[12Z GFS-ENS Christmas Day forecast for 500 mb height anomalies with an upper level trough in the eastern US and impressive blocking high pressure in eastern Canada; map courtesy tropicaltidbits.com]
There will be a break in the overall weather pattern over the next week or so in the Mid-Atlantic region from the recent “stormy and cold” conditions to generally dry, chilly and rather uneventful. However, looking ahead to Christmas week, it appears as though the overall pattern may return to “stormy and cold” and that type of weather pattern may just continue right into the New Year.
The stalled out significant Northeast US storm that has impacted the region for the past several days is finally relinquishing control of the weather to building high pressure in the Mid-Atlantic and this will lead to a decent weekend and the nicer weather should continue right into next week. In fact, it looks relatively dry for much of next week and temperatures will gradually climb from chilly levels this weekend to slightly above normal by Tuesday afternoon.
[Probabilities for a white Christmas across the US; courtesy NOAA]
Looking ahead to Christmas week, computer forecast models tend to agree on the re-establishment of a deep trough of low pressure in the eastern US and impressive blocking high pressure in eastern Canada and this will allow for more cold air intrusions from Canada into the US and it could lead to storminess near the east coast. The 12Z GFS-Ensemble 500 millibar height anomaly forecast map (above) shows the eastern US upper-level trough of low pressure (blue) for Christmas Day and the blocking high pressure to the north (orange) - all of which indeed raises some hope for a white Christmas in the Mid-Atlantic region. Stay tuned.