Synopsis: A generally quiet weather pattern, with normal to above normal temperatures, with the potential for a strong Nor’Easter centered around the Tuesday to early Wednesday time frame.
A cold frontal passage returned temperatures relatively close to normal across the area today. The departing low pressure system was responsible for the windy conditions the state experienced. Tonight will be a clear, cool night, typical for early December. Low temperatures through the state should range through the 30s.
Cool, but not cold, high pressure will remain in control for tomorrow. With the high pressure center getting closer, the pressure gradient will relax, and as a result, winds will diminish. There shouldn’t be any huge differences in high temperatures tomorrow, with readings close to 50 degrees throughout the state, with a few cooler readings possible at higher elevations.
High pressure will crest over the region on Saturday. After a cool start, in the 30s, high temperatures will once again rise to near 50, or perhaps even a few degrees warmer, especially in Southern sections.
The high pressure system will slide offshore Sunday. This generally means a warmer, southwesterly wind flow. As a result, low temperatures will only start off within a few degrees of 40, and temperatures will then rise into the low to mid 50s.
Although the air mass on Monday is not any cooler, temperatures will likely be a couple degrees cooler, as clouds increase ahead of the next system.
The main system of interest in this forecast period is the development of a strong coastal low/ Nor’Easter type system. Models, as usual, are showing some differences with the track and exact evolution of this system, as one would expect from 5.5 days out. The latest GFS has come a bit more in line with other guidance. While it’s way too early to pin down the exact details of this system, it is safe to say that a strong coastal low will have the potential to produce at least a raw, cloudy, and windy day, and perhaps heavy rain and coastal flooding.
In general, this storm looks to be compact, which actually complicates the forecasting details at this range. Compact storms have a smaller geographic range of effects, but this does not mean they are weaker- in fact, the winds can sometimes be stronger, since their pressure gradient is over a smaller area, and therefore more intense.
This throws a monkey wrench into the forecast, because with a tight, compact storm system, you’d have to exactly nail the track to nail the apparent weather forecast, and from 5.5 days out, that’s nearly impossible to do.
At any rate, for now, the best idea would be to have rain overspreading the state from south to north around midday Tuesday and going for about 24 hours. As of this writing, it appears the entire state should get in on the action. However, if one area did not, it would be further north. There could also be winds gusting to 40-45 MPH with this system, as it will feature a fairly intense pressure gradient. As for temperatures, low temperatures would range within a few degrees of 40 and highs just in the mid 40s, making for a raw and chilly day Tuesday. Add a few degrees to those numbers for Wednesday’s temperatures. With basically no cold air on the map east of the Rockies, there will be no precipitation type issues and any precipitation will fall as rain.
High pressure builds in behind the system for Thursday and Friday, with temperatures ranging in the 30s for lows and generally upper 40s for highs. Looking into the long range, temperatures look to range generally above normal, at least until mid-month, when they may start to begin a cool down. Overall, the pattern also looks quite stormy, as the Southern branch of the jet stream is now becoming quite active and that looks to only intensify.
The map below is the 12Z GFS, six hours earlier. You can see here that the coastal low is further east, meaning most of Connecticut is spared, but the Southeastern part of the state gets hit hard. The image above is closer to the model consensus. However, given that we're still a ways out, neither solution can be discarded completely at this time.
Southern Connecticut Weather is brought to you by Timothy Wrightington Jr(TW), Spencer Aronstein(SA), Greg Petridis(GP), and Don Bell(DB).