On the current weather map, the region lies in a squeeze play between two pressure systems. It is not windy, however, as one might expect, given that both pressure systems are weak and the pressure gradient is only 9 MB. Weak high pressure, which has the majority of control of our weather, was located over the Appalachians, while weak low pressure, associated with the remnants of Julia, was located over the Outer Banks of NC. This was also located along a cold front, which is undergoing frontolysis, or the death of a front. This front extended from the Outer Banks of NC, to the Delmarva, to Montauk Point to Cape Cod. The mid and high clouds across the area today are from the remnants of Julia.
For tonight, with cloudy skies and a rather humid air mass in place, temperatures will not get very cold. Expect lows to be from the upper 50s to the mid 60s.
For tomorrow, METAR obs will likely report cloudy all day, but we'll still see good amounts of sun. This is because clouds will tend to thin out as the day wears on, but there still will be a high cloud canopy. But most people will not think of tomorrow as a cloudy day. High temperatures should be mostly in the low 80s, but the NW hills could stay in the upper 70s.
For tomorrow night and Thursday, the last of the high clouds will depart tomorrow night from north to south. Since the clouds will be slow to depart, low temperatures will show a very large range from north to south, since the north country will be able to radiate and much of the south coast will only have a few hours, toward dawn, to radiate. Low temperatures could get as low as near 50 in the north, but stay in the low 60s along the south coast. On Thursday, although it is the first day of fall, temperatures will rise to levels more common in the summer. High temperatures should be 80 to 85 across the state, with even a few upper 80s possible in the CT valley!
Longer Term: A strong cold front, a front which will usher in the first true autumn air mass, will move through on Friday. Although this front does not have copious amounts of moisture to work with, I feel pretty confident that most locations should see a quick shower with the frontal passage. There are a few reasons for this. First, the front will be moving into a very warm air mass. Secondly, temperatures will really crash with the frontal passage. Finally, since cold air usually sinks from the top down, the upper levels will cool first. This will create very high lapse rates. The lapse rate is the rate at which the temperature cools as you rise. Typically, the temperature will cool about 6 degrees for every 1,000 feet of height rise. With a strong cold front like the one moving through Friday, these lapse rates will be higher than normal, as the upper levels cool faster than the lower levels. The higher the lapse rate, the greater the instability. Surface-based models often have a hard time picking up on this and underdo the amount of convection that can form in that type of setup. Also keep in mind, the air does not have to be saturated to get convection to form in a situation like that. We're not looking at flooding rains, just quick hitting cells. If everything panned out just right, it wouldn't even surprise me to see small hail with stronger cells, since the freezing level will be lower than normal, but I'll leave that out of the forecast for now. As for temperatures on Friday, expect highs in the 75 to 80 degree range, with some lower 80s in the CT valley.
The first weekend of fall will feel like the first weekend of fall. The rest of the extended period should be dry. So instead of going into a long discussion about each day, let's just look at temperatures and brief weather conditions for the rest of the extended.
Saturday could start out with a few clouds in SE CT, so expect lows 50 to 60, with a few low 60s down there. Highs should be 65 to 70, with some low 70s in the typically warmer CT Valley.
Sunday should see lows in the 40s, with a few 30s possible the NW Hills! Highs on Sunday should be only 60 to 65, with a few upper 60s in the CT valley. Get the jackets ready!
Monday should see the same lows as Sunday, with highs 65 to 70, except a few low 60s in the NW Hills.
Tuesday should see lows in the low 40s to low 50s, with highs 65 to 70.
A reinforcing shot of cold air moves through late Monday night into early Tuesday morning. There could be a few sprinkles associated with that. Once again, moisture is lacking and timing is not great.
Looking out further, behind the secondary cold front Wednesday to Thursday could see an even stronger shot of cold air than the one for this weekend. Beyond that, the pattern could moderate and we could see an extended period of temperatures averaging a bit above normal. But climatological normals lower with time and slightly above normal heading into October will feel chilly compared to what we have been experiencing!
Here is a look at some of the weather that will be affecting the state this upcoming week. Since we don't have many precipitation-making events to speak about, I'll post a map showing Friday's frontal passage, then we'll look at Sunday morning's lows. Here's a look at the frontal passage for Friday afternoon:
Now, here's a look at the GFS' predicted low temperatures for Sunday morning. Low temperatures are actually about 2 degrees cooler than what is shown on this map. You can see the dark green (30s) covering W MA. Another 2 degrees cooler (achieved an hour or two earlier) would bring some of those 30s into W CT.