textproduct: Boston / Norton

WHAT HAS CHANGED

High Wind Warning has been converted to a Wind Advisory through predawn hours of Wednesday for the higher terrain of northern and western Massachusetts. Plus, a Winter Weather Advisory was issued at Nantucket and Martha's Vineyard is in effect Wednesday evening through late Thursday morning, for snow amounts between 2-4 inches. Elsewhere, minor snow accumulations are expected, which will lead to slick conditions New Year's Eve into New Year's Day.

KEY MESSAGES

- Strong wind gusts continue tonight with cold temperatures and isolated snow showers. Dry and chilly Wednesday.

- Period of snow New Year's Eve into New Year's Day, followed by a chilly first day of 2026.

- Temperatures remain below normal through the rest of the week and into the start of next week. - Vessel icing due to accretion of light freezing spray over the waters is possible late this week into this weekend.

DISCUSSION

KEY MESSAGE 1...Strong wind gusts continue tonight with cold temperatures and isolated snow showers. Dry and chilly Wednesday.

Strong westerly gusts 40-50 MPH continue through the first half of tonight across southern New England. Minor changes to the forecast at this time, dropped the High Wind Warning for interior sections of Massachusetts, which were replaced with a Wind Advisory. Core of the strongest wind aloft shifts away from southern New England during the overnight, easing gusts by daybreak. Overnight is still fairly cold with minimum temperatures in the teens and lower 20s, the feels like temperature lowers into the single digits and lower teens.

Given the prevailing wind direction and lake effect snow across the eastern Great Lakes, cannot rule out a few light snow showers across western Massachusetts and northern Connecticut, otherwise dry.

Dry and chilly conditions to wrap up the final day of 2025, but snow is on the horizon for the New Year's celebration, more on that in the next key message.

KEY MESSAGE 2...Period of snow New Year's Eve into New Year's Day, followed by a chilly first day of 2026.

There is growing confidence in a period of snow starting Wednesday evening and ending Thursday morning, coinciding with New Year's Eve celebrations. Please plan accordingly.

For many, this should be a minor snow event with snow amounts around one inch, but there is increasing odds for widespread totals between 2-4 inches at Nantucket, Martha's Vineyard, Cape Cod, and southeast Massachusetts. The synoptic features include; potent 500mb shortwave and developing surface low-pressure system. There is not a ton of moisture to be had, interior locations near 0.25" and 0.40" at the coast. Reasoning for higher totals across the areas mentioned above is due to ocean enhancement. Southwest flow over relatively warmer ocean waters adds a level of instability and with assistance of sea air, salt nucleation tends to shift the snow growth lower than what we'd see over land, closer to -10C. A BUFKIT forecast sounding indicates saturation between -8C and -12C and within the layer there is strong lift/OMEGA, thus an effective snow producer. Adding to our confidence, HREF probs for snowfall rates 1+ inch/hr are 60-80% for the Cape and Islands, with a 30% probability of rates 2+ inch/hr at Nantucket. Now, cannot take this verbatim, but shows the potential for heavy snowfall between midnight and 6am.

Opt'd to issue a Winter Weather Advisory due to these conditions for Nantucket and Martha's Vineyard, 7pm Wednesday to 1pm Thursday, with the steadiest snow between midnight and 6am. Here snowfall amounts are forecast 2-4". It's possible the advisory expands into Cape Cod and southern Plymouth and Bristol Counties, but at this time, have low confidence in totals exceeding 3".

Snow ends mid to late morning on New Years Day, followed by dry and cold temperatures in the 20s. Breezy northwest winds with gusts 15 to 25 MPH lead to feels like temperatures in the single digits and teens.

KEY MESSAGE 3...Temperatures remain below normal through the rest of the week and into the start of next week.

