Unusual-tracked summer Nor’easter to bring cool and rainy weather mid-week especially in drought-stricken eastern New England; hotter and drier this weekend with continued warmth but better chance of thunderstorms next week

Plain-language summary:

A summer Nor'easter taking an unusual track will bring cool and rainy weather mid-week, especially in drought-stricken eastern New England. The storm will weaken and move out by Friday, leaving a hotter and sunnier but not humid weekend. Humidity, showers, and clouds increase next week, with warmth but not extreme heat continuing.

Meteorological discussion:  

The weather pattern changed substantially last week, with the strong north-to-south temperature gradient characteristic of most of this summer having suddenly vanished or even reversed. It’s actually cooler in the mid-Atlantic U.S. than over central Quebec over the past couple of days. This is due to a ridge building in eastern Canada (with warm air aloft and plenty of sunshine) overtop a slow-moving upper-level low in the eastern U.S. (with cooler air aloft along with clouds and showers). This ridge over top of a closed upper-level low pattern is usually a slowly-moving pattern, with weird things happening, including this time

Source: TropicalTidbits

An initially weak system will get going off the U.S. East Coast but then strengthen over the Gulf Stream Tuesday night and then move straight north or even northwestward into Maine by Thursday morning, like a Nor’easter with the ridge to the north blocking the usually quick path out to sea. The models have been in an amazing amount of disagreement for being so close to the event but Nor’easters are usually tricky to forecast. GFS had shown a big storm a few days ago, then nothing, only to show something in between now. 

Source: TropicalTidbits

 

My guess is that the storm will bring rain, heavy at times, from eastern Vermont to Maine first Wednesday night, with lighter showers spreading northwestward into northern New York and southern Quebec on Thursday as the storm occludes and stops strengthening by then. Eastern New England, which will receive the heaviest rain, is in a severe to extreme drought and could use the rain the most. It will also be on the northwest or cool side of the storm, with a steady, light to moderate rain that will easily soak into the dry ground, instead of flash-flooding causing torrential downpours.

 

Source: U.S. Drought Monitor

Source: TropicalTidbits

After that, ridging returns to eastern Canada, bringing moderately hot weather returns for this weekend but not too extreme (daytime highs up to 32C in lower elevations) with relatively low humidity. With the low humidity and mostly clear skies, nighttime lows will still be comparatively cool. 

Source: TropicalTidbits and PivotalWeather

Warm to hot weather looks to continue next week as well, though perhaps with more clouds, showers, and humidity as another slow-moving upper-level low approaches from the west. With this scenario, daytime highs would be cooler but nighttime lows would be warmer, with no real cool air masses likely coming from the north. This should push August to be at least slightly warmer than average in the region, and therefore make the whole summer (June to August) a tad above average, but much less so than in most of the U.S.

Source: TropicalTidbits