The unseasonably mild weather pattern we’ve been experiencing appears to be breaking down over the next few days. Monday will be seasonably cold.
With the exception of this Tuesday, temperatures will be colder and closer to average, with even some below average temperatures towards the end of this week. We may even see some light snow Saturday if a storm passing to our south moves further north.
By the end of next week (around the 20th), a large outbreak of cold air is expected to move into the continental US.
The graphic below shows predicted global temperatures (NAVGEM model) now and in 11 days. Notice the colder temperatures at the poles, Siberia and Greenland.
Current Global Temperatures
Predicted Global Temperatures January 16th
This colder air has to go somewhere. Current forecasts show it descending into the US but current predicted configurations will block storms, keeping them to our south. No snowstorms are in the long range forecast.
Two more rain storms forecast for this week –one Thursday (possibly missing us, staying to the south) and on Saturday. The Saturday storm may be a nor’easter, but the lack of cold air makes this an atypical nor’easter for January. It looks like rain!
The current weather pattern is quite anomalous for January. There’s little evidence of deep intrusions of cold air into the continental US for the first two to three weeks of January!
There will be short duration cold air intrusions into the Northeastern US which will alternate with mild air and wet flows from the southwest.
The current climate model forecast captures this nicely:
What we need for winter to return is for the height contours (shown in black) to take the following configuration, (shown in blue.)
Obviously, there would have to be giant changes in the current weather pattern to support my early December climate forecast of significant cold weather and significant precipitation. I’m not very confident about that forecast at this time.
So enjoy the relatively mild weather!
The current long range climate models show colder intrusions around the third to fourth week in January, a time when we usually get the “January Thaw”.
All models are on-board with a low pressure system that moves in late Thursday into Friday. Rain, possibly heavy (more than 1″), is very likely for much of Friday. It will be very mild. High temperature near 60.
Saturday dries out and it will be colder and closer to seasonable. There may be instability clouds.
There’s a wide range of model forecasts for Sunday, as a low pressure system tracks to our south. We may get some light precip Sunday if the low tracks a bit further north. Type will depend on timing, but mostly like very light rain showers.
The storm I mentioned a week ago for New Years Eve/Day is on track to be a rain-storm.
Right now, I don’t see much in the way of snowy winter weather.
There’s no giant slug of cold air predicted to descend into the central US.
Cold intrusions will repeatedly occur in the North Eastern section of the US that will effectively block storms coming up the coast.
These cold intrusions will alternate with mild air and wet flows. Things would have to change big-time for my colder-than-normal climate forecast from late November to become a reality.
Reviewing the major models, at this time, it appears that the balance of December won’t have a pattern for snow in Philadelphia.
Short duration dips in the jet stream will bring cold periods, but moisture flow from the southwest will make these colder periods of moderate duration, allowing wet and mild weather to return along with deep storms whose tracks will be moving to our west instead of along the coast.
Today’s (Sunday) GFS and FV3-GFS differ significantly in the very long range with these similar models having very different forecasts by New Years Eve.
For this week— A storm for Friday is a now posing to be a significant rain storm and the storm potential mentioned for Sunday into Monday also appears to be wet instead of white.
The chance of seeing a white Christmas here have faded, at least for now.
The global models show very frigid air building in the polar region, Siberia and Greenland during the last week in December. A shift to much colder weather and stormer conditions (snow) is expected by the end of December into the first week of January.