The image above is a depiction of the rain band associated with the cold frontal passage Monday night.
A large ridge off the Eastern US Coast is pumping in record warm air for the time of year. Temperatures were not quite as warm as they could have been, thanks to a back door cold front, which brought in an onshore flow off the cool waters. However, most of the Northeastern United States has seen record or near record heat the past few days, and there may be two more days of such record heat.
Short Term Discussion: The main highlight of the short term period will be a quick period of heavy rain later tomorrow and tomorrow night, perhaps even accompanied by some thunder and gusty winds, and then perhaps more gusty "gradient" winds after the frontal passage on Tuesday.
First off, for tonight, it will be a generally cloudy night. There is the potential for some drizzle, especially towards morning, generally in the eastern half of the state, where there are deeper into the "back door frontal air mass". Low temperatures will generally be in the upper 40s to lower 50s.
For tomorrow, temperatures will be quite tricky. We still have the back door frontal boundary to deal with. This boundary will finally begin to lift northeastward, for two reasons: First, this tends to happen diurnally, during the day. Secondly, as the Pacific cold front approaches, Southwesterly winds will increase at all levels of the atmosphere, and this will help push the front northeastward. The front may very well clear the southwestern part of the state in the morning, and then have a lot of trouble pushing Northeastward. This could keep areas East of I 91 in the drizzle (and patchy fog) for most of the day. I could see valleys in Western and Central Connecticut being the warm spots during the day tomorrow, with some mid 60s possible, with areas east of I 91 stuck in the upper 50s. High temperatures will probably occur for most of the state late at night, ahead of the cold front, tomorrow night. Most of the state may be able to get into the mid 60s for a couple hours. Rain ahead of the front could arrive in the southwest during the evening rush hour, but may wait until fairly late at night in the northeast. Rain may be accompanied by 30 MPH wind gusts and even isolated thunderstorms.
On Tuesday, any rain should end before dawn. Skies rapidly clear and there could still be wind gusts in excess of 30 MPH behind the front from a strong pressure gradient. Daytime temperatures should still reach the upper 50s, due to the fact that the air mass behind the front is of Pacific, and not polar or Arctic, origin.
For Wednesday, clouds will gradually increase during the day, but most of the day should be partly to mostly sunny. Wednesday could be a day where interior locations, which are usually cooler, may be warmer, because the wind flow will be onshore, off a cool Long Island Sound. In fact, coastal locations may even see the marine layer bring some drizzle later in the day. Temperatures will range in the 50s.
For Thursday, the combination of an approaching cold front and a developing wave of low pressure could trigger rain, which could become heavy at times. Despite the fact that it could rain much or all of the day, temperatures should still make it into the upper 50s.
Friday's forecast becomes complicated. Some models want to linger the frontal zone closer to the coast, and develop, a second, cooler rain storm along the front. This would keep precipitation going into Friday. Right now, this is a low confidence scenario, since getting low pressure to develop along a moving boundary. However, there could be some meteorological credence that a front would move slower than normal, or even stall, since it's moving into such a strong ridge. IF the front did stall and a low developed along it, it would even be possible for rain to change to snow during the day on Friday. However, this is even lower confidence, since not only would the front have to stall, but it would have to stall in just the right place for Connecticut to both a) receive precipitation, and b) have the column cold enough for snow. It's not likely, but will be monitored. For now, to compromise everything, I'll go with rain lingering for some of the day Friday east of I 91 and clearing elsewhere, with temperatures generally in the upper 40s and not mention snow anywhere.
Next weekend will feature temperatures struggling to get out of the 30s during the day and low temperatures possibly making the 20s at night, actual normal weather for this time of year. There's a low probability of a few snow showers or flurries Saturday with a trough swinging through.
The long range looks to see a return of above to much above normal (and occasionally record breaking) warmth. Normally, one would approach such a long range forecast (warm or cold) with trepidation and limited confidence. However, when every run of every model is advertising nearly the same thing, it's hard not to have high confidence. It may be harder to pinpoint when each storm will occur, but temperatures look to return to much above normal levels.
The map below shows the 11 day pattern, as advertised by the GFS Ensembles. Ensembles are an average of various perturbations of a model- in other words, they are a smoothed average of all possibilities. You can clearly see the strong ridging over the Eastern part of North America, which would promote well above normal temperatures.
Finally, the last image is a bit off topic, but it shows an incredible storm system in the Bering Sea. (Yes, weather geeks who don't have very exciting weather in their area sometimes look at other parts of the world to see what's going on). At any rate, this is the strongest low pressure system ever recorded in the Bering Sea. Land observations in Western Alaska are reporting wind gusts over 150 MPH!