AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 307 PM EST Mon Dec 22 2025 .WHAT HAS CHANGED... No significant changes. Minor snow accumulations still expected Tuesday generally on the order of 1 to 3 inches. Potential for accumulating snow for Friday into part of Saturday but still a low-confidence forecast. && .KEY MESSAGES... - Minor snow accumulations of 1-3" likely Tue into Tue night. - Intervals of snow/rain showers thru afternoon of Christmas Eve for eastern MA coast; otherwise dry and seasonable through Christmas Day. - Lower-confidence forecast for the post-Christmas weekend, with potential for snow/ice/rain mix Fri into Sat. && .DISCUSSION... Key Message 1...Minor snow accumulations of 1-3" likely Tue into Tue night. Our next bout of unsettled weather arrives on Tuesday, a clipper system that exits east into the Atlantic for the most part by early on Wednesday. We have high confidence that this will be a low end event, with minimal impacts, but the one wrinkle is that Tuesday is such a big travel day ahead of Christmas. The surface low moves into NY state early Tuesday with an isentropically forced shield of snow overspreading SNE during the early morning (west) to mid/late morning (east). Temperature profiles are subfreezing to start, with warmer low level air infiltrating from the south so areas generally south and east of the I-95 corridor will switch over to a mix and rain. Given marginal temperatures, locations that do see accumulation will see better accum on grassy surfaces than on the roads. Snowfall rates also will be on the low end with poor omega in the DGZ for most of the event. Given QPF values on the low end (0.15 to 0.30") and marginal temp profiles the most likely outcome is a general 1-3" of snow north and west of the I-95 corridor with an inch or less along/just south; again, accumulation likely also struggles more on pavement. The low moves over the Atlantic overnight taking the bulk of the moisture with it (i.e. snow/rain comes to an end). PWATs drop below 0.25" except along the immediate east coast where a few lingering snow/rain showers are expected to linger. Temperatures hover near or above freezing overnight except for the high elevations; this is where lingering moisture could cause some slick roads. Key Message 2...Intervals of snow/rain showers thru afternoon of Christmas Eve for eastern MA coast; otherwise dry and seasonable through Christmas Day. As low pressure from Tuesday pulls away from the eastern coast, residual/leftover ocean-enhanced bands of precip still seem possible for the eastern coast of MA, Cape Cod/Islands into Wednesday afternoon. Minor accums are possible but adverse travel impact isn`t likely. High pressure then builds in from interior Southern New England, offering dry weather with seasonable temps through Christmas Eve night into Christmas Day (mid 30s/low 40s highs, lows in the upper teens to mid 20s). Key Message 3...Lower-confidence forecast for the post- Christmas weekend, with potential for snow/ice/rain mix Fri into Sat. Models have picked up on a shallow cold air mass filtering southward from Canada/northern New England Friday allowing for widespread sub- freezing highs. More uncertainty in the details exists regarding a wave of low pressure which treks ESE from the Gt Lakes region Fri night into part of Sat. Models vary on the exact track of this wave, ranging from the mid-Atlantic states to as far north as interior SNE. Besides track differences, as well as unknown sub-synoptic- scale details involving potential for possible bands in warm advection pattern, some model forecast soundings suggest loss of saturation in snow-growth-region at some point either late Fri night or Sat, which could cut into any accums but instead force possible freezing drizzle into the mix. Still a large amt of uncertainty given the above for specifics on accumulations/possible impacts if any; but based on ensemble 24-hr snow probs, moderate (25-50%) probs for accumulating snows at plowable (2-4") levels mainly for CT Valley, western MA/CT and into parts of RI, with low (nil to 20%) probs of 6" or more. && .AVIATION /19Z MONDAY THROUGH SATURDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 18Z TAF update...No changes. This afternoon through Tuesday night...High Confidence. VFR through tonight. Cigs and vsbys lowering to MVFR-IFR during Tue as snow overspreads the region from W to E. Snow may mix with rain along and south of PVD-TAN-PYM. NW and gusty winds this morning then gradually diminishing throughout the rest of the day. Light winds tonight becoming SE-SW Tue. KBOS Terminal...High confidence in TAF. Moderate confidence in start time of -SN. KBDL Terminal...High confidence in TAF. Moderate confidence in start time of -SN. Outlook /Wednesday through Saturday/... Wednesday: VFR. Windy with local gusts up to 30 kt. Chance FZRA, slight chance SN. Wednesday Night: VFR. Christmas Day through Thursday Night: VFR. Breezy. Friday: VFR. Chance SN. Friday Night: Mainly VFR, with areas IFR possible. Breezy. SN likely. Saturday: Mainly VFR, with local MVFR possible. Breezy. Chance SN. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. W winds 10-20 kt tonight becoming S-SW Tue. Rough seas will begin to subside below 5 ft over outer waters tonight. Rain or mixed rain/snow develops Tue with lowering vsbys, exiting overnight into Wednesday. Outlook /Wednesday through Saturday/... Wednesday: Strong winds with gusts up to 35 kt. Areas of rough seas. Chance of rain, chance of snow. Wednesday Night: Winds less than 25 kt. Areas of rough seas. Christmas Day: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Local rough seas. Slight chance of rain. Thursday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Friday: Winds less than 25 kt. Seas up to 5 ft. Chance of snow. Friday Night: Winds less than 25 kt. Rough seas up to 11 ft. Snow likely. Areas of visibility 1 nm or less. Saturday: Winds less than 25 kt. Rough seas up to 11 ft. Chance of snow, slight chance of rain. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 7 PM EST this evening for ANZ250- 256. Small Craft Advisory until 1 AM EST Tuesday for ANZ254-255. && $$