Cold Front to Bring Scattered Storms Today as Oppressive Heat Peaks for Many

This heat will peak for much of New England today as temperatures aloft reach their climax and southerly flow continues to strengthen, 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. For southern and central New England, the cold front won't arrive before temperatures are able to soar, which will happen quickly through the early afternoon.

Below: HRRR showing temperatures early this afternoon:

A cold front will be dropping southward through the day, igniting scattered thunderstorms across the region this afternoon and evening. It will likely enter into northern New England earlier in the day and slow down as it moves southward. With that said, the overall timing of the front has trended faster, likely arriving to the northern Massachusetts border by early afternoon.

Storms will likely be most numerous where the front crosses in the afternoon and evening, which is likely for the southern half of New England. 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. It looks like the best chance for storms will be 11am-4pm for northern New England and 2pm-7pm for southern New England. Storms should weaken rapidly after sunset.

Below: HRRR showing potential weather around the middle of the afternoon:

The overall potential for strong to severe storms currently looks to be on the lower end of the spectrum all things considered. Storms will be scattered in nature rather than widespread. As mentioned before, plenty of areas may miss a storm entirely. With the trends toward a faster arrival of the frontal passage, the severe threat will be highest across southern New England with the threat gradually decreasing moving north.

Areas that do see a strong to severe thunderstorm (and there will likely be a few), will see strong to damaging winds. Any storm today (severe or not) will have the chance to create torrential downpours and localized flash flooding. The large hail threat will be rather low given poor lapse rates (the rate of cooling with altitude). The threat for spin-up tornadoes will also be very low to none.

Looking at the main ingredients for severe weather, plenty of moisture will be in place, along with lift from the cold front. Shear values will be on the lower end, especially for northern New England, but they should be sufficient to allow for some organization and strengthening within storms.

Instability will be marginal, but sufficient for the southern half of New England with CAPE values climbing into the 1,000-1,500 range. As stated above, lapse rates will be generally poor for severe weather, but the other sufficient ingredients should make up for this. All of this will make widespread, organized severe activity unlikely, but these ingredients may support a few storms strengthening.

Below: WRF-ARW showing potential surface-based CAPE values this afternoon, with instability increasing as you make your way south in the region:

The other area to watch out for will be for the potential of torrential rainfall and flash flooding. This threat will remain localized and isolated given the scattered nature of the storms today, but areas that do see a storm will have the chance to see rainfall rates of 1-2 inches an hour for a time. The good news is that winds aloft should keep storms moving along at a nice pace, so a storm shouldn't sit over one area for an extended period of time.

The front will continue to slide southward on Saturday. While it will slow down, it looks to push far enough south on Saturday to allow for a very nice mid-summer day. High pressure will build in, bringing a drier air mass with seasonable temperatures and lower humidity. A system will ride the front and begin to pull it back north on Sunday, bringing unsettled weather back into the picture with showers and a couple thunderstorms, mainly in the afternoon. While there's still a spread on where the most numerous showers will set up, it appears to be focusing on the southern half of New England.