Benign, relatively dry for foreseeable future; still variations between hot and humid Monday, Sunday and cooler Friday; showers and thunderstorms likely on Tuesday, maybe next Sunday or Monday; likely mostly dry with gradual warmup for first half of following week

Plain-language summary:

 

The weather pattern looks mostly benign for the foreseeable future, though still with variations between occasional hot and humid days (e.g. Monday and likely next Sunday) and cooler days (e.g. Friday). Most days will be mostly dry with decent sunshine, though showers and thunderstorms are likely on Tuesday, though west of Maine, the timing late in the night or early in the morning will preclude severe thunderstorms. Showers and thunderstorms are also likely next Sunday or following Monday, though with somewhat uncertain timing, with them also being possible but more scattered on Thursday night into Friday. A few days of dry weather with a gradual warmup but no extreme heat is likely through the middle of the following week.

 

Meteorological discussion: 

 

Unexpectedly cool and cloudy today, hot and humid Monday, then showers and thunderstorms Tuesday 

 

It's been unexpectedly cool and cloudy in most of the region today as low-level moisture trapped underneath an inversion has led to persistent stratocumulus clouds, though it is finally clearing from west to east. It will turn hot and humid tomorrow with weak southerly flow, with a sea breeze keeping coastal areas cooler. A disturbance will bring a round of showers and scattered thunderstorms fueled by the heat and humidity late Monday night in eastern Ontario and northwestern New York, moving east to Maine by Tuesday afternoon. Any severe thunderstorms appear to be isolated especially west of Maine, where the early morning timing, when instability is the lowest, does not favor severe thunderstorms.

 

Source: Penn State Meteorology

 

Source: TropicalTidbits

 

 

Still warm and moderately humid Tuesday and Wednesday, then notably cooler and showery late Thursday into Friday 

 

Behind the disturbance and its weak cold front, it will still be warm and very humid Tuesday and moderately humid on Wednesday, but a stronger upper-level trough will bring some scattered showers and thunderstorms late Thursday into Thursday night before ushering a stronger cool air mass straight from the north for Thursday night into Friday. This trough, possibly cutting off into a closed upper-level low, is aided by the building upper-level ridge in the western U.S. (slightly positive PNA), opposite of earlier this past week. The cold air aloft and showers will keep most areas cool on Friday, especially along and east of the Green Mountains, mostly below 75F (24C). Canadian surface high pressure will build in Friday night, leading to cool nighttime lows for the beginning of July, perhaps getting below 50F (10C) in normally cooler spots.

 

Source: TropicalTidbits

 

 

Quick warmup next weekend with showers and thunderstorms likely next Sunday 

 

The cool air mass will not last long, with the +NAO keeping everything moving quickly and not promoting cut-off lows that move slowly and persist over a region for a long time. Also, the upper-level ridge in the western U.S. will be temporarily beaten down by at least two relatively weak upper-level troughs later this week into next weekend, promoting downstream upper-level ridging in our region for at least several days. As the surface high pressure moves southeastward into the western Atlantic by Saturday, southerly to southwesterly flow on the back side of the surface high pressure will quickly warm the region up on Saturday and Sunday. However, a cold front will likely pass through next Sunday or Sunday night accompanied by showers and thunderstorms, though the timing of the cold front is a bit uncertain.

 

Source: TropicalTidbits

 

 

Period of dry weather with gradual warmup but no extreme heat likely for following week

 

While it turns cooler behind the front, the air mass does not look particularly cool, and given that it will be July, the hottest month of the year on average, these cold fronts will often not carry the kind of truly chilly air that sometimes comes in early June or the end of August, instead just lowering the humidity and nighttime temperatures substantially while it is still warm during the daytime. Also, in this case, the upper-level ridge in our region will only be partially beaten down, deflecting most of the cold air off to the north. The surface high pressure behind the cold front co-located with modest upper-level ridging still in our region could persist for several days, leading to a gradual warmup but without extreme heat and mainly dry weather through the middle of the following week, limiting any clouds and convection in our region. If the surface high pressure slips to our south, southwesterly flow would lead to hotter temperatures by the middle of the following week. The +NAO and low-pressure systems frequently passing to the north could block any real cool air masses from reaching our region, leading to generally modestly above average temperatures in our region even with the slightly positive PNA, though the models disagree substantially on how strong the PNA and western U.S. ridge signal will be. Given that we will be in the hottest time of the year, only a modest warm surge will lead to a hot and humid day. Still, the +PNA likely will prevent the strong upper-level ridging in our region needed for big heat waves like the one earlier this week.

 

Source: TropicalTidbits

 

 

Source: Climate Prediction Center