Outlook for Thanksgiving

The much heralded “pattern change” is still on track for just after Thanksgiving. I’m still thinking we will see a trend toward cooler and more normal late November weather with some bouts of below normal temperatures during the first week of December. Nothing has really changed in my thinking here.

As for the Wednesday/Thursday time frame we still have some kinks to work out. The 12z GFS develops a major low over southern New England phasing 2 shortwaves as a massive trough/closed low moves toward the coast. The shortwave responsible for the forecasted major cyclogenesis is still hundreds of miles west of Vancouver, Canada so it’s going to take a few more model runs to pin this down.

Backing up a bit, on Wednesday we should have quiet weather in the northeast with no travel issues. Ridging overhead to start the day with a digging trough to the west will mean quiet weather from Maine to the Mid Atlantic. I’m not expecting a lot of sun with warm advection and increasing moisture bringing in plenty of cloudiness. Even with a big cut-off low over the Great Lakes, in terms of high impact weather, there’s not a whole lot to talk about on Wednesday. The only issue I can see in the Lower 48 is a period of snow in the upper midwest (Minneapolis and maybe some light snow near Chicago?). This could cause some minor aviation issues but at this point I don’t think it’s a big deal.

As that big trough rumbles east toward the northeast it looks like we’ll see a storm develop over New England as some upper level energy interacts with some baroclinicity off the east coast and a strong low develops near Long Island. The low will occlude, and move north and northwest toward Quebec and Ontario. The 12z GFS and Euro both say this is will happen and result in a period of rain late Thanksgiving followed by scattered showers and blustery conditions by Friday. With strong cold advection by late Friday temperatures will drop and there could even be some light snow showers on Saturday behind this storm.

As always it’s not that easy as some of our other computer models are not showing much. The 18z GFS is weaker with the low and develops it further north (sparing us from any notable rain) as the shortwaves don’t phase in time. The 12z GGEM also shows a weak (no phase) solution while the 12z UKMet is in the camp on the 12z Euro and 12z GFS.

My thinking right now is a period of rain late Thursday into early Friday morning. Winds shouldn’t be an issue on Thursday but behind the storm on Friday they will pick up and may be quite gusty if some of the strong model solutions come to pass. The strength of this storm should dictate how cold we will become over the Thanksgiving weekend. We’ll see what happens.

Ryan

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