peak gusts early in the 30-35 mph range. Sunshine will be quite prominent, so at the least we will have that going for us. Overnight a warm front will push to our north and become a stationary boundary on which a weak wave of low pressure will ride during the day Monday. Rain will overspread the area by the afternoon, but it’s difficult to say how heavy things will be as the timing of the second wave will be critical in determining how heavy the rain becomes.
Our troubles really begin Monday night and the second wave tracks eastward from the Ohio Valley. Colder air will press southward with a surface high edging southeastward from Ontario as precipitation blossoms. Rain will gradually change to snow across the area and it appears that accumulations are likely for much of the viewing area. We’ve elected to keep the forecast fairly conservative for now with accumulations of an inch or two (highest amounts just north)… but the potential is there, depending on the track of this system, that some areas could pick up several inches of accumulation. Confidence is increasing in accumulations for the Baltimore area, but it is in no means a lock (though St. John’s is awfully close after knocking off Pitt now). Beyond this Tuesday looks cold with gusty winds once again to make things even more unpleasant. The good news is that Wednesday and Thursday should feature appreciable moderation with rain chances returning for Friday. The long range outlook for next weekend features a very active pattern more reminiscent of La Nina (in the East) with a fairly zonal flow and a sharp north/south gradient with regard to temperatures. This also means quite a spread in potential outcomes.