Oppressive Heat Briefly Returns Before a Cold Front Brings Storms to New England

As we head into the late week, a heat dome will continue to build across the south and midwest, with heat and humidity continuing to rise across New England as the ridge axis builds into the northeast. Today, temperatures will be well into the 80s to low 90s for most of New England. New England will be more on the edge of the high heat, so the northern tier (with the exception of the Champlain Valley) won't get as hot.

Below: Geopotential heights on Thursday, showing the ridge axis building into New England:

Humidity will also begin to build as flow at the surface strengthens from the south, however, there are limiting factors that will likely prevent dew points from reaching their full potential today. The main factor is the potential of efficient mixing. This would help bring down slightly drier air to the surface from aloft. This will help keep feels-like temperatures pretty close to air temperatures today.

The heat will likely peak for much of New England on Friday as temperatures aloft reach their climax and southerly flow continues to strengthen. Temperatures at the 925mb level (about 2,500 feet above sea level) will peak in the 75-82° range, which will support surface temperatures well into the 80s to mid 90s. The northern tier will be kept cooler due to the earlier arrival of a cold front and more clouds.

Below: HRRR showing potential temperatures Friday afternoon

For southern and central areas, the cold front, and clouds associated with it, are unlikely to arrive before temperatures are able to soar. Some areas could see highs into the upper 90s across southern New England. With deeper moisture and more favorable conditions for higher humidity than Thursday, feels-like temperatures will soar into the low 100s for much of southern New England on Friday.

That cold front mentioned earlier will continue to drop southward through the afternoon and evening Friday. It will likely enter into northern New England earlier in the day Friday and slow down as it moves southward. The front likely won't clear the south coast until overnight Friday. This front will bring lowering temperatures and humidity along with scattered thunderstorms as it crosses through the day.

Storms will likely be most numerous where the front crosses in the afternoon and evening. This would also be where storms should be most likely to become strong to severe. With that said, overall storm coverage appears to be more scattered rather than widespread with plenty of areas potentially missing out on a storm. Spread in exact timing remains (as expected), but it looks like the best chance for storms will be 12pm-5pm for northern New England and 2pm-7pm for southern New England. Storms should weaken rapidly after sunset.

Below: HRRR showing potential weather around mid-afternoon Friday:

The overall potential for strong to severe storms currently looks to be on the lower end of the spectrum. Looking at the ingredients for severe weather, plenty of moisture will be in place, along with lift from the cold front. The atmosphere will likely only be marginally unstable and shear will be on the weaker side. This will make organized severe activity unlikely, but these ingredients may support a few storms strengthening here and there.

The front will likely have cleared New England by the weekend, but its slow progress southward will cause it to stall near New England’s south coast as it weakens and eventually washes out. This means temperatures and humidity won't drop a great deal, but it will certainly be noticeably cooler and less humid behind the front. Saturday will see drier air work in behind the front, leading to a superb day. Energy will ride along the stalled front Sunday, bringing unsettled weather back into the picture with showers and a couple thunderstorms.