Metro Boston, North Shore and Metro West: The showers of yesterday afternoon and last evening have been pushed offshore as a cold front slid through here overnight. This has allowed for periods of sunshine early this morning. The front will stall across extreme southern New England today remaining in place through the weekend. Meanwhile, low pressure emerges out of the Tennessee Valley through today and is expected to be positioned in the Chesapeake Bay area by Sunday morning. From there the system moves very slowly across the open waters south of New England and should be centered just south of Nantucket Island by Monday morning.
The combination of the stalled front and low pressure means a mostly wet weekend, especially from later this afternoon through Sunday night. There may be a period during Sunday afternoon where the heavier rain shuts down for awhile with lighter showers and drizzle persisting through the afternoon. Upwards of two inches of rain, locally higher amounts, are likely through Sunday night. As a result of the heavy rainfall that is expected along with snow melt through the far interior, there is concern for minor river and stream flooding along with poor drainage and urban flooding. The National Weather Service has issued a Flood Watch for portions of the interior. In our forecast area that includes Middlesex and western Essex Counties. The watch remains in effect into Monday morning for this long duration rain event. It is not out of he question that some areas exceed three inches of rain into Monday.
Coastal flooding is also a concern, although at this time it appears any flooding will be minor. The astronomical high tides are running on the high side and with a constant northeast fetch coming off the Atlantic over the next two days we do run the risk for some coastal flooding and beach erosion. Locally, areas from Cape Ann northward to Salisbury Beach are most likely to be impacted through multiple high tide cycles into Monday. This includes Plum Island which is always a concern with nor’easters.
Temperatures will cool down beginning tonight with a cold rainy and raw day expected Sunday. As the low slowly pulls away later Sunday night and Monday it will draw cooler air down on its backside and it is possible that the rain changes to a wintry mix across the interior Monday before winding down through the day. Precipitation on Monday should be more of a showery nature, whether it be rain or snow.
The low will finally push far enough eastward into the Atlantic by Tuesday to allow for some clearing and drying Tuesday and Wednesday.
Three Day Outlook:
Saturday: Bright skies early will give way to cloudy skies by afternoon with rain likely late in the day. Mild, high temperatures in the low to mid 50s, cooling down mid to late afternoon. Light winds becoming northeast less than 10 mph.
Saturday night: Rain, with pockets of heavy rain possible at times. Areas of fog developing. Cooler, lows in the upper 30s to 40 degrees. Northeast winds 8 to 18 mph.
Sunday: Rain likely, possibly tapering to showers and drizzle in the afternoon. Areas of fog. Breezy and chilly. Near steady temperatures in the low 40s, around 45 in Boston. Northeast winds 10 to 20 mph with higher gusts possible.
Sunday night: More rain is likely, chilly, raw and breezy. Lows in the 30s. Winds turn north and become gusty up to 25 to 30 mph.
Monday and Monday night: Rain tapering to afternoon showers, possibly ending with a mix of snow across the far interior. Remaining mostly cloudy overnight with a spot rain and or snow shower possible. Cold and breezy. Highs in the upper 30s to low 40s. Lows in the mid 30s.