New Cutoff Low to Bring New England a Soaking Rain Friday

The cutoff low and stalled frontal boundary from earlier this week has finally cleared out of the region. This will allow for a much nicer day (for the most part) today. With that said, we're still in a blocking pattern and a new slow-moving frontal boundary will enter the picture today. Another cutoff low will slide up the east coast along this boundary, bringing more rain and cool temperatures.

This new cold front has entered New England this morning. The front will stall right across New England once again. Areas north and west of the front will see continued cooler weather today while areas south and east of it will see another milder day compared to earlier this week. A few pop-up showers will continue to be possible along the front this afternoon, but much of the day will be dry with at least partial sunshine.

Below: CMC showing temperature departure from average this afternoon:

Starting this evening, waves of low pressure will ride along the stalled front, allowing for more widespread shower activity to develop. With moisture increasing once again, a quick quarter to half inch of rain will be possible for areas that get under a downpour this evening. These scattered evening downpours will be most likely across interior central and southern New England.

Below: HRRR showing potential weather this evening:

The main wave of low pressure along this front will move up the east coast and will very slowly cross over southern New England through the rest of this week. This will bring a widespread soaking rain to New England from southwest to northeast Friday into Saturday morning. Torrential downpours embedded within the steady rain will be possible from Friday afternoon through Saturday morning.

Showers will be ongoing for most of Friday for interior New England. It will likely take some time for more widespread activity to push eastward toward the coastal plain. For eastern areas, widespread rain currently looks to hold off until later in the day Friday. Much of Maine may end up mostly dry through the afternoon.

Below: FV3 showing potential weather Friday mid-morning (1st image) and Friday mid-afternoon (2nd image):

For many, the peak of the rain and the greatest potential for downpours will come more toward Friday evening. The rain will continue to steadily push northeastward Friday night into Saturday morning. The area of low pressure will be slow to cross southern New England, so showers will be slow to break down Saturday. Wrap-around showers will continue to be possible through at least the first half of Saturday for many. A general drying trend from west to east is likely for the second half of Saturday.

Below: FV3 showing potential weather Saturday morning (1st image) and RGEM showing potential weather Saturday afternoon (2nd image):

This low pressure system will be one to slowly meander its way eastward as it will be sitting between two ridges of high pressure. A deep southerly flow will allow for increased moisture to stream into New England ahead of the system. This deep moisture will be acted upon by a strengthening surface low pressure system, allowing for steady to at times heavy rainfall. A widespread 1-3 inches of rain is likely across much of New England by Saturday evening.

The bull's eye for up to three inches of rain continues to look like it will be focused over the Berkshires, southern Green Mountains and into the Litchfield Hills. This will come as a modest easterly low-level jet will allow for upslope enhancement in these areas, basically allowing for more frequent heavier downpours. This area will also likely see the effects from frontogenesis (the strengthening of a frontal boundary). Outside of these areas, rainfall likely won't last as long, leading to generally lower amounts (but still a good soaking).

The flood threat remains on the lower end for most with this system. The threshold for flash flooding to occur is currently 1-1.5 inches of rain in an hour or 1.5-2.5 inches of rain in three hours. Rainfall rates within the downpours could reach up to 0.25 to 0.5 inches an hour. Downpours will also likely remain progressive, meaning they aren't likely to sit over one area for a prolonged period of time. This keeps the chance for flash flooding on the lower end. The Weather Prediction Center has much of New England in the "marginal" category (level 1 of 4) for excessive rainfall.

The main flooding threat from this system will come from the potential for minor river flooding. Several rivers are currently expected to reach action stage as grounds remain saturated and rivers and streams are running high from earlier this week. Minor flood stage is forecast for the Connecticut River. A flood watch is in effect for southern Vermont, western Massachusetts and northern Connecticut. Flood watches could be expanded to account for the potential of minor river flooding elsewhere.

All of this still looks to move out in time for Mother's Day. Starting next week, a pattern shift will occur that places New England under ridging rather than the constant troughing over the past week and a half. This will likely lead to a gradual warming trend with temperatures returning to the 70s and 80s by early next week.