Breaking down New England's thunderstorm chances through the weekend

The overall setup will favor unsettled weather continuing through the weekend, but all-day washout potential is low and there will be plenty of dry times between scattered storms.

FRIDAY

Today starts off with ridging in place, bringing plenty of sun with efficient warming through the day. It'll be another hot, humid day with mid 80s to mid 90s likely across New England. Dew points in the upper 60s to low 70s will bring feels-like temperatures into the upper 90s for a good portion of southern and central New England.

In the afternoon and evening, a weakening system will push into New England, bringing scattered thunderstorms. These scattered storms will arrive in Connecticut and western Massachusetts by late afternoon and push northeast through the evening. The storms will weaken as they push north and east, eventually fizzling into some scattered light showers for the overnight hours.

HRRR showing potential weather this evening:

Photo byHRRR/Tropical Tidbits

The severe storm threat is very low for New England. This moist atmosphere, along with weak shear and modest instability, is more favored for potentially heavy rainfall rates rather than damaging winds and large hail. The bulk of the severe activity is expected to remain just to New England's south and west. With that said, a rogue severe storm in Connecticut or western Massachusetts can't be completely ruled out.

SATURDAY

Saturday will be a generally unsettled day, but nowhere near an all-day washout. The timing on storms through the day is at a lower confidence than it should be at this short-range point in the forecast. It looks like there will generally be scattered storms and showers across Vermont, interior New Hampshire and much of Maine through the morning with more isolated activity in southern New England. This will come as Friday night's disturbance departs.

HRRR showing potential weather around mid-morning Saturday:

Photo byHRRR/Tropical Tidbits

Heading later into the afternoon, another trough of low pressure will approach New England, renewing scattered storm chances for the afternoon and evening hours. Ridging between the departing and incoming disturbances may bring a largely dry spell in the middle of the day. The general idea is that there will be scattered storms around throughout the day, but most areas will see many more dry hours than wet hours.

GFS showing potential weather heading into the evening:

Photo byGFS/Tropical Tidbits

Like Friday, the severe threat will remain low with much of the severe activity staying to the south and west of New England, where better dynamics will be set up. With high humidity sticking around, continued heavy downpours will be the main issue. The day will be warm, but not as hot as Thursday and Friday thanks to increased cloud cover and occasional storms.

SUNDAY

Sunday could end up pretty similar to Saturday. On Sunday, an upper trough will swing through New England. A frontal boundary will likely move into New England and slow down or stall over New England for the day. Another boundary will likely set up to the north of New England. All of this should lead to another day of scattered storms, but not an all-day washout with dry hours between storms.

Photo byNew England Storm Center

As for timing of the storms, they will likely favor the afternoon and evening, but the exact timing remains subject to flexing. The severe threat looks to remain low at this time, but dynamics may be a bit better, mainly in regards to stronger shear, so this threat could trend upward. Still, instability favors limited severe potential at this point. The biggest threat will continue to be torrential downpours within the storms.

These thunderstorm threats currently include Friday through Sunday, though Sunday is still subject to change:

Photo byNew England Storm Center

These repeated rounds of showers and thunderstorms may lead to localized flooding issues. Any storm from now through Sunday will be able to produce heavy rainfall rates with the moisture-rich nature of the atmosphere. Precipitable water values (PWAT; which is a measure of the moisture in the atmosphere) will approach 2 inches. This indicates a highly moisture-rich atmosphere. The PWAT value does not correspond to how much rain is expected, so a PWAT of 2 inches does not automatically mean 2 inches of rain is expected.

Potential PWAT values Sunday afternoon, showing a highly moist air mass up the east coast:

Photo byGFS/Pivotal Weather

The question will become how much storms are able to take advantage of all this moisture. On Sunday, the greatest chance for this to happen will be near where the frontal boundary sets up.

The overall threat for isolated issues will be determined by what exactly occurs through the weekend. If the same areas see heavy thunderstorms multiple times through Sunday, it may lead to heightened issues for the area. This is especially true for areas that have seen heavy rain recently (Northeast Kingdom & White Mountains namely).

LOOKING AHEAD

Monday is looking generally drier as the trough over New England weakens. It's also looking to be another pretty steamy day with hot, humid weather persisting. Monday may be hotter than the weekend if more sun is able to break through. Despite the drier weather, scattered afternoon storms can't be ruled out, but the coverage will likely be lower than over the weekend.

A cold front looks to sweep through New England by Tuesday. This front looks to lower both the heat and humidity out of the region for the rest of the week. The front may stall just to the south of New England, keeping rather cloudy and unsettled weather around, but time will tell how this ends up playing out. As we mentioned in our monthly outlook yesterday, a cool-down looks to be in store for next week, and may have some staying power.

Photo byClimate Prediction Center

One other item to watch for next week would be the potential interaction between this stalled front with a developing tropical cyclone. A tropical storm will likely form and move near Florida this weekend. This system may move up the east coast thereafter. There's plenty of possibilities, so it's something to keep an eye on for now. Naturally, there are significant differences on where exactly the system will go at this point.

Photo byNational Hurricane Center