An active week is in store, with two separate systems lined up to bring some much-needed rain to the state. With these systems will come warmer temperatures, but if the long range guidance is correct, they will not last as we transition towards a more wintry regime moving into December.
A cold front is currently moving across the state, bringing below-normal temperatures in its wake for the short-term, although not as chilly as what we saw earlier this week. We should see highs in the mid 40s on Sunday and in the low to mid 40s on Monday, with lows around freezing tomorrow morning and in the upper 20s Monday morning. While there will still be some clouds around tomorrow, we will see ample sunshine through most of the day and into Monday morning before more clouds arrive Monday afternoon in advance of our duet of systems.
Tuesday morning will start out a bit below normal, with low temperatures below freezing in the hilltowns and just above freezing elsewhere. Rain will move into the state later in the morning into the afternoon associated with a system cutting well to our west. While temperatures aloft will have warmed above freezing, preventing any snowfall, it’s possible that due to the high pressure to our north, we could see some cold air damming at the surface in the northern elevated valleys resulting in a brief period of freezing rain at the onset of the system. While I don’t expect icing to be significant or widespread, and any icing that does develop should turn over to rain, I’m always wary of the low levels in a situation like this, as we’ve seen time and time again that modeling is too quick to warm the surface in a cold air damming scenario. My confidence in any icing is low, but given the impacts that it can have, I figured it was worth it to mention the possibility. Otherwise, expect rain overspreading the state throughout the morning, with up to an inch of rain expected by the time the system moves out in the wee hours of Wednesday morning.
We’ll see a quick break from the rain Wednesday morning, but by mid afternoon, the next wave arrives and lasts into Thursday morning. Guidance differs somewhat here, with the GFS keeping the storm weaker and more progressive compared to the Euro. The result is less rain and warmer temps if the GFS were to verify, but for our area, the only real difference is the strength of the rain, as the timing and track are relatively similar on both models, and neither solution would be cold enough for snow in our area(In northern NH and ME, different story, where the Euro brings a foot+ of snow while the GFS has a cold rain). We will see a rainy start to the day on Thursday, but it should dry out for the afternoon, with perhaps a peek of sunshine in southern areas in the last afternoon.
Here’s a great model image from the 18z GFS, valid for 1 AM Wednesday morning that illustrates the setup for this week.
The Long Range
As we move past this system, we begin to see a wholesale change in the pattern as the deck is reshuffled aloft. The EPO looks to go negative, dumping a shot of arctic cold into the west, which will then move eastward with time. In addition, it looks as though we will see strong poleward ridging develop, which favors a colder and more active look. Combine that with the blocking that we have seen in the Atlantic (AO and NAO), and you get a setup that is favorable for below normal temperatures and wintry chances. We often see a gradient pattern develop in this background state, where overrunning systems can move along the gradient and bring snow on their northern flanks. The big question is where the gradient decides to set up, and it’s way too early to speculate on where that may be, or when we may see any specific snow threat. All we can say is that it does look like we are heading towards a pattern that will allow us to see those threats as we move into December and the official start to meteorological winter. Don will be beginning his two-week outlooks around December first, with much more insight into the medium and long-range patterns, so stay tuned for more to come!
Sunday: Partly sunny, with highs in the mid 40s.
Monday: Partly cloudy, with highs in the low to mid 40s.
Tuesday: A slight chance of freezing rain, otherwise, rain likely, with highs in the upper 40s. Chance of precipitation is 90%
Wednesday: A chance of showers in the morning, then rain likely in the afternoon. Highs in the upper 40s to lower 50s. Chance of precipitation is 80%.
Thursday: Rain ending in the morning, otherwise, mostly cloudy. Highs in the mid 50s. Chance of precipitation is 70%.
Friday: Mostly sunny, with highs in the mid to upper 40s.
Have a great rest of your weekend and thank you for reading Southern Connecticut Weather!