Currently: Current surface analysis shows a complex frontal system and a low pressure center near Louisville, KY. High pressure was stretched in an arc from James Bay, Canada, to the Gulf Of Maine. This high pressure is important in our weather picture, as well, because it will help keep the area in the cold sector tomorrow, which means a chilly rain, and less chance of thunderstorms.
Tonight: Most of tonight will be dry, with lowering & thickening clouds and increasing onshore flow. Rain should get going by dawn in most places, especially the SW. Lows should be in the mid 50s.
Tomorrow: Gloomy. Steady rain in the morning, then a break during the afternoon. However, models often underestimate low level moisture, so even after the steady rain stops, there could be light rain & drizzle. It will stay rather chilly all day, with high temperatures only 55-60. There could also be wind gusts in the 35-40 MPH range during the afternoon. Because of prolonged onshore flow, minor to locally moderate coastal flooding will be possible during the high tide cycles.
Tomorrow Night and Friday: As the low rotates closer to the area, there should be another period of steadier, heavier rain, especially East of I 91. This should be predominately during the overnight hours. So a rainy night on the way, with low temperatures 50 to 60. Temperatures will probably only drop a couple of degrees from Thursday's highs. On Friday, we may really need to divide the state into two parts, with the dividing line being around I 91. East of I 91, morning heavy rain will clear out and yield periods of sun. West of I 91, there will be a clear window during the late morning hours, then there could be more showers and thunderstorms in the afternoon. High temperatures on Friday should generally make the upper 60s, except cooler in the NW hills.
Long Term: Memorial Day weekend and Beyond: For Saturday, a previously dry forecast may need editing. A new upper level piece of energy has shown up on guidance and models are now generating at least widely scattered showers and thunderstorms along it during the afternoon hours, again only to the West of I 91. East of I 91 should have a nice day. But this feature is very real and does need to be watched. Soundings due show fairly steep lapse rates on Saturday, so systems like this do tend to overperform, if anything. Saturday's high temperatures should range from 70-75.
On Sunday, the first half of the day should be fair. Thereafter, a frontal system should produce severe weather over Pennsylvania and Ohio. By the time it arrives in Connecticut late in the day, there won't be much left of it from a severe weather standpoint. However, as systems like this move into a more stable, but moist, atmosphere, they tend to coalesce into a blob of heavy rain. So Sunday afternoon, then night, should feature an area of heavy rain, possibly still containing a little imbedded thunder, traversing the state from west to east. With more clouds, Sunday's temperatures should be cooler than those of Saturday, with highs of 65-70.
For Memorial Day, a stronger cold front, combined with better timing and a warmer air mass, will kick off a round of showers and thunderstorms. Although we're getting into garbage time with regards to convective forecasts, I'll take a stab at it, and say that there could be a line of strong to severe thunderstorms west of the CT River/ I91, degenerating to "garden variety" showers and thunderstorms east of that line. These storms should move through during the afternoon and evening hours. Highs on Monday should be in the low 70s, and this little bit of extra warmth should be enough to give the thunderstorms a little extra punch.
On Tuesday, we may actually be able to sneak in a dry day. Temperatures will actually be warmer behind Monday's cold front, but with lower levels of humidity, and temps should get into the mid to upper 70s. For Wednesday, yet another impulse moving down will trigger isolated showers and thunderstorms in the afternoon and evening hours. With increased cloudiness, Wednesday's temperatures should be a bit cooler than Tuesday's- in the 70-75 degree range.
Looking into the longer range, the pattern still looks generally unsettled, with more frontal boundaries nearby than is normal for this time of year. However, there may actually be a trend toward a more normal mode of Rossby wave spacing, which would mean that at least the fronts would be about 60 hours apart. One thing having an anomalously large number of fronts in this area does mean this time of year is that you really can't get a sustained heat wave, because the main two ingredients for that are a large, nearly stationary Bermuda high and not many frontal systems, and we have neither right now. That's not to say it can't get hot for a day or two, and it can, but the heat would likely get kicked out quickly.
Now, let's take a look at some of the systems that will be affecting the area this week... since we have so many of them, I'll take a look from a spatial and temporal perspective, and we'll highlight tomorrow and Sunday's rains.