Another Saturday, Another System for New England

A weak shortwave trough will slide into central New England today, providing just enough forcing for a few showers this afternoon and evening. Mid-layer ridging will prevent widespread precipitation, but a few areas will likely see some activity. The greatest chance of seeing some activity will be across southern New Hampshire, central Massachusetts and northern Connecticut. Guidance has continued to be consistent showing a line of scattered showers developing along a weak frontal boundary in this area.

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

Heading into tonight and Saturday, a cutoff low area of low pressure meandering to New England's north will help produce the next round of rain. A more moisture-rich southern stream system will likely emerge off the east coast and move through the region as another nor'easter. The system looks to move straight through New England, which will lead to the heaviest rainfall amounts across western and northern New England.

One large difference between this storm and last week's storm is that this one appears to be much more progressive. The storm looks to enter New England Friday night and exit Saturday evening. Rain will likely break out across Connecticut in the pre-dawn hours and quickly spread northeast through the morning. By the afternoon, the heaviest and most widespread rain will have likely pushed into northern New England. Showers will likely be isolated in southern New England with much of the afternoon ending up dry.

Below: HRRR showing potential weather around sunrise Saturday (1st image) and mid-afternoon Saturday (2nd image):

The exact track of the secondary low will heavily influence rainfall totals and where the highest amounts end up in the region. A track straight through New England would produce the most amount of rain over western and interior New England with areas closer to the coast getting into a dry slot with rain transitioning to scattered showers by the afternoon. This continues to be the favored outcome. As of now, the center of the storm looks to track along, or very close to, the Connecticut River.

The highest rain totals will likely be just to the west of the storm track. Areas to the east east will likely get into the aforementioned dry slot while areas well north and west of the track won't see as great of forcing for heavier bouts of rain. The storm will likely drop a good 1-2 inches across a wide band in interior New England. A half inch to inch will be possible outside of these areas. Should the storm trend a bit farther east, the higher totals would get pulled farther east as well.

These setups tend to produce their heaviest and most widespread rainfall on their north and west sides. Areas east and south of the track could see a dry slot develop, which is favored for Saturday afternoon. On the west side of the system, cooler conditions will prevail, which will favor a longer period of steady rainfall. Areas on the east side look to get within the system's warm sector, which would result in rain becoming more scattered in nature after a round of widespread, steady rain in the morning.

Areas on the west side tend to see more stratiform rain (which is rain that's generally continuous and uniform) while the east side will tend to see more convective rain (which results in brief scattered downpours between longer dry periods, caused by warm air rising along a warm front). Within the warm sector, breaks of sun will even be possible in the afternoon between pop-up showers.

This storm is quite strong given the time of year. Guidance continues to show the system with a central pressure over New England dropping to around the 985 millibar range. Despite the seemingly strong system, this will remain a low-impact event. The progressive nature of the system and the system's overall track straight through New England will keep rainfall amounts manageable with a low flooding threat. Some minor and localized poor drainage flooding is possible, but more impactful, widespread flooding is not expected. No river flooding is expected, either. An interior track will also keep wind in check as well.

While the nor'easter will lift north and east by Saturday night, the upper-level, cutoff low will linger just to the north through Sunday, resulting in continued cool conditions with plenty of clouds and some showers. With the low to the north, the best chance for some lingering showers on Sunday will be across the northern tier of New England. After this system passes, a gradual warm-up to early summer-like temperatures continues to look likely through next week. This warmth is apt to fall apart depending on if another closed low develops over the east, however.