Tonight will feature a large range of temperatures between hilltops, cities, coastal locales, and valleys. This is because the skies are clear and the winds are calm. A cold air mass remains in place, though it is not quite as bitter as what was experienced 24 hours ago. Still though, it will be a cold night, with low temperatures ranging from the single digits in the valleys and away from the urban centers in Northern Connecticut, to the mid teens along the south coast. Tonight could be a night where temperatures could be 10F colder north of the Merritt Parkway, vs South of the Merritt.
Temperatures will rebound nicely tomorrow, with full sun, nearly calm winds, and high pressure drifting offshore, allowing for some warmer air to move in. Highs should mainly be within a few degrees of 40, though it could be a few degrees cooler in the sheltered valleys in the northern half of the state.
For tomorrow night and Thursday, not a whole lot going on weatherwise, with a continued moderation of the pattern. Once again tomorrow night will feature a large range of temperatures, with clear skies and calm winds. Temperatures may get close to ten degrees in the normally cooler locations in Northern Connecticut's valleys away from the urban centers, but only in the mid and upper 20s along the south coast. On Thursday, temperatures rebound once again into the low to mid 40s, although the normally colder spots could be stuck in the upper 30s one more day.
Looking into the longer term...
Friday: Friday morning's lows will be very tricky, and it all comes down to when the high clouds arrive. The NAM has high clouds arriving faster than the GFS and just the difference of a few hours makes about a ten degree difference in temperatures between the two models! Now, the NAM is a far inferior model to the GFS. However, these clouds are from overrunning processes, and they tend to go faster than models might suggest. Even so, models tend to underdo radiational cooling, so the cooler temperatures may make more sense, even if those lows occur around 2 AM vs. 7 AM. So once again, I anticipate a night where lows could be in the lower teens (even get near 10 in the coldest spots) to the mid 20s in the urban centers and along the south coast. During the day, clouds increase. Despite this, however, temperatures will rise quickly, as a southerly wind flow of warmer air increases. High temperatures on Friday should be in the low to mid 40s.
Saturday: The first part of a duel-faceted system affects the area. Rain will overspread the state before dawn and probably end around noon, although it could linger substantially longer further NE, as a coastal low develops. It is also possible that drizzle could linger all day as low level moisture hangs in there- something models are often not too good at forecasting at this range. A few of the very colder places may be cold enough to start as freezing rain early Saturday morning, but it will be close. At least we have time to monitor that. For Saturday's temperatures, expect readings to be very close to those of Friday's daytime temperatures.
Sunday: Part II of this system affects the area. There are very large differences between the ECMWF (European) model and the GFS models, where the GFS has a weak frontal wave with some light rain, and the ECMWF has a large rain storm with very heavy rain. The GFS has trended wetter and the ECMWF has been much better at this range. However, I don't want to jump all in like the ECMWF, because the latest run is a bit of a departure from what it showed earlier. But I would think this is a more substantial event than the GFS has. This rain probably arrives within a few hours of midnight, and lasts until early to mid afternoon on Sunday. Sunday's temperatures will be very warm, with high temperatures in the mid to upper 50s!
Monday: Temperatures could be steady or fall through the day. A strong cold front moves through Sunday night. High temperatures on Monday, near or a degree or two above 40, will probably occur around noon, before the secondary reinforcing shot of cold air moves in. This reinforcing shot could be accompanied by a few snow showers/squalls especially in the North. But to be honest, models tend to underdo the extent of flurries associated with systems like this. There are two explanations for this. First, models only show QPF (Quantitative Precipitation Forecast) amounts in .01" increments. 99% of the time, snow flurries are not measurable. So if they don't show measurable precipitation affecting a certain area, it can still flurry there and the model is not technically "wrong". Second off, snow flurries tend to be very weak forms of convection. Convection usually does not evaporate before hitting the ground, which is typical of virga, which you'll see sometimes along the leading edge or fringes of a large storm system, as precipitation falls into dry air. The upshot of all this is I wouldn't be surprised at all to see wind-driven snow showers anywhere with the secondary cold frontal passage on Monday.
Tuesday: A chilly day, but probably not as cold as this last cold shot. Still, temperatures struggle to get much past freezing anywhere, and low temperatures probably in the teens everywhere.
Longer Range: Overall, below to much below normal temperatures are expected during this time period. There could be a warm up to near or a bit above normal for a few days somewhere in this period, but given the facts that the models like to rush things in the long range, and are sometimes just abysmal at that range, we'll just call it generally below normal temperatures for now. In addition (and it may not be fair to do this just yet, because it is so far out), but there is a very strong signal (given the range) for an East Coast Winter storm in the MLK Day weekend time frame.
Here are some maps, depicting the upcoming weather pattern, with some explanations:
Stay tuned for future updates regarding the weekend systems and the pattern!