After this, forecast confidence decreases with an active weather
pattern developing across the area. Long range model guidance is in
general agreement that sharp trough will evolve into a mid-level cut-
off low somewhere near our area. This is likely to bring a soaking
rainfall to the region Thursday into Thursday night.
This will, eventually, be followed by much colder weather as this
system slides to our east and brings in colder air with 850 mb
temperatures dropping to around -15c by Saturday. However, model
guidance is in poor agreement how we get there, making the Christmas
eve/Christmas Day forecast a low confidence one. There are
differences in both timing and track of the system which are
unlikely to be resolved for at least a couple of days. For example
the 00Z GFS is faster with the system with temperatures in the lower
20s on Christmas Day, while the slower/west GGEM has temperatures in
the 50s. Since warm weather on Wednesday and Thursday should melt
the snow on the ground at most locations, the evolution of this
system will determine if there will be any snow on the ground for
Christmas morning. Stay tuned...
Multi-model and ensemble consensus along with standard deviation
anomaly charts favor a massively anomalous event in the period
staring Christmas eve and extending through Christmas. A negatively-
tiled mid-level short wave looks to advance northeastward toward the
area in a strengthening and highly-curved upper jet pattern.
Although location is uncertain, this has the potential to produce 2+
inches of rain somewhere in the northeastern states. There`s also a
potential for a convective shower-line with gusty winds, however 00Z
model guidance has shifted the best chance for this to the south and
east of our region.
Looking ahead to next weekend, there is little doubt that it will be
much colder, supporting the potential for lake effect snow. It`s too
early to pin down location yet, but significant accumulations are
possible.