A mid level trough will continue to sit over Quebec and the northeastern US through the weekend. Guidance remains in consensus with this overall pattern. As a result, this stretch of below normal temperatures will only continue. 925 mb temperatures will remain between -15C and -10C through the weekend and into the start of next week. Surface high pressure will start to creep in from the southwest, but a weak low from Ontario may also pass through northern New England sometime this weekend. Only a few members of the guidance highlight that brief disturbance, though, and confidence in possible impacts to southern New England is low at this time. The main thing, though, will be high pressure moving in to keep the region dry and cold through Monday morning. Highs remain relatively unchanged from tomorrow through the weekend, generally staying in the 20s and low 30s. Lows continue to fall into the teens and single digits. There may be a slight improvement for Monday as the trough starts to shift off to the east and slightly warmer air gets a chance to move in from the south, but a significant warm-up is not expected. NAEFS guidance has temperatures around 2 standard deviations below average through the weekend, improving to around 1 standard deviation below normal for the start of next week. So, any improvement would be quite modest.

With continued high pressure, the region should remain mostly dry from Friday onward. Snow showers should move out of the region heading into Friday morning. Confidence decreases in chances for additional precipitation for the start of next week as guidance varies significantly past Monday morning.

KEY MESSAGE 4...Vessel icing due to accretion of light freezing spray over the waters is possible late this week into this weekend.

Mostly for marine interests, but with a prolonged period of cold air over the relatively milder ocean waters, periods of freezing spray could accrete on vessels through the first week of January. It doesn't look like anticipated freezing spray on any particular day would reach the moderate to heavy icing rates, which would necessitate freezing spray headlines for the waters. Days which have lower significant wave heights would have a lesser risk. However, we did want to give it at least a mention, since the risk for light vessel icing due to freezing spray could exist for a prolonged period given the spell of colder temperatures upcoming.

AVIATION /06Z WEDNESDAY THROUGH SUNDAY/

Forecaster Confidence Levels...

Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent.

Wednesday: High confidence.

VFR through the day. Westerly wind gusts 20-25 kts near the eastern coast gradually diminishing through the morning.

Wednesday night: Moderate confidence.

MVFR conditions, with pockets of IFR, under -SN spread from west to east 03-06z Thursday. Minor accumulations likely, especially across SE MA and Cape/Islands. Southwesterly winds 5-10 kts.

Thursday: High confidence.

MVFR improves to VFR gradually throughout Thursday once the snow moves out 12-15z.

KBOS Terminal...High confidence in trends. Moderate confidence in arrival time of snow.

KBDL Terminal...High confidence in trends. Moderate confidence in arrival time of snow.

Outlook /Thursday through Sunday/...

New Years Day: VFR. Windy with local gusts up to 30 kt. Slight chance SHSN.

Thursday Night: VFR. Windy with local gusts up to 30 kt.

Friday through Saturday Night: VFR. Breezy.

Sunday: VFR.

MARINE

Forecaster Confidence Levels...

Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent.

Tonight through Wednesday...High confidence.

Gale-force westerly wind gusts up to 40 kt are expected into tonight as strong cold air advection pushes through. Winds and seas begin to diminish late tonight into Wednesday morning.

The risk for light freezing spray across the coastal waters, mainly the nearshore waters into Wednesday.

Outlook /Thursday through Sunday/...

New Years Day: Strong winds with gusts up to 30 kt. Areas of rough seas. Chance of snow showers, freezing spray.

Thursday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Seas up to 5 ft. Chance of freezing spray.

Friday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Chance of freezing spray, slight chance of snow.

Friday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of seas approaching 5 ft.

Saturday: Winds less than 25 kt. Seas locally approaching 5 ft.

Saturday Night through Sunday: Winds less than 25 kt.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...Winter Weather Advisory from 7 PM this evening to 1 PM EST Thursday for MAZ023-024. RI...None. MARINE...Gale Warning until 1 AM EST early this morning for ANZ230-236. Gale Warning until 7 AM EST this morning for ANZ231>235-237- 250-251-254>256